Option H: Further Human Physiology 4/5

Question 1

H.5.1 Explain the events of the cardiac cycle, including arterial and ventricular systole and diastole, and heart sounds.

Answer 1

Systole:
-blood returning to the heart will freely flow from atria to the ventricles as AV valves are kept open by pressure in the atria
-SA node receives signals when ventricle is 70% full
-AV node receives signal and delayed contraction of ventricle
-pressure in ventricles closes AV valves causing 1st heart sound
Diastole:
-increased pressure causes the semilunar valves to open and blood to flow away from the heart
-blood flows into the arteries, ventricle pressure falls
-arterial backflow causes semilunar valves to close and the 2nd heart sound

-when pressure in ventricle drops below pressure in the atria the AV valves open and the cardiac cyles can repeat

Question 2

H.5.2 Analyse data showing pressure and volume changes in the left atrium, left ventricle and the aorta, during the cardiac cycle.

Answer 2

.

Question 3

H.5.3 Outline the mechanisms that control the heartbeat, including the roles of SA (sinoatrial) node, AV (atrioventricular) node and conducting fibres in the ventricular walls.

Answer 3

myogenic: contractions of the hear muscles originate from within the heart muscle
Sino-arterial (SA) node: origin of nerve impulses which causes atrial contraction, pace maker, specialized muscle cells
SA node–> activates Atrio-ventricular (AV) node
AV node: impulse to ‘contract’ travels down the septum of the heart, insulated from ventricle muscle fibres, impulse emerges first at the apex of the heart, this causes this region to contract first, impulse now emerges higher up causing that region to contract, effect is to spread the contraction from the apex upwards, pushing blood towards the semi-lunar valves

Brain: impulses from brain stem via the parasympathetic part of the autonomous nerve system decrease, via the sympathetic nerves will increase
Hormones: adrenaline from adrenal glands near kidney increase

pacemaker can be artificial

Question 4

H.5.4 Outline atherosclerosis and the causes of coronary thrombosis.

Answer 4

atherosclerosis: the hardening and narrowing of arteries caused by chronic inflammation of the walls of the arteries, which can be caused by the accumulation of lipids on the inner surface–> hinders blood flow –> blood clots –> blockage of the coronary artery (coronary thrombosis)–> heart attack

Question 5

H.5.5 Discuss factors that affect the incidence of coronary heart disease.

Answer 5

• genetic risk factors: if one or more family members have CHD, the risk increases
• age: more common at increased
• gender: more common in males
• smoking: increases chances
• obesity: increases chances
• diet: high cholesterol and sat. fats (esp. trans fatty a) increase chances
• lack of exercise: increases

Question 6

H.6.1 Define partial pressure.

Answer 6

Partial Pressure(P):

Question 7

H.6.2 Explain the oxygen dissociation curves of adult hemoglobin, fetal hemoglobin and myoglobin.

Answer 7

Adult Hb:
Fetal Hb:
Myoglobin:

Question 8

H.6.3 Describe how carbon dioxide is carried by the blood, including the action of carbonic anhydrase, the chloride shift and buffering by plasma proteins.

Answer 8

holy shit

Question 9

H.6.4 Explain the role of the Bohr shift in the supply of oxygen to respiring tissues.

Answer 9

blah

Question 10

H.6.5 Explain how and why ventilation rate varies with exercise.

Answer 10

Exercise:

Question 11

H.6.6 Outline the possible causes of asthma and its effects on the gas exchange system.

Answer 11

Causes:
Effects:

Question 12

H.6.7 Explain the problem with gas exchange at high altitudes and the way the body acclimatizes.

Answer 12

Problem:
Acclimatization: