Biology (Combined Science) - Paper 2 - Homeostasis and Response

?
What is homeostasis?
The regulation of the internal conditions of a cell or organism in response to internal and external changes.
1 of 75
Why is homeostasis important?
It keeps conditions constant for enzyme activity and cell functions.
2 of 75
Homeostasis includes the control of...
...blood glucose concentration, body temperature and water and ion levels in the body.
3 of 75
All control systems in the body include...
...cells called receptors, coordination centres (e.g. brain, spinal chord and pancreas) and effectors (e.g. muscles or glands).
4 of 75
What is a receptor?
A cell or group of cells at the beginning of a pathway of neurones that can detect an external stimulus (e.g. light, heat, etc.) and generate an electrical impulse.
5 of 75
What is a coordination centre?
An organ that receives and processes information from a receptor.
6 of 75
What is an effector?
A muscle or gland that brings about a response to the stimulus to restore/maintain optimum levels.
7 of 75
Different forms of response include...
...responses involving nerves (physical responses) and responses involving hormones (chemical responses).
8 of 75
What is the process of negative feedback?
A receptor detects a stimulus. The coordination centre compares the stimulus to a set point. An effector then produces a response to correct any difference from the set point.
9 of 75
The nervous system allows humans to...
...react to their surroundings and coordinate their behaviour.
10 of 75
What does CNS stand for?
Central Nervous System
11 of 75
What is contained within the nervous system?
The brain, spinal cord and nerves.
12 of 75
What is contained within the CNS?
The brain and spinal cord.
13 of 75
What is the sensory neurone?
The neurone that carries an electrical impulse from the receptor towards the CNS.
14 of 75
What is the relay neurone?
The neurone that carries an electrical impulse within the CNS.
15 of 75
What is the motor neurone?
A neurone that carries an electrical impulse away from the CNS to the effector.
16 of 75
Explain the process from receptor to effector in the nervous system.
The pain stimulus is detected by receptors. Impulses from the receptor pass along a sensory neurone to the CNS. AN impulse then passes through a relay neurone. (continues on next card...)
17 of 75
continued...
A motor neurone carries an impulse to the effector. The effector (usually a muscle) responds, e.g. to withdraw a limb away from the source of pain.
18 of 75
Senses - Organs - Stimuli
Sight - Eyes - Light | Hearing - Ears - Sound | Taste - Tongue - Chemicals in food | Smell - Nose - Chemicals in the air | Touch - Skin - Touch/Pressure/Temperature/Pain/Itching.
19 of 75
Neurones are not directly connected. How do they communicate with one another?
Via synapses.
20 of 75
What are synapses?
The gaps between the axon of one nerve cell and the dendrites of another where chemical neurotransmitters transmit an electrical impulse.
21 of 75
What happens when an electrical impulse reaches a synapse?
A chemical is released that diffuses across the gap between the two neurones, causing an electrical impulse to be generated in the second neurone.
22 of 75
What is the endocrine system?
A collection of glands that secrete hormones directly into the blood stream to bring about an effect to maintain optimum conditions in the body.
23 of 75
What are hormones?
Chemical messengers that are carried in the blood to a target organ where they produce an effect.
24 of 75
Compared to effects of the nervous system, the effects of hormones in the endocrine system are...
...slower yet longer lasting.
25 of 75
The main glands that produce hormones in the body and their location...
Pituitary Gland (brain), Thyroid Gland (neck), Pancreas (behind the stomach), Adrenal Gland (top of each kidney), Ovaries in females (lower abdomen), Testes in males (scrotum).
26 of 75
What is known as the master gland?
The pituitary gland, located in the brain.
27 of 75
What does the master gland do?
It secretes several hormones in response to body conditions. Some of these hormones act on other glands to stimulate the release of hormones and bring about further effects.
28 of 75
Where is adrenaline produced and when?
In the adrenal glands in times of fear/stress.
29 of 75
What does adrenaline do?
It increases the heart rate, boosting the delivery of oxygen and glucose to the brain and muscles. Prepares the body for 'fight or flight' response.
30 of 75
Where is thyroxine produced?
In the thyroid gland.
31 of 75
What does thyroxine do?
It increases the metabolic rate and controls growth and development in young animals.
32 of 75
What is thyroxine controlled by?
Negative feedback
33 of 75
What is controlled and monitored by the pancreas?
Blood glucose concentration
34 of 75
What happens if blood glucose concentration becomes too high?
The pancreas releases more of the insulin hormone. Insulin cause glucose to move from the blood into the cells. In liver and muscle cells, excess glucose is converted into glycogen for storage.
35 of 75
What happens if blood glucose concentration becomes too low?
The pancreas releases glucagon. Glucagon stimulates the conversion of glycogen into glucose and the release of this glucose into the blood.
36 of 75
This response is an example of...
...negative feedback.
37 of 75
What causes type 1 diabetes?
