BIO 461 - Exam 1 - CV System PowerPoint

Question 1

What is the function of the cardiovascular system?

Answer 1

To transport materials among the organs of the body, in a manner to ensure organs, regardless of location, receive supplies and eliminate waste as required for their current needs.

Question 2

What is being transported?

Answer 2

• water
• oxygen (needed for aerobic metabolism)
• carbon dioxide (waste product produced by aerobic metabolism)
• components for immune function
• hormones
• electrolytes
• clotting components
• proteins (for delivery of materials and osmotic balance)
• nitrogenous waste

Question 3

How is this done?

Answer 3

Artery: Transfer blood away from the heart. No permeable wall; whatever enters the artery is the exact same component at the end of the cycle. Nothing can leave the blood.

Veins: Transfer blood back to the heart. Also, not permeable.

Capillaries: Where the transfer between the cardiovascular system, from the blood to the cells occurs. This is where you get movement of those materials.

Right Atrium and Left Atrium receive blood from the body.

Right Ventricle and Left Ventricle are the pumping chambers.

Question 4

What are the delivery networks in a mammalian cardiovascular system?

Answer 4

• pulmonary circuit: short, only to lungs.
• systemic circuit: long, to all other tissues.
• arteries / arterioles: transport blood from heart; impermeable walls.
• veins / venules: transport blood to heart; impermeable walls.
• capillaries: transfer of materials between blood and cells.

Question 5

What are the 2 purposes of having a complete septum?

Answer 5

1. So, blood cannot get from one side to the other; the problem if that happens is that it is not going through the circuit. You may have poorly oxygenated blood coming back from the body. A more relevant role involves pressure.
2. It enables you to have two different pressure systems.

Question 6

What is the difference between proximate and ultimate?

Answer 6

Ultimate explanations are concerned with why a behavior exists, and proximate explanations are concerned with how it works.

Question 7

Why are animals shaped the way they are?

Answer 7

Systemic circuit must pump blood to your extremities and often against gravity. This is why animals are shaped the way they are.

Question 8

Why is there low pressure in the right ventricle?

1 Proximate and 1 ultimate reason

Answer 8

Proximal reason: has thinner muscle vs left side.

Ultimate reason: shorter distance. If you put a big, massive pump there, it makes things worse. If you take a car tire pump to fill up a balloon, it is going to pop. High demand and farther travel require a high-pressure system.

Question 9

What does a valve do?

Answer 9

Prevent backflow. It does not determine when things are open or not, that is a sphincter. Valves affect the direction of flow, so that it only goes one way. Between atria and ventricles and valves between the ventricles and pulmonary artery and aorta.
The majority of your blood filling occurs when the heart is at rest. Atrial systole is where the atria contract, and the blood in the atrium is going to squeeze the ventricle.

If you are going to choose a chamber in your body for your heart to fail, the atria is the one to choose. If you have ventricular problems, in terms of contractions, blood cannot leave the heart.

Question 10

Definitions for:

Stroke volume
End diastolic volume
End systolic volume
Cardiac output
Flow

Answer 10

Stroke Volume: how much blood is pumped out of the heart in one beat.

End diastolic volume: The volume at the end of diastole (the end of the filling of the heart before it begins contracting).

End systolic volume: The amount of blood at the end of systole (the end of the contraction, where most of the blood goes into circulation).

Cardiac Output: Amount of output from the heart per minute. Cardiac Output = Stroke Volumes X Heart Rate

Flow: A change in blood pressure (from high pressure to low pressure). The difference in blood pressure between the source and where it’s going divided by resistance to that flow.

Question 11

Why does the right ventricle have lower pressure? (proximate and ultimate reasons)

Answer 11

p: thinner muscular wall
u: 1) shorter distance
2) to avoid damage to lung tissue

Question 12

Why does the left ventricle have higher pressure? (proximate and ultimate reasons)

Answer 12

p: thicker muscular wall
u: high demand, farther travel, & often against gravity

Question 13

What are the equations for:

Stroke Volume

Cardiac Output

Flow

Answer 13

Stroke Volume = End Diastolic Vol – End Systolic Vol

Cardiac Output = Stroke Volumes X Heart Rate

Flow = ΔBlood Pressure / Resistance

Question 14

What are the 4 things that influence resistance?

