Homeostasis And Response

Question 1

What is homeostasis

Answer 1

Homeostasis is the regulation of internal conditions inside cells or organisms, to create the optimum conditions for biological function.

Question 2

How does the body maintain optimum internal conditions

Answer 2

Maintaining blood glucose concentration.
Maintaining body temperature.
Maintaining water levels.

Question 3

What is an involuntary action

Answer 3

Process by which the body maintains the conditions of the internal environment autonomically (without thought)

Question 4

What happens during an involuntary action

Answer 4

1) receptors detect stimulu and sends information to the coordination centres such as the brain and the spinal cord

2) Cooridnation centres process information and organise a response

3) Effectors produce a response to return the conditions to its optimum level. Response may be nervous ( electrical impulses causing muscle contraction) or chemical (hormone secretion)

Question 5

How do humans react to stimuli

Answer 5

1) Stimuli is a change in the external environment

2)receptor cells detect the stimuli

3) Electrical impulses carried from the receptors to the sensory neurones and then towards the CNS

4) Brain and spine recieve and process the information from the electrical impulses and organise a response

5) Electrical implses travel along a motor neurone from the CNS to the effetors

6) The effectors recieve the electrical impulse from the CNS and respond to the stimuli. This could be from a muscle (contraction) or gland (secretion of hormones)

Question 6

What is a synapse

Answer 6

When two neurones join together and use chemicals to transfer the electrical nerve impulses across a gap between them.

Question 7

What happens when information is passed along a synapse

Answer 7

1)electrical impulses travel along the first neurone to the end

2) This causes a chemical called neurotransmitter to be released between the neurones

3) Neurotransmitter diffuse across the gap and binds to receptors on the second neurone

4) Electrical impulses travel across using the neurotransmitter to set off a new electrical impulse in the second neurone

Question 8

Explain what happens in a reflex arc

Answer 8

1) danger is detected by receptors

2) Impulses is sent from receptors, down a sensory neutone to the CNS

3) In the spine a relay neurone recieves the electrical impulses through the diffusion of neurotransmitter across a synapse

4) The electrical impulses are then diffused across another synapse from the relay neurone to the motor neurone through diffusion of neurotransmitter

5) Electrical impulses travel across the motor neurone to the effetors

6) The effector generates a response to the stimuli (contraction) muscle or (secretion of hormones) gland

Question 9

Why are involuntary reactions important

Answer 9

It keeps us away from danger and keeps us slive (heart beating)

Question 10

What does the involuntary reaction not involve

Answer 10

The conscious part of our brain

Question 11

What do neurone cells combine to create

Answer 11

Nerves

Question 12

Required practical

Investigating human reaction times

Answer 12

Doing the experiment

1) Ask an uncaffeinated person to hold out their hand

2) Hold a ruler vertically downwards above the hand

3) Hand must be straight ( resting horizontally on the edge of the table) and still and should only catch the ruler when they see it drop

4) At a random time drop the ruler

5) Record where the top of the finger is on the ruler when they catch it.

6) Repeat for a number of times

7) Repeat the whole experiment with the same person 10 minutes after drinking caffeine

8) Compare results

Control any variables to make the test fair

Make sure caffiene isn’t consumed too much

Question 13

What is reaction time

Answer 13

Time taken to respond to a stimulus

Question 14

What is the pituitary gland

Answer 14

‘master gland’ that releases essential hormones and controls other glands around the body

Question 15

What is the endocrine system

Answer 15

Consists of many endocrine glands that release specific hormones into the blood. The hormones transported by the blood to particular cells in the target organs where they produce an effect

Question 16

Differences between chemical and nervous reaction

Answer 16

Nerves made of neurones carry though electrical impulses (chemicsl through synapses)

Nerves transport messages rapidly but are short term

Neves target specific areas

Hormones transported via blood

Hormones are used when a message requires a long response as it is more long lasting

Hormones are much more general

Question 17

Examples of organs in the endocrine system

Answer 17

Pituitary gland, thyroid gland ,pancreas,ovaries,adrenal gland,testes

Question 18

Endocrine gland organs and their function

Answer 18

Pituitary gland- )’ master gland’ releases lots of hormones that regulate body conditions and also some that act on other glands e.g release TSH causes thyroid to release thyroxine.

Thyroid- produces throxine that helps regulate rate of metabolism(basal metabolic rate) , among other things

Pancreas- produces insulin which is important in controlling blood glucose levels

Adrenal gland- produces adrenaline which is involved in fight or flight responses

Ovaries- produces oesteogen in females vital part of menstrual cycle

Tetses-produces testosterone in males which controls puberty and sperm production

Question 19

What happens when blood glucose concentration is too high

Answer 19

Blood glucose concentration is foo high the pancreas releases insulin which gets tarnsported by the blood stream to the target organ.

Insulin causes glucose to move out of the blood and into the surrounding cells. Additionally, it stores glucose into glycogen in the liver and muscle cells for later hse

Question 20

What happens when blood glucose concentration is too low

Answer 20

Pancras releases the hormone glucagon into the blood which turns glycogen (insoluble molecules of glucose) in the liver into glucose (soluble).

