B12 Homeostatis in Action

Question 1

What is hypothermia?

Answer 1

When the body’s average temperature is too LOW

Question 2

What is hyperthermia?

Answer 2

When the average body temperature is too HIGH

Question 3

What is the average human body temperature?

Answer 3

Around 37°C

Question 4

What happens if the body temperature is too low?

Answer 4

Enzymes and substrates don’t have enough energy to collide so that the metabolic rate is really low.

Question 5

What happens if the body temperature is too high?

Answer 5

Enzymes denature and metabolic reaction will stop.

Question 6

How does the body control hypothermia?

Answer 6

• Shivering
• Hair on skin stands up (goosebumps)
• Vasoconstriction

Question 7

How does shivering help the body warm up?

Answer 7

Vigourous muscle contractions release thermal energy by respirstion

Question 8

How does hair on skin standing up help warm up the body?

Answer 8

It traps air to provide a layer of insulation.

- air is a good insulator

Question 9

What is vasoconstriction?

Answer 9

Blood vessels (that supply blood to the skin) constrict so that blood dosen’t flow closer to the skin.

Question 10

How does vasoconstriction help warm up the body?

Answer 10

It reduces the amount of heat lost by radiation

Question 11

How does the body control hyperthermia?

Answer 11

• Vasodialation
• Hair on skin stays flat
• Body starts to sweat

Question 12

What is vasodialation?

Answer 12

Blood vessels (which supply blood to the skin) dialets so that blood flows closer to the skin.

Question 13

How does vasodialtion help cool down the body?

Answer 13

It increases the amount of heat loss by radiation.

Question 14

How does flat hair on the skin help cool down the body?

Answer 14

Air level above the skin is thinner for less insulation.

Question 15

How does sweating help cool down the body?

Answer 15

Respiration releases heat energy. Evaporation of water in sweat absorbs heat energy from the body.

Question 16

What controls the body’s temperature?

Answer 16

The thermoregulatory centre in the hypothalamus.

Question 17

What is the function of the renal artery?

Answer 17

It carries oxygenated blood to the kidneys

Question 18

What is the function of the renal vein?

Answer 18

It carries deoxygenated blood away from kidneys.

Question 19

What are the kidneys?

Answer 19

The place where blood is filtered and where urine is produced.

Question 20

What is the function of the ureters?

Answer 20

They are small tubes which transport urine from kidneys to the bladder.

Question 21

What is the function of the bladder?

Answer 21

To store urine temporarily.

Question 22

What is the function of the urethra?

Answer 22

To release urine from the bladder.

Question 23

What control the opening and closing of the urethra?

Answer 23

Rings of circular muscles.

Question 24

Protiens are digested into….

Answer 24

amino acids by protease in the stomach.

Question 25

Like glucose, can excess amino acids be stored.

Answer 25

No

Question 26

What happens to excess amino acids?

Answer 26

They are broken down in the liver to make urea (*a metabolic watse product*)

Question 27

What are the kindeys made up of?

Answer 27

Large number of small units called **Nephrons**.

Question 28

What are the three stages of urine production?

Answer 28

1) Ultra-Filtration 2) Selective Reabsorbtion 3) Excretion of Urine

Question 29

What happens during **ultra-filtration**?

Answer 29

Blood travels through the **glomerulus** at a high pressure so small molecules in the blood plasma are filtered into the **bowman's capsule** (*the molecules are small enough to travel through the tiny gaps into blood cappilaries*)

Question 30

What are some small molecules in the blood plasma that are filterd out?

Answer 30

- Vitamins - Water - Amino Acids - Urea - Glucose - Salt

Question 31

What is **selective reabsorbtion**?

Answer 31

When the filtrate travels through the nephron some useful substances are reabsorbed into the blood.

Question 32

What are useful substances that are reabsorbed and how much of it are reabsorbed?

Answer 32

- Glucose (all) - Amino acids (all) - Vitamins (some) - Water (some) - Salt (some)

Question 33

Why is none of the urea reabsorbed?

Answer 33

Because it is a waster product.

Question 34

What happens at the excretion of urine?

Answer 34

When the filtrate travels into the collecting duct it has a high concentration of urea, some water, some salt and some vitamins. This is now called urine and is excreted into urethra.

Question 35

What happens during a **dialysis**?

Answer 35

Patients blood is pumped out and it's passed through a tube of partially permable membrane, *which is placed in a dialysis fluid*. This fluid has the same composition as patients blood plasma but dosen't contain any urea, which means urea diffuses out from patients blood into dialysis fluid.

Question 36

What are the **advantages** of a dialysis?

Answer 36

- Clear blood - No risk of surgery

Question 37

What are the **disadvantages** of a dialysis?

Answer 37

- Diet of protien must be controlled - Long term expense - Dependant - Infectious and blood clotting risks - Not a permenant cure

Question 38

What is a kidney transplant?

Answer 38

A healthy kidney from a matching donar is used to replace the kidney which is not functioning.

Question 39

What are the **advantages** of a kidney transplant?

Answer 39

- Permanant Treatment - One time cost - Independant

Question 40

What are the **disadvantages** of a kidney transplant?

Answer 40

- Hard to find - Surgey Required - Risk of immune rejection means immuno-suppressed drugs are taken making patient susceptible for infections

Question 41

What is immune-rejection?

Answer 41

If cell surface recpetors of patiens white-blood cells and donar's cells don't match then patients cells start to produce anti-bodies to destroy the kidney.

Question 42

What happens when water level in the blood is too low?

Answer 42

1) Osmoregulatory centre (in the hypothalamus) detects the low water level in blood 2) It send signals to secrete more ADH in the blood 3) More ADH is transported to the kindeys 4) Walls of the collecting duct become more permeable to water 5) More water is reabsorbed into the blood and less water is released in urine

Question 43

What happens when the water level in the blood is too high?

Answer 43

1) Osmoregulatory centre (in the hypothalamus) detects the high water level in blood 2) It send signals to secrete less ADH in the blood 3) Less ADH is transported to the kindeys 4) Walls of the collecting duct become less permeable to water 5) Less water is reabsorbed into the blood and more water is released in urine

Question 44

What are the main waster products of the body?

Answer 44

- Excess water - Urea - Excess ions - Carbon Dioxide

Question 45

Why are amino acids converted into urea?

Answer 45

Excess amino acids are deamimated in the liver to form ammonia which is toxic, so it's immediatelt converted to urea.

Question 46

What is nitrogen balance?

Answer 46

The control of excess amino acids in the blood