Homeostasis

Question 1

Explain how insulin reduces the blood glucose concentration

Answer 1

• (More) insulin binds to receptors;
• (Stimulates) uptake of glucose by channel/transport proteins
• Activates enzymes which convert glucose to glycogen;

Question 2

Explain the action of Glucagon

Answer 2

• Attaches to receptors on target cells and activates/stimulates enzymes;
• Glycogen to glucose / glycogenolysis;
• Gluconeogenesis;

Question 3

Explain the effect of sweating or panting on temperature control.

Answer 3

• Evaporation (of water from lining of mouth or skin);
• Heat transferred from blood;

Question 4

Describe how a change in blood pH or blood pressure can cause a change in heart rate.

Answer 4

• (Carbon dioxide) detected by chemoreceptors / (pressure) detected by baroreceptors;
• Medulla/cardiac centre involved;
• More impulses to SAN/along sympathetic nerve;
• (Decrease) pH detected by chemoreceptors in carotid artery /aorta;
• Sends (more) impulses to medulla (oblongata);
• More Nerve impulses sent by sympathetic nervous system to SAN;

Question 5

Less CO2 in the blood leads to a reduction in heart rate.

Describe how.

Answer 5

• (less CO2 in blood) Detected by chemoreceptors;
• (Chemoreceptors) located in aorta / carotid artery;
• Fewer impulses to cardiac centre / medulla (oblongata);
• (More) impulses along parasympathetic nerve OR less impulses along sympathetic nerve;
• (To) SAN