1. Compare and contrast endocrine vs endocrine glands. Use examples.

Exocrine glands-

• Secrete their products into DUCTS that carry the secretions into the body cavities, into the lumen of an organ, or to the outer surface of the body

• NONE ARE HORMONES

• Examples include-

  • Sudoriferous (sweat) glands

  • Sebaceous (oil) glands

  • Mucous glands

  • Digestive glands

Endocrine glands-

• Secrete their HORMONES directly into the INTERSTITIAL FLUID that surrounds them

• From the interstitial fluid, hormones diffuse into the bloodstream through blood CAPILLARIES and are carried to TARGET CELLS *receptor specific throughout the body

• Examples include-

  • Pituitary gland

  • Thyroid gland/parathyroid gland

  • Adrenal gland

  • Pineal gland

• Hormone-secreting cells can be found in the hypothalamus, thymus, skin, pancreas, gonads, stomach, liver, heart…

1. Discuss hormone function and activity.

Receptors *protein receptors are hormone-specific receptors like enzymes

• Continually being synthesized and broken down

• Maybe down-regulated in the presence of high concentrations of hormone→# of target cell receptors to decrease **up-regulated is the opposite process

Types of hormones

• Circulating hormones- carried through the bloodstream to act on DISTANT target cells (through interstitial fluid+bloodstream)

• Local hormones- act LOCALLY on neighboring cells or on the same cell that secreted them WITHOUT entering the bloodstream (just interstitial fluid)

  • Paracrine (neighboring cell) /autocrine (same cell)

• Lipid soluble hormones- *diffuses easily through the lipid bilayer

  • Bind to receptors WITHIN nucleus or mitochondria of target cells

  • In CAPILLARIES, the hormone is carried through the blood with a TRANSPORT PROTEIN (moves not very easily in the blood)

  • Transport protein then releases the hormone into the interstitium

• Water soluble hormones

  • Bind to receptors on the EXTERIOR surface of a target cell

  • Move through the blood quickly WITHOUT transporting proteins (easily)

1. Outline and discuss the mechanisms of hormone action.

How/why it responds to hormones-

• Hormones concentration in the blood itself

• The number of hormone receptors on a target cell

• Influences from other hormones

• Synergistic effect→ ex: estrogen and prolactin work together to achieve the same goal

• Antagonistic effect→ ex: insulin and glucagon work opposite of one another

Hormone secretion is regulated by-

• Signals from the nervous system

• Chemical changes in blood

• Other hormones

1. Discuss negative and positive feedback for the control of hormone secretions. Use an example.

Negative feedback- responding to a disruption/stimulus (example)

• Stimulus: disruption in homeostasis by decreasing…

• Controlled condition: decreasing glucocorticoid levels in the blood

• Receptors: neurosecretory cells in the hypothalamus provide input

• Input: increased corticotropin-releasing hormones (CRH) and decreased cortisol to the …

• Control center: corticotrophs in the anterior pituitary provide output

• Output: increased adrenocorticotropic hormone (ACTC) to

• Effectors: cells of zona fasciculata in the adrenal cortex which secrete glucocorticoids

• Response: increased glucocorticoid levels in the blood

• Return to homeostasis: when the response brings glucocorticoid level in the blood back to normal the “loop” turns off

Positive feedback- disrupting homeostasis

• Ex: childbirth: hormone oxytocin stimulates contraction of the uterus to in turn stimulate more oxytocin release

1. Make a flow chart for all classes of hormones.

2. Discuss the function of the hypothalamus. Outline and discuss all regulatory hormones.

• Hypothalamus: secretes releasing and inhibiting hormones that control the release of hormones by the pituitary gland

  • Hormones reach the pituitary gland via the hypophyseal portal system (blood vessels that connect the hypothalamus and anterior pituitary gland)

  • Anterior pituitary hormones- 7 regulatory hormones of the hypothalamus

  • Posterior pituitary hormones- 2 hormones of the hypothalamus

• Hypophyseal portal system

  • *anterior pituitary Superior hypophyseal artery picks up hormones in the hypothalamus through capillary beds through capillary plexus and takes hormones in the blood through the body *hypophyseal portal vein

  • *posterior pituitary inferior hypophyseal artery into the capillary plexus of infundibular processes and picks up all hormones being stored in neurohypophysis and carries them throughout the body (in the blood)

1. Outline and discuss the hormones of the pituitary. (details here)

Hormones (anterior pituitary) make and secretes + glandular *adenohypophysis

• Growth hormone (GH) is secreted by somatotropic cells

  • Stimulates secretion: growth hormone-releasing hormone (GHRH)

  • Inhibits secretion: growth hormone inhibiting hormone (GHIH)

  • Thyroid-stimulating hormone (TSH) is secreted by thyrotropic cells

    • Stimulates secretion: thyrotropin-releasing hormone (TRH)

    • Inhibits secretion: growth hormone inhibiting hormone (GHIH)

  • Follicle-stimulating hormone (FSH) is secreted by gonadotropic cells

    • Stimulates secretion: gonadotropin-releasing hormone (GnRH)

  • Luteinizing hormone (LH) is secreted by gonadotropic cells

    • Stimulates secretion: gonadotropin-releasing hormone (GnRH)

  • Prolactin (PRL) is secreted by prolactin cells

    • Stimulates secretion: prolactin-releasing hormone (PRH)

