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YEAR 1 BIO > the heart > Flashcards

the heart Flashcards

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1
Q

what is single circulation

A

blood pressure reduced as blood passes through the gill capillaries. slows down flow to the rest of the body. limits the rate of delivery of O2 and nutrients to cells and removal of waste
efficient for level of activity of fish and don’t need to maintain body temp - respire relatively less than mammals
only goes to the heart once

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2
Q

what is double circulation

A

heart is composed of two separate pumps
right side pumps blood to the lungs to pick up oxygen left side pumps blood at high pressure to body
necessary because of higher level of activity to maintain body temp
need to deliver and remove materials to and from cells

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3
Q

what is a mammals heart made almost entirely of

A

cardiac muscle which contracts without resting and doesnt need nerve muscles

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4
Q

what are the four chambers of the heart

A

right ventricle and right atrium

left ventricle and left atrium

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5
Q

do atria have thin or thick walls and why

A

thin

don’t need to generate huge force

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6
Q

do ventricles have thin or think walls and why

A

thick

need a huge force to pump blood around the whole body

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7
Q

what separates the left and right side of the heart

A

septum

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8
Q

what are the purpose of valves

A

to prevent backflow

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9
Q

what valve is in-between the left atrium and ventricle

A

left atrioventricular valve

bicuspid valve

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10
Q

what valve is in between the right atrium and ventricle

A

right atrioventricular valve

tricuspid valve

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11
Q

what is the valve between the aorta and pulmonary arteries

A

semi lunar valves

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12
Q

how are valves attached to the cardiac muscle

A

via tendons

tendinous chordae

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13
Q

what are the major vessels of the heart

A 
coronary vessels
pulmonary veins 
pulmonary arteries 
aorta artery 
vena cava
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14
Q

what is the coronary vessel for

A

responsive for gas/nutrients/waste exchange in the cardiac muscle

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15
Q

what is the pulmonary vein for

A

one from each lung (oxygenated) converging into left atrium

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16
Q

what is the pulmonary artery for

A

from the right ventricle to the lungs (deoxygenated)

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17
Q

what is the aorta artery for

A

left ventricle to body (high pressure)

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18
Q

what is the vena cava for

A

one from upper body one from lower body to right atrium

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19
Q

in what direction does blood flow in veins

A

to the heart

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20
Q

in what direction does blood flow in arteries

A

away from the heart

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21
Q

what is an artery

A

large vessels which carry blood from the heart

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22
Q

what is an arterioles

A

small arteries which deliver blood to capillaries

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23
Q

what is a capillary

A

tiny tubes which deliver/collect blood as close as possible to cells. they link arterioles and venues

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24
Q

what are venules

A

small veins which collect blood from capillaries

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25
Q

what are veins

A

carry blood towards the heart

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26
Q

what is structure of blood vessels

A
  • tough outer layer (collagen) to resist pressure
  • muscle layer can contract and control the flow of blood
  • elastic layer can stretch and recoil to maintain blood pressure
  • endothelium smooth layer to prevent friction
  • lumen not a layer but a cavity
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27
Q

describe the structure of veins

A
  • wide lumen due to a low pressure in veins
  • thins walls, less elastic and less muscular
  • valves (semi lunar) to prevent back flow
  • deoxygenated blood to heart from tissues
    except pulmonary veins from lungs
  • non pulsatile - smooth flow of blood
28
Q

describe the structure of arteries

A
  • narrow lumen so high pressure
  • highly elastic to expand and recoil
  • thick muscular wall to withstand force
  • more elastic fibres (recoil)
  • no valves (except aortic and pulmonary artery semi lunar at start)
  • oxygenated blood from heart
    except pulmonary artery to lungs
  • pulsatile blood flow (expansion and recoil)
  • pulse can be felt
29
Q

describe the structure of capillaries

A
  • no muscle
  • no elasticity
  • no valves
  • only one cell thick
30
Q

what does endothelium mean

A

thin layer of cells that lines the interior surface of blood vessels

31
Q

how does the structure of capillaries help the function

A
  • thin layer of cells for short diffusion pathway
  • numerous and highly branched so larger surface area
  • narrow diameter to keep all cells close by and slow blood speed
  • narrow lumen to bring red blood cells close to the cells so short diffusion distance
  • spaces between cells allow white blood cells to escape
32
Q

describe the structure of arterioles

A
  • smaller than arteries
  • thicker muscle layer than arteries to adjust their diameter
  • thinner elastic layer than arteries
  • no valves
33
Q

what is systole

A

period of contraction

34
Q

what is diastole

A

period of relaxation

35
Q

what are the general principles of the cardiac cycle

A
  • contraction of the myocardium generates pressure changes which result in the orderly movement of blood
  • blood flows from an area of high to an area of low pressure unless flow is blocked by a valve
  • events on the right and left of the heart are the same but pressure on the right is lower
36
Q

what is atrial systole

A

the heart is full of blood and the ventricles are relaxed
both the atria contract and blood passes down to the ventricles
the atrio-ventricular valves open due to blood pressure
70% of the blood flows passively down to the ventricles so the atria do not have to contract a great amount

