Homeostasis

Question 1

What is homeostasis? And what is it needed for?

Answer 1

Homeostasis is the regulation of internal conditions of a cell or an organism. This is needed for enzymes and all cell functions.

Question 2

What does homeostasis control?

Answer 2

Body temperature
Blood concentration levels
Water levels

Question 3

What would happen if the temperature was too high in the body?

Answer 3

Chemical reactions won’t be able to take place. Causing enzymes to denature and stop working.
Sweating, hairs go flat, blood flow near the skin increases

Question 4

What would happen if the body temp was too low in the body?

Answer 4

Chemical reactions would be too slow to keep up alive.
Shivering, hairs go flat goes up, blood flow near the skin decreases.

Question 5

Temperature is controlled by what?

Answer 5

By the brain

Question 6

What would happen if the glucose levels were too low in the body?

Answer 6

Affects the brain function and respiration.
Pancreas releases glucagon hormone which causes the liver to rise up the glucose levels.

Question 7

What would happen if the glucose levels were too high in the body

Answer 7

It can cause a long term damage to the circulatory system.
Pancreas releases insulin hormone causing the liver to decrease the blood glucose levels

Question 8

What examples can decrease the blood glucose levels, and what examples can increase the blood glucose levels?

Answer 8

Exercise, respiration in cells requires glucose.

Eating foods filled with carbohydrates.

Question 9

What are the steps that occur when the blood glucose levels are high?

Answer 9

Meal that is rich in carbs is eaten.
The concentration of glucose increases in the blood.
Stimulus is detected by the pancreas.
Pancreas releases insulin hormone.
Insulin allows the glucose to move from the blood and into the liver and muscle cells.
Liver causes Excess glucose to be converted into glycogen and will be stored.

Question 10

What is negative feedback?

Answer 10

When there is enough output (glycogen) being produced to restore normal blood levels, the production of insulin will stop.

Question 11

What are the steps that occur when the glucose is too low?

Answer 11

Glucose concentration decreases in blood
stimulus is detected by the pancreas
pancreas releases a hormone in blood which is glucagon
Glucagon stimulates the liver to convert stored glycogen into glucose and release glucose in the blood
Blood glucose rises to normal.

Question 12

How does type 1 diabetes occur in an individual?

Answer 12

Pancreas produces low amounts of insulin to control the concentration of glucose in the blood.
Persons own immune cells destroys pancreatic cells that produce insulin.
Treatments- low carb diet, insulin injections.

Question 13

Why does type 2 diabetes occur in an individual?

Answer 13

Body no longer responds to the insulin that is being produced.
Body is producing insulin but the cells are resistant to it.
Risks-
Obesity
High consumption of carbohydrates
Treatments-
Low carb diet
Exercise
Drugs to make insulin more effective

Question 14

How does the Thermoregulatory center sense the temperature of the body?

Answer 14

The TC in the hypothalamus senses the temperature of the blood flowing in the hypothalamus.

Question 15

What is vasodilation? DWhat would happen if the body temperature was too high (refer to vasodilation)

Answer 15

Vasodilation is when heat is lost to bring the body to the normal temperature.
If the body temperature was too high:
More sweating (acting as a cooling evaporation)
Vasodilation would occur, when blood vessels that are supplying the skin would dilate.
There would be more blood flowing near your skin (which sometimes makes the skin appear red)
Hair erector muscles would be relaxed and so the hairs would be flat.

Question 16

What is vasoconstriction? And what would happen if the body temperature was too low?

Answer 16

Vasoconstriction means heat will be conserved in the body so that the body temperature will be returned back to normal.

More shivering (to release energy during respiration)
Vasoconstriction will occur which causes the blood vessels that are supplying the skin to constrict.
Less blood flowing near the skin (which makes you appear more pale)
Hair erector muscles contract, and so the hair stands up right to trap air. Which acts as an insulator for heat loss.

Question 17

When babies are first born, their skin is wet. Wrapping premature babies
in plastic film immediately after birth reduces the risk of hypothermia.
Explain how the use of plastic film reduces the risk of hypothermia.
Premature babies have some physiological systems not yet fully functioning.
For example, the normal ‘shiver’ mechanism does not work and the muscles of
the blood vessels in the skin do not contract effectively.
(c) Describe how these problems could increase the chances of hypothermia
in premature babies

Answer 17

Less shivering and less muscle contraction.
Which causes Less respiration.
Blood vessels supplying the skin will not constrict effectively.
Causing greater energy transfer to the surroundings.
So the baby cannot maintain optimum temperature due to the greater effect due to the greater effect of heat loss, and not being able to release heat.

Question 18

Describe what happens in the body to keep the body temperature constant- ( 6 marker)

Answer 18

The temperature receptors are the thermaregulatory centre, the skin.
The TC in the hypothalamus will be able to sense the temperature due to the blood flowing in the hypothalamus.
The temperature receptor in the skin sends impulses to the TC. Which the impulses states the skin temperature.

If the temperature was too high-
Heat is lost in the body to return to the normal body temperature.

