Circulation 2

Question 1

what is the split between water and air breathers in craniates

Answer 1

• quite even split between both groups

Question 2

how many circuits can a closed circulatory system have (2)

Answer 2

• single-circuit (most fishes)
• double-circuit (all birds & mammals)

Question 3

what is the basic circulatory plan of vertebrates (8)

Answer 3

• muscular, chambered heart contracts to increase pressure of the blood
• blood flows away from heart into arteries
• arteries branch to form more numerous, but smaller diameter, arteries
• small arteries branch into arterioles within tissues
• blood flows from arterioles into capillaries
• capillaries coalesce to form venules
• venules coalesce to form veins
• veins carry blood to the heart

Question 4

what occurs at the capillaries

Answer 4

• site of diffusion of molecules between blood and interstitial fluid

Question 5

vertebrate blood vessels (2)

Answer 5

• complex wall surrounding a central lumen
• thickness of all varies among vessels

Question 6

vertebrate blood vessel: layers (3)

Answer 6

• tunica intima
• tunica media
• tunica externa

Question 7

vertebrate blood vessels: tunica intima (3)

Answer 7

• internal lining
• smooth, epithelial cells that make up a vascular endothelium
• in direct contact with the blood

Question 8

vertebrate blood vessels: tunica media (3)

Answer 8

• middle layer
• smooth muscle
• elastic connective tissue to allow expansion and compression

Question 9

vertebrate blood vessels: tunica externa (3)

Answer 9

• outermost layer
• collagen
• structural support against pressure

Question 10

why are the arteries more muscular and elastic than veins (3)

Answer 10

• arteries must maintain and restrict blood pressure from the heart
• arteries must evenly distribute pressure to transport blood
• venous side has lower pressure system

Question 11

large vein structure (6)

Answer 11

• largest diameter vessel of the venous system
• thin layers
• tunica externa
• tunica media
• tunica intima
• endothelium

Question 12

vein structure (5)

Answer 12

• thin layers
• tunica externa
• tunica media
• tunica intima
• endothelium

Question 13

venule structure (4)

Answer 13

• smallest vessel diameter of the venous system
• thin layers
• tunica externa
• endothelium

Question 14

elastic artery structure (6)

Answer 14

• largest vessel diameter of the artery system
• thicker layers
• tunica externa
• tunica media
• tunica intima
• endothelium

Question 15

muscular artery structure (4)

Answer 15

• thin tunica externa
• very thick tunica media
• thin tunica intima
• endothelium

Question 16

arteriole structure (3)

Answer 16

• thin layers
• tunica media
• endothelium

Question 17

capillaries structure and types (2)

Answer 17

• lack tunica media and tunica externa
• can be continuous, fenestrated, or sinusoidal

Question 18

continuous capillaries (2)

Answer 18

• cells held together by tight junctions, blocking transport through cell junctions
• present in skin and muscle

Question 19

fenestrated capillaries (3)

Answer 19

• cells contain pores, making them “leaky” for passive transport
• specialized for exchange
• present in kidneys, endocrine organs, and intestines

Question 20

sinusoidal capillaries (2)

Answer 20

• few tight junction and most porous for exchange of large proteins
• present in liver and bone marrow

Question 21

tank treading (2)

Answer 21

• when capillary diameter is less than RBC diameter
• forces RBC to squeeze through capillary to mix their contents

Question 22

jawed vertebrates: circulatory system (2)

Answer 22

• all have closed systems
• structure varies depending on respiratory strategy (air vs water breathing)

Question 23

water-breathing fish: circulatory system (3)

Answer 23

• closed system
• single circuit
• some fish have accessory hearts in the tail to help pump blood

Question 24

air-breathing tetrapods: circulatory system (2)

Answer 24

• closed system
• two circuits

Question 25

air-breathing tetrapods: two circuits (2)

Answer 25

- pulmonary circuit for perfusing lungs: right side of heart - system circuit for perfusing other tissues: left side of heart

Question 26

single-circuit, closed circulatory system: basics (2)