37
Q

what is ventricular systole

A

the atria relax. the ventricle walls contract, forcing the blood out. the pressure of the blood forces the atria ventricular valves to shut (producing the heart sound ‘lub’)
the pressure of blood opens the semi lunar valves
blood passes into the aorta and pulmonary arteries

38
Q

what is diastole

A

the ventricles relax. pressure in the ventricles falls below that in the arteries. blood under high pressure in the arteries causes the semi lunar valves to shut (this produces the second heart sounds ‘dub’)
during diastole all the muscle in the heart relaxes
blood from the vena cava and pulmonary veins enters the atria and the cycle starts again

39
Q

what is meant by myogenic stimulation

A

the heart produces its own electrical impulses for muscle contraction
these originate at the sino atrial node (SA) or pacemaker

40
Q

what does the SA node do

A

generates impulses that initiate contraction of the heart muscle

41
Q

why does there need to be an AV node

A

it is the only point in which the impulse can pass through the non conducting layer between atria and ventricle

42
Q

what is the purpose of the branches of His

A

conducts the impulse to the apex of the heart

43
Q

what do the Pikenji fibres do

A

cause the muscle to contract from the base upwards

44
Q

how does an ECG work

A

detected by electrodes placed on the body and the reading is known as the electrocardiogram

45
Q

on an ECG what does p represent

A

atrial systole

46
Q

on an ECG what does qrs represent

A

ventricular systole

47
Q

on an ECG what does t represent

A

ventricular diastole

48
Q

what is bradycardia

A

resting heart rate is less than 60bpm (e.g. fit athletes, but also due to heart diseases, drugs or hypothermia)

49
Q

what is tachycardia

A

heart rate greater than 100bpm (e.g. during exercise but also due to stress, CHD, anaemia)

50
Q

what is arrhythmia

A

irregular heart beat

51
Q

what is ventricular fibrillation

A

uncoordinated contraction of the heart muscles

the heart ‘quivers’

52
Q

purpose of red blood cells

A 
contains haemoglobin (formation requires Fe) 
Hb transports o2 from the lungs to cells
53
Q

what are erythrocytes

A

red blood cells

54
Q

what are phagocytes

A

white blood cells

55
Q

function of white blood cells

A

defence - phagocytosis

contains enzymes which engulf microbes and digests them

56
Q

what is the purpose of lymphocytes

A

defence - immune response
produces antibodies and antitoxins
killer cells - destroy cells infected with viruses

57
Q

what is the purpose of platelets

A

rupture and release enzymes at site of cut
initiates a cascade of reactions
converts insoluble blood protein FIBRINOGEN into insoluble FIBRIN THREADS which trap blood cells and platelets to form a blood clot

58
Q

what is blood plasma

A

the straw coloured liquid (90% water) containing solutes, glucose, amino acids, vitamins, waste (urea), plasma proteins, antibodies. it also distributes heat

59
Q

adaptations of red blood cells

A
  • biconcave shape maximises surface area for gas exchange
  • small and flexible to pass through narrow capillaries
  • no nucleus - more room to carry respiratory gases
  • packed with haemoglobin
60
Q

what is haemoglobin made up of

A

4 globular polypeptides
4 iron ions (prosthetic groups)
haemoglobin is the molecule that allows erythrocytes to carry respiratory gases (especially oxygen)
it has an affinity for oxygen (can carry 4O2molecules)
when haemoglobin becomes oxygenated it is known as oxyhemoglobin

61
Q

how does oxygen get into haemoglobin

A

diffuses into blood plasma, it then passes down a concentration gradient and into red blood cells
oxygen binds to haemoglobin to maintain this gradient
oxygen binds to the haem Fe2+ group of haemoglobin

62
Q

what is cooperative binding

A

used to describe the fact that as each O2 binds the shape of Hb is changed is changed and it is easier for more O2 to bind

63
Q

what happens in respiring tissues

A

oxygen dissociated from oxyhemoglobin

oxygen can then diffuses out of the erythrocytes and to respiring cells

64
Q

what is the reversible reaction for the bonding of oxygen and haemoglobin

A

Hb + 4O2 ——> Hb(02)4

65
Q

why is it hard for the first and last oxygen molecule to bond

A
  • when first oxygen molecules associates the conformation of the haemoglobin changes
  • so it is easier for the 2nd and 3rd oxygen molecules to associate
  • difficult to associate the 4th oxygen molecule. this is because the haemoglobin molecule becomes full
  • this is why the curve plateaus below 100%
66
Q

why can foetal haemoglobin take in more oxygen

A

in pregnancy, foetal and maternal blood is kept separate

foetal Hb was a higher oxygen affinity means they can become saturated at a low pO2 (partial pressure)

YEAR 1 BIO (16 decks)

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