Answer 14

(1) diameter of vessels (greater diameter = less resistance)
(2) length of vessels
(3) gravity
(4) viscosity of blood (how dehydrated you are).

Answer 15

Why you need a strong left ventricle depends on these things – how big is the resistance? If the resistance is not that great, you will not have a big pressure gradient, and do not need a strong left heart. The amount of resistance plays a lot in the design of the heart as we go across the different groups of animals.

Question 16

What do red blood cells do?

S:V ratio increase or decrease?

Answer 16

Transport oxygen. Empty bags of hemoglobin (binds oxygen). Increases surface to volume ratio. Something small has a lot of surface, but the volume is relatively small.

Question 17

Why does a red blood cell want a lot of surface area?

Answer 17

Gas diffusion

Very small, high surface to volume ratio, increases transport of oxygen into the cell, and therefore, at the rate to which you can load hemoglobin.

You have to get the oxygen across from the lungs to the plasma, and then move across the cell membrane and bind to hemoglobin before more oxygen can dissolve in (no longer O2 but oxyhemoglobin).

Question 18

Why does a red blood cell have a bi-concave shape?

Answer 18

It looks like a do-nut with the middle not completely gone. It looks like an inflatable raft.
1. The function is very similar: by being curled in, there is more surface area than if it were flat (increases surface area).

2. It also increases flexibility in the bloodstream against high flow rates. By being flexible, they do not damage easily (wooden boat vs inflatable raft example – pressure on the wooden boat causes it to break). The bi-concave shape adds flexibility that is necessary if there is really high flow.

There is not nucleus or organelles. They are a cell membrane full of hemoglobin.

Question 19

Red blood cell: What is the advantage of not having a nucleus or organelles?

Answer 19

(1) Mitochondria and DNA do work, which takes energy and oxygen. They are going to use some of the oxygen being transported, which means you would not be delivering as much.

It reduces the metabolism of the cells / demand of the cell for oxygen, so it can deliver more.

(2) More room for hemoglobin

Question 20

Red blood cell: What is the disadvantage of not having a nucleus or organelles?

Answer 20

It cannot repair itself. There are no repair mechanisms – require proteins that require transcription that requires DNA, and DNA means you have a nucleus. Half life of a red blood cell is short.

Question 21

Why is there only one type of red blood cell but different types of white blood cells?

Answer 21

The role of the red blood cells is to carry oxygen. One role = one cell type. Most cells have only one function that they can do. White blood cells are part of the immune system, and part of your defense against pathogens (bacteria, viruses, parasites, foreign bodies like splinters) that can be delt with using different cells that have different functions.

Question 22

What does a platelet do?

Answer 22

They help with stopping bleeding. Involved in sealing-up damage to the vessels. Bricks like in a wall, and the mortar is made of poly-factors.

Question 23

What is the role of plasma?

Answer 23

Carries everything (nutrients, ions, enzymes, hormones, cells).

Answer 24

If you do not have a complete septum, you do not have a high-pressure side, which means you are not going to be able to fight an enormous amount of resistance. A complete septum is critical for the pressure difference, which is critical for the shape of the organism (tall, long) and for the demands of the cells (high demand for verticality = high demand for pressure – high pressure needs a complete ventricular system so you do not blow out the lung).

Flow = Δ Blood Pressure / Resistance.

Question 25

What is the primary ultimate determinant of flow rate?

Answer 25

The demand of tissues. The more demand they have, the more flow they need.

Question 26

What are the 4 things that influences resistance?

Answer 26

(1) diameter of vessels
(2) length of vessels
(3) gravity
(4) viscosity of blood.

Question 27

What two things does a complete ventricular septum do for your heart?

Answer 27

(1) It can differentiate pressure. Left side of the heart (systemic circuit) could be much higher pressure than the right. If you do not have a compete septum, when they both squeeze, it is going to move from the right to the left to a lower pressure.

(2) Keeps the circuits separate, preventing backflow and preventing blood from the right side of the heart from going to the left side (blood will not get oxygenated – it will not go to the lungs – maintains a greater oxygen differential between the two sides).

Pectoral fins are close to the heart. Does not take much energy.