    • Inhibits secretion: prolactin-inhibiting hormone (PIH), which is dopamine

  • Adrenocorticotropic hormone (ACTH) is secreted by corticotropic cells

    • Stimulates secretion: corticotropin-releasing hormone

  • Melanocyte-stimulating hormone (MSH) is secreted by corticotropic cells

    • Stimulates secretion: corticotropin-releasing hormone

    • Inhibits secretion: dopamine

    • **fetal development pars intermedia (very small or absent in adulthood)

Hormones (posterior pituitary) secretes and stores + not glandular *neurohypophysis

• Oxytocin (OT)

  • Stimulates contraction of smooth muscle cells of the uterus during childbirth; stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection

• Antidiuretic hormone (ADH)

  • Conserves body water by decreasing urine volume; decreases water loss through perspiration; raises blood pressure by constricting arterioles

1. Outline and discuss the adrenal glands. Identify all layers/regions and what they do.

Adrenal gland: secretes DHEA, a hormone that makes men masculine during puberty but is insignificant for females until menopause when there is no more estrogen

• Adrenal medulla- norepinephrine and epinephrine are secreted from chromaffin cells

  • Hormones increase heart rate, and blood pressure, and mobilize/utilize glucose for energy

• Adrenal cortex-

  • 3 regions

    • Zona glomerulosa- secretes aldosterone to maintain homeostasis between sodium and potassium

      • Aldosterone- RAA pathway

      • Mineralocorticoids (class)

    • Zona fasciculata- cortisol, anti-inflammatory and makes glucose

      • Glucocorticoids

    • Zona reticularis- sex hormones

      • Androgens

1. Outline and discuss the stress response. **sympathetic division of the autonomic nervous system

• Eustress is helpful, everyday stress that prepares us to meet good challenges *good stress

• Distress is any type of harmful stress that may become damaging

  • 1st stage of stress- sympathetic nervous system

  • 2nd stage of stress- resistance reaction

    • This stage lasts much longer and if overused can cause exhaustion

1. Identify and discuss the endocrine disorders discussed in class.

Suprarenal gland disorders:

• Cushing’s syndrome- hypersecretion of the suprarenal cortex

• Addison’s disease- hyposecretion of glucocorticoids and aldosterone

• Pheochromocytoma- benign tumors that cause hypersecretion of epinephrine and norepinephrine

Pancreatic disorders:

• Type 1 diabetes- autoimmune disorder in which the body destroys its beta cells in the pancreatic islet cells creating an insufficient amount of insulin

  • Symptoms include: high levels of sugar in urine/blood, dehydration, and constant thirst

• Type 2 diabetes- adult onset, caused by obesity, poor diet, and lack of exercise causing beta cells to ignore the stimulus to make insulin

  • Can be fixed by weight loss, exercise, and a better diet

• Gestational diabetes- *females when they are pregnant

  • Can be diagnosed with a simple glucose test when high levels of sugar show up in urine

  • This disease causes babies to be born big and increase the chances of a c-section or other procedure

Thyroid disorders:

• Hypothyroid- (underactive thyroid) weight gain, stores glucose, and slow metabolism

• Hyperthyroid (overactive thyroid) weight loss, super fast metabolism

• Goiter- enlarged thyroid gland

• Hashimoto syndrome- autoimmune disease, hypothyroid

  • Affects women more than men

Parathyroid disorders:

• Hypoparathyroidism- too much potassium, causes dropping of the face

1. Outline and discuss the functions and properties of blood.

• Blood plasma (55%)

  • Consists of water (91.5%), proteins (7%), and other solutes (1.5%)

• Red blood cells (45%) *erythrocyte

  • The number of RBCs and platelets remains rather steady while that of WBCs varies depending on invading pathogens and other foreign antigens

  • Contain hemoglobin that is used to carry oxygen to all cells and to carry some carbon dioxide to the lungs

• Buffy coat is composed of white blood cells and platelets

• Cellular components (formed elements) of blood include red blood cells, white blood cells, and platelets *thrombocyte

• White blood cells *leukocyte

• Functions of blood

  • Blood transports oxygen, carbon dioxide, nutrients, hormones, heat, and waste products

  • Blood regulates the homeostasis of all body fluids, pH, body temperature, and water content of cells

  • Blood protects against excessive loss by clotting and uses white blood cells to protect against infections

1. Outline and discuss the composition of blood.

• Blood plasma (55%)

  • Consists of water (91.5%), proteins (7%), and other solutes (1.5%)

  • Blood plasma proteins (7%)

    • Albumins (54%) smallest and most numerous plasma protein

    • Globulins (38%) large protein

    • Fibrinogen (7%) large protein

  • Other solutes (1.5%)

    • Electrolytes- help maintain osmotic pressure and play essential roles in cell functions

    • Nutrients- essential roles in cell functions, growth, and development

    • Gasses- oxygen (important in cellular functions), nitrogen (no known function), carbon dioxide (involved in the regulation of blood pH)

    • Enzymes- catalyze chemical reactions

    • Hormones- regulate metabolism, growth, and development

    • Vitamins- cofactors for enzymatic reactions

    • Waste products- breakdown products of protein metabolism that are carried by the blood to organs of excretion

• Red blood cells (45%) *erythrocyte

  • The number of RBCs and platelets remains rather steady while that of WBCs varies depending on invading pathogens and other foreign antigens

  • Contain hemoglobin that is used to carry oxygen to all cells and to carry some carbon dioxide to the lungs

