B3.3 (Homeostasis)

Question 1

What is the job of the pancreas?

Answer 1

The pancreas moniters and controls the concentration of glucose in the bloodstream and releases insulin into the blood stream when the glucose levels are TOO HIgh

Question 2

Why is it important to moniter the levels of glucose?

Answer 2

Glucose is an important part of respiration to produce energy and also can change the rate of osmosis if it is not at the right amount in the bloodstream

Question 3

What is the name of glucose when it is stored in the liver or muscle cells?

Answer 3

Glycogen

Question 4

What is type 1 diabetes?

Answer 4

Type 1 diabetes occurs when the pancreas is unable to produce enough insulin to bring glucose levels down when they are too high

Question 5

How can you control type 1 diabetes?

Answer 5

• Self conducting blood tests and injecting with glucose
• Moniterring diet to not eat foods that will cause quick increases in blood glucose
• Doing exercise to increase respiration and lower blood glucose

Question 6

What are the advantages and disadvantages of self injecting with insulin at multiple points throughout the day?

Answer 6

+ Cheaper
+ More discrete

• Uses more insulin
• Requires more careful control over diet and exercise
• Often does not control levels as well

Question 7

What are the advantages and disadvantages of wearing a blood glucose pump?

Answer 7

+ Allows more precise amounts of insulin to better maintain blood glucose levels
+ Uses less insulin and moniters how much you use
+ Reduces risk of long term side effects

• More expensive
• Uncomfortable to wear
• Scar tissue around injection sites

Question 8

What is glucagon?

Answer 8

Glucagon is a hormone secreted by the pancreas that causes the liver to turn stored glucose (glycogen) back into the blood stream as glucose and increase the blood glucose level

Question 9

What are examples of waste products removed by the body?

Answer 9

Carbon dioxide and Urea

Removed as they could interfere with chemical reactions in the body or damage cells

Question 10

Why is carbon dioxide produced and how is it removed?

Answer 10

Carbon dioxide is a waste product of respiration and is removed through exhalation

Question 11

Why is Urea produced and how is it removed?

Answer 11

Urea is produced in the breakdown of amino acids in the liver and is removed through the kidneys to make urine

Question 12

What organ is responcible for maintaining the amount of water we take in and the amount of water we lose through breathing, sweating, and excretion?

Answer 12

The kidneys

Question 13

How do the kidneys maintain homeostasis within the moisture levels of the body?

Answer 13

When water levels in blood plasma is low, more water is reabsorbed back into the blood stream by the kidneys. This causes the urine to be very concentrated

When the water in the blood plasma is high, less water is reabsorbed into the blood stream causing the concentration of the urine to be dilute

Question 14

What factors affect the levels of blood water in the body?

Answer 14

• External temperature, as you lose heat when you sweat
• Exercise, as exercise causes you to sweat
• Fluid intake that dilutes blood plasma
• Salt intake

Question 15

When is blood plasma at its most concentrated?

Answer 15

When it has lost the most water

Question 16

What are the tiny filtering units in the kidneys called?

Answer 16

Nephrons

Question 17

How do the nephrons clean the blood?

Answer 17

By removing urea and excess minerals

Question 18

What is the first stage of cleaning the blood?

Answer 18

Filtration
Blood passes through the capillary and small molecules such as urea, water, and ions are filtered into the nephron whereas the larger molecules continue in the blood stream

Question 19

What is the second stage of cleaning the blood?

Answer 19

Selective reabsorbtion
Not all the small molecules filtered out are harmful and so the kidney must reabsorb some into the blood through active transport by osmosis.
These molecules include glucose, water, ions

The nephron have a large surface area and mitochondria to maximise active transport rate

Question 20

What is the third and final stage of cleaning the blood?

Answer 20

Urine
The waste molecules that are not reabsorbed continue in the nephron tubule and are passed down to the bladder to be excreted

Question 21

What is kidney failure?

Answer 21

Where the kidney cannot efficiently moniter and clean the blood causing fatal amounts of urea and co2 to build up in the blood stream

Question 22

How can dialysis to be used to treat kidney failure?

Answer 22

• High urea levelled blood is removed from the patient and mixed with blood thinners to prevent clotting
• In the machine, the blood and dialysis fluid are separeated with a partially permeable membrane and run against eachother
• This dialysis fluid causes a concentration gradient allowing an exchnage of urea to the dialysis fluid and the blood is clean! it is returned to the body ody ody

Question 23

Why does dialysis fluid contain a similar level of glucose and ions to that in normal blood plasma?

Answer 23

This means a concentration gradient will not occur and so glucose or ions will not be accidently removed or added to the patient

However, if the patient is too low or high in either, a concentration gradient will form and the dialysis will be able to replenish them!

Question 24

Why is there no urea in the dialysis fluid?

Answer 24

To maximise the concentration gradient and cause the urea in the blood stream to quickly diffuse into the dialysis fluid

Question 25

How can dialysis negatively affect a persons lifestyle?

Answer 25

• Patient must be connected 2-3 times a week for 4-6 hours

- When not connected they must moniter their diet carefully and avoid high salt foods and high protein foods

Question 26

What precautions can doctors take to avoid organ rejection?

Answer 26

• Make sure the patient and the donor have similarly formed antigens, however this can lead to long waits
• The patient can take immuno-suppressant drugs for the rest of their life which suppresses the immune system (making them more succeptible to infeciton)

Question 27

What are the advantages and disadvantages of donor kidneys?

Answer 27

+ Process is cheaper for NHS
+ Patient can lead a normal, worry free life

• Must take immuno suppressant drugs
• Kidney only lasts 8-9 years
• Long wait / shortage of organ donors

Question 28

What are the advantages and disadvantages of kidney dialysis?

Answer 28

+ Available and accessible to all patients
+ No need for drugs

• Expensive
• Impacts greatly on lifestyle of patient
• Patient must limit their diet in between sessions

Question 29

What is the optimum constant core temperature?

Answer 29

37 degrees c

Question 30

How does a body react when it is too cold?

Answer 30

• Capillaries and blood vessels constrict, minimising heatloss from skin (VASOCONSTRICTION)
• Shivering causes muscle movements meaning they respire and release energy that warms the body

Question 31

How does the body react when it is too hot?

Answer 31

• Capillaries and blood vessels dilate maximising heatloss by radiation (VASODILATION)
• Body sweats, increasing heat loss due to the heat energy it takes to evaporate water

Question 32

What part of the brain dictates the bodies responce to temperature change?

Answer 32

The thermoregulatory centre

Question 33

How can hair keep us cool or warm?

Answer 33

When we are cold, hairs stand up and trap a layer of air around the skin as an extra layer of insulation