Circulation and Gas Exchange

Question 1

Circulatory systems link exchange surfaces with

Answer 1

cells throughout the body.

Question 2

Coordinated cycles of heart contraction drive

Answer 2

double circulation in mammals.

Question 3

Patterns of blood pressure and flow reflect the structure and arrangement of

Answer 3

blood vessels.

Question 4

Blood components function in

Answer 4

exchange, transport, and defense.

Question 5

Gas exchange occurs across

Answer 5

specialized respiratory surfaces.

Question 6

Breathing ventilates the

Answer 6

lungs

Question 7

Adaptations for gas exchange include

Answer 7

pigments that bind and transport gases.

Question 8

Why are gas exchange and circulation linked in multicellular organisms? What’s the deal for a unicellular organism?

Answer 8

direct transfer of materials between every cell and the environment is not possible. Instead multicellular rely on specialized systems that carry out exchange and the rest of the body;
Unicellular exchange occurs directly with the external environment

Question 9

What’s going on with axolotl?

Answer 9

tiny blood vessels lie close to the surface of each filament in the gills. Across the surface, there is a net diffusion of O2 from the surrounding water into the blood and of CO2 from the blood into water. The short distances involved allow diffusion to be rapid. Pumping of the hear propels the o2 rich blood from the gill filaments to all other tissues of the body. There more short range exchange occurs, involving nutrients and o2 as well as co2 and other wastes

Question 10

O2 and CO2 (and other small nonpolar molecules) can move between cells and their immediate surroundings by

Answer 10

diffusion

Question 11

What are the limits of diffusion? How long does it take for a substance to diffuse from one point to another? Why does this put a substantial constraint on the body plan of any animal?

Answer 11

very slow for distances more than a few millimeters;
time it takes is proportional to the square of the distance;
Cannot diffuse as quickly as it needs to over big areas

Question 12

Natural selection has resulted in two general solutions to the diffusion problem. What are they?

Answer 12

A body plan that places many or all cells in direct contact with the environment;
A circulatory system

Question 13

How are the organisms the moon jelly Aurelia and the planarian Dugesia able to get nutrients (including oxygen) to their cells and get wastes (including carbon dioxide) away from their cells?

Answer 13

a central gastrovascular cavity functions in the distribution of substances through the body

Question 14

What are the basic component of a circulatory system?

Answer 14

a circulatory fluid, a set of interconnecting vessels, and a muscular pump(the heart)

Question 15

What is the basic structure of an open circulatory system? What is the circulatory fluid? Is it distinct from the interstitial fluid?

Answer 15

the circulatory fluid, called hemolymph, is also the interstitial fluid that bathes body cells; Heart contraction pumps the hemolymph through the circulatory vessels into interconnected sinuses, spaces surrounding the organs. Within the sinuses, chemical exchange occurs between the hemolymph and body cells. Relaxion of the heart draws hemolymph back in through pores, which are equipped with valves that close when the heart contracts

Question 16

What are the advantages of an open circulatory system?

Answer 16

lower hydrostatic pressures make it less costly

Question 17

What is the basic structure of a closed circulatory system? What is the circulatory fluid? Is it distinct from the interstitial fluid?

Answer 17

a circulatory fluid called blood is confined to vessels and is distinct from the interstitial fluid. One or more hearts pump blood into large vessels that branch into smaller ones that infiltrate the organs. Chemical exchange occurs between the blood and the interstitial fluid, as well as between the interstitial fluid and body cells

Question 18

What are the advantages of a closed circulatory system?

Answer 18

high blood pressure, which enables the effective delivery of o2 and nutrients to the cells of larger and more active species; also well suited to regulating the distribution of blood to different organs

Question 19

What is another term for the closed circulatory system of humans and other vertebrates?

Answer 19

cardiovascular system

Question 20

What are the components of the cardiovascular system?

Answer 20

Arteries, veins, and capillaries

Question 21

What distinguished veins from arteries?

Answer 21

Arteries carry blood from the heart to organs veins carry blood back to the heart

Question 22

The hearts of all vertebrates contain two or more chambers. The chambers that receive blood entering the heart are called ________, and the chambers responsible for pumping blood out of the heart are called _________.

Answer 22

atria; ventricles

Question 23

tell me about single circulation.

Answer 23

blood passes through the heart once in each complete circuit through the body

Question 24

tell me about double circulation.

Answer 24

the pumps for the two circuits are combined into a single organ; one pump delivers oxygen poor blood to the capillary beds of the gas exchange tissues, where there is a net movement of O2 into the blood and of CO2 out of the blood; then this now oxygen rich blood enters the other pump contract of the heart propels this blood through the body

Question 25

What is the overall organization of the mammalian cardiovascular system? What is the path of blood around the body?

