Dysfunctions

Question 1

Hypothermia

Answer 1

Failure of the body’s homeostatic mechanisms to control body temperature within the thermoneutral zone results in hypothermia (abnormally low body temperature)

Failure to increase temperature, can result in frostbite, organ failure, cardiac arrest and even death.

Question 2

Hyperthermia

Answer 2

Failure of the body’s homeostatic mechanisms to control body temperature within the thermoneutral zone results in hyperthermia (abnormally high body temperature)

Failure to lower temperature results in heat stroke and ultimately death.

Question 3

Heat exhaustion

Answer 3

At temperatures between 38 degrees and 40 degrees, people sweat, become flushed and feel increasingly uncomfortable. Their heart rate increases and they may experience nausea, headaches and may feel dizzy, become confused or faint. It is treated by resting in a cool area and drinking water.

Question 4

Heat stroke

Answer 4

At temperatures above 4 degrees people experience heat stroke. Heart rate becomes very fast. Above 42 degrees people are likely to lapse into a coma and people will die above 43 to 44 degrees.

Question 5

Control of breathing

Answer 5

1. Diaphragm
2. Intercostal muscles

Question 6

Diaphragm

Answer 6

Stimulated by phrenic nerve

Question 7

Intercostal muscles

Answer 7

Stimulated by intercostal nerves

Question 8

The respiratory centre

Answer 8

Normal breathing is controlled by a group of neutrons in medulla oblongata controlled by the respiratory center
Made up of
- inspiratory center
- expiratory center

Question 9

Chemicals affecting breathing

Answer 9

Oxygen, carbon dioxide and hydrogen ions all have some effect on the regulation of breathing activity

Question 10

Chemoreceptors

Answer 10

2 types of chemoreceptors, peripheral and central

Question 11

Peripheral chemoreceptors

Answer 11

• Groups of cells within walls of the aorta and carotid arteries
• Sensitive to changes, in the concentration of oxygen, carbon dioxide and hydrogen ions in the blood plasma
• Known as the aortic and carotid bodies

Question 12

Central chemoreceptors

Answer 12

• Located in the medulla oblongata
• Sensitive to changes in the concentration of carbon dioxide in the blood and hydrogen ions in the cerebrospinal fluid

When chemoreceptors are stimulated, they send a nerve impulse to the area of the respiratory center that regulates breathing

Question 13

Oxygen concentraton

Answer 13

If oxygen falls below normal while other factors are constant, breathing rate increases
If within normal range, effect on breathing rate is minimal
Must fall to VERY LOW levels to have major stimulatory effect. e.g. respiratory diseases such as emphysema or bronchitis, high altitudes and some depressant drugs like heroin.

Question 14

Carbon dioxide concentration

Answer 14

Carbon dioxide in plasma is the MAJOR factor in regulation of breathing rate. A relatively small increase in the concentration of carbon dioxide is enough to cause a marked increase in the rate and depth breathing.

Question 15

Hyperventilation

Answer 15

Is a series of rapid deep breaths. This lowers the level of CO2 in the blood while increasing the concentration of O2. May be voluntary or stimulated by physical stress - severe pain, emotional stress, anxiety.
Often taken by swimmers to remain underwater for longer periods of time. As the swimmer uses up the O2 the CO2 levels which stimulate the need to breathe, do not reach their critical threshold point. Can result in shallow water blackout.