B3.3

Question 1

What is homeostasis?

Answer 1

Maintenance of a constant internal environment.

Question 2

Why is homeostasis important?

Answer 2

Keeps optimum conditions for enzyme action & all cell functions.

Question 3

Where is the thermoregulatory centre found?

Answer 3

In the brain.

Question 4

What does the thermoregulatory centre do?

Answer 4

Monitors and controls body temperature

Question 5

What do receptors in the thermoregulatory centre detect?

Answer 5

Temperature of the blood.

Question 6

What do skin receptors detect?

Answer 6

Send impulses about external temperature to the thermoregulatory centre.

Question 7

What is the normal human body temperature?

Answer 7

37.5 degrees Celsius.

Question 8

What happens when body temperature is too high?

Answer 8

Sweat produced from glands, evaporates from skin → energy transferred away from body
Vasodilation

Question 9

What is vasodilation?

Answer 9

Blood vessels widen → more blood flows near skin → more energy lost.

Question 10

What happens when body temperature is too low?

Answer 10

Sweating stops, skeletal muscles contract rapidly (shivering) - generate heat from respiration, hairs stand up - insulating layer:traps warm air, vasoconstriction

Question 11

What is vasoconstriction?

Answer 11

Blood vessels narrow → less blood near skin → less heat lost.

Question 12

Why must blood glucose be kept within limits?

Answer 12

Needed for respiration.

Question 13

What organ controls blood glucose?

Answer 13

Pancreas

Question 14

What happens when blood glucose is too high?

Answer 14

Pancreas releases insulin.

Question 15

What does insulin do?

Answer 15

Binds to cells in target organs - liver + muscle.

Question 16

What are insulin’s effects on the target organs?

Answer 16

1.glucose move from blood into muscle cells used for respiration
2. Excess converted to glycogen & is stored in liver

Question 17

What happens to blood glucose after insulin acts?

Answer 17

It is reduced.

Question 18

What happens when glucose levels are too low?

Answer 18

Pancreas releases glucagon.

Question 19

Where does glucagon act?

Answer 19

Liver

Question 20

What does glucagon do?

Answer 20

Binds to liver cells and breaks down glycogen into glucose
That glucose is then released into blood - increasing glucose concentration

Question 21

How do insulin and glucagon maintain glucose levels?

Answer 21

Negative feedback.

Question 22

What is negative feedback?

Answer 22

When a change occurs, a hormone is secreted to oppose it.

Question 23

What causes an increase in blood glucose?

Answer 23

Eating foods that contain carbohydrates

Question 24

What causes a decrease in blood glucose?

Answer 24

Rigorous activity - exercise
Glucose used for respiration for energy but then reduced in blood

Question 25

What is type 1 diabetes?

Answer 25

Pancreas cannot make insulin.

Question 26

What are the effects of type 1 diabetes?

Answer 26

High blood glucose, glucose in urine, lots of thirst.

Question 27

How is type 1 diabetes treated?

Answer 27

Insulin injections at meals.

Question 28

What is advised for type 1 patients?

Answer 28

Limit simple carbs (high in glucose).

Question 29

What are researchers trying to do for type 1?

Answer 29

Pancreas + islet cell transplants, genetically engineer insulin.

Question 30

What is type 2 diabetes?

Answer 30

Body cells stop responding to insulin.

Question 31

Risk factor for type 2?

Answer 31

Obesity

Question 32

How is type 2 treated?

Answer 32

Diet (less simple carbs), exercise & losing weight, drugs to improve insulin response.

Question 33

What happens if blood water conc. increases?

Answer 33

Water moves into cells → swelling → lysis (bursting)

Question 34

What happens if blood water conc. decreases?

Answer 34

Water leaves cells → shrink.

Question 35

Why are kidneys important?

Answer 35

Maintain water + ion balance in the body

Question 36

How do kidneys make urine?

Answer 36

Filter out waste products from blood at high pressure - water,ions,urea And then selectively reabsorb useful substances - glucose, ions, water

Question 37

What is removed from the blood?

Answer 37

Water, ions, urea (amino acids)

Question 38

What is selectively reabsorbed?

Answer 38

Glucose, ions, water.

Question 39

What is the outer part of the kidney called?

Answer 39

Cortex

Question 40

What is the inner part of the kidney called?

Answer 40

Medulla.

Question 41

What carries urine to bladder?

Answer 41

Ureter

Question 42

What supplies blood to kidney?

Answer 42

Renal artery.

Question 43

What removes blood from kidney?

Answer 43

Renal vein.

Question 44

What are nephrons?

Answer 44

Millions of kidney tubules.

Question 45

What is the glomerulus?

Answer 45

Ball of capillaries for selective reabsorption.

Question 46

What is ADH?

Answer 46

Anti-diuretic hormone controlling urine water content.

Question 47

Where is ADH made?

Answer 47

Pituitary gland but is released into pancreas.

Question 48

What does ADH do?

Answer 48

Hormone involved in the control of loss of water as urine

Question 49

When is ADH released?

Answer 49

When blood is too concentrated

Question 50

Where does ADH act?

Answer 50

Travels in bloodstream to kidney tubules.

Question 51

What does ADH do?

Answer 51

Increases permeability of tubules → more water reabsorbed back into blood

Question 52

What is the result of more ADH?

Answer 52

More concentrated (yellow) urine - more water reabsorbed into blood

Question 53

What happens in high temperatures to water & salt content?

Answer 53

More sweat → more salt loss. - dehydration too

Question 54

How do kidneys respond to dehydration?

Answer 54

Retain more salt.

Question 55

What does the brain do during dehydration?

Answer 55

Makes us feel thirsty → drink water to dilute salt in our blood