    • Each hemoglobin molecule constraints an iron ion which allows each molecule to bind to four oxygen molecules

    • Hemoglobin is involved in regulating blood flow and BP via the release of NO

      • Nitric oxide (NO) causes vasodilation, which improves blood flow and enhances oxygen delivery

  • No nucleus or other organelles *biconcave discs- this allows them to carry O2 better

  • RBCs contain carbonic anhydrase, which catalyzes the conversion of carbon dioxide and water to carbonic acid

    • Carbonic acid transports about 70% of the carbon dioxide in plasma

  • Live for only 120 days

    • Dead cells are removed from circulation by the spleen and liver

  • Breakdown products from the RBCs are recycled and reused

  • Erythropoiesis (production of RBCs) begins in the red bone marrow

    • Erythropoietin, a hormone secreted by the kidneys in response to lowered oxygen concentration (hypoxia) stimulates the differentiation of hematopoietic stem cells into erythrocytes

  • Reticulocytes (immature RBCs) enter the circulation and mature in 1 to 2 days

  • Stimulus→controlled condition→receptors→input→control center→output→ effectors→response *return to homeostasis when o2 delivery to kidneys increases to normal

• Buffy coat is composed of white blood cells and platelets

• Cellular components (formed elements) of blood include red blood cells, white blood cells, and platelets *thrombocyte

• White blood cells *leukocyte

  • Contain a nucleus and organelles, but NO HEMOGLOBIN

  • May live for several months or years- the main function is to combat invading microbes

    • During an invasion, many WBCs can leave the bloodstream and collect at sites of invasion

      • This is called emigration

      • An elevation in the white blood count indicates an infection or inflammation

      • A low white blood cell count may develop due to several causes

        • A differential white blood cell count will help to determine if a problem exists

  • Classified as granular and agranular

    • Granular- containing vesicles that appear when the cells are stained

      • Granular leukocytes: neutrophils, eosinophils, basophils

    • Agranular- containing no granules

      • Agranular leukocytes: lymphocytes, monocytes

• (most abundant to least: Never Let Monkeys Eat Bananas

  • Neutrophils (60-70%)

  • Lymphocytes (20-25%)

    • Able to live for years, while most other blood cells live for hours, days, or weeks

  • Monocytes (3-8%)

  • Eosinophils (2-4%)

  • Basophils (0.5-1%)

1. Outline and discuss the formation of blood cells.

Hematopoiesis- formation of blood cells

• Pluripotent stem cells differentiate into each of the different types of blood cells

1. Outline and discuss the epidemiology of sickle cell anemia.

• People with this disorder have an abnormal kind of hemoglobin

• RBC is sickle or crescent-shaped

• Sickled RBCs break down prematurely (5-7 days)

• Sickle cells do not move easily through blood vessels preventing O2 transport

  • People with sickle cell anemia are not allowed to do high-impact activities ex. sports due to this risk

  • Symptoms include- shortness of breath, fatigue paleness, and delayed growth in children

• Positive- builds resistance to malaria

  • Because sickled cells last 5-7 days, we get rid of the third stage of malaria

1. Outline and discuss the different types of white blood cells and what they do.

Classified as granular and agranular

• Granular- containing vesicles that appear when the cells are stained

  • Granular leukocytes: neutrophils, eosinophils, basophils

• Agranular- containing no granules

  • Agranular leukocytes: lymphocytes, monocytes

• (most abundant to least: Never Let Monkeys Eat Bananas

  • Neutrophils (60-70%)

    • The high count may indicate: bacterial infection, burns, stress, inflammation

    • The low count may indicate: radiation exposure, drug toxicity, vitamin b12 deficiency, systemic lupus erythematosus

  • Lymphocytes (20-25%)

    • The high count may indicate: viral infections, some leukemias, infectious mononucleosis

    • The low count may indicate: prolonged illness, HIV infection, immunosuppression, treatment with cortisol

    • Able to live for years, while most other blood cells live for hours, days, or weeks

  • Monocytes (3-8%)

    • The high count may indicate: viral or fungal infections, tuberculosis, some leukemias, or other chronic diseases

    • The low count may indicate: bone marrow suppression, treatment with cortisol

  • Eosinophils (2-4%)

    • The high count may indicate: allergic reactions, parasitic infections, autoimmune diseases

    • The low count may indicate: drug toxicity, stress, acute allergic reactions

  • Basophils (0.5-1%)

    • The high count may indicate: allergic reactions, leukemias, cancers, hypothyroidism

    • The low count may indicate: pregnancy ovulation, stress, hypothyroidism

** LAB MANUAL

1. Outline and discuss the steps in hemostasis.

Hemostasis- is a sequence of responses that stop bleeding

• Process involves-

  • Vascular spasm

  • Platelet plug formation

  • Blood clotting (coagulation)

• Blood clotting involves several clotting (coagulation) factors

• Blood clotting can be activated in one of two ways-

  • Extrinsic pathway

  • Intrinsic pathway

• Both pathways lead to the formation of prothrombinase and, from there, the common pathway continues

1. Outline and discuss the steps in clot formation. Be sure to discuss all three pathways including all clotting factors.