Question 28

Ultimate reason why don’t fish need a 2-circuit system?

Answer 28

• low metabolic rate
• horizontal body shape

Question 29

Proximate reason why do fish need only a 2-chambered heart?

Answer 29

It is only a one-circuit system. One receiving chamber and one pumping chamber. Only having one circuit needs one of each. Goes from the heart to the gills (where they pick up oxygen) and instead of going back to the body to be pumped, it can go through the gills (low pressure system to not damage the gills) and continue to whatever capillaries they need to go to before going back.

Lungfish: They have two vascular circuits, one that can go to the gills and the whole body, and another one will go though the gills, to the lungs, and back to the heart.

Question 30

How does having gills & lungs change delivery network?

Answer 30

Two sources of blood come into the heart, from the lungs (pulmonary and systemic veins). They have a septum in the atrium (the two are separated – deoxygenated blood coming from the body that is separate from the oxygenated blood coming from the lungs). They have a partial ventricular septum; it is not complete (partial wall). They are not able to create a high pressure and low pressure; the gap in-between is going let the pressure equalize. There is some mixing – blood that is coming back oxygenated can cross over to the other side of the heart, and some of the blood from the other side of the heart can mix with the other side. The spiral fold helps guide blood that comes back oxygenated is mostly going to be sent to the brain, bypass the gills and lungs, due to just coming back from the lungs, and blood that came back from the body is going to the gills to be oxygenated for the lungs to be oxygenated.
It is a low-pressure system – you do not want to send blood somewhere that you do not need to send it.

Peripheral vasoconstriction and vasodilation control where the blood is going. If you do not need a lot of flow somewhere, you can cut that down so there is more blood flow somewhere else. Humans have a very high tissue demand.

Vasomotor – movement or altering the diameter (vasoconstriction and vasodilation) of the vessels going to the lungs. They can contract this part of the pulmonary artery to limit how much blood flow there is to the lungs. If they are underwater, they do not need a flow. Keep flow going to the dorsal aorta. There is not a dedicated circuit.

Question 31

Why don’t lungfish have a 4-chambered heart (i.e., complete ventricular septum)?

Answer 31

If this was a complete 4-chambered heart with no mixing of the ventricle, no blood from the lungs means that no blood is going to the brain.

Having an opening between the ventricles, it makes mixing of the blood, and enable the blood coming back will go to the gills to be oxygenated, and blood will pump forward. You are going to ensure that, even though you are shutting down flow to the lungs, saving flow for other tissues, you are still ensuring blood is going to the brain, by having this incomplete septum. It gives the animal options.

Question 32

Why do lung fish have gills & lungs?

Answer 32

Avoid predation.

They can live in murky, low-oxygen water. They can estimate; the water they live in can dry up, and as the mud is still soft, they dig down into the mud and create a mucous cocoon (so they do not lose much water in the environment) with a breathing tube. The pond is now dry.

Question 33

Why do lung fish live in a pond that dries up?

Answer 33

There is less competition for food and lack of predators.

Question 34

Slide 10

Question 35

Amphibians: Why breathe through the skin then?

Answer 35

To get oxygen while underground or in water. Sitting on the bottom of a pool of water does not take much oxygen, and they can get that through their skin. It is move expensive to use muscles to breathe air into the lungs than let your skin sit out in the open. They are low-energy experts.
Using only cutaneous breathing (not going to the lungs): if they are not sending blood to the lungs, no blood is coming back through the pulmonary vein to the heart. The white line is gone. No flow from the vein, coming into the atrium. Because flow is coming in from the other side (right atrium, not the left atrium) this septum through the atrium is going to get pushed over. Pressure differences move it over, causing a change in the routing of the blood. It will push the septum and cover the opening of the pulmonary artery. The blood that just came back from the body is going to go back to the body, due to the fold covering over the opening to the pulmonary artery (so nothing comes to and from the lungs).

Question 36

Amphibians: How does it get oxygenated?

Answer 36

It goes to the skin. The blood in the systemic circuit that goes underneath the skin is going to pick up oxygen and circulating.

Question 37

Why does a frog cardiovascular system work for itself?

