Among members of the Annelida, there are closed circulatory systems.
The exchange of gases and fluids occurs when they are spread across the capillary walls.
Excess fluids and waste move in opposite directions.
The heart pumps the deoxygenated blood to the respiratory organ, where arteries branch into a capillary bed for gas exchange.
The blood returns to the heart through the veins.
The blood is pumped from here to the rest of the body.
The valves on the left side of the heart are similar to the valves on the right side.
In the systemic circuit, oxygenated blood is transported in arteries and deoxygenated blood is transported in veins, while in the pulmonary circuit, it is reversed.
The valves are forced to close.
The characteristic "lub-dup" sounds of the heart can be heard after the closing of the semilunar valves.
Blood moves through the arteries when the heart is pumping.
Blood pressure drops as blood reaches the capillaries.
The blood moves through the veins because of the movements of adjacent muscles that squeeze the blood vessels.
Blood moves in the direction of the heart because of the valves in the veins.
Excess fluids enter the circulatory system when they diffuse into the capillaries.
Not all of the fluids enter the capillaries.
Backflow is prevented by valves in the lymphatic veins.
There are two ducts in the shoulder region that carry the Lymph back to the blood.
The lymphatic system filters fluids from the circulatory system.
Red blood cells that are mature lack a nucleus and thus maximize their ability to transport O2.
Platelets adhere to the wall of the damaged blood vessel and release various substances that initiate a cascade of reactions, some of which attract additional platelets.
Substances that attract more platelets are released.
The active and solid form of fibrin is converted from dissolved in the blood.
Blood flow is stopped by a network of platelets that are bound together.
The plug is tightened by pulling the fibrin fibers together.
In general, excretory systems help regulate water balance and remove harmful substances.
Water is lost by osmosis.
In order to maintain their internal environment, marine fish drink, rarely urinate, and excrete salts that they acquire when they drink.
The water diffuses into the fish.
In response, freshwater fish don't drink, urinate, or absorb salts through their gills.
Animals have evolved excretory mechanisms for the purpose of osmoregulation and the removal of toxic substances.
Nitrogen products ofProtein breakdown are by-products of cellular metabolism.
The vacuoles accumulate water and release it to the environment.
The flame cells are distributed along a tube system.
The fluids are moved through the tube system by internal cilia.
Water and salts leave the body through the tube system.
A tube-type excretory system is where body fluids pass through a tube.
Materials to be retained are released back into the body fluids, while concentrated waste goes through the tube to be eliminated.
Body fluids are collected from the hemolymph that bathes the cells by tubes attached to the midsection of the insects.
The fluids are deposited into the midgut.
As the fluids pass through the hindgut of the insect, materials to be retained pass back in across the walls of the digestive tract.
The waste is removed through the anus.
The human kidneys have a tube and blood vessels.
The tubule wasvoluted.
There is a dense network of capillaries surrounding the tubule.
The capillaries exit the nephron.
The blood passes through the two capillary beds and the capillary network surrounding the tubule.
Duct is being collected.
When blood enters the glomerulus, pressure forces water and solutes through the capillary walls into the capsule.
Substances small enough to pass through the capillary walls are suites.
There are red blood cells in the capillaries.
The filtrate passes through the tubule and then through the tubule and then through the tubule.
Salts and water are reabsorbed through the surrounding fluids as the filtrate passes through the tubule.
The filtrate descends through the duct.
Water moves out of the collecting duct and into the interstitial fluids when it passes through the salts concentrated in the interstitial fluids.
Concentration of urine is when the filtrate goes into the kidneys.
Adequate amounts of water must be available to the organisms.
When water is lost through excessive sweating, when the bicyle struggles with abacterial infections, or even when very salty foods are eaten, there is a need for additional water.
As water diffuses out of the collecting duct, urine becomes more concentrated.
ADH is produced by the hypothalamus in response to elevated osmolarity in the blood.
More Na+ is absorbed out of this tubule and duct.
The Na+ increases the salt concentration outside the tubule.
Nitrogen is a major waste product.
Toxic ammonia is released when the nucleic acids are broken down.
Several mechanisms have evolved to rid the body of this toxin.
The animals excrete NH3 into the water.
It requires less water to excrete urea than NH3.
uric acid forms a solid when it's mostly in water.
Nitrogen waste can be removed as a solid in order to conserve water.
Digestion is the breakdown of food.
The large amount of food eaten by most animals is too much for individual cells.
Four different groups of molecule are encountered during digestion.
The following sequence of events happen in humans and other mammals.
In particular, note which kinds of molecule are broken down.
Increasing the surface area upon which amylase can operate is achieved by reducing the size of food particles.
