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BIOL 186 > Animal Circulation > Flashcards

Animal Circulation Flashcards

1
Q

How can diffusion be calculated?

A

t is proportional to X^2/2*D, where x = distance, t = time and D is diffusion coefficient.

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2
Q

How does circulation in protosomes with simple body plans function?

A

They have very little specialization in their circulatory systems and gastrovascular cavities help minimize their diffusion distances.

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3
Q

What are the main (three) parts of a circulatory system in animals?

A

There needs to be a fluid, interconnecting vessels, and a pump.

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4
Q

Describe the characteristics of a open circulatory system.

A

The internal fluid is circulated through the body cavity and there is no distinction between blood and interstitial fluid (hemolymph).

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5
Q

Open circulatory systems don’t have continuous interconnecting vessels and thus internal pressure rapidly dissipates. What are two ways they can over come this?

A

Heart rate is very fast and/or they have multiple hearts.

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6
Q

Describe the characteristics of a closed circulatory system.

A

Blood is confined to vessels and is distinct from interstitial fluid.

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7
Q

Why is a closed circulatory system more effective at transporting circulatory fluids to tissues and cells?

A

The blood diffuses to interstitial fluid (IF) and the IF to the cells.

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8
Q

How are arteries and veins distinct?

A

Arteries carry blood AWAY from the heart (usually) and veins carry blood to the heart. (A for Away)

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9
Q

What are arteries?

A

Carry oxygen rich heart away from the heart and from the lungs to the heart in double circulation systems.

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10
Q

What are arterioles?

A

Carry oxygen rich blood from arteries to capillary beds.

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11
Q

What are capillaries?

A

Carry oxygen rich blood from arterioles and arranged in capillary beds. Turn blood from oxygen rich to poor and vice versa in lungs/gills.

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12
Q

What are capillary beds?

A

The site of chemical exchange between blood and IF with nearby cells. Turn blood from oxygen rich to poor and vice versa in lungs/gills.

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13
Q

What are venules?

A

Converge from capillaries to veins, carrying oxygen poor blood to the heart or lung capillaries.

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14
Q

What is singular circulation?

A

Blood enters through the atrium and out through the ventricle. The heart has two chambers. Blood leaves the heart as oxygen poor blood through the arteries, through two capillary beds and then back to the body.

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15
Q

What are some possible disadvantages of singular circulation?

A

There is no fresh perfusion and has low pressure.

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16
Q

Describe the characteristics of double circulation in amphibians.

A

Amphibians have three chambers in their heart; two atria, one ventricle. The ventricle pumps blood to the forked artery and splits ventricle output into pulmocutaneous (lung/skin capillaries) and systemic circuit.

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17
Q

Describe the characteristics of double circulation in mammals.

A

Mammals have a four chambered heart; two atria and two ventricles. Oxygen rich and oxygen poor blood do not mix.

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18
Q

What is the difference between the systemic circuit and pulmonary circuit in mammals?

A

The systemic circuit delivers oxygen rich blood from the heart to the rest of the body, while the pulmonary circuit only focuses on the heart and lungs.

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19
Q

Why do endotherms require more oxygen than ectotherms?

A

They have higher metabolic rates.

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20
Q

What is cardiac output?

A

It is the volume of blood into the systemic circuit per minute, and it depends on the amount of blood pumped per contraction.

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21
Q

What is the central lumen?

A

The cavity within a vessel; vein, artery, capillary

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22
Q

What is endothelium and why is it important?

A

Endothelium is the epithelial layer of cells that lines the blood vessels; it is very smooth and minimizes resistance so blood can flow efficiently.

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23
Q

What are the three types of tissue that make up veins and arteries? (minus capillaries)

A

Endothelium, smooth muscle and connective tissues.

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24
Q

What is the one type of tissue that arteries and veins have that capillaries do not have?

A

Smooth muscle.