Answer 37

The idea of no complete septum enables them to shift from a two-circuit system to a one-circuit system. With a complete septum, this would not be possible. Low pressure – you do not want to send blood where you do not need it.

Question 38

How does a tadpole’s cardiovascular system change?

Answer 38

A tadpole’s cardiovascular system is going to be more like a fish, because it is behaving more like a fish (single circuit, two-chambered heart, going to the gills to the body and back to the heart). As they get into land, they develop a dual-circuit. The ventricle split in half, there is another septum, you have another circuit, multiple vesicles coming and going. This happens while the animal is still active and moving around, rather than a caterpillar being in a cocoon and turning into a butterfly.

Question 41

Why have the Foramen of Panizza?

Answer 41

When the animal is breathing, taking in oxygen to be delivered to the body, we want blood flow to go to the lungs to pick up the oxygen. When the heart contracts, blood is going to the lungs and to the aortic arches to deliver to the systemic circuit with higher blood flow on the left side (stronger left ventricle). Because the flow is higher on the left side, when we get to the connecter, we get flow going straight, but also flow going into the left aortic arch. The aorta on the right side of the heart does not have as much pressure, plus it is being divided into two outputs that prevent much more flow of forceful blood. By having an open Foramen, we can move some of the blood coming out of the left ventricle to the right aortic arch, and balance the flow between the two aortas.

When the animal is under water, the animal closes the sphincter, preventing any blood from the right side of the heart to go to the lungs – why waste blood flow when there is no oxygen to pick up? Closing flow to the pulmonary artery will stop flow from the pulmonary vein. Therefore, no blood will go to the left ventricle. If they did not have this Foramen (connector), there would be no flow to the right aorta (no flow to the head or body). The connector allows blood from the right side to flow to the right aorta and to the head and body. The blood is deoxygenated, but it is underwater, doing nothing. There is not a high demand for oxygen.

Question 42

What is the Ductus Arteriosus?

Answer 42

a connector between the right side (pulmonary artery) (lower pressure, deoxygenated blood), and the aorta (higher pressure, oxygenated blood). This connecter can bypass the lungs, instead of going to the pulmonary artery.

Question 43

Birds

Answer 43

Have a complete atrial septum. Every group has a complete atrial septum that we have talked about. It does have a complete ventricular septum. It has lost its left systemic artery and aorta – kept right systemic artery (greater diameter). Mammals got rid of the right and kept the left (convergence).

Question 44

Birds

What is the advantage of only having one aortic arch?

Answer 44

There is less resistance, due to greater diameter of the vessel (decrease pressure), lower resistance then two smaller ones. A high-demand endotherm, high moving activity, there needs to be a lot of blood moving with less resistance.

Question 45

Birds

Why have a four-chambered heart with no potential for mixing?

Answer 45

(1) Birds always have a high-energy and oxygen demand. They need to breathe continuously – you do not need alternative flow patterns.
(2) They also need high flow to the organs throughout the body. They need high pressure to the non-lung organs, but low pressure to the lungs.

Answer 46

Coronary vessels: There are two primary coronary arteries, the right coronary artery (RCA) and the left main coronary artery (LMCA). Both originate from the root of the aorta. The RCA emerges from the anterior ascending aorta and supplies blood primarily to the right atrium, right ventricle. Vessels on the outside of the heart and capillaries that dive down into the heart to provide with well-oxygenated blood. If you block one of the major vessels, it is called a heart attack (coronary blockage).

Fish: do not have a high-demand on their cardiac muscles. Most fish can get enough blood to the cardiac muscles by having pockets in the ventricle that let blood penetrate into the heart. In mammals, it comes from right where as the aorta leaves the left ventricle. When blood leaves the ventricle of a fish, it is lower-oxygenated blood (one circuit to the gills to the tissues). If you are a fast-moving fish, high activity, you do not want to give your heart low-oxygenated blood.

Question 47

Where would you put the origin of the coronary arteries?

Answer 47

Oxygen is highest in the blood right after the gills instead of at the base of the heart for fast-swimming fish, not for slower fish. Affects resistance rather than distance (ΔP).

Question 48

Amphibians have no coronary vessels; why?

Answer 48

Amphibians sit around and do nothing. The heart does not need to work hard and does not need a lot of oxygen.

Question 49

Coronary circulation between species?