The wall of the stomach can expand because of its accordion-like folds.
In addition, the gastric juice loosens the cementing substances between the cells of the food.
The HCl kills a lot of thebacteria that accompany the food.
pepsin is produced by other stomach cells.
After pepsinogen is released into the stomach, it can begin the process of digestion.
The stomach is protected by a layer of mucus from other cells.
Most ulcers are now known to be caused bybacteria and can be successfully treated with antibiotics.
A controlled release.
The duodenum can be entered through the pancreatic duct with an alkaline solution that neutralizes the HCl in the chyme.
Trypsinogen is converted to its active form by the small intestines.
Trypsin converts chymotrypsinogen to its active form.
Emulsification is the breaking up of fat droplets into smaller droplets, increasing the surface area upon which fat-digesting enzymes can operate.
bile does not change anything.
The HCl in the chyme can be mitigated with the help of bile.
The small intestine takes in the breakdown products of food.
Most of the fat and glycerol are absorbed into the lymphatic system.
Some of the harmless and symbioticbacteria that live in the large intestine produce vitamins K and C. There is a short branch to a dead end pouch at the beginning of the large intestine.
The appendix is only important when it becomes inflamed and causes appendicitis.
It hasbacteria that help in digestion.
There are hormones involved in the process of digestion.
Gastrin enters the bloodstream and stimulates other cells of the stomach.
When secretin is deposited into the small intestine, it stimulates the pancreas to produce bicarbonate, which counteracts the acidity of the chyme.
Cholecystokinin stimulates the gallbladder to release bile.
The sarcolemma is visible through the swelling of the nuclei.
The myosin molecule has a head at one end.
An array of myosin molecule have protruding heads.
Actin and myosin are arranged side by side within the myofibril.
Skeletal muscle is striated by the pattern of the overlapping filaments.
The actin and myosin are separated by the Z-line.
The myosin head is put into a high energy state when the myosin head is hydrolysis of ATP.
Ca2+ binding to the troponin molecule causes tropomyosin to expose positions on the actin filament for the attachment of myosin heads.
The myosin heads bind actin to form cross bridges when attachment sites are exposed.
This causes a change in the shape of the myosin head from its high-energy state to its low-energy state, which causes a sliding movement of the actin toward the center of the sarcomere.
The Z-lines are pulled together, contracting the muscle fiber.
The cross bridges are unbinded.
The cross bridge between the actin and myosin breaks when a new molecule is attached to the myosin head.
Without the addition of a new molecule, the cross bridges are still attached.
The corpses are stiff because of this.
The neurotransmitter acetylcholine diffuses across the synaptic cleft when an action potential of a neuron reaches the neuromuscular junction.
The sarcolemma hasreceptors that initiate a depolarization event.
Ca2+ is released by the sarcoplasmic reticulum.
Ca2+ is released by the sarcoplasmic reticulum as a result of the action potential.
Myosin crosses bridges.
The Ca2+ released by the sarcoplasmic reticulum causes tropomyosin to expose binding sites for myosin cross-bridge formation.
muscle contraction begins if the ATP is available.
Smooth muscle does not have the striated appearance of skeletal muscle due to its arrangement of actin and myosin.
The sarcolemma doesn't form a system of tubules, and as a result, contraction is controlled, which is appropriate for its function.
The cardiac muscle is branched and has cells connected by gap junctions.
The action potential of cardiac muscle is generated by electrical connections between the gap junctions.
A review of the material presented in this chapter is provided by the questions that follow.
They can be used to evaluate how well you understand the concepts.
AP multiple-choice questions are often more general, covering a broad range of concepts.
The two practice exams in this book are for these types of questions.
Four possible answers or sentence completions are followed by each of the following questions or statements.
The one best answer or sentence is what you choose.
There is no movement of Na+ across the ion channels.
With respect to the inside, the outside becomes more negative.
In some areas of the human circulatory system, arteries branch into capillaries, then branch into veins a second time, before merging again into veins and returning to the heart.
The actin binding sites are exposed by Tropomyosin.
The myosin is bound to the myosin.
Ca2+ is released by the sarcoplasmic reticulum.
The questions that follow are typical of an entire AP exam question or just that part of a question that is related to this chapter.
There are two types of questions on the AP exam.
It takes about 20 minutes to answer a long free-response question.
Sometimes they offer you a choice of questions to answer.
6 minutes is the time it takes to answer a short free-response question.
diagrams can be used to supplement your answers, but a diagram alone is not adequate.
White blood cells are attacked by the human immunodeficiency virus.
Explain in three or four sentences why it's hard for the immune system to defend against HIV.
