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biology module 3 > mammalian circulatory system > Flashcards

mammalian circulatory system Flashcards

1
Q

5 reasons why multicellular organisms need transport systems

A
  • multicellular organisms have greater metabolic rates
  • SA:V decreases as size increases so greater diffusion distances
  • molecules may be made in one place but needed in other specific cells/organs
  • food is digested in one organ system but nutrients must be transported to every cell
  • waste products of metabolism need to be removed from cells and transported to excretory systems
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2
Q

what type of circulatory system do most mammals have

A

double closed circulatory system

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3
Q

what are the benefits of a double circulatory system

A

heart is able to simultaneously pick up oxygen and return oxygenated blood to organs and tissues at high speed + pressures
this is necessary due to the high levels of activity in the body needed to keep temperature at 37C
it also helps with the need to deliver and remove substances from cells rapidly

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4
Q

outline the structure + function of an artery

A

arteries take high pressure blood away from the heart

from inside to out:
small lumen maintains high pressures
tunica intima - smooth endothelium lining reduces friction for increased blood flow
tunica media - thick layer of smooth muscle and elastic fibres allows walls to stretch + recoil to absorb pressure and push blood along
tunica externa - fibrous layer of connective tissue made of collagen which is tough and can resist high pressures

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5
Q

outline the structure + function of a vein

A

veins return low pressure blood to the heart

from inside to out:
larger lumen with valves to prevent backflow of low pressure blood and accommodates large volume of blood being transported
tunica intima - smooth endothelium lining reduces friction
tunica media - thin layer of smooth muscle and elastic fibres is sufficient as blood is not at high pressures
tunica externa - fibrous layer of connective tissue made of collagen which is tough and durable

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6
Q

outline the structure + function of a capillary

A

capillaries allow for the exchange of materials between blood cells and tissues, forms a network through tissues that connect arteries to veins

from inside to out:
lumen has a diameter of 7 micrometers which = diameter of a rbc
made up of 1 layer of smooth endothelium which is 1 cell thick so short diffusion distance for rapid exchange between cells and body tissues, endothelium also has perforations in walls allowing for the seepage of plasma

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7
Q

what type of cells are endothelium made of

A

squamous epithelial cells

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8
Q

closed circulatory system definition

A

the transport medium is enclosed in vessels and does not come into contact with the cells of the body

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9
Q

double circulatory system definition

A

a circulatory system where the blood flows through the heart twice during a complete circuit of the body

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10
Q

pulmonary circulation definition

A

the part of the circulatory system which carries deoxygenated blood away from the right side of the heart to lungs, returning oxygenated blood to left side of heart

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11
Q

systematic circulation definiton

A

the part of the circulatory system which carries oxygenated blood away from the left side of the heart to the body and returns deoxygenated blood back to the right side of the heart

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12
Q

what makes double closed circulatory systems very efficient

A

each circuit passes through only one capillary network, maintaining high blood pressures so fast flow of blood back to the heart is maintained

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13
Q

what are the general features of circulatory systems

A
  • fluid to transport dissolves gases, nutrients and waste
  • a pumping mechanism to move fluid
  • sometimes vessels to carry around fluid
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14
Q

what is an advantage of a closed circulatory system

A

they are more efficient

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15
Q

what is a disadvantage of closed circulatory systems

A

more energy is required to maintain it

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16
Q

what 4 components make up blood + their functions

A

red blood cells - oxygen and CO2 transport
white blood cells - immunity
platelets - initiate process of blood clotting
plasma - transports dissolved substances

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17
Q

what are platelets

A

cell fragments

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18
Q

10 examples of substances dissolved in plasma

A

red blood cells, white blood cells, platelets, glucose, amino acids, plasma proteins, mineral ions, hormones, albumin, fibrinogens

