Homeostasis

Question 1

What is homeostasis?

Answer 1

Maintainence of a stable internal environment despite changes in the external environment

Question 2

How does osmoregulation work?

Answer 2

-hypothalamus detects changes in conc of blood
-if too concentrated stimulate pituitary gland to release ADH ∴ kidneys reabsorbed more water into blood, and stimulates thirst ∴ we drink. Trine production suppressed
-if too dilute, ADH suppressed ∴ less water reabsorbed into blood
∴ blood concentration restored

Question 3

How does CO₂ regulation work?

Answer 3

• receptors in control centre in medulla sense changes in CO2 conc
• if too high, sends nerve impulses to diaphragm and intercostal muscles to contract. ∴ breathing rate increases, O₂ levels rise, CO₂ levels drop
• if too low, no nerve impulses sent to diaphragm and IC muscles ∴ relax and breathing rate drops. O₂ levels drop, CO₂ levels increase

Question 4

How does thermoregulation work?

Answer 4

• body temp controlled by hypothalamus which has receptors for temp of brain blood, and also sensors in skin send impulses to alert it to change in temp
• if body temp too high: blood vessels near skin surface vasodilator ∴ more blood through them ∴ more heat lost via radiation. Sweat glands open and make sweat ∴ evaporates and cools you down. Hairs lie flat ∴ heat lost via evaporation. As more sweat lost, need to take in more fluid
• too low: blood vessels vasoconstriction ∴ less blood flow ∴ less heat lost. Sweet glands close, and no sweat made. Hairs on skin stand up to trap air, as good insulator ∴ heat loss reduced. Shivering ∴ muscles produce heat by contracting, which involves resp, which is exo

Question 5

Why is too much or too little glucose dangerous?

Answer 5

Too much- increases solute concentration of blood ∴ water lost from cells
Too little- need it for resp

Question 6

How does glucose regulation work?

Answer 6

• blood sugar levels change
• receptors in pancreas detect this
• islets of langerhans in pancreas secrete hormones
• if too high: insulin secreted ∴ cell take in glucose and use in resp. Muscle and liver cells take in glucose and change it to glycogen for storage
• if too low: glucagon secreted ∴ liver breaks down glycogen to glucose and releases it to bloodstream
• blood sugar levels return to normal

Question 7

How do you test diabetes?

Answer 7

• blood sugar levels- finger prick

- testing for glucose in urine

Question 8

What is the difference between type 1 and type 2 diabetes?

Answer 8

Type 1: diagnosed age 10-14yrs. Insufficient insulin production in pancreas. Treat via insulin injections. These can come from animals, but there are side effects, e.g, skin rashes ∴ human best
Type 2: ineffective use of insulin. Due to excess body weight and physical inactivity. Mostly affects older people. Must be treated through change in lifestyle, e.g. Eating healthier diet