Answer 25

Contraction of the right ventricle pumps blood to the lungs via the pulmonary arteries. As the blood flows through capillary beds in the left and right lungs, it loads O2 and unloads CO2. Oxygen rich blood returns from the lungs via the pulmonary veins to the left atrium of the heart.. Next O2 rich blood flows into the heart's left ventricle via the aorta, which conveys blood to arteries leading thought the body. First branches to coronary arteries then to capillary beds in the head and arms. The aorta then depends into the abdomen, supplying o2 rich blood to the arteries leading to capillary beds in the abdominal organs and legs. With in the capillaries there is a net diffusion of o2 from the blood to the tissues and of CO2 into the blood. Capillaries rejoin, forming venues, which convey blood to veins. O2 poor blood from the head, neck and forelimbs is channeled into the superior vena cava vein. The inferior vena cave, drains blood from the trunk and hind limbs. they both empty their blood into the right atrium

Question 26

What is the overall organization of the mammalian heart?

Answer 26

Located behind the sternum Size of a clenched fist and consists mostly of cardiac muscles. The two atria have relatively thin walls and serve as collection chambers of blood returning to the heart from the lungs or other body tissues. Much of the blood enters the atria flows into the ventricles while all heart chambers are relaxed. Remainder is transferred by contraction of the atria before the ventricles begin to contract.

Question 27

What are the basics of a cardiac cycle?

Answer 27

When the heart contracts, it pumps blood; when it relaxes, its chambers fill with blood . one complete pumping and filling is the cardiac cycle

Question 28

What is cardiac output? What are the two factors that determine cardiac output?

Answer 28

the volume of blood each ventricle pumps per minute; heart rate and stroke volume

Question 29

Four valves in the heart prevent backflow and keep blood moving in the correct direction. What are these valves?