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25
Why are arteries thicker (more smooth muscle) than veins?
Because of the high blood pressure from the heart.
26
Why are veins thinner (less smooth muscle, so wider lumen) than arteries?
Blood flows back to the heart via one-way valves, gravity and muscle action - moved by smooth and skeletal muscle contraction and expansion of vena cava with inhalation.
27
What are the characteristics of capillaries?
Capillaries have very thin walls and are just slightly larger than a red blood cell. The endothelium and basal lamina (connective tissue) facilitate the exchange of materials.
28
How is distribution of materials through capillary beds regulated?
Arteries constrict/dilate to supply blood, and by pre-capillary sphincters that control blood flow between arterioles and venules. Only 5-10% of capillaries are filled at any one time.
29
What is blood made of?
Plasma (55%), blood cells (45%), and a buffy coat (white blood cells, platelets) (1%)
30
What is blood plasma made of and what is its function?
Plasma is 55% of blood volume. It is made of mostly water, electrolytes (inorganic salts, minerals) and specialized proteins. These proteins influence blood pH, maintain osmotic pressure with blood and IF, undergo lipid transport, system immunity, and blood clotting.
31
What are the three types of blood cells?
Erythrocytes (red), leukocytes (white) and platelets.
32
Where and how are blood cells made?
They originate from stem cells in red bone marrow.
33
What are erythrocytes (red blood cells) and their function?
They are concave, disc shaped cells packed with hemoglobin. Mature erythrocytes lack nuclei and mitochondria. Their main purpose is to deliver oxygen around the body from the lungs and return co2 to lungs for exhalation.
34
What stimulates erythrocyte production when oxygen delivery is low?
Kidneys detect low oxygen and secrete erythropoietin (EPO) that stimulates production.
35
What are the five major types of leukocytes (white blood cells?)
Monocytes, neutrophils, basophils, eosinophils, lymphocytes.
36
What are leukocytes (white blood cells) and their main function?
They are in and outside of the circulatory system and their main function is defense. Neutrophils and eosinophils and microphages phagocytize (eat/absorb) bacteria and debris. Lymphocyte T & B cells provide immune system defense.
37
What are platelets and their function?
They are fragments of specialized bone marrow cells responsible for the structural and molecular functions of blood clotting.
38
How does blood clotting occur?
It is activated by clotting factors: plasma, platelets, or damaged cells. Thrombin is released and upon activation, a platelet plug is formed and a fibrin clot is formed.
39
What is a thrombus?
A clot within a blood vessel that blocks blood flow.
40
What are the three steps to blood clotting?
1. The blood vessel constricts to reduce flow. 2. A platelet plug is formed: platelets adhere, activate and combine to form a temporary plug. 3. Coagulation: fibrin mesh forms to stabilize clot.
41
What is the main function(s) of the lymphatic system?
The lymphatic system returns fluid that leaks out of capillary beds, drains into the veins in the neck, and the valves prevent backflow of fluid.
42
What are lymph nodes?
Organs that filter lymph and are important for defense.
43
What makes up the pulmonary circuit?
Pulmonary arteries and veins.
44
What makes up the systemic circuit?
The aorta and the superior/inferior vena cava.
45
What makes up the heart?
The atria, the ventricles, and the valves.
46
What is the function of the pulmonary arteries?
Bring deoxygenated blood from the left ventricle in the heart to the lungs.
47
What is the function of the pulmonary veins?
Return oxygenated blood to the left atrium in the heart from the lungs.
48
What is the aorta and what is its function?
The aorta is made up of ascending/descending branches that stem from the left ventricle in the heart and distributes oxygenated blood throughout the body.
49
What is the function of the superior vena cava?
To return deoxygenated blood from the upper body to the right atrium in the heart.
50
What is the function of the inferior vena cava?
To return deoxygenated blood from the lower body to the right atrium in the heart.
51
What are the atria in the heart and what is their function?
The atria have thin walls and are collection chambers for blood returning from circulation.
52
What are the ventricles in the heart and what is their function?
The ventricles have thick walls and contract forcefully to eject blood to distal sites.