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19
Q

what is albumin and why is it important

A

a plasma protein found in vertebrates which helps to maintain osmotic pressure

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20
Q

what is fibrinogen and why is it important

A

a plasma protein which is involved in blood clotting

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21
Q

what are 6 functions of blood

A
  • transport of oxygen and CO2 to and from respiring cells
  • transport of hormones
  • transport of nitrogenous waste products from cells to excretory organs
  • transporting cells and antibodies involved in the immune response
  • maintenance of steady body temps
  • acts as a buffer to minimise pH changes
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22
Q

what is the function of arterioles

A

regulate the flow of blood into capillaries

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23
Q

what is the function of venules

A

regulate the flow of blood from capillaries to veins

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24
Q

what are 3 differences in structure of arteries and arterioles

A
  • arterioles have a higher proportion of smooth muscle than arteries
  • arterioles have a lower proportion of elastin in walls compared to arteries
  • arterioles have slightly larger lumens
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25
Q

why do arterioles have less elastin in walls than arteries

A

blood flow isn’t as pulsatile/throbbing

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26
Q

why does blood move slower in arterioles

A

due to friction with vessel walls

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27
Q

what effect does the slightly larger lumen of arterioles have on blood

A

reduces the pressure slightly

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28
Q

what is blood flow like in arteries

A

fast
pulsatile
high pressure

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29
Q

what is blood flow like in capillaries + why

A

slow - gives a longer time for the exchange of substances
low pressure - prevents them from bursting

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30
Q

what makes up the walls of venules

A

mostly collagen

31
Q

what is blood flow like in veins

A

slow
low pressure
smooth

32
Q

what are 3 mechanisms in veins to aid flow of blood back to heart

A
  • movement of skeletal muscles contract + relax to push blood through veins as they lie near the surface
  • valves prevent backflow
  • breathing mechanism causes negative pressure in the thorax which pulls blood towards heart
33
Q

outline the process of chloride shift

A
  • CO2 from respiring tissues diffuses into red blood cell cytoplasm
  • CO2 reacts with water to form carbonic acid H2CO3 in a reaction catalysed by carbonic anhydrase with Zn cofactor - keeps CO2 conc down to maintain conc gradient
  • carbonic acid dissociates into H+ and HCO3
  • HCO3 - diffuses out of red blood cell and into plasma, creating a charge imbalance
  • Cl- ions move into red blood cell to reverse charge imbalance (chloride shift) and H+ ions force O2 out of haemoglobin by binding to it forming haemoglobinic acid
  • O2 diffuses out of red blood cells and into respiring tissues
34
Q

why is carbonic anhydrase + Zn2+ used as a catalyst

A

ensures fast reaction rate which maintains conc gradient of CO2

35
Q

how is CO2 transported in blood

A

5% is dissolved in blood plasma as carbonic acid
20% forms carbaminohaemoglobin, which dissociates back when CO2 conc is low
75% travels in blood as HCO3 -

35
Q

how do plasma proteins help in transportation of CO2

A

plasma proteins buffer H+ ions which protects the pH of blood from decreasing and denaturing proteins in blood

36
Q

what is the equation for CO2 transport in blood plasma

A

CO2 + H2O <> H2CO3 <> H+ + HCO3 -

37
Q

tissue fluid definition

A

a liquid produced from the circulatory system when blood plasma passes out and bathes tissue cells, containing dissolved nutrients or waste molecules

38
Q

lymph definition

A

modified tissue fluid collected in the lymph system

39
Q

3 functions of tissue fluid

A
  • transports substances to tissues and returns waste products of cells back to the circulatory system
  • bathes cells which protects them
  • allows cells to take up products when needed
40
Q

4 examples of substances found in tissue fluid

A
  • glucose
  • oxygen
  • amino acids
  • CO2
41
Q

what is the lymphatic system

A

system of blind-ended lymph vessels that excess tissue fluid is drained into - now known as lymphatic fluid

42
Q

outline the the process of tissue fluid formation

A
  • at arteriole end of capillaries hydrostatic pressure is greater than oncotic pressure due to arteries, so fluid is forced out
  • this fluid is tissue fluid
  • 90% of tissue fluid is reabsorbed at the venule end of the capillary, where hydrostatic pressure is less than oncotic pressure because lots of water has left the blood, so water/fluid moves back in via osmosis
43
Q

oncotic pressure definition

A

plasma proteins are hydrophilic and decrease the water potential of plasma, creating a water potential gradient therefore increasing the tendency of water to move into blood - this is oncotic pressure

44
Q

what are 2 examples of things that don’t leave capillaries when fluid is forced out + why

