Module 4: Blood Vessels and Circulation

Arteries

Carry blood away from the heart

Capillaries

Allow diffusion between the blood and surrounding tissues

Veins

Carry blood toward the heart

Elastic Arteries

Large vessels designed to transport large volumes of blood to major regions of the body.

Muscular Arteries

Distribute blood throughout the muscles and organs

Arterioles

Smallest of all the arteries, regulates the amount of blood that flows to a particular set of capillaries

Continuous capillaries

Most abundant in the skin and muscles.

Most common type

The endothelial cells of these capillaries form a continuous lining

Intercellular clefts

Gaps in the endothelial cells of continuous capillaries

Fenestrations

Pores within endothelial cells

Blood flow

Movement of blood through a vessel, tissue, or organ

Blood pressure

Force exerted by blood upon the walls of the blood vessels/ heart chambers.

Systemic arterial blood pressure

Pressure of blood flowing in the arteries of the systemic circulation

What is the systemic arterial blood pressure measured in?

mmHg, obtained from brachial artery

Systolic pressure

Reflects the arterial pressure from blood ejection during ventricular contraction/systole.

The higher value

What is the normal systolic pressure of your heart?

Usually around 120mmHg

Diastolic pressure

The arterial pressure of blood during ventricular relaxation/diastole

The lower value

What is the normal diastolic pressure of your heart?

Usually around 80mmHg

Pulse pressure

The difference between the systolic and diastolic pressure

Usually at least 25% of the systolic pressure

What are the six variables that influence blood flow and blood pressure?

Cardiac Output

Blood viscosity

Vessel Length

Vessel Diameter

Compliance

Blood Volume

Cardiac Output(CO)

measurement of the amount of blood flowing through the heart

What is CO measured in?

Liters per minute

An increase in CO results in which of the following:

An increase in blood flow

OR

A decrease in blood flow

An increase in blood flow

Blood viscosity

thickness of blood that affects their ability to flow

Increased viscosity causes:

Increased flow and decreased resistance

OR

Increased resistance and decreased flow

Increased resistance and decrease flow

Increased vessel length results in which of the following:

Increased resistance

OR

Decreased resistance

Increased resistance

Increased vessel diameter results in which of the following:

Increased resistance

OR

Decreased resistance

Decreased resistance

Compliance

The ability of any compartment to expand to accommodate increased content

Blood volume

the amount of blood circulating within an individual

Perfusion

Blood flow through tissues

Total cross sectional area

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True or false:

the pressure gradient pushing blood from the capillaries, through the veins, to the heart is much bigger than the pressure gradient pushing blood from the heart, through the arteries, to the capillaries.

False, they are much smaller

What are the two mechanisms that work with valves in the veins to maintain venous blood flow to the heart?

The skeletal muscle pump and the respiratory pump

True or False:

When skeletal muscles contract, they squeeze the veins and raise the pressure of the blood within them.

True

When an individual is at rest do they need a higher or lower rate venous return?

Lower, higher rate when active

Increase in pressure of the thoracic cavity does what?

It helps to push blood into the heart, and valves prevent blood from flowing back into the abdomen.

Where does exchange between the blood and tissues occur?

At the capillaries

Bulk flow

The movement of fluid through gaps or fenestrations in the capillaries

Fluid moves from ____ pressure to ____ pressure.

High to low

Hydrostatic pressure

The pressure on a fluid resulting from some force

Colloid osmotic pressure

created by the presence of large molecules that cannot diffuse across the capillary wall.

Net Filtration Pressure (NFP)

the sum of the effects of filtration and reabsorption.

Vasomotor center

Sends signals to smooth muscle cells in arterioles throughout the body

Does the vasomotor center increase or decrease TPR?

The vasomotor center increases TPR

Baroreceptors

Monitors the degree to which blood vessels are stretched

Function of ADH

promotes retention of water and a reduction in urine production by the kidneys

Atrial Natriuretic Hormone

Stimulates vasodilation and increases urine output.

Brings BP down

Capilary

Where material exchange occurs

How does material exchange occur in capillaries?

Through diffusion

What is the NFP equation?

NFP= (HPb-HPif)-(COPb-COPif)

Filtration

movement of fluid out of the blood

At which end does filtration occur?

The arterial or venous end

The arterial end

Reabsorption

Movement of fluid into the blood

At which end does reabsorption occur?

The arterial or venous end

The venous end

Is hydrostatic pressure higher or lower than the osmotic pressure in the venous end?

Lower

What pathway do the nutrients and hormones take after leaving the blood during diffusion?

Blood→ interstitial fluid→ tissue cells

What happens to the remaining fluid that is not absorbed at the venous end?

The lymphatic system absorbs this fluid and returns it to the bloodstream.