Steps in clot formation

• (Hemostasis) Process involves-

  • Vascular spasm

  • Platelet plug formation

    • Platelet adhesion → platelet release reaction → platelet aggregation

  • Blood clotting (coagulation)

    • Blood clotting cascade

    • Once the clot forms, it tightens to pull the edges of the damaged vessel together

      • Vitamin K is needed for normal clot formation because it is used in the synthesis of 4 clotting factors

    • Small, unwanted clots are dissolved by plasmin, an enzyme that is part of the fibrinolytic system

• Clotting (coagulation) factors

  • I Fibrinogen: source- liver

    • Pathways of activation → common

  • II Prothrombin: source- liver

    • Pathways of activation → common

  • III Tissue factor (thromboplastin): damaged tissues and activated platelets

    • Pathways of activation → extrinsic

  • IV Calcium ions: diet, bones, and platelets

    • Pathways of activation → all

  • V Proaccelerin, labile factor or accelerator globulin: liver and platelets

    • Pathways of activation → extrinsic and intrinsic

  • VII Blood serum prothrombin conversion accelerator (SPCA): liver

    • Pathways of activation → extrinsic

  • VIII Antihemophilic factors (AHF): liver

    • Pathways of activation → intrinsic

  • IX Plasma thromboplastin component (PTC): liver

    • Pathways of activation → intrinsic

  • X Stuart factor: liver

    • Pathways of activation → extrinsic and intrinsic

  • XI Blood plasma thromboplastin antecedent (PTA): liver

    • Pathways of activation → intrinsic

  • XII Hageman factor: liver

    • Pathways of activation → intrinsic

  • XIII Fibrin-stabilizing factor (FSF): liver and platelets

    • Pathways of activation → common

1. Outline and discuss the plasma proteins found in the blood.

• Blood plasma (55%)

  • Consists of water (91.5%), proteins (7%), and other solutes (1.5%)

  • Blood plasma proteins (7%) *MOST are produced by the liver

    • Albumins (54%) smallest and most numerous plasma protein

      • Help maintain osmotic pressure *important factor in the exchange of fluids across blood capillary walls

    • Globulins (38%) large proteins (plasmocytes produce immunoglobulins)

      • Immunoglobulins help attack viruses and bacteria *alpha and beta globulins transport iron, lipids, and fat-soluble vitamins

    • Fibrinogen (7%) large protein

      • Plays an essential role in blood clotting

1. Discuss blood groups and blood types.

• Blood is characterized into different blood groups based on the presence or absence of agglutinogens on the surface of RBCs

  • 24 blood groups and more than 100 antigens

  • Blood types vary among different populations

  • Classification is based on antigens labeled A, B, or AB, with O being no antigens

  • 85% of the population is Rh positive

• Blood plasma usually contains antibodies that react with A or B antigens

• An individual will not have agglutinins against his or her blood type *hemolytic disease

  • Type A

    • An antigen

    • Anti-B antibody

    • Compatible donor blood types: A, O

  • Type B

    • B antigen

    • Anti-A antibody

    • Compatible donor blood types: B, O

  • Type AB

    • Both A and B antigens

    • Anti-A antibody

    • Compatible donor blood types: A, B, AB, O

    • *Universal recipient

  • Type O

    • Neither A nor B antigen

    • Both anti-A and anti-B antibodies

    • Compatible donor blood types: O

    • *Universal donor

1. Discuss the hemolytic disease of newborns.

• At birth small amounts of fetal blood leak into the maternal circulation

  • If the baby is Rh+ and the mother is Rh-, she will develop antibodies to the Rh factor

  • During her next pregnancy with an Rh+ baby, when she transfers antibodies to the fetus, the transferred anti-Rh antibodies will attack some of the fetal’ RBCs causing clotting and hemolysis

1. Outline and discuss the different components of the pericardium and any possible infections that can occur.

The heart is enclosed and held in place by the pericardium (heart wall)

• Consists of an outer fibrous pericardium and an inner serous pericardium

• The serous pericardium has 2 layers-

  • The Visceral- (epicardium) adheres to the surface of the heart

  • Parietal-fused to the fibrous pericardium

• The visceral and parietal layers are separated by the serous cavity, a fluid-filled space

  • This fluid reduces friction between the layers of the serous pericardium as the heart moves

• Infection: Pericarditis- inflammation of the pericardium; chest pain and pericardial friction rub

• The wall of the heart (pericardium) has 3 layers

  • Epicardium (visceral pericardium) *outer layer

  • Myocardium- cardiac muscle; responsible for pumping action of the heart (contracts to help move blood throughout the heart); thickest layer

    • Cardiac muscle is involuntary, arranged in bundles that swirl diagonally around the heart *striated + intercalated discs

    • Infection: myocarditis- inflammation of the myocardium; may cause fatigue, chest pain, irregular heartbeat *severe cases lead to cardiac failure and death

  • Endocardium- the innermost layer of the heart

    • Has a slip and slide texture→ water=blood plasma, produces a friction-free environment for formed elements to move through without any damage

    • Infection: endocarditis- inflammation of endocardium; may cause fever, heart murmurs, irregular heartbeat, fatigue

1. Trace blood flow through the heart and identify all the blood vessels, valves, and chambers it passes through. (systemic and pulmonary circulations)

• Right atrium- pushes deoxygenated blood through the tricuspid valve →

• Right ventricle- pushes deoxygenated blood through the pulmonary valve →

• Pulmonary trunk- where deoxygenated blood moves out through the left and right pulmonary arteries →

• Left and right lungs- in the pulmonary capillaries, blood loses CO2 and gains O2 **blood is now oxygenated →

