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42 Cards in this Set

  • Front
  • Back
Cardiac cycle
The contraction and relaxation of the heart in a rhythmic cycle
Systole
The contraction, or pumping, phase
Diastole
The relaxation, or filling, phase
Autorhythmic
Cardiac muscle cells that contract without any signal from the nervous system
Purkinje fibers
Specialized fibers that conduct signals for contraction in ventricle walls
AV node
Atrioventricular node, delays impulses from the Sinoatrial (SA) node so that the heart may fill with blood
Blood pressure
Hydrostatic pressure that blood exerts against the wall of a vessel
Pulse
Rhythmic bulging of artery walls with each heartbeat
Systolic pressure
Pressure in the arteries during ventricular systole; highest pressure in the arteries
Diastolic pressure
Pressure in the arteries during diastole; lower than systolic pressure
Lymph
Fluid within the lymphatic system (returns water and proteins back to the circulatory system)
LDL
Low-density lipoproteins are associated with plaque formation; “bad cholesterol”
HDL
High-density lipoproteins reduce the deposition of cholesterol; “good cholesterol”
Tidal volume
Volume of air inhaled and exhaled with each breath
Vital capacity
Tidal volume during maximum inhalation and exhalation
Residual volume
Air that remains after forced exhalation
Natural selection has resulted in two general solutions to the limitations of the diffusion process, what are they?
Body size and shape keeps cells in direct contact with the environment (Sponges, cnidarians, flatworms)
Transport systems connect the organs of exchange with the body cells (Complex animals, uses systems that circulate fluid)
List the differences and similarities between open and closed circulatory systems. Which is the most energy efficient? Which is the most effective in delivering O2 to the tissues?
Open circulatory systems have fluid bathe the organs directly. The circulatory fluid is the interstitial fluid. Closed circulatory systems have blood confined in vessels. Blood is distinct from interstitial fluid. Open circulatory systems are more energy efficient, as they have lower hydrostatic pressure. Closed circulatory systems have higher pressures, therefore making O2 delivery to tissues more efficient.
List the three main types of blood vessels and distinguish among them.
Arteries: Carry blood to capillaries, away from heart.
Veins: Carry blood away from capillaries, return to heart.
Capillaries: Sites of chemical exchange between the blood and interstitial fluid.
The hearts of all vertebrates contain two or more muscular chambers, what are they?
Atria: Chambers that receive blood
Ventricles: Chambers that pump blood out of the heart
How do single and double circulation differ? What is the advantage of the latter?
Single circulation has blood pass through the heart, travel to the gill capillaries and then straight to the body capillaries. This method causes very low blood pressure. Double circulation has a single heart with two atria and at least one ventricle. The blood first passes through the lung capillaries where it is oxygenated and then travels back into the heart to be pumped to the body capillaries. The return to the heart boosts blood pressure, and a higher blood pressure allows for more oxygenated blood to pass through the body tissues in a shorter amount of time than it takes for a single circulation.
How do the hearts of amphibians and non-avian reptiles differ from those of birds and mammals?
Amphibians and non-avian reptiles have hearts that are either undivided or only partially divided (3 chambers). The completely divided heart of birds and mammals (4 chambers) ensures that only oxygenated blood leaves the heart for the body and that only oxygen poor blood travels from the heart to the lungs.
For circulation in mammals, list the sequence of events in order beginning with the contraction of the right ventricle.
1. Right ventricle contracts: Pumps blood to the lungs via pulmonary artery
2. Lungs: Blood takes in oxygen and unloads carbon dioxide
3. Left atrium: Oxygen-rich blood has left lungs via pulmonary veins and entered left atrium
4. Left atrium to ventricle: Blood flows from left atrium to left ventricle
5. Left ventricle: Pumps oxygen-rich blood to the body and heart muscles itself via the aorta
6. Right atrium: Oxygen-poor blood has returned to the heart via the superior vena cava and inferior vena cava
What are the AV and semilunar valves? Where are they found and what do they do?
The atrioventricular valves separate each atrium and ventricle. The semilunar valves separate the left ventricle fro the aorta and right ventricle from the pulmonary artery. These valves prevent backflow of blood into the heart.
What is a heart murmur?
A heart murmur is a backflow of blood through a defective valve.
What is cardiac output and how is it calculated? If an individual has a cardiac output of 4.6 L/min and a heart rate of 65 beats/min what is their stroke volume?
