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3 ADAPTIONS FOR TRANSPORT IN ANIMALS > THE HEART > Flashcards

THE HEART Flashcards

1
Q

What is the heart?

A
  • 2 pumps to circulate blood around the body
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2
Q

label the heart

A

labled drawing of the heart

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3
Q

myogenic

A

it can contract and relax rhythmically of their own accord

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4
Q

systole

A

heart contracting

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5
Q

distole

A

heart relaxes

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6
Q

Atrial systole (4)

A
  • atrium walls contract
  • blood pressure in atria increases
  • pushes blood through bi & tri cuspid valves to ventricles
  • ventricles are relaxed
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7
Q

Ventricular systole (4)

A
  • ventricle walls contract
  • blood pressure in ventricle increases
  • forces blood up through semi-lunar valves into pulmonary artery and aorta
  • blood cannot flow back bc tri & bi valves are closed by rise in pressure
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8
Q

Distole (5)

A
  • ventricles relax
  • volume of ventricles increases
  • ventricle pressure falls
  • semi-lunar valves shut to prevent backflow
  • atria relax during systole so cycle can begin again with blood from vena cava and pulmonary veins
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9
Q

flow of blood through the left side of the heart (7)

A
  • left atrium relaxes and receives oxygenated blood from pulmonary vein
  • when full, pressure forces bi/tricuspid valve open
  • relaxation of left ventricle drew blood from left atrium
  • left atrium contracts pushing remaining blood into left ventricle through the valve
  • left atrium relaxed and bicuspid valve closed left ventricle contracts
  • strong muscle exerts high pressure
  • pressure pushes blood out of heart through semi-lunar valves to aorta and closes bicuspid, preventing backflow
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10
Q

heartbeat (2)

A
  • a complete contraction and relaxation of the entire heart

- atria contract at the same time, followed by the ventricles

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11
Q

what happens when a chamber of the heart relaxes/contracts (2)

A
  • empties when contracted

- fills when relaxed

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12
Q

why is left ventricle thicker than the right? (2)

A
  • the left has to pump blood around the entire body

- the right only has to pump the short distance to the fragile lungs

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13
Q

What are valves for?

A
  • prevent backflow
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14
Q

when do valves open and shut in the cardiac cycle

A

diagram

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15
Q

sino-atrial node (3)

A
  • cluster of cardiac cells
  • acts as a pacemaker
  • located in the right atrium
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16
Q

how electrical stimulation of the heart works? (7)

A
  • electric stimulation occurs at SAN and spreads of atria causing contraction
  • ventricles insulated by a thin layer of connective tissue
  • so charge spreads to AVN (atrio-ventricular node)
  • AVN delays impulse until atria has finished contracting
  • AVN passes excitation down nerves of the bundle of His, left and right to the apex of the heart
  • excitation travels through the purkinje fibres in the ventricle walls
  • ventricles contract simultaneously, from the apex up
17
Q

ECG

A
  • electrocardiogram, voltage changes produced by heart
18
Q

diagram explain points P, PR, QRS, T, TP (5)

A
  • P wave shows voltage generated by SAN
  • PR interval is time taken for excitation to spread from AVN to ventricles
  • QRS complex shows depolarisation/contraction of the ventricles (more muscle, bigger wave)
  • T is repolarisation of ventricular muscles
  • TP/isoelectric line is the separating the two cycles
19
Q

heart issues shown by ECG (4)

A
  • Atrial fibrillation = rapid heart rate/ no P wave
  • Post-heart attack = wide QRS complex
  • Enlarged ventricle walls = QRS with greater voltage
  • Insufficient blood supply = ST height change - could be blocked arteries
20
Q

heart rate calculation

A

60/ distance between isoelectric lines = heart rate

21
Q

pressure changes in blood vessels (7)

A
  • highest in aorta/large arteries - rises and falls with ventricular contraction
  • friction between blood and vessel causes progressive drop, also depends on whether dilated or constricted
  • extensive capillary beds reduce bp as fluid leaks to surrounding tissues
  • distance from the heart increases as bp lowers
  • veins are not effected by ventricles so low bp
  • veins have a large lumen, so blood flows faster than in capillaries
  • blood is not returned to the heart rhythmically, but by massaging effect of surrounding tissues
22
Q

Blood

A

45% cells in 55% plasma

23
Q

Why are blood cells red?

A
  • Red because pigment haemoglobin
24
Q

Why are rbc unusual? (2)

A
  • biconcave discs - thin middle reduces diffusion distance

- no nucleus - so more room for haemoglobin

25
Q

Plasma (4)

A
  • pale yellow liquid
  • 90% water
  • contains biological molecules, waste, hormones and proteins
  • distributes heat

3 ADAPTIONS FOR TRANSPORT IN ANIMALS (6 decks)

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