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Biology A-level > mass transport in animals > Flashcards

mass transport in animals Flashcards

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1
Q

what is diffusion?

A

the movement of particles from an area of high concentration to an area of low concentration - it is a passive process

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2
Q

what is metabolism?

A

all of the chemical reactions happening in a living organism, including respiration

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3
Q

as the size of a mammal increases, the SA:Vol decreases. this justifies the need for…

A

a mass transport system

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4
Q

examples of mass transport systems

A

the heart
the circulatory system

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5
Q

common features of a mass transport system.
(4 things)

A

. a suitable medium in which to carry materials normally liquid based on water as water readily dissolves substances and is easy to move around (e.g. blood)
. transports things over large distances
. closed system of tubular vessels that contain the transport medium and branch to all parts of the organism
. mechanism for moving transport within vessels. requires a press/con difference between one part of the system and another

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6
Q

what type of system is the heart? and what does this mean?

A

a double pump system, meaning that blood passes through each circuit of the heart twice.

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7
Q

right hand side of the heart -
.what blood
.to where
.through which circuit

A

deoxygenated blood travelling to the lungs through the pulmonary circuit

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8
Q

left hand side of the heart -
.what blood
.to where
.through which circuit

A

oxygenated blood travelling to the body through the systematic circuit

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9
Q

what is the central divider of the heart called

A

the septum

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10
Q

arteries (5 points)

A

. takes high pressure, oxygenated blood away from the heart
. narrow lumen
. thick walls
. biggest artery = aorta
. exception = pulmonary arteries. this takes deoxygenated blood to the lungs

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11
Q

veins (3 points)

A

. takes low pressure, deoxygenated blood to the heart
. wide lumen
. have valves

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12
Q

capillaries ( 3 points)

A

. walls are 1 cell thick - exchange is a short diffusion pathway
. lots of them = large surface area and a good blood supply
. very narrow lumen

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13
Q

renal =

A

kidneys

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14
Q

what do kidneys do?

A

they filter urea and toxins from the body and control the body’s water levels

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15
Q

what is urea?

A

the breakdown of proteins

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16
Q

EXAM QUETSION
in a healthy person, blood moves in one direction as it passes through the heart. Give two ways in which this is achieved. (2 marks)

A

valves stop the backflow of blood and there is a pressure gradient. Blood moves from high to low pressure.

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17
Q

EXAM QUESTION
explain how the highest blood pressure is produced in the left ventricle (1 mark)

A

the thicker muscular wall allows the left ventricle to contract stronger, in order to move blood throughout the whole body

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18
Q

EXAM QUESTION
some babies are born with a hole between the right and the left ventricles. these babies are unable to get enough oxygen to their tissues. suggest why. (2 marks)

A

blood will move from the LV to the RV, causing less oxygenated blood to get around the body, reaching their tissues.

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19
Q

describe the relationship between blah blah and blah blah on a graph (2 points)

A

. describe the trend
. state the correlation
. describe the trend using statistics.

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20
Q

left and right atrium

A

. thin walled, as blood only needs to travel a short distance
. elastic tissue that stretches and recoils to allow the atrium to hold more blood.

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21
Q

left and right ventricle

A

. thicker muscular walls for stronger contraction to pump blood to the lungs/body.
. LV has a thicker wall than the RV
. some elastic tissue in the ventricles too.

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22
Q

what do valves do?

A

prevent the backflow of blood and keeps blood moving in 1 direction

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23
Q

where are the atrioventricular valves found?

A

inbetween the atria and the ventricles.
. LHS = bicuspid valve
. RHS = tricuspid valve

24
Q

where are the semilunar valves found?

A

. aortic valve = between the LV and aorta
. Pulmonary valve = between the RV and the pulmonary artery

25
Q

if AV valves are damaged, ….

A

… blood flows back into the atria

26
Q

if semilunar valves are damaged, …….

A

… blood flows back into the ventricles

27
Q

where are the coronary arteries found and what do they do?

A

. they surround outside of the heart and muscle.
. they provide the heart muscle with oxygenated blood and glucose , so that the heart muscle cells can respire and contract

28
Q

the cardiac cycle = 1 heartbeat.
how long is the average cardiac cycle?

A

0.7 seconds

29
Q

average resting heart rate =

A

60 - 100 bpm

30
Q

what is systole?

A

when the heart is pumping blood (contracting)

31
Q

what is diastole?

A

when the heart chambers are filling with blood (relaxation)

32
Q

what happens during the process of diastole?