• The oxygenated blood moves through the left and right pulmonary veins →

• Left atrium- oxygenated blood is then pushed through the bicuspid valve →

• Left ventricle- pushes oxygenated blood through the aortic valve →

• Aorta and systemic arteries- where the oxygenated blood is →

• Systemic capillaries- where blood loses O2 and gains CO2 *because O2 is being absorbed

• The deoxygenated blood moves through the superior vena cava, inferior vena cava, ad coronary sinus back into the right atrium

1. Outline and discuss the conduction system through the heart (5 steps).

• Cardiac cells are self-excitable (autorhythmic)- repeatedly generate spontaneous pulses that trigger heart contractions *these cells form the conduction system

• 5 steps of the conduction system

**SA node, AV node, AV bundle, right and left bundle branches, Purkinje fibers

• SA node in the wall atrium is activated and atrial activations begin

  • Time=0

  • SA node cells repeatedly depolarize to threshold spontaneously→ pacemaker potential

  • When the pacemaker potential reaches the threshold, it triggers an action potential that propagates both atria

  • Stimulus spreads across the atrial surfaces and reaches the AV node

    • Elapsed time: 50 msec

    • The AV node is located at the interatrial septum

  • There is a 100 msec delay at the AV node; atrial contraction occurs

    • Elapsed time=: 150 msec

    • Both atria are fully depolarized

    • AV valves open (atrioventricular)

    • SL valves close (semilunar)

  • The impulse travels along the interventricular septum within the atrioventricular bundle and the bundle branches into the right and left bundle branches to the Purkinje fibers via the moderator band, to the papillary muscles of the right ventricle

    • Elapsed time: 175 msec

  • Impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium- atrial contraction is completed, and ventricular contraction begins

    • Both ventricles are fully depolarized

    • AV valves closed

    • SL valves opened

    • Time elapsed: 225 msec

**Hormones can modify the heart rate and force of contraction but they do not set the fundamental rhythm for the heart (medulla oblongata)

1. Discuss an EKG tracing and identify all the waves and complexes.

• Action potential in a (ventricular) contractile fiber:

  • AP initiated by the SA node travels along the conduction system and spreads out to excite the “working” atrial and ventricular fibers (contractile fibers)

  • An AP in a contractile fiber is characterized by a rapid depolarization

Steps/patterns shown on EKG:

• (1) Rapid depolarization- due to Na+ inflow when collage-gated fast Na+ channels open (contractile fibers are brought to threshold)

• (2) Plateau (maintained depolarization)- due to Ca2+ inflow when voltage-gated slow Ca2+ channels open and the K+ outflow when some voltage-gated slow K+ channels open

  • *Ca2+ inflow balances out K+ outflow

  • Allows a sustaining of longer contraction cycling of the heart muscle

    • Allowing time for blood to move its respective parts

    • *Prevents tetanus in cardiac muscle fibers

• (3) Repolarization (return to resting membrane potential)- due to closing of Ca2+ channels and K+ outflow when additional voltage K+ channels open

  • Refractory period- occurs during the plateau phase and parts of repolarization

    • There cannot be another AP coming to stimulate another depolarization phase until this construction is complete

      • Important in preventing tetanus and arrhythmias

• Electrocardiogram (EKG):

  • Measures electrical conduction through the heart

  • P wave- small upward deflection on ECG that represents atrial depolarization

  • PQ interval- from the start of the P wave to the beginning of the QRS complex, the time required for the AP to travel through the atria, AV node, and remaining fibers of the conduction system

  • QRS complex- represents rapid ventricular depolarization

  • ST segment- from the end of the QRS complex to the start of the T wave that represents a time when the ventricular fibers are depolarized during the plateau phase of the AP

  • T wave- represents ventricular repolarization (ventricles relaxing) occurs more slowly than depolarization (wave is smaller and wider than QRS complex)

  • QT interval- from the start of the QRS complex to the end of the T wave

Contraction of ECG waves with atrial and ventricular systole

*depolarization causes contraction and depolarization causes relaxation of cardiac muscle fibers

• Depolarization of atrial contractile fibers produces P wave

• Atrial systole (contraction) after the P wave begins

  • Atrial diastole (relaxation) is masked by QRS complex

• Depolarization of ventricular contractile fibers produces QRS complex

• Ventricular systole (contraction) shortly after QRS complex begins

• Repolarization of ventricular contractile fiber produces T wave

• Ventricular diastole (relaxation) shortly after the T wave begins

One cardiac cycle consists of the contraction )systole) and relaxation (diastole) of both atria, rapidly followed by the systole and diastole of both ventricles

• During atrial systole (contraction)

  • Electrical events of EKG-

    • Atrial depolarization (marked by P wave) causes atrial systole

    • The onset of ventricular depolarization with the onset of QRS complex

  • Pressure change

    • As the atria contract, pressure is exerted on the blood within, forcing the blood through the open AV valves into the ventricles

    • Aortic pressure is slightly decreasing (think: because atria are contracting, not the ventricles thus, BP is low)

    • Left ventricular pressure is low (small hump before ventricular systole)

    • Left atrial pressure is low (small hump_ because the distance is not very far (only pushing blood into ventricles right below it)

  • Volume changes

    • Volume in the ventricle increases (being filled with blood)

    • The end of each atrial systole is also the end of each ventricular diastole (relaxation)

      • This blood volume is called end-diastolic volume (EDV)

  • Heart sounds- Auscultation: s4, but can’t hear it with a stethoscope

  • Mechanical event- atrial systole (contraction) and ventricle diastole (relaxation)

