B12 Homeostasis in Action

Question 1

Where is your thermoregulatory system and how does it monitor temperature

Answer 1

Hypothalumus senses the temperature of the blood flowing through it
It also receives information via the sensory neurones from heat receptors in the skin

Question 2

How does blood play an important part in thermoregulation

Answer 2

Blood carries heat from the core around the body
As blood flows throw capilleries close to the surface of the skin, heat is lost to the bodies surroundings
The arteriole ( which supply the capilleries in the skin ) have smooth muscle walls which means they can constrict or dilate to control the flow of blood into the capilleries

Question 3

What happens in vasodilation

Answer 3

If core temperature of the body rises
Smooth muscle in the arteriole walls relaxes and the arteriole dilates
More blood flows through capillaries nervthe surface of the skin
This increases the rate of heat loss from the body

Question 4

What happens in vasoconstriction

Answer 4

The core temperature of the body drops
Smooth muscles in the arteriole walls contract which constricts the arteriole
Less blood flows through the capilleries close to the skin as blood is redirected through the shunt vessel which are found in the layers of the skin

Question 5

How do the pili erector muscles and goosebumps work

Answer 5

Each of our body hairs has a small muscle attached to the base
When this muscle contracts, the hair is pulled upright
When the rate of heat loss from the body increases, these muscles contract so that the hairs stand on end creating an insulating layer of still air. This decreases the rate of heat loss

Question 6

How does sweating cool the body

Answer 6

Skin produces sweat if temperature rises
Water is sweat evaporates. In oder to do so, it must absorb heat from the body
This increases the rate of heat loss

Question 7

How does shivering work in thermoregulation

Answer 7

Muscles require energy to contract. This energy is supplied by respiration
During respiration some energy is lost as heat energy
When we shiver, the muscles contract repeatedly so the rate of respiration in the muscles increases, and more heat is generated

Question 8

What is the negative response for when the body temperature rises

Answer 8

Blood temperature rises
Change detected by hypothalamus
Vasodilation, sweating
Temperature falls again

Question 9

What is the negative response loop for when the body temperature drops

Answer 9

Blood temperature falls
Change detected by hypothalamus
Vasoconstriction, goosebumps, shivering
Temperature rises

Question 10

How are lungs involved with excretion

Answer 10

Remove carbon dioxide, a product of respiration

Question 11

How is the liver involved with excretion

Answer 11

Converts excess protein ( amino acids ) into urea

Question 12

How is the skin involved in excretion

Answer 12

Provides a surface area for small amounts of water and salt to move out of the body

Question 13

How are the kidneys involved in excretion

Answer 13

Remove unwanted substances such as urea, excess water and salt

Question 14

What are the steps for how excess amino acids are excreted in the urine

Answer 14

Excess amino acids cannot be used for fuel so they are broken down by the liver
Liver removes the amino group from the amino acids ( deamination ), forming toxic ammonia which is then immediately converted into urea
Once formed, urea is transported by circulatory system to kidneys
Kidneys filter blood, removing urea and excess water and salt which forms urine
Urine is stored in the bladder before being excreted
The remaining part of the amino acid molecule can be used in respiration or to make other molecules

Question 15

Why does carbon dioxide have to be excreted and how

Answer 15

Dissolved CO2 produces carbonic acid. This affects the working of all enzymes in your cells
CO2 diffuses out of the blood down a concentration gradient to the alveoli and exhaled
You may lose water when moist air from the inside of your lungs is forced out of the body

Question 16

Why does urea have to be excreted and how is it done

Answer 16

Urea is poisonous and if levels build up then it will cause damage to cells
Urea is filtered out of the blood by your kidneys and is passed out in the urine

Question 17

Where does the water and mineral ions in your body come from and why does it have to be excreted

Answer 17

Water comes from respiration and food/ drink and mineral ions come from the diet
If the cells lose too much water by osmosis to the fluids surrounding them they can be crenated and if they gain too much water from from the surrounding fluids, they undergo lysis which means they do not function efficiently

Question 18

What are the methods of water excretion that you can’t control

Answer 18

Water leaves lungs when exhaling

Mineral ions and urea are lost through the skin in sweat

Question 19

What are the methods of water excretion that you can control

Answer 19

Urea, water and mineral ions are removed from the body via the kidneys and excreted in urine

Question 20

What does water and mineral ions removal regulate

Answer 20

Maintains water and mineral ion content of blood
Remove urea ( poisonous waste )

Question 21

What do the kidneys do

Answer 21

Send the wastes to your bladder to be excreted
Removes wastes from our blood
Adjusts the amount of water and mineral ions in the blood

Question 22

What is urine made from

Answer 22

Water
Urea (nitrogenous wastes )
Salts ( mineral ions )

Question 23

How do the kidneys work

Answer 23

1. Glucose, salts, urea and water all move out kf the blood into the kidney. Blood cells and large proteins are too big to pass through the filtering process
2. Any useful substances like glucose, some ions and the right amount of water will be reabsorbed into the blood through selective reabsorbtion
3. Anything not needed is removed in the urine

Question 24

How is the concentration of urine controlled

Answer 24

Conc of urine is controlled by ADH Anti Diuretic Hormone
Brain monitors water content of blood and tells pituitary gland to release ADH into the blood depending on how much is needed
This is a negative feedback loop

Question 25

What is the negative feedback loop for too high water concentration

Answer 25

Too much water not enough salts in the blood
Pituitary gland releases less ADH 
Kidneys tubules reabsorb less water 
Blood restored to normal
( lots of urine produced, pale yellow )

Question 26

What is the negative feedback loop for too low water concentration

Answer 26

Too many salts not enough water
Pituitary gland releases more ADH
kidney tubules reabsorb more water
Blood restored to normal
( little urine produced, dark yellow)

Question 27

What are 2 problems with the kidney

Answer 27

Kidney stones: high salt and minerals in your diet can lead to stones precipitating out, have to be passed in the urine which is painful
Renal damage/ failure: kidney no long able to filter the blood effectively

Question 28

What are methods to fix a kidney

Answer 28

Dialysis

Transplantation

Question 29

What is dialysis

Answer 29

Blood goes through a dialysis machine where urea and excess salt diffuse out of a partially permeable membrane
For this reason the dialysis fluid keeps moving so there is a constant urea flow of low concentration for the waste to move out

Question 30

What are disadvantages of dialysis

Answer 30

Have to do it 3 - 4 times a week and for 4 hours each session

Question 31

Disadvantages of kidney transplant

Answer 31

Risk of rejection

Risk of infection