Answer 29

``` 2 Atrioventricular (AV) valve; 2 Semilunar valves ```

Question 30

steps involved in controlling heart rhythm.

Answer 30

Signals from SA node spread through atria; Signals are delayed at AV node; Bundle branches pass signals to heart apex; signals spread through ventricles

Question 31

The heartbeat originates within the heart itself. What are autorhythmic cells?

Answer 31

they can contract and relax repeatedly without any signal from the nervous system

Question 32

What is the sinoatrial node and what does it do?

Answer 32

Pacemaker, sets the rate and timing at which all cardiac muscle cells contract

Question 33

What is the atrioventricular node and what does it do?

Answer 33

other autorhythmic cells ; delays the impulses for about .1 sec; this allows the atria to empty completely

Question 34

What are the walls of capillaries like?

Answer 34

Very thin walls, which consist of just an endothelium and a surrounding layer called basal lamina

Question 35

As blood passes from arteries to arterioles to capillaries, what is happening to the velocity of the blood? Why?

Answer 35

It slows because the number of capillaries is enormous; the total cross-sectional area is much greater in capillary beds than in the arteries

Question 36

What does decreased velocity of blood flow (along with the thin walls of the capillaries) have to do with what is happening in capillary beds?

Answer 36

the vessels generate substantial resistance to flow

Question 37

What is systolic pressure?

Answer 37

When the heart contracts

Question 38

What is diastolic pressure?

Answer 38

ventricles are relaxed

Question 39

What is pulse?

Answer 39

the rhythmic bulging of the artery walls with each heartbeat

Question 40

Relatively high blood pressure is responsible for the movement of blood through arteries. But, blood pressure in veins is relatively

Answer 40

low

Question 41

What are the mechanisms that assist with the return of venous blood to the heart?

Answer 41

valves help maintain the unidirectional flow

Question 42

What’s the deal with smooth muscle in veins?

Answer 42

smooth muscles in the walls of venues and veins contract during exercise to help keep the unidirectional flow

Question 43

What’s the deal with exercise and skeletal muscle in veins?

Answer 43

if you stop exercising abruptly; the muscles stop contracting and not enough blood can return to the heart

Question 44

Blood pressure is very low in capillary beds, and capillaries lack

Answer 44

smooth muscle.

Question 45

What regulates blood flow through capillary beds?

Answer 45

constriction or dilation of the arterioles that supply capillary beds; or pre capillary sphincters

Question 46

What’s the deal with fluid exchange between capillaries and the interstitial fluid?

Answer 46

blood pressure tends to drive fluid out of the capillaries, and the presence of blood proteins tends to pull fluid back

Question 47

If there is a net loss of fluid from capillaries, what happens to it?

Answer 47

the lost fluid and proteins return to the blood via the lymphatic system

Question 48

What is the lymphatic system?

Answer 48

includes a network of tiny vessels intermingled among capillaries of the cardiovascular system, as well as larger vessels into which small vessels empty

Question 49

What is lymph?

Answer 49

the fluid lost by capillaries after it enters the lymphatic system by diffusion

Question 50

What are lymph nodes and what do they do?

Answer 50

small, lymph-filtering organs which play an important role in the body defense;

Question 51

Blood is composed of about 55% plasma and 45%

Answer 51

cellular elements.

Question 52

What are the components of plasma and what are their functions?

Answer 52

ions and proteins that, together with the blood cells, function in osmotic regulation, transport, and defense

Question 53

What are the cellular elements of blood and what are their functions?

Answer 53

leukocytes (white blood cells)- defense and immunity platelets- blood clotting erythrocytes (red blood cells)- transport o2 and some co2

Question 54

Cellular elements of blood have limited life spans. Where do new cells come from?

Answer 54

stem cells

Question 55

Cholesterol travels in blood plasma mainly in particles that consist of thousands of

Answer 55

cholesterol molecules and other lipids bound to a protein.

Question 56

What is low-density lipoprotein (LDL) and what does it do?

Answer 56

delivers cholesterol to cells for membrane production

Question 57

What is high-density lipoprotein (HDL) and what does it do?

Answer 57

scavenges excess cholesterol for return to the liver

Question 58

What’s the deal if your ratio of LDL to HDL is high?

Answer 58

individuals with a high ratio of LDL to HDL are at substantially increased risk for atherosclerosis

Question 59

What is atherosclerosis?

Answer 59

the hardening of the arteries by accumulation of fatty deposits

Question 60

What is a heart attack (myocardial infarction)?

Answer 60

the damage or death of cardiac muscle tissue resulting from blockage of one or more coronary arteries

Question 61

What is a stroke?

Answer 61

the death of nervous tissue in the brain due to lack of O2

Question 62

Why do people take statins to reduce the risk of cardiovascular disease?

Answer 62

they can lower LDL levels and thereby reduce the risk of heart attack

Question 63

Why do people take aspirin to reduce the risk of cardiovascular disease?

Answer 63

inflammation plays a central role in atherosclerosis and thrombus formation and aspirin inhibits the inflammatory response

Question 64

Why do people control blood pressure to reduce the risk of cardiovascular disease?

Answer 64

chronic high blood pressure damages the endothelium that lines the arteries, promoting plaque formation

Question 65

What are the parts of the mammalian respiratory system pharynx, larynx, trachea, bronchus,bronchiole, diaphragm, nasal cavity

Answer 65

nasal cavity and pharynx- where air is inhaled larynx- tips the epiglottis of the glottis so food goes down the esophagus trachea- wind pipe bronchi- trachea branches into two of these each one leading to the lung bronchioles- within the lung the bronchi branch into these alveoli- where gas exchange occurs

Question 66

Where exactly is gas exchange happening?

Answer 66

alveoli

Question 67

What is the surface area of alveoli like compared to the surface area of the skin?

Answer 67

it is 50 times that of the skin

Question 68

What protects alveoli from contamination?

Answer 68

white blood cells patrol the alveoli, engulfing foreign particles

Question 69

Mammals employ negative pressure breathing. What’s happening here?

Answer 69

pulling, rather than pushing, air into their lungs; using muscle contraction to actively expand the thoracic cavity

Question 70

What happens when the diaphragm moves down and the rib cage expands?

Answer 70

inhalation

Question 71

Involuntary mechanisms ensure that gas exchange is coordinated with

Answer 71

blood circulation and with metabolic demand.

Question 72

Describe the chart with medulla and blood ph

Answer 72

As CO2 level increases in the blood, pH gets lower. This is detected in the cerebrospinal fluid that surrounds the brain and spinal cord by the medulla. Ventilation increases and CO2 level decreases, raising blood pH.

Question 73

This control of breathing is in response to the level of CO2 in the blood and blood pH. Can blood O2 level have an effect on breathing? What’s the connection between the aorta/carotid sensors and breathing control centers in the brain?

Answer 73

o2 usually has little effect; when the o2 level drops very low, o2 sensors in the aorta and the carotid arteries in the neck send signals to the breathing control centers, which respond by increasing the breathing rate

Question 74

Blood flowing through the alveolar capillaries has lower PO2 and higher PCO2 than air in the alveoli. What’s going to happen?

Answer 74

net diffusion of o2 down its partial pressure gradient from the air in the alveoli to the blood

Question 75

Blood flowing through the systemic capillaries has higher PO2 and lower PCO2 than body tissue cells. What’s going to happen?

Answer 75

net diffusion of o2 out of the blood and co2 into the blood

Question 76

O2 is not really very soluble in water (and thus in blood), which poses a problem for animals that rely on the circulatory system to deliver O2. What is the animal’s answer to this problem?

Answer 76

animal transport most of their o2 bound to proteins called respiratory pigments

Question 77

What is the respiratory pigment of almost all vertebrates and many invertebrates?

Answer 77

hemoglobin

Question 78

Where is hemoglobin located in vertebrates?

Answer 78

contained in erythrocytes (red blood cells)

Question 79

What is a hemoglobin molecule like?

Answer 79

has four subunits (polypeptide chains), each with a cofactor called a heme group that has an iron atom at its center

Question 80

How is O2 transported by hemoglobin?

Answer 80

each iron atom binds one molecule- thus each hemoglobin can care 4 o2 molecules

Question 81

What causes O2 to be released from hemoglobin in the systemic capillaries?

Answer 81

the production of co2 during cellular respiration promotes the unloading of o2

Question 82

How is CO2 transported from the interstitial fluid surrounding tissues to the lungs and into the alveolar spaces?

Answer 82

through plasma into erythrocytes