• During ventricular systole (contraction)

  • Electrical events of EKG

    • Ventricular depolarization causes ventricular systole, marked by QRS complex

    • T wave in ECG marks onset of ventricular repolarization

  • Pressure change

    • As ventricular systole (contraction) begins, pressure rises inside the ventricles and pushes up against the AV valves, forcing them to shut

    • Isovolumetric contraction- period of about (0.5 secs) when both semilunar and AV valves are closed

      • During this interval, cardiac muscle fibers are contracting and exerting force but are not shortening (yet)

      • All four valves are closed- ventricular volume remains the same

      • Continued contraction of the ventricles causes pressure inside the chambers to rise sharply

        • When left ventricular pressure surpasses aortic pressure at 80mmHg the aortic semilunar valve opens and the ventricular ejection begins (pressure continues to rise to 120mmHg)

  • Volume changes

    • The blood volume in ventricles decreases (ventricle is ejecting blood)

    • End systolic volume- volume remaining in each ventricle at the end of systole

    • Stroke volume- volume ejected per beat from each ventricle

      • SV= end diastolic volume (-) end systolic volume

      • At rest: SV is about 130 mL-60mL=70mL

  • Heart sounds- auscultation: heart 1st sound (s1), a club sound

    • This sound is caused by blood turbulence associated with the closure of AV valves soon after ventricular contraction begins

  • Mechanical event: isovolumetric contraction and ventricular ejection

• During ventricular diastole (relaxation):

  • Electrical events of EKG

    • Ventricular repolarization causes ventricular diastole, as marked by the end of the tZ wave in the EKG

  • Pressure change

    • As the ventricles relax, the pressure within the chambers falls, and blood in the aorta and pulmonary trunk begins to flow backward toward the region of lower pressure in the ventricles

    • Back-flowing blood catches in the valve cusps and closes the semilunar valves

    • Aortic valves close

    • The rebound the blood from the closed cusps of the aortic valve produces the dicrotic wave on the aortic pressure curve

    • Following the aortic pressure decreases

  • Volume changes

    • After the SL valves close, there is a brief period (isovolumetric relaxation) when ventricular blood volume does not change because all 4 valves are closed

    • Pressure falls quickly as ventricles relax

    • When ventricular pressure drops below atrial pressure, the AV valves open and blood rushes rapidly into the ventricles

    • Another P wave signals the start of another cardiac cycle

    • The blood volume in the ventricle increases because the AV valve is open and blood is flows in

  • Heart sounds- auscultation:

    • Hear the 2nd sound, s2, a dubb sound

    • Sound is caused by blood turbulence associated with the closure of SL valves

  • Mechanical event

    • Isovolumetric relaxation and ventricular filling

• Cardiac output:

  • The volume of blood ejected from the heart (ejected from the left or right ventricle into the aorta or pulmonary trunk each minute)

  • Stroke volume=amount of blood pumped out of the ventricle in one beat

    • (mL/beat) x (heart rate)= about 75 beats per minute

    • In a typical man: SV is mL/beat and heart rate is about 75 beats per minute

    • CO= 70 x 75= 5250 mL/min= 5ish liters a minute

• Regulation of stroke volume

  • Preload

    • The degree of stretch on the heart before it contracts

    • The volume of the blood in ventricles at the end of diastole (just before contraction is about to begin)

    • A greater stretch (preload) on cardiac muscle before contraction increases the force of contraction

    • The more the heart fills with blood during diastole, the greater the force of contraction during systole

    • Preload is increased in:

      • Hypervolemia: increased BV

      • Regurgitation of cardiac valves

      • Heart failure

  • Contractility

    • The forcefulness of contraction of individual ventricular muscle fibers

    • The ability which the heart can contract

    • Affects stroke volume

    • Get older, the compliance of the heart reduces, and it is harder for the heart to contract

  • Afterload

    • The pressure that must be exceeded before rejection of blood from the ventricles can occur

    • The resistance the left ventricle must overcome to circulate blood

      • Resistance may be: the length of blood vessels or the diameter of the lumen of blood vessels

    • Increased in:

      • Hypertension (high BP)

        • The heart is working overtime to produce more pressure

        • The delicate aorta can rupture (aneurysm)

        • Vasoconstriction (smaller lumen, increased BP)

• Factors that regulate heart rate:

  • Autonomic nervous system

    • The sympathetic nervous system increases the heart rate

    • The parasympathetic nervous system decreases the heart rate

  • Hormones

    • Adrenaline (epinephrine and norepinephrine) increases heart rate

  • Ions

    • Increase Ca2+ ions, increase contractility, increases heart rate

    • Na+ ions need to be exactly regulated- if the flow of Na is disrupted the heart beats irregularly

  • Age

    • The older we get, the harder our heart has to work to pump

    • Kids: have faster heart rates because their metabolism is faster

  • Gender

    • Females have higher heart rates because of estrogen and progesterone

  • Physical fitness

    • Better shape= lower heart rate *heart is much more efficient

  • Temperature

    • Increase body temperature increases heart rate

• Nervous system control of the heart

  • Input to cardiovascular center in the medulla oblongata

    • From higher brain centers: cerebral cortex, limbic system, and hypothalamus

    • From sensory receptors

      • Proprioceptors- monitor body position/movement

      • Chemoreceptors- monitor blood chemistry

      • Baroreceptors- monitor blood pressure

  • Output to heart

    • Through cardiac accelerator nerves (sympathetic)