A
  • red blood cells
  • plasma proteins
    they are too large to fit through pores in capillaries
45
Q

what are the functions of lymph nodes

A

involved in immune response and contains lymphocytes

46
Q

2 examples of lymphoid organs

A
  • bone marrow
  • thymus gland
    where B-cells and T-cells differentiate
47
Q

hydrostatic pressure definition

A

the pressure created by water in an enclosed system
- created by high pressure in arteries as plasma is aqueous

48
Q

what happens to hydrostatic pressure from arteriole to venule end of capillaries + why

A

it decreases
due to increased distance from the heart and branching of arterioles into many capillaries

49
Q

what happens to oncotic pressure from arteriole to venule end of capillaries + why

A

it stays the same
plasma proteins which generate the pressure do not fit through pores so cannot leave capillaries

50
Q

partial pressure of oxygen definition

A

the amount of O2 in tissues aka pO2

51
Q

what is partial pressure of oxygen like in lungs + why + what effect does this have

A

pO2 is high due to ventilation
this means O2 is easily able to associate with haemoglobin so haemoglobin saturation is high here

52
Q

is haemoglobin saturation proportional to pO2 + why

A

no
this is because O2 association causes conformational changes which affect the ability of haemoglobin to associate with more O2 molecules

53
Q

how does haemoglobin saturation change its ability to associate with more O2

A
  • after 1st O2 conformational changes make it easier for haemoglobin to associate with 2nd and 3rd O2 molecules
  • the 4th O2 is very difficult to associate with as haemoglobin molecule becomes full
  • this is why % Hb O2 saturation - pO2 graphs have a characteristic S-shaped curve
54
Q

what is the difference between foetal haemoglobin and adult haemoglobin

A

foetal haemoglobin has a greater affinity for O2
this is necessary as it needs to be able to take O2 directly from mothers haemoglobin

55
Q

what happens to hydrostatic pressure as blood moves away from the heart

A

it decreases
this is because blood divides into smaller vessels, which have a larger total cross sectional area
also there is a loss of plasma from capillaries

56
Q

how many oxygen molecules is 1 haem group capable of binding to

A

1 O2 molecule

57
Q

how many oxygen molecules can 1 haemoglobin molecule bind to

A

1 haemoglobin molecule has 4 haem groups so it can bind to 4 O2 molecules

58
Q

give the equation for haemoglobin binding to oxygen

A

Hb + 4O2 <> HbO8

59
Q

what is formed when haemoglobin binds to O2

A

oxyhaemoglobin

60
Q

positive cooperativity

A

the conformational change of a protein following the binding of the first subunit which then makes binding easier for the next subunits
- seen in haemoglobin

61
Q

what does an oxygen dissociation curve show

A

it shows how the binding of O2 molecules varies as different pO2

62
Q

what is pO2 like in the lungs

A

very high

63
Q

what is pO2 like in respiring tissues

A

low

64
Q

what does the s shape of an oxygen dissociation curve show

A

x axis - pO2 (kPa)
y axis - %Hb saturation with O2
for a relatively small change in pO2 there is a large change in %Hb saturated with O2
- this is due to positive cooperativity of Hb

65
Q

why can the O2 saturation of haemoglobin never be 100%

A

some Hb will be bound to CO2

66
Q

what is formed when haemoglobin binds to CO2

A

carbaminohaemoglobin

67
Q

what is formed when haemoglobin binds with H+

A

haemoglobinic acid

68
Q

what 4 main conditions cause haemoglobin to dissociate from O2

A
  • drop in [O2]
  • increase in [CO2]
  • increased temperature
  • increased blood pH

this causes oxygen dissociation curve to shift to the right

69
Q

what is the Bohr effect

A

the phenomenon that Hb oxygen affinity is inversely related to blood pH and [CO2]

the movement of the oxygen dissociation curve to the right under these specific conditions

70
Q

how does haemoglobin differ in animals that live in environments with low pO2

A

the haemoglobin has a higher affinity for O2

e.g. a foetus

71
Q

what effect does a higher affinity for O2 have on the oxygen dissociation curve

A

the curve shifts to the left

72
Q

what happens to oxygen dissociation curve at respiring tissues

A

respiring tissues have high [CO2] so curve shifts to right so more O2 is released from Hb

biology module 3 (7 decks)

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