Answer 26

- blood leaving heart makes a **single circuit** before returning to the heart - cardiac output passes through two, in-series capillary networks

Question 27

single-circuit, closed circulatory system: in-series capillary networks (2)

Answer 27

- respiratory (gills; bronchial) capillaries for O2 uptake and CO2 excretion - system (peripheral;tissue) capillaries for tissue O2 delivery and CO2 removal

Question 28

single-circuit, closed circulatory system: vessel resistance (3)

Answer 28

- vessel resistant to blood flow in gills & tissue is additive - Ohm’s Law - a lot of pressure is needed to get through two capillary beds

Question 29

fish hearts (3)

Answer 29

- two contractile chambers (cardiac muscle) - two other cardiac chambers - valves direct blood flow when chambers contract

Question 30

fish hearts: two contractile chambers (3)

Answer 30

- atrium (thinner-walled) and ventricle (thicker-walled) - wall thickness if indicative of the blood pressure it can generate - chambers contract in sequence and generate sufficient blood pressure to propel blood around entire body

Question 31

fish hearts: two cardiac chambers (2)

Answer 31

- sinus venosus and bulbus arteriosus - located inside pericardial cavity

Question 32

fish hearts: sinus venosus (2)

Answer 32

- elastic chamber that collects venous blood before it enters the atrium - sinoatrial region is site of the cardiac pacemaker

Question 33

fish hearts: bulbus arteriosus (2)

Answer 33

- elastic chamber connected to aorta - takes deoxygenated blood to the gills

Question 34

double-circuit, closed circulatory system: basics (2)

Answer 34

- blood returns twice to the heart to complete a circuit of the body - contains two functional pumps in one heart, each having an atrium and ventricle

Question 35

double-circuit, closed circulatory system: right side (2)

Answer 35

- right atrium and right ventricle pump deoxygenated blood to the pulmonary circuit - low pressure system

Question 36

double-circuit, closed circulatory system: left side (2)

Answer 36

- left atrium and left ventricle pump oxygenated blood into the systemic circuit - high pressure system

Question 37

double-circuit, closed circulatory system: benefits (2)

Answer 37

- two functional pumps can work at different blood pressures, but their flow outputs are identical - don't have to create sufficient pressure to go through two capillary beds

Question 38

circulatory system: birds & mammals (3) - heart chambers - circuits & pressure - blood mixing

Answer 38

- four-chambered heart: two atria and two ventricles - system and pulmonary circuits are divided into two different pressure systems - oxygenated and deoxygenated blood are completely separate

Question 39

law of bulk flow

Answer 39

Q = △P/R

Question 40

law of bulk flow: Q

Answer 40

- flow

Question 41

law of bulk flow: △P

Answer 41

- pressure drop

Question 42

law of bulk flow: R

Answer 42

- resistance

Question 43

resistance formula

Answer 43

8Ln/πr^4

Question 44

resistance formula: n

Answer 44

- viscosity of the fluid

Question 45

Poiseuille's equation

Answer 45

- more detailed version of law of bulk flow - Q = △Pπr^4/8Ln

Question 46

what does Poiseuille's equation reveal (2)

Answer 46

- radius affects flow much more than length or other factors - vasoconstriction and vasodilation will greatly affect flow

Question 47

how can blood vessels be arranged (2)

Answer 47

- in series - in parallel

Question 48

resistance in series formula

Answer 48

Rt = R1 + R2 + R3.....

Question 49

resistance in parallel formula

Answer 49

1/Rt = 1/R1 + 1/R2 + 1/R3 ....

Question 50

flow (Q)

Answer 50

- volume of fluid transferred per unit time

Question 51

blood velocity formula

Answer 51

blood velocity = Q/A

Question 52

blood velocity: A

Answer 52

- cross-sectional area of the channels/vessels

Question 53

how does the large cross-sectional area of the capillaries affect blood flow and diffusion (2)

Answer 53

- blood velocity through capillaries is very slow - there is a longer time for diffusion to occur