      • Increased rate of spontaneous depolarization in SA and AV nodes

      • Increases heart rate and contractility of atria and ventricles (SV)

    • Through Vagus (X) nerves (parasympathetic)

      • Decreased rate of spontaneous depolarization in SA and AV nodes

      • Decreases heart rate

• Factors that increase cardiac output

  • Increased end-diastolic volume (stretches the heart( → increased preload → within limits, cardiac muscle fibers will contract more forcefully with stretching → increased stroke volume → increased cardiac output

  • Increased contractility→ increase stroke volume→ increased cardiac output

  • Decreased arterial BP during relaxation decreased afterload→ increases stroke volume→ increased cardiac output

  • Nervous system: cardiovascular centers in the medulla oblongata receive input from the cerebral cortex, limbic system, hypothalamus, proprioceptors, chemoreceptors, and baroreceptors → increased sympathetic stimulation and decreases parasympathetic stimulation → increased heart rate → increased cardiac output

  • Chemicals: catecholamine or thyroid hormones in the blood; moderate increase in extracellular Ca2+ → increased heart rate → increases cardiac output

  • Other factors: infants and elderly; females; low physical fitness; increased body temperature → increased heart rate → increased cardiac output

1. Discuss layers of blood vessels

Arteries and arterioles

*Carry blood away from the heart to the tissues

• The walls of the arteries are ELASTIC, allowing them to absorb the PRESSURE created by ventricles of the heart as they pump blood into the arteries

• PRESSURE RESERVOIRS

  • *high pressure within them

• Because of the smooth muscle in the tunica media (the thickest layer in arteries), arteries can regulate their diameter

• Layers of arteries

  • Tunica intima (endothelium)- the innermost layer of the artery

  • Basement membrane- between endothelium/ tunica intima and internal elastic membrane

  • Internal elastic membrane- swiss cheese looking membrane that surrounds the tunica media on the medial to the lumen

  • Tunica media (smooth muscle)- middle layer; the thickest layer of the arteries; surrounded by elastic membranes (more elastic tissue and less smooth muscle tissue)

  • External elastic membrane- swiss cheese looking membrane that surrounds the tunica media lateral to the lumen

  • Tunica Externa- the outermost layer of the artery

Veins and venules

• Venules are small vessels that are formed by the union of several capillaries

• Venules drain blood from capillaries into veins

  • VOLUME RESERVOIR

  • *low pressure within

• Layers of veins

  • Tunica intima (endothelium)- the innermost layer of the vein; adjacent to the lumen

    • Compared to arteries this is thinner in veins

  • Basement membrane- between endothelium/tunica intima and tunica media

  • Tunica media (smooth muscle)- middle layer; smooth muscle and elastic fibers (more smooth muscle less elastic)

    • Compared to arteries this is thinner in veins

  • Tunica Externa- the outermost layer of the vein; adjacent to surrounding tissue

    • Compared to arteries this is thicker in veins

  • Does not have elastic membranes within it

  • Histologically very different

  • Vein contain VALVES

Capillaries

• Capillaries are microscopic vessels that usually connect arterioles and venules

• Layers of capillaries

  • Capillary walls are composed of a single layer of cells and a basement membrane

    • Because their walls are so thin, capillaries permit the exchange of nutrients and wastes between blood and tissue cells

    • *Think of popped blood vessels (those are capillaries) that exploded due to high pressure -strap bar

1. Discuss types of arteries and veins.

• Types of arteries

  • Elastic arteries (conducting arteries)

    • Large diameter

    • More elastic fibers, less smooth muscle

    • Function as PRESSURE RESERVOIRS

  • Muscular arteries (distributing arteries)

    • Medium diameter

    • More smooth muscle, few elastic fibers

    • Distribute blood to various parts of the blood

• Anastomoses- the union of the two branches of 2 or more arteries supplying the same region of the body **alternate route (backroads think traffic)

  • Arteries that do not form these are called “end arteries”

    • If an end artery is blocked, blood cannot get to that region and tissues can die

• Types of veins

  • Postcapillary venules

    • Pass blood into muscular venules; permit exchange of nutrients and wastes between blood and interstitial fluid function in white blood cell emigration

  • Muscular venules

    • Pass blood into a vein; act as reservoirs for accumulating large volumes of blood (along with postcapillary venules)

  • Veins

    • Return blood to the heart, facilitated by valves in limb veins

  • Varicose and spider veins

    • Formed when venous valves become weak or damaged

    • Veins are dilated and twisted in appearance

    • Dilated venules close to the skin, especially in the lower limb of the face

    • They appear red, blue, or purple, resembling a spider web

1. Outline and discuss capillary types and locations.

• Types of capillaries

  • Continuous capillaries

    • Formed by endothelial cells

    • Consist of a basement membrane, pinocytic vesicle, nucleus of endothelial cell, lumen, and intercellular cleft

  • Fenestrated capillaries

    • Consists of a fenestration, intercellular cleft, lumen, pinocytic vesicle, basement membrane, and nucleus of endothelial cell

  • Sinusoid capillaries

    • Consists of an incomplete basement membrane, lumen, nucleus of endothelial cell, and intercellular cleft

1. Discuss blood flow through capillaries.

• Blood flow into the capillaries is controlled by smooth muscle tissue located at the arterial end of a capillary called a precapillary sphincter (which may close or open the capillary, by contracting or relaxing)