Question 50

3 reasons why smaller animals typically have higher heart rates?
(1) higher ______ ______ on a per gram basis
(2) smaller hearts mean ______ ______ ______
(3) maintain ______ ______ by increasing HR

Answer 50

(1) higher metabolic rate on a per gram basis
(2) smaller hearts mean lower stroke volume (SV X HR = CO)
(3) maintain CO by increasing HR

Question 51

Why do birds typically have higher heart rate than similarly sized mammals?

(1) higher resting ______ ______
(2) higher ______ ______ ______
(3) therefore require 5-7X the ______ ______ (also due to RBC morphology)

Answer 51

(1) higher resting metabolic rate
(2) higher peak energy demand (i.e., fight)
(3) therefore require 5-7X the tissue perfusion (also due to RBC morphology)

It is not because they have lower stroke volume than mammals. They just have a higher demand and need more cardiac output, so heart rate needs to be higher. Stroke volume is similar between the two.

Question 52

Why are pulmonary pressures so low?

Answer 52

Respiratory membranes are delicate.

Because they go to the lungs. We do not want to damage the tissue you have for respiratory memory. It is also very close; you do not need high pressure to travel short distances.
Mammals and birds have a lower pressure than the other groups. How would you explain that? Birds and mammals have a greater oxygen demand. To get more oxygen across the membrane, it needs to be thinner and more fragile than other animals. Extremely fragile pulmonary (vessels) membranes, so they are going to have very low pulmonary pressures.

Question 53

Why do mammals and birds need lower pulmonary pressures (proximately & ultimately)?

Answer 53

Proximately:
- thinner respiratory membranes so more delicate

Ultimately:
- higher metabolic rate & sustainable activity levels require higher respiration (i.e., gas transfer) rate, which requires thinner barriers to gas flow

Question 54

Why do birds & mammals have much higher systemic pressures (both proximately & ultimately)?

Answer 54

Proximately:
- complete ventricular septum in heart enables an interventricular pressure difference.
- better developed coronary arteries allow for a stronger heart (stronger contractions).

Ultimately:
- higher resting metabolic rate and peak aerobic activity requires more blood flow.
- more verticality imposes the need to deal more with gravitational forces.

Question 55

What is the pulmonary pressure going to be in a crocodilian?

Answer 55

There lungs are near the heart, so it will be comparative to the other animals on that list. Their lungs have reasonable thin respiratory membranes, compared to other tissues.

Question 56

What would you predict for the systemic circuit in a crocodilian?

Answer 56

They are not vertical, so they do not need to be on a bird & mammals’ level. To have a sustainable aerobic capacity, they cannot be amphibians either.

Question 57

Why can they be higher systemic than pulmonary?

Answer 57

They have a complete ventricular septum. The only groups that have a dramatic difference.
Fish do not have a pulmonary circuit because they do not have lungs.

Question 58

How are RBCs different?
Implications of having a nucleus?

Answer 58

• reduces proportion of space for hemoglobin (Hgb)
• increases cell metabolism
• limits cell flexibility
• enables longer cell life

Question 59

Implications of larger size RBCs?

Answer 59

(1) more cytoplasm
(2) reduced Surface: Volume ratio – you must move oxygen from plasma into the cell. The rate of that is dependent on how much surface red blood cell you can move.
(3) oval shape: Why does a larger RBC need to be oval rather than round? To fit inside the capillaries.

Question 60

How do birds tolerate nucleated RBCs?

Answer 60

(1) larger size → more space for Hgb
(2) different Hgb biochemistry

Question 61

Hemoglobin-oxygen dissociation curve:

Answer 61

The amount of oxygen that is bound to the red blood cell (hemoglobin). How much oxygen is in the environment. The ability for red blood cells (hemoglobin) to bind to oxygen. It is not just how many do I have, but what is the oxygen concentration. The more concentrated the environment is, hemoglobin has a higher affinity for oxygen and bind more. High oxygen content in the pulmonary capillaries of the lungs.
Delivery of oxygen is not the same as carrying capacity. The blood not only has to carry the oxygen, it needs to drop it off. How much oxygen it drops off vs. how much it comes back with is based on the affinity of the hemoglobin molecule for oxygen.