Aqa Igcse Biology. Key Facts Chapter 7

Front 1

What is homeostasis?

Back 1

The process by which your body maintains a constant internal environment.

Front 2

Name some of the internal conditions that are controlled during homeostasis?

Back 2

Water content, ion content, temperature, blood sugar level

Front 3

How does water leave the body?

Back 3

When breathing, when sweating and excess water is lost in the urine.

Front 4

How are ions lost from the body?

Back 4

In sweat and in urine

Front 5

What would happen if our core body temperature is not kept constant?

Back 5

The enzymes in the body will not work properly (or at all)

Front 6

What does the sugar in the blood do?

Back 6

It is the energy source for cells

Front 7

What controls the level of sugar in the blood?

Back 7

The pancreas

Front 8

Carbon dioxide is a waste product, how is it produced and how is it removed?

Back 8

Produced during respiration, removed via the lungs when we breathe out.

Front 9

Urea is a waste product, how is it produced and how is it removed?

Back 9

Produced in the liver from the breakdown of amino acids, removed by the kidneys in the urine and temporarily stored in the bladder.

Front 10

What happens in the liver?

Back 10

Excess amino acids are changes to urea. The amino group is removed from the amino acid in deamination. This forms ammonia which is converted to urea.

Front 11

Draw a flow diagram to show the changes from amino acids to urine

Back 11

Amino acids --> ammonia --> urea --> urine

Front 12

What is the function of the kidneys?

Back 12

They filter the blood, excreting substances you do not want and keeping those that the body needs.

Front 13

How does a healthy kidney produce urine?

Back 13

First filtering the blood. Reabsorbing the sugar. Reabsorbing the dissolved ions needed by the body. Reabsorbing as much water as the body needs. Releasing urea, excess ions and water in the urine.

Front 14

What is it called when only certain substances are reabsorbed?

Back 14

Selective reabsorption

Front 15

What happens if the water content of your blood is too low?

Back 15

The pituitary gland releases a hormone called ADH

Front 16

What does ADH do?

Back 16

Causes the kidneys to reabsorb more water and results in more concentrated urine.

Front 17

What happens if the water content in the blood is too high?

Back 17

Less ADH is released, therefore less water is reabsorbed in the kidneys resulting in more dilute urine.

Front 18

What sort of system is keeping the water balance?

Back 18

A negative feedback system

Front 19

What does dialysis do?

Back 19

Restores the concentrations of dissolved substances in the blood to normal levels if the kidneys are not working properly.

Front 20

How does dialysis work?

Back 20

In a dialysis machine a person's blood flows between partially permeable membranes, the dialysis fluid contains the same concentration of useful substances as the blood of a person without kidney disease. This ensures that glucose and useful mineral ions are not lost but harmful substances such as urea pass out of the blood.

Front 21

What are the advantages of dialysis?

Back 21

Available to all patients (no shortage)

no need for immune-suppressant drugs

Front 22

What are the disadvantages of dialysis?

Back 22

Patient must limit their salt and protein intake between dialysis sessions.

expensive for the NHS

Regular dialysis sessions impact on the patient's lifestyle

Front 23

What are the advantages of kidney transplants?

Back 23

Patients lead a more normal life (don't have to watch what they eat or drink)
Cheaper for the NHS overall

Front 24

What are the disadvantages of kidney transplants?

Back 24

Must take immune-suppressant drugs which increase the risk of infection.

Shortage of organ donors

kidney only lasts 8-9 years of average

any operation carries risks

Front 25

What temperature must the human body be kept at for enzymes to work efficiently?

Back 25

37 degrees

Front 26

What monitors and controls the body temperature?

Back 26

The thermoregulatory centre in the brain

Front 27

What do the receptors in the centre do?

Back 27

Detect the temperature of the blood flowing through the brain.

Front 28

What do the temperature receptors in the skin do?

Back 28

Send impulses to the brain to information about skin temperature

Front 29

What happens regarding blood if the core temperature rises?

Back 29

Blood vessels near the surface of the skin dilate, allowing more blood to flow through the skin capillaries. Energy is transferred by radiation and the skin cools.

Front 30

What happens regarding sweat if the core temperature rises?

Back 30

Sweat glands produce more sweat. The water in the sweat evaporates from the skins surface, so we cool down.

Front 31

What happens regarding blood if the core temperature falls?

Back 31

Blood vessels near the surface of the skin constrict so less blood flows through skin capillaries and less energy is radiated.

Front 32

What happens regarding muscles if the core temperature falls?

Back 32

We "shiver". Muscles contract quickly, this requires respiration, and some of the energy released warms the blood.

Front 33

What monitors and controls the levels of glucose in our blood?

Back 33

The pancreas.

Receptors in the pancreas detect levels of blood glucose.

Front 34

What happens if there if too much glucose in the blood?

Back 34

The pancreas produces insulin

Front 35

What does insulin do?

Back 35

Causes the glucose to move from the blood into the cells.

Front 36

What is excess glucose converted to?

Back 36

In the liver and muscles, excess glucose is converted into glycogen for storage. When these stores are full, the glucose is stored as a lipid and this can eventually make a person obese.

Front 37

What happens if the blood glucose levels fall too low?

Back 37

Receptors in the pancreas detect the low level and the pancreas releases glucagon.

Front 38

What does glucagon do?

Back 38

Glucagon causes the glycogen in the liver to change into glucose. This glucose is released back into the blood.

Front 39

What is type 1 diabetes?

Back 39

if no, or too little, insulin is produced by the pancreas, the blood glucose level may become very high.

Front 40

How is type 1 diabetes controlled?

Back 40

By injection of insulin and careful attention to diet and exercise.

Front 41

How does type 2 diabetes develop?

Back 41

When the body doesn't respond to its own insulin

Front 42

What is a significant factor in the development of type 2 diabetes?

Back 42

Obesity

Front 43

How can type 2 diabetes be controlled?

Back 43

By a careful diet, exercise and drugs that help the cells to respond to insulin

Front 44

How is type 1 diabetes treated?

Back 44

By injecting human insulin, produced by genetically engineered bacteria, before meals every day.

Front 45

What are some of the methods of treating and curing type 1 diabetes that doctors and scientists are trying to develop?

Back 45

Pancreas transplants

transplanting pancreas cells

using embryonic stem cells to produce insulin-secreting cells

Using adult stem cells from diabetic partients

Genetically engineering pancreas cells to make them work properly

Front 46

Doctors can prescribe drugs to help treat type 2 diabetes, what to the drugs do?

Back 46

Help insulin to work better

help the pancreas to make more insulin

help to reduce the amount of glucose you absorb from your gut