Glucose is then released into the bloodstream to be used by cells and the blood glucose concentration increases again

Question 21

Explain the negative feedback reaction of insulin and glucagon

Answer 21

1) pancreas detects that the blood glucose concentration is too high or low

2) pancreas releases hormones in response insulin if there is too much glucose

Glucagon released if there is too little glucose

3) Insulin helps glucose move into cells and converts it into glycogen which decreases blood glucose concentration to a normal amount

Glucagon converts glycogen back to glucose which gets releases into the bloodstream, increasing the blood glucose concentration to a normal amount

Question 22

What is type 1 diabetes

Answer 22

When the pancreas produces too little or no insulin resulting in blood glucose concentration to rise to dangerous levels

Question 23

How to treat type 1 diabetes

Answer 23

Insulin injections

Question 24

Prevention of type 1 diabetes

Answer 24

Carb controlled diet, exercise

Question 25

What is type 2 diabete

Answer 25

Pancreas produces insulin but the body cells don’t respond to it they sre resistant

Question 26

How to control type 2 disbetes

Answer 26

Carb controlled diabetes, exercise (don’t become obese)

Question 27

What happens during puberty

Answer 27

Reproductive hormones start being released at puberty which causes the production of secondary sexual characteristic and maturation of the egg in women (10-16)

Question 28

Main reproductive organ in men and women

Where are they produced

Answer 28

Testosterone in men produced in the testes

Oesteogen in females produced in the ovaries

Question 29

Secondary characteristics men

Answer 29

Development of sexual organs,facial hair and body hair,voice break (deeper)

Question 30

Secondary characteristics females

Answer 30

Breats develop and sexual organs, growth of pubic hair, and widening of hips.

Question 31

What is the menstrual cycle

Answer 31

Female body prepares for pregnancy by building up the lining of the uterus and developing and releasing an egg cell from the ovaries.

If no egg land son the uterus lining after 28 days, it breaks down and the cycle repeats

Question 32

Explain the days of the menstrual cycle

Answer 32

Day 1: menstruation- the uterus lining is broken down if there is no fertilised egg, causing bleeding

Day 4: The lining of the uterus begins to build back up in preparation for a fertilised egg

Day 14: Ovulation- an egg is released from the ovary and travels down the oviduct into the uterus

Day 28: Wall is maintained for 14 days until day 28. No fertilised egg on the lining of the uterus results in the menstrual cycle to releat

Question 33

What hormones control the menstrual cycle and what do they do

Answer 33

Follicle stimulating hormone (FSH) is produced by the pituarity gland in the brain and causes eggs to mature in the oavries

Luteinising hormone (LH) produced by the pituitary gland and causes the release of the egg from the ovaries (ovulation)

Oestrogen is produced by the ovaries and causes the lining of the uterus to grow and thicken

Progesterone is produced in the ovaries by an empty egg follicle and maintains the lining of the uterus

Question 34

How do all four hormones react with each other

Answer 34

FSH causes an egg to mature and develop in a follicle in the ovaries then stimulates the ovaries to produce oestrogen.

Oestrogen then causes the lining of the uterus to grow, inhibits the release of FSH and stimulates the release of LH

LH stimulates the release of the egg (ovulation) from the follicle in the ovaries

Follicle in the ovaries peoduce progesterone that maintains the uterus lining for 14days and inhibits both FSH and LH. When progesterone decreases so does the uterus lining until FSH and LH are no longer inhibited

The cycle repeats

Question 35

What hormonal methods prevent contraception

Answer 35

Oral contraceptive pills conaining oestrogen and progesterone. Inhibit FSH so eggs cannot mature in ovaries. They are very effective and cause many side effects and offer no protetcion agsinst STD

Contraceptive patches , release oestrogen and progesterone into the body, decreasing fertility for a week. Contraceptive implants last for a 3 years. Progesterone can also be injected which last for a few months

Coils are inserted into the uterus (plastic release progesterone) and copper kill sperm. Last for 10 years

Question 36

What are non-hormonal methods of contraception

Answer 36

Barrier methods decrease fertility by stopping the sperm and egg meeting. Condoms on the males penis and female condoms inside the womans vagina. Protetc against STD but csn break

Diaphragms fit over the cervix and are inserted after sex. Release spermicides which kill sperm.

Male vasectomy sperm duct cut/tied or fallopian tubes can be cut/tied in females. Prevents pregnation permanently

Question 37

What happens in an IVF treatment

Answer 37

1) mother given LH and FSH stimulates the maturation and ovukation of several eggs

2) Eggs collected from mother and fertilised by fathers sperm in a lab

3) Fertilised egg develops in embryos and a fee are implanted into the mothers uterus where they develop

Question 38

Positives of IVF

Answer 38

Safe way for infertile people to increase chances oof having a baby

Unused egg used for research

Babies can be selected based on heath (child doesn’t suffer)

Question 39

Issues of IVF treatment

Answer 39

Success rate if relatively low and decreases with age of the mother

Side effects to drugs used in the process

Emotional and physicsl stress on mother

Very expensive

Unethical some embryos are thrown away

People believe people may select desireable qualities in babies and use it as an advanatge

Question 40

What is a negative feedback sequence

Answer 40

When the body detects and counteracts the changes in bodily conditions, returning them back to optimum level.

Question 41

Explain the negative feedback sequence of the thyroid gland

Answer 41

TSH (Thyroid stimulating hormone) released from pituitary gland and stimulates the thyroid gland to release thyroxine

Thyroxine levels too high, TSH inhibited reducing the amount of thyroxine released from the thyroid gland. Thyroxine levesl fall back to normal.

Thyroxine levels too low, TSH increases, increasing amounr of thyroxine released from the thyroid gland

Question 42

Expalin the negative feedback sequence of adrenaline

Answer 42

Fear and stress detected by the brain which sends electrical impulses to the adrenal gland which secrete adrenaline.

Adrenaline increase delivery of oxygen and glucose to the brain and msucles (heart and rate, break down of glucose increases). Body responds quickly to dangerous situations