Unit 6 - Organisms respond to changes in their internal and external environments

Question 1

Homeostasis defintion

Answer 1

maintaining a constant internal environment within restricted limits in organisms

Question 2

What happens when there is an increase in body temperature?

Answer 2

• receptors (skin, hypothalamus) detect change
• hypothalamus
• sweat glands, vasodilation, hairs lie flat

Question 3

What happens when there is a decrease in body temperature?

Answer 3

• receptors (skin, hypothalamus) detect change
• hypothalamus
• vasoconstriction, shivering, hairs erect

Question 4

Vasodilation

Answer 4

arterioles dilate so blood in capillaries flows near surface of skin

Question 5

Vasoconstriction

Answer 5

arterioles constrict so blood in capillaries flows further from the surface of the skin

Question 6

Glycogenesis

Answer 6

glucose to glycogen

Question 7

Glycogenolysis

Answer 7

liver breaks down glycogen to glucose

Question 8

Gluconeogenesis

Answer 8

production of glucose from other sources e.g. glycerol, pyruvate and amino acids

Question 9

What are the specialised cells in the pancreas called?

Answer 9

islets of langerhans

Question 10

alpha cells

Answer 10

make and secrete glucagon when there is a low blood glucose conc

Question 11

beta cells

Answer 11

make and secrete insulin when there is a high blood glucose conc

Question 12

What does insulin stimulate?

Answer 12

• glycogenesis
• increased absorption rate (activates carrier proteins)
• increased respiratory rate
• fat

Question 13

What does glucagon stimulate?

Answer 13

• gluconeogenesis
• glycogenolysis