bio homeostasis and response

What is the nervous system?

It means that humans can react to their surroundings and coordinate their behaviour

What is the central nervous system

In vertebrates it consists of the brain and spinal cord only. In mammals the CNS is connected to the body by sensory and motor neruones

Sensory neurons

They are the neurones that carry info as electrical impulses from the receptors to the CNS

Motor neurones

They are neurones that carry electrical impulses from the CNS to the effectors

Effectors

All your muscles and glands which respond to nervous impulses

What are synapses ?

They are the connection between two neurones

When the impulse reaches the end of the first neurone a chemical is released into the synapse. This chemical diffuses across the synapse. When the chemical reaches the second neuron it trggers the impulse to begin again in the next neurone.

What are reflexes

They help prevent injury

They are rapid automatic responses to certain stimuli that dont involve the conscious part of the brain, they reduce the chances of being injured

What is a reflex arc

The passage of information in a reflex

What are hormornes

They are chemical molecules released directly into the blood. They are carried in the blood to other parts of the body but only affect particular cells in particular organs. They control things in organs and cells which need constant adjustment

Where are hormornes produced

Endocrine glands which make up the endocrine system

What is the pituatry gland ?

produces many hormornes that regulate body conditions. It is sometimes called the master gland because these hormornes act on other glands directing them to release hormornes which bring about change

What are ovaries

They produce oestrogen whihc is involved in the mentrual cycle

What are the testes

The produce testorsterone which is controls puberty and sperm production

What is the thyroid?

Produces thyroxine which is involved in regulating things like metabolism and heart rate

What is the adrenal gland

Produces adrenaline which is used to prepare the body for flight or fight response

pancrease

Produces insuline that controls blood glucose level

What are the differences between the hormornes and nerves

Nerves - very fast action , acts for a short time , acts on a precise area

Hormornes - short action , long time, act in a more general way

What is type 1 diabetes

Where the pancreas produces too little or no insulin. This means a persons blood glucose can rise to a level which can kill them. Its effective and the amount of insulin depends on the persons diet and how active they are

What is type 2 diabetes

When a person becomes resistant to their own insulin. This can cause a persons blood glucose level to rise to a dangerous amount.

What can increase your chance of getting type 2 diabetes

obesitiy

How can type 2 diabetes by controlled

eating a carbohydrate controlled diet and getting regular exercise

what do people with type 1 diabetes do to make sure that they get enough insulin?

They get insulin therapy whihc is when they get injections every day usually at meal times.This makes sure glucose is removed from the blood quickly once the food has been digested stopping the level getting too high.

what are the four stages of the mentrual cycle ?

stage 1 - day 1 , menstruation starts, the uterus lining breaks down for about four days

stage 2 - the uterus lining builds up again, from day 4 to 14 into a thick spongy layer of blood vessels ready to recieve a fertilised egg.

stage 3 - an egg develops and is released from the ovary at day 14 called ovulation

stage 4 - the wall is then maintained for about 14 days until day 28. If no fertilised egg has landed on the uterus wall by day 28, the spongy layer will start to break down and the whole cycle repeats

what hormornes control the mentrual cycle

FSH

LH

OESTROGEN

PROGESTERONE

Describe the role of FSH

produced in the pituatry gland

causes an egg to mature in one of the ovaries in a structure called the follicle

stimulates the ovaries to produce oestrogen

Describe the role of oestrogen

produced in the ovaries

causes the lining of the uterus to grow

stimulates the release of LH and inhibits the release of FSH

describe the role of LH

Produced in the pituatry gland

stimulates the release of a egg at day 14

describe adrenaline

Its a hormorne released by the adrenal gland which is just above the kidney

Its released in response to scary or stressful situations- your brain detects scary or stressful situations and sends nervous impulses to the adrenal glands which respond by secreting adrenaline

It also gets the body ready for fight or flight by trigerring mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles

What is homeostasis

The regulation of the conditions inside your body to maintain a stable internal environment in response to changes in both external and internal environments.

what is a negative feedback

a mechanism that restores a level back to optimum in a system

what happens when the level of something gets too high or low

• receptor detects a stimulus saying that levle is too high or low

• The coordination centre recieves and processes this informaiton and organises a response

• effector then produces a response which counteracts the change and restores the optimum level