B5 Homeostatis and Response"

What is homeostasis?

Homeostasis is the regulation of the internal conditions of a cell or organism in response to internal or external changes to the enviroment.

Why is homeostasis important?

Because it keeps conditions constant for enzyme action and cell functions.

What does homeostasis include the control of? [3]

- Blood glucose concentration - Body temperature - Water and ion levels

What may control systems involve? [2]

- Responses using nerves - Chemical responses using hormones

What is a receptor cell?

It detects a stimuli

What is a stimuli?

A change to the enviroment

Give examples of coordination centres? [3]

- Brain - Spinal cord - Pancreas

What do coordination centres do?

Receive and process information from the receptors

What do effectors do?

They bring about responses that restore optimum levels

What are examples of effectors? [2]

- Muscles - Glands

What happens in negative feedback? [3]

- A receptor detects a change in a stimulus - The coordinating centre commpares the stimulus to a set point - An effector then produces a response to correct any difference from the set point

What does the nervous system enable humans to do?

Enables them to react to their surroundings and coordinate their behaviour

Where does information from the receptors pass to?

Passes to the central nervous system.

What does the CNS coordinate?

It coordinates the response of effectors.

What are reflex actions like?

Automatic and rapid so they can protect the body

Explain the nervous system

Stimula --> Receptor --> Sensory Neurones --> Relay Neurones --> CNS --> Relay Neurones --> Moto Neurones --> Effector --> Response

How do neurones communicate with each other?

Via synapses

What is the electrical impulse name that when it reaches the synapse and has to diffuse across the gap to the other synapse?

Neurotransmitters

What is the endocrine system?

It is made up of glands that secrete hormones directly into the bloodstream.

What are hormones?

Hormones are chemical messengers that are carried in the blood to a target organ or tissue.

Compared with the effects of the nervous system, are the effect of hormones longer?

Yes, they are also slower.

What is the pituitary gland?

It is the 'master gland'. - It secretes several hormones in response to body conditions.

Where is adrenaline produced?

In the adrenal glands

What does adrenaline do to your body?

It increases heart rate, boosting the delivery of oxygen and glucose to the brain and muscles.

What does adrenaline prepare your body or?

Flight or fight

Where is Thyroxine produced?

In the Thyroid gland

What does Thyroxine regulate? [3]

- Rate of metabolism - Heart rate - Temperature

Where is testosterone produced?

Testes

What does testosterone do?

Controls puberty and sperm production in males.

Where is oestrogen produced?

In the ovaries

What does oestrogen do?

It is involved in the menstrual cycle

What monitors and control the blood glucose concentration?

Pancreas

What happens if the blood glucose is too high? [3]

- Pancreas releases more of the hormone insulin - Insulin is transported to the liver, where it binds with liver cells and causes the glucose to move into the liver cells. - Excess glucose is converted into glycogen for storage

What hormone is secreted by the pancreas if the blood glucose concentration is too high?

Insulin

What hormone is secreted by the pancreas if the blood glucose concentration is too low?

Glucagon

What happens if the blood glucose concentration is too low? [2]

- Pancreas releases glucagon - Glucagon stimulates glycogen to be converted into glucose and released into the blood

What is Type 1 diabetes caused?

- It is caused by the pancreas failing to produce enough insulin

What does Type 1 diabetes result in?

High blood glucose levels

How is type 1 diabetes treated?

By insulin injections

What is Type 2 diabetes caused by?

It is caused by the body cells no longer responding to insulin

What is type 2 diabetes risk factor?

Obesity

How is type 2 diabetes treated?

It is treated with a carbohydrate-controlled diet and regular exercise

When does the lining of the uterus break down?

Between day 1 and day 4

When does the lining of the uterus build up?

Between day 4 and day 14

What happens on day 14?

Egg is released

What happens between day 14 and 28

Lining of the uterus is maintained

Where is the Follicle Stimulating Hormone (FSH) produced?

Pituitary gland

What does FSH do? [2]

- Causes egg to mature in the ovaries in the first stage of the cycle - Stimulates the ovaries to produce oestrogen

Where is oestrogen (oes) produced?

Ovaries

What does oestrogen (oes) do? [3]

- Inhibits FSH release - Stimulates LH release - Makes the lining of the uterus grow again after menstruation

What is LH?

Luteinising Hormone

What is FSH?

Follicle Stimulating Hormone

Where is LH produced?

Pituitary gland

What does LH do? [1]

It stimulates the release of the egg from the ovary (ovulation)

Where is progesterone produced?

Empty follicle in the ovaries

What does progesterone do? [2]

- Maintains the lining of the uterus during the second half of the cycle - Inhibits both FSH and LH release

How can fertility be reduced?

By a variety of methods of contraception

What does oral contraceptives contain? [2]

- Oestrogen - Progesterone

What do oral contraceptives do?

It inhibts FSH production so that no eggs are released

What does a contraceptive patch contain? [2]

- Oestrogen - Progesterone

What does a contraceptive patch do?

Prevent the release of eggs for a number of weeks, months or years

What do contraceptive implant's do? [4]

It releases a continuous amount of progesterone, which as a result - Stops the ovaries releasing eggs - Makes it hard for sperm to swim to the egg - Stops the fertilised egg from implanting into the uterus. It can last for 3 years.

What is hormonal contraception?

Use of a chemical to prevent an egg being released

What is an example of hormonal contraception? [3]

- Oral contraceptives - Contraceptive implant - Contraceptive patch

What is a non-hormal contraceptive?

The use of a barrier to prevent the sperm reaching the egg

What are examples of non-hormonal contraceptives? [3]

- Condom - Diaphragms - Vasectomy

What is vasectomy?

Sperm ducts are cut and tied