53
What are the three tissues that make up the heart wall?
Myocardium, endocardium and pericardium.
54
What is myocardium?
Heart muscle
55
What is endocardium?
The tissue that lines the inside of the heart.
56
What is pericardium?
The fibrous, protective sheathe around the heart.
57
What are the two types of valves within the heart?
The atrioventricular and semilunar valves.
58
What is the function of the atrioventricular valves?
They control blood flow within the heart between the atria and ventricles.
59
What is the function of the semilunar valves?
They control cardiac output through the aorta and pulmonary arteries.
60
Describe the three steps of the cardiac cycle in detail.
Three steps: 1) Atrial and ventricular diastole: the heart relaxes, atria fill, valves close, AV valves open and ventricles fill. 2) Atrial systole and ventricular diastole: ventricles fill 80%, atria contract and ventricles fully fill. 3) ventricular systole and atrial diastole: ventricles contract and force AV close, contraction builds and force open SL valves.
61
What is systole?
The contraction/pumping phase of the cardiac cycle.
62
What is diastole?
The relaxation/filling phase of the cardiac cycle.
63
What is systolic pressure?
Occurs in arteries during ventricular systole (3rd phase). It is the highest in arteries.
64
What is diastolic pressure?
Occurs in arteries during diastole phases; lower pressure than systolic pressure.
65
How is blood pressure maintained in arteries and arterioles?
Arteries have elastic walls that help maintain blood pressure; resistance to blood flow in narrow capillaries and arterioles helps dissipate blood pressure. Homeostatic mechanisms also regulate arterial blood pressure by altering the diameter of arterioles via vasoconstriction and vasodilation.
66
Does blood vessel diameter impact blood flow?
Yes. For instance, the velocity of blood is slowest within capillary beds (has high resistance, a large cross-sectional area, slow to allow the exchange of materials).
67
Where does the exchange of substances between blood and the IF take place?
In the endothelia walls of capillaries.
68
How does the exchange of substances between blood and the IF occur?
The difference between blood pressure and osmosis drives fluid in and our of capillaries.
69
Is the exchange of substance between blood and IF stronger at the arteriole or venule end?
The arteriole end. Arteriole end exchanges more, venule end receives more waste.
70
What is vasoconstriction within arteries and how does it affect blood pressure?
The contraction of smooth muscle in arteriole walls, increasing blood pressure.
71
What is vasodilation within arteries and how does it affect blood pressure?
The relaxation of smooth muscle in arteriole walls and decreases blood pressure.
72
What controls the pacing of the heart?
The SA (sinoatrial) node.
73
Does the heart rely on the nervous system to contract?
No, cardiac muscle cells are autorhythmic, meaning they contract without any signals from the nervous system. However, it is regulated by the nervous system.
74
What is the SA (sinoatrial) node and its function?
It is the pacemaker of the heart that sets the rate and timing for the contraction of muscle. Impulses from the SA node transfer to the AV node.
75
What is the AV (atrioventricular) node?
It delays impulses from the SA node so the atria has time to empty blood into the ventricles before the signal continues to the purkinje fibers.
76
What are the Purkinje fibres?
They contract the ventricles.
77
Describe the 4 steps in pacing the heart
1) Signals from SA node spread through atria. 2) Signals delayed at AV node. 3) Bundle branches pass signals to heart apex. 4) signals spread through ventricles by purkinje fibres.
78
How is the rhythm of the heart regulated?
The pacemaker (SA node) is regulated by two portions of the nervous system: the sympathetic and parasympathetic.
79
What is the sympathetic division that regulates the heart?
The sympathetic division speeds up the pacemaker.
80
What is the parasympathetic division that regulates the heart?
The parasympathetic division slows the pacemaker.
81
The sympathetic and parasympathetic divisions of the nervous system regulate the heart pacemaker, the SA (sinoatrial) node. What are some factors that regulate them?
They are regulated by hormones and temperature.
82
What are baroreceptors?
They are a type of mechanoreceptor located in heart muscles, the aorta and carotid arteries that provide blood pressure info to medulla.

BIOL 186 (17 decks)

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