More sweating which causes cooling evaporation.
Vasodilation (blood vessels supplying the skin will dilate)
Blood flow near the skin increases
Hair erector muscles are relaxed, so the hairs go flat.

If the temperature was too low-
Heat is conserved in the body to return to the normal body temperature.

More shivering; to release energy during respiration
Vasoconstriction occurs: blood vessels supplying the skin constrict.
Less blood flow near the skin.
Hair erector muscles contract causing the hairs to stand up right to trap air which acts as an insulator for heat loss.

Question 19

What are the waste products in the body’s cells? What could happen if waste products build up?

Answer 19

Carbon dioxide and urea.
It could be deadly.

Question 20

How does the excess water leave the body?

Answer 20

In a liquid called urine

Question 21

State the role of carbon dioxide as a waste product-

Answer 21

Produced by cells during respiration.
Dissolved CO2 is acidic which causes enzymes to be denatured.
As carbon goes down the concentration gradient it moves from your blood and into your alveoli.
As you breathe out, carbon leaves your body with the moist air that’s in your lungs.

Question 22

State the role of urea as a waste product-

Answer 22

Produced in the liver as a by- product of breaking down excess amino acids.
Very nitrogen rich
Passed from liver cells to the blood
If it builds up it could cause damage to the cells.
Filtered out your body by your kidneys.
Waste urea leaves by the urine.

Question 23

Deamination in the liver- (4 marker)
Describe what happens to the excess amino acids-

Answer 23

Excess amino acids are broken down by enzymes in the liver.
The breakdown produces ammonia which is toxic to cells.
Ammonia is converted into urea which is a less toxic waste.
Urea travels to the kidneys via the bloodstream.
The kidneys filter the urea and it is removed by urine.

Question 24

What are the functions of liver-

Answer 24

Stores glycogen
Deamination of excess amino acids
Deamination of poisonous substances such as ethanol in alcohol

Question 25

State two jobs of the kidney-

Answer 25

Filters the blood
Removes excess water, ions, urea as the form of urine from the blood

Question 26

What are the jobs of ureters,urethra,bladder, renal vein, renal artery:

Answer 26

Ureter: transports urine from the kidneys to the bladder
Bladder: stores urine
Urethra: excretes urine out of the body
Renal vein: Takes blood away from the kidneys after excess water, ions, urea have been removed.
Renal artery: brings blood containing excess water, ions, urea towards the kidneys.

Question 27

Why are kidneys important?

Answer 27

To maintain water and ion concentration constant in the blood

Question 28

What are the substances that are in filtrate?

Answer 28

Glucose
Urea
Salts (ions)
Water

Question 29

Why do the substances move out of the glomerulus? And where do they move to?

Answer 29

They move out due to the blood being under high pressure, they move to the bowman’s capsule

Question 30

Why do RBC and proteins not pass to the bowman’s capsule?

Answer 30

Because they’re too big to fit through the filter

Question 31

Explain why sometimes the concentration of urea in
the liquid in the bladder is much greater
than the concentration of urea in the liquid
that is filtered in the kidneys.

Answer 31

Because most of the water is reabsorbed in the loop henle, when the liquid reaches the bladder theres greater concentration of urea.

Question 32

Explain the process of ultrafiltration-

Answer 32

The blood in the glomerulus is under high pressure which causes the filtrates/substances (urea, water,glucose, salts) to be moved from the blood and into the bowman’s capsule.

Question 33

Explain the process of selective absorption-

Answer 33

After the glomerular filtrates move into the bowman’s capsule, glucose is the first to be reabsorbed in the proximal convoluted tubule via active transport.

The filtrates then drip down the loop of henle, in which salts are reabsorbed in the blood via diffusion.

water can also be reabsorbed due to osmosis in the loop of henle, and it can also be reabsorbed in the distal convoluted tubule depending on how much water the body requires.

The filtrates which have not been absorbed will then go through the collecting duct forming urine.

Question 34

Why is there no glucose present in the urine?

Answer 34

The kidneys reabsorb glucose from the blood as it passes through our body

Question 35

Why is the concentration of glucose in the filtrate and the blood the same?

Answer 35

Because glucose passes through the filter and is reabsorbed in the bowman’s capsule

Question 36

Explain how the human body reduces the volume of urine produced when less water is consumed-

Answer 36

Blood will become more concentrated.
Hypothalamus detects this stimulus
ADH is released from the pituitary
Increases reabsorption of water
Less water being released from the body, so less urine will be produced.

Question 37

Any excess glucose can be used to produce another type of storage compound, which is not glycogen, then what?

Answer 37

Lipids/fats

Question 38

Describe how the water content in the blood is controlled (6 marker)

Answer 38

If the water content was too low:
Blood becomes more concentrated. Hypothalamus detects this stimulus. ADH hormone is released by the pituitary gland. Increased reabsorption of water in the kidneys.

If the water content was too high:
Blood becomes less concentrated. ADH is not produced. Less water being reabsorbed in the kidneys. Larger volume of urine being produced.