Cardiac output is the volume of blood pumped into the systemic circulation per minute. Depends on both the heart rate and stroke volume. It is calculated by dividing the amount of blood, often in liters, by the time. Cardiac output=SxH Stroke volume=.071 L or 71 ml
What is the function of the SA node?
The sinoatrial node sets the rate and timing at which cardiac muscles cells contract. It is a “pacemaker”.
What are the three types of input that can influence the rhythm of the SA node?
The SA node is influenced by nerves, hormones, body temperature, and exercise.
Know the differences in structure and function of the capillaries, arteries and veins.
Capillaries
Structure: Thin walls made of endothelium and its basal lamina. Smallest diameter. Largest surface area.
Function: Where exchange of materials takes place.
Arteries
Structure: Thick walls made of an endothelium, smooth muscle, and connective tissue.
Function: Transport blood away from heart towards capillary beds.
Veins
Structure: Thin walls made of an endothelium, smooth muscle, and connective tissue.
Function: Return blood to heart away from capillary beds.
Why is blood flow slowest in the capillary beds? Why is this reduction in flow rate of benefit to the organism?
Blood flow is slowest in the capillary beds due to high resistance from the small diameters of the capillaries and the large size of the beds. Slowing the flow rate allows for a longer transfer of substances between the blood and interstitial fluid.
What is the relationship between vasodilation, vasoconstriction and blood pressure? If vasodilation to the capillary bed in the skin occurs (for example when entering an overly hot room) what should happen to the systemic blood pressure? Why does this not occur?
Vasoconstriction, the contraction of smooth muscle in arteriole walls, increases blood pressure. Vasodilation, the relaxation of smooth muscle in the arterioles, decreases blood pressure. Vasodilation should make the blood pressure drop significantly, however cardiac output increases to ensure that the pressure is maintained to have the necessary amount of blood flow.
What is the effect of gravity on blood pressure?
Additional pressure is necessary to push blood back up to the heart. This increases the pressure.
How is blood pressure in humans measured?
A rubber cuff inflated with hair is first used to stop the blood from flowing through the artery. As the cuff is slowly deflated, blood will begin to slowly trickle back through the artery. When the sound of the blood first flowing back through the artery is heard, the pressure of the air in the cuff is recorded. This is the systolic pressure. Once the sounds can no longer be heard, this pressure is also recorded. This is the diastolic pressure.
What are the mechanisms that assist in the return of venous blood to the heart?
Rhythmic contraction of smooth muscles in the walls of venules and veins.
Contraction of skeletal muscle.
Expansion of vena cavae and other large veins during inhalation.
How is blood flow in capillary beds controlled?
It is controlled by the contraction of the smooth muscle layer in the wall of an arteriole adjoining a capillary bed. This reduces the diameter of the arteriole and decreases the amount of blood that enters the capillary bed. The action of precapillary sphincters at the entrance of capillary beds also decreases the blood flow by regulating how much blood may enter the capillary beds.
What is the relationship between blood pressure and osmotic pressure with respect to the movement of fluids between the capillaries and interstitial fluid?
Higher blood pressure drives fluid out of the capillaries and into the interstitial fluid, while higher osmotic pressure pulls fluid back from the interstitial fluid into the capillaries.
What is the role of the lymph system in maintaining fluid balance?
The lymphatic system returns water and proteins back to the circulatory system. These proteins increase the osmotic pressure, which can help with the loss of fluid due to blood pressure.
What is atherosclerosis and how is it caused?
Artherosclerosis is the hardening of the arteries. This hardening increases the resistance of blood flow. It is caused by a build-up of plaque deposits in the arteries.
What is LDL and HDL? How do environmental factors influence their relative proportions in the body?
LDLs are low-density lipoproteins associated with plaque formation. They are known as “bad cholesterol”. HDLs are high-density lipoproteins associated with reducing the deposition of cholesterol. They are known as “good cholesterol”. Exercising increases blood flow which inhibits plaue buildup, smoking decreases HDL, and foods with trans fat increase LDL.
What are the major components of the lungs?
The respiratory system consists of the pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.
What is the role of surfactants in breathing?
Surfactants are secretions required to relieve surface tension in the alveoli. This prevents them from collapsing, which would block the entrance of air.
What is meant by “negative pressure breathing” and how is it accomplished in humans?
As an animal’s diaphragm and rib muscles contract, this expands the thoracic cavity. This expansion creates a negative pressure, pulling air in from outside the cavity. This is the method used in humans, and while humans can voluntarily inhale and exhale, breathing is still regulated by neurons in the medulla and pons.