  • The precapillary sphincter responds to the demands of the cells the capillary supplies

  • When contractions of oxygen and nutrients in these cells are low, the precapillary sphincter relaxes,, and blood flow increases; the precapillary sphincter contracts again when cellular requirements have been met

1. Discuss the blood distribution in the body.

• At rest, the largest portion of the blood is in the systemic veins and venules, which are considered “blood reservoirs”

  • Systemic veins and venules- 64%

  • Systemic capillaries- 7%

  • Systemic arteries and arterioles- 13%

  • Heart- 7%

  • Pulmonary vessels- 9%

1. Discuss capillary exchange.

Substances across capillary walls by:

• Diffusion

  • Substances such as oxygen, carbon dioxide, g;glucose, amino acids, and some hormones cross capillary walls via simple diffusion

• Transcytosis

  • Large, lipid-insoluble molecules (like insulin) cross capillary walls in vesicles via transcytosis

• Bulk flow

  • Bulk flow is a passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction

    • Occurs from an area of HIGH PRESSURE to an area of LOW PRESSURE, and it continues as long as a pressure difference exists

  • Bulk flow is more important for the regulation of the relative volumes of blood and interstitial fluid

Filtration and reabsorption

• Filtration is pressure- the driven movement of fluid and solutes from blood capillaries into the interstitial fluid

  • Blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure (IFOP) promote filtration

• Reabsorption is the pressure-driven movement of fluid and solutes from the interstitial fluid into blood capillaries

  • Interstitial fluid hydrostatic pressure (IFHP) and blood colloid osmotic pressure (BCOP) promote reabsorption

1. Outline and discuss the dynamics of capillary exchange, with a formula.

Arterial end: *positive

• Blood hydrostatic pressure (BHP)= 35mmHg

• Blood colloid osmotic pressure (BCOP)= 26mmHg

**NPF=(35+1)-(26+0)=10mmHg

NET FILTRATION

Venous end: *negative

• Blood hydrostatic pressure (BHP)= 16mmHg (*lower on venous side)

• Blood colloid osmotic pressure (BCOP)= 26mmHg (same on both sides)

**NFP= (16+1)-(26+0)=-9

NET REABSORPTION

In between (Arterial side and venous side) CONSTANT VALUES

• Interstitial fluid osmotic pressure (IFOP)= 1mmHg

• Interstitial fluid hydrostatic pressure (IFHP)=0mmHg

Under normal conditions, the volume of fluid and solutes reabsorbed is almost as large as the volume filtered → NFP=(BHP + IFOP) - (BCOP + IFHP)

*Starling’s Law of the Capillaries

1. Discuss vascular resistance.

• R is the opposition to blood flow due to friction between blood and the walls of blood vessels

  • The higher the R, the smaller the blow flow

• R depends on:

  • Size of the blood vessel lumen

  • Blood viscosity *polycythemia

  • Total blood vessel length (*obese people have very long blood vessels)

1. Outline venous return.

Venous return- the volume of blood flowing back to the heart through the systemic veins, occurs due to the pressure generated by contractions of the heart’s left ventricle

• Venous return is assisted by:

  • Valves

  • Respiratory pumps

  • Skeletal muscle pumps *primary way

    • During exercise,, blood moves faster through the body

    • Ex. in a still leg the valves within this pump close

1. Discuss the relationship between the blood velocity and cross-sectional area of BVs.

• Blow flow is the volume of blood that flows through tissue in a given period

• Blood flow is inversely related to the cross-sectional area of blood vessels

*surface area versus blood flow

Things to remember- BP

• BP is highest at the aorta and continues to decrease

• At the capillaries,, BP is the lowest (thin vessels can not handle a lot of pressure)

• In the veins and venules,, BP starts to raise again but not nearly as high as before

Things to remember- surface area

• Within the aorta, arteries, and arterioles the surface area is at its lowest, but slowly increasing

• Within the capillaries,, the surface area reaches its peak (greatest distance within the body)

• In venules, veins, and venae cavae the surface area initially plummets, but then slowly starts to raise again as blood moves back to the heart

1. Outline and discuss factors that affect and control Blood pressure.

Cardiac output

• Increased heart rate and contractility- increases BP

Systemic vascular resistance

• Increases BP- vasoconstriction

• Decreases BP- vasodilation

Blood volume

• Blood volume increase- increases BP

• Blood volume decrease- decreases BP

*Green side of the chart

• Increased blood volume, vasoconstriction, and activations of skeletal muscle pumps and respiratory pumps

  • Causes: Increased venous return

• Decreased parasympathetic impulses and increased sympathetic impulses and hormones from the suprarenal medulla

  • Causes: Increased heart rate (HR)

• Increased venous return and increased sympathetic impulses and hormones from the suprarenal medulla

  • Causes: Increased stroke volume (SV)

• Increased heart rate and increased stroke volume

  • Causes: Increased cardiac output (CO)

• Increased cardiac output

  • Causes: Increased mean arterial pressure (MAP)

*Blue side of the chart

• Increased number of RBCs (polycythemia)

  • Causes: Increased blood viscosity

• Increased body size, as in obesity

  • Causes: Increased total blood vessel length

• Increased blood viscosity, increased total blood vessel length, and decreased blood vessel radius (vasoconstriction)

  • Causes: Increased systemic vascular resistance (SVR)

• Increased systemic vascular resistance (SVR)

  • Causes: Increased mean arterial pressure (MAP)