People are thirsty when they eat salty foods.
Explain why in three or four sentences.
Each event requires the recognition of a molecule.
Target cells are capable of recognizing hormones.
B cells recognize something.
The neurotransmitters are recognized by the postsynaptic membranes.
How a feedback mechanism contributes to the maintenance of homeostasis is one of the following topics.
The arteries and veins in the legs of wading birds and in the fins and tails of marine mammals are close together so that heat transfer from outgoing arteries to incoming veins is maximized.
The direction of blood flow through the vessels in the gills is different to the direction of the water.
The loop of Henle maximizes the effect of the concentration gradients.
CO2 enters erythrocytes where it is converted to carbonic acid.
H2CO3 diffuses back into the plasma.
There are small air sacs in the lungs.
The arteries that carry blood from the heart to the lungs are called the pulmonary arteries.
The contraction of the left ventricle maintains systolic blood pressure.
Blood pressure is maintained by the semilunar valve in the aorta when the left ventricle relaxes.
There are double capillary beds in the glomerulus and the capillaries that surround the loop of Henle.
Don't confuse excretory and digestive functions.
The absorbable molecule is broken down by the digestive system.
Most of the feces consist of undigested food andbacteria that never entered the cells of the body.
The stomach is a hole that goes through the body.
It is similar to skin in that it protects the body's outer surface.
The hole in the donut is not really part of the donut.
As the filtrate moves up the limb, the concentration of solutes in the filtrate increases.
When it moves down the duct, it is most concentrated.
Antidiuretic hormone increases the amount of water in the kidneys and makes urine more concentrated.
The duodenum of the small intestine is the only place in the body where digestion takes place.
There are polypeptides in the stomach.
When cAMP stimulates the activity of specific enzymes, hormones are initiated in certain target cells.
The sarcoplasmic reticulum is stimulated when a neuron stimulates a muscle.
The binding sites on the actin are exposed by the Ca2+.
HIV is different from other viruses because it attacks white blood cells.
The production of additional T cells, killer T cells, and B cells is stimulated when helper T cells become infections.
As the number of T cells increases, more of them become HIV positive.
The destruction of most T cells allows the proliferation of diseases such as pneumonia and skin cancer.
Salt is absorbed into our circulatory system when we eat salty foods.
The osmolarity of the blood increases and it affects the solute gradient between intercellular and cellular fluids.
The hypothalamus causes the kidneys to conserve water by concentrating urine when there is a change in the blood.
The brain gets a message of thirst from the hypothalamus.
There are two ways in which cells recognize hormones.
The steroid hormone diffuses through the nuclear envelope and into the nucleus in cells that recognize it.
Specific genes are activated by these receptors.
If the hormone is a peptide, it can bind to a special receptor.
The production of a second messenger is triggered by the conversion of ATP to cAMP, which in turn is activated by a particular cellular function.
B cells have a special function.
In the production of B cells, millions of combinations of genes are used to make B cells with different kinds of receptors.
The B cell will be the only one that will be bound to the specific antigen.
When this happens, B cells grow and produce the same cells that have the same receptors.
The antigens are released into the body fluids as antibodies, which bind and inactivate them.
When a neurotransmitter, such as acetylcholine, is released by the presynaptic membrane, it diffuses across the synaptic cleft to the postsynaptic membrane.
The neurotransmitter binding to a specific receptor on the postsynaptic membrane is what causes it.
An excitatory postsynaptic potential can be caused by an influx of Na+ or an efflux of K+, depending on the type of postsynaptic membrane.
The question requires you to address similar mechanisms.
The AP exam uses this kind of question to evaluate your knowledge.
There are three answers, all of which involve the plasma membrane.
Each time you indicate that the plasmamembrane is involved, you will receive points.
You should first state whether the feedbackmechanism is positive or negative.
Explain how a deviation away from the normal range of values is detected, how the deviation is restored to normal, and how the action is terminated once normal has beentained.
Write down the mechanism that drives the condition to values further and beyond normal and what causes the mechanism to stop.
The information questions require you to demonstrate your knowledge of a specific area of human biology.
They don't require you to apply this knowledge to a new situation or to synthesise information from several areas.
Information questions are easy to answer because you don't have to think a lot, just remember as much as you can.
Your knowledge of the nervous, immune, and theendocrine systems is required by the AP exam according to the introduction to this chapter.
Specific questions about these systems can be found in multiple-choice and free-response questions.
You can use a system as an example in a broad free-response question if you understand the processes involved.
The exam may use any of the organ systems to evaluate your understanding oflab processes or your ability to demonstrate scientific inquiry and reasoning, so an understanding of all the systems will work in your favor.