The pancreas failing to produce enough insulin.
38 of 75
What is the result of this?
Uncontrolled, high blood glucose levels.
39 of 75
How is type 1 diabetes typically treated?
Via insulin injections.
40 of 75
What causes type 2 diabetes?
The body cells no longer responding to insulin.
41 of 75
What is the result of this?
Uncontrolled, high blood glucose levels.
42 of 75
What is a risk factor of type 2 diabetes?
Obesity
43 of 75
How is type 2 diabetes typically treated?
With a carbohydrate-controlled diet and regular exercise.
44 of 75
What effect does an insulin injection have on those with type 1 diabetes?
The insulin lowers the blood glucose level by stimulating the liver to convert the glucose into glycogen.
45 of 75
What effect does an insulin injection have on those with type 2 diabetes?
There is little effect because the cells do not respond to insulin.
46 of 75
What is the main female sex hormone?
Oestrogen, from the ovaries.
47 of 75
What is ovulation?
When eggs (ova) produced by the ovaries mature and are released (discharged).
48 of 75
What is the main male sex hormone?
Testosterone, from the testes.
49 of 75
What does testosterone do?
It stimulates sperm production.
50 of 75
What does FSH stand for?
Follicle Stimulating Hormone
51 of 75
What does LH stand for?
Luteinising Hormone
52 of 75
What are the 4 main hormones involved in the control of the menstrual cycle.
FSH, Oestrogen, LH and Progesterone.
53 of 75
Where is FSH secreted?
From the pituitary gland.
54 of 75
What is the function of FSH in the menstrual cycle?
It causes eggs to mature in the ovaries in the first part of the cycle and stimulates the ovaries to produce oestrogen.
55 of 75
Where is oestrogen secreted?
From the ovaries.
56 of 75
What is the function of oestrogen in the menstrual cycle?
It inhibits FSH release, stimulates LH release and makes the uterus lining grow again after menstruation.
57 of 75
Where is LH secreted?
From the pituitary gland.
58 of 75
What is the function of LH in the menstrual cycle?
It stimulates the release of the egg from the ovary. This is known as ovulation.
59 of 75
Where is progesterone secreted?
From an empty follicle in the ovaries.
60 of 75
What is the function of progesterone in the menstrual cycle?
It maintains the uterus lining during the second half of the cycle and inhibits the release of both FSH and LH.
61 of 75
What happens if a fertilised ovum becomes embedded in the uterus lining?
The woman becomes pregnant and progesterone continues to be produces to continue the build up of the uterus lining (to protect the foetus) and also to prevent menstruation, which would abort a developing foetus.
62 of 75
What is a contraceptive?
A means of preventing pregnancy.
63 of 75
Hormonal methods of contraception - Oral contraceptives
Oral contraceptives contain oestrogen and progesterone, which inhibit the release of FSH so that no eggs are released.
64 of 75
Hormonal methods of contraception - Injection, Implant or Skin Patch
All slowly release progesterone to stop FSH secretion and thus stop the release of eggs for a number of months or years.
65 of 75
Non-hormonal methods of contraception - Barrier Methods
Barrier methods (e.g. condoms/diaphragms) prevent the sperm from reaching an egg.
66 of 75
Non-hormonal methods of contraception - Intrauterine Devices
Intrauterine devices prevent embryos from implanting in the uterus.
67 of 75
Non-hormonal methods of contraception - Spermicidal Creams
Spermicidal creams kill/disable sperm.
68 of 75
Non-hormonal methods of contraception - Abstinence
Abstinence (reforming from intercourse) prevents sexual activity and thus there is no risk of pregnancy.
69 of 75
Non-hormonal methods of contraception - Surgical Methods
Surgical methods of male and female sterilisation (e.g. cutting sperm ducts or tying fallopian tubes) eliminate the risk of pregnancy from intercourse.
70 of 75
What does IVF stand for?
In Vitro Fertilisation
71 of 75
IVF involves...
...giving a woman FSH and LH to stimulate the growth of many eggs, collecting the eggs from the woman, fertilising the eggs with sperm from the father in the laboratory and finally inserting one or two embryos into the woman's uterus (womb).
72 of 75
What is the fertility drug?
A drug containing FSH an LH which is given to women with low levels of FSH to stimulate eggs to mature, thus making her more fertile.
73 of 75
Disadvantages of fertility treatments (such as IVF)...
It is emotionally and physically stressful, the success rates are very low and it can lead to multiple births, which are a risk to both the babies and the mother.
74 of 75
Ethical issues surrounding fertility treatments (such as IVF)...
Some people argue that it is unnatural, some embryos are unused as some may be unhealthy which some regard as immoral as they are technically alive and, in some cases, it allows same-sex couples to have children, which is an issue for many religions.
75 of 75

Other cards in this set

Card 2

Front

Why is homeostasis important?

Back

It keeps conditions constant for enzyme activity and cell functions.

Card 3

Front

Homeostasis includes the control of...

Back

Preview of the front of card 3

Card 4

Front

All control systems in the body include...

Back

Preview of the front of card 4

Card 5

Front

What is a receptor?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

Biology
BIOLOGY
Biology
See all Biology resources »See all Homeostasis resources »