A

. blood returns to the atria through the pulmonary vein and the vena cava
. during this process, AV valves must be closed
. blood volume in the atria increases, so does pressure
. when pressure in the atria is higher than pressure in the ventricles, the AV valves open, allowing blood to move into the ventricles
. the movement of blood is aided by gravity

33
Q

what happens during the process of atrial systole?

A

. forces the remaining blood out of the atria
. muscle of the ventricle wall must remain in ventricular diastole in order to receive the blood from the atria

34
Q

what happens during ventricular systole?

A

. there is a short delay to allow the ventricles to fill with blood, then their walls contract simultaneously
. this increases blood pressure within the ventricles, forcing the AV valves to shut, to prevent the backflow of blood in the atria
. the closing of the AV valves creates the sound “lub”
. as blood pressure increases within the ventricles, the semilunar valves open - they close when pressure in the aorta and the pulmonary artery is greater than the pressure within the ventricles

35
Q

how to calculate cardiac output

A

heart rate x stroke volume

CO = SV x HR

36
Q

what is stroke volume?

A

volume of blood pumped/ejected out of the LV. this is roughly around 70ml (depends on fitness levels)

37
Q

TEXTBOOK QUESTION
after a period of training, the heart rate is often decreased when at rest although the cardiac output is unchanged. suggest an explanation for this.

A

training builds up the muscle of the heart, and so stroke volume increases/more blood is pumped out each beat. this means that if the cardiac output is the same, the number of beats per minute is the same.

38
Q

what does SNAACK stand for ?

A

s - sinoatrial node
n - nonconducting tissue
a - atrioventricular node 1
a - atrioventricular node 2
c - contraction
k - purkinje fibres

39
Q

EXAM QUESTION
describe how a heartbeat is initiated and coordinated.
(SNAACK)

A
  1. SAN sends an impulse across both atrium
  2. NCT prevents the impulse from reaching the ventricles
  3. AVN delays impulse while blood leaves the atria/ventricles fill
  4. AVN sends impulse down the bundle of his and up the purkinje fibre
  5. contraction occurs from the apex up, allowing lots of blood to leave the heart at a high pressure
40
Q

functions of arteries

A

carry blood away from the heart and into the arterioles

41
Q

function of arterioles

A

smaller arteries that control blood flow from arteries to capillaries

42
Q

function of capillaries

A

tiny vessels that link arterioles to venules/veins

43
Q

function of venules

A

smaller veins that return blood from the capillary beds back to the venules/veins

44
Q

function of veins

A

carry blood from capillaries back to the heart via venules

45
Q

what does TMELT stand for?

A

t - tough fibrous outer layer
m - muscle layer
e - elastic layer
l - lumen
t - thin inner lining (endothelium)

46
Q

definition of osmosis

A

the diffusion of water molecules from an area of high water potential to an area of low water potential through a semi-permeable membrane

47
Q

how is tissue fluid formed?

A

from blood plasma

48
Q

what does tissue fluid contain?

A

glucose, water, amino acids, fatty acids, ions (sodium and potassium)

49
Q

what is tissue fluid?

A

a medium by which materials are exchanged between blood and cells - it surrounds all of the cells in the body

50
Q

what happens at the arterial end of a capillary?

A

. high hydrostatic pressure is created by the contraction of the LV
. this causes small molecules to move out of the blood plasma through ultrafiltration
. once these molecules move out, they become a part of tissue fluid

51
Q

what happens in the middle of the capillary?

A

other cells and large proteins remain in the blood as these are too large to cross the membrane

52
Q

what happens at the venous end of the capillary?

A

because water is forced out the arterial end and large proteins remain inside the capillary, this lowers the water potential at the venous end.
some H2O moves back into the capillaries via osmosis and some other small molecules

53
Q

what does the lymphatic system do?

A

it removes any excess tissue fluid

54
Q

what is oedema?

A

the build up of tissue fluid

55
Q

how does oedema occur?

A

when the heart beats too hard, this increases ultrafiltration so the excess tissue fluid cannot drain into the lymph vessels, so it remains in the intercellular spaces. this is further compounded by the lack of lymph vessels in the feet

56
Q

EXAM QUESTION
explain how tissue fluid is formed and how it may be returned to the circulatory system (6 marks)

A

there is a high hydrostatic pressure at the arterial end of the capillary. small molecules are forced out of the capillary (e.g. water, fatty acids, amino acids). large proteins remain in the capillary. some water is reabsorbed in the venus end of the capillary via osmosis. the lymphatic system collects any excess tissue fluid which is returned to the blood.

57
Q

define digestion

A

the process in which large biological molecules are hydrolysed by enzymes into smaller molecules that can be absorbed across cell membranes

Biology A-level (3 decks)

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