homeostasis etc

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  • Created by: harri5742
  • Created on: 07-05-18 19:41

Homeostasis And Responses.

-Homeostasis is the equilibrium of a constant internal environment where the external environment changes.It is important to maintain optimum conditionms for enzyme action and cell function.

Receptors in the body detect stimuli (a change in the environment)

Concentration centers such as the brain spinal chord and pancreas recieve and process the information from the receptors

Effectors such as muscles and glands activate responses that result in optimum levels being restored.

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The Nervous System

-Neurons transmit electrical impulses which occurs very quickly.

-A nervous system allows humans to react to their surroundings and coordinate their behaviour

The central nervous system consists of the brain and spinal chord

The effectors (muscles and glands) contract or sectrete hormones

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Synapses And Reflexes

A synapse is the junstion between to neurons.

An electriacl impulse or action potentialis sent along the axon of a neuron. this stimulates the chemical neurotransmitters to diffuse across the synapse and then bind to the receptors on the next neuron. This then starts off the electriacl impulse in the next neuron. 

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Reflex Response

A reflex action is a rapid, automatic and protective response to a stimulus that doesnt involve the concious part of the brain. 

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The Endocrine System: Hormones

-Hormones are chemical messengers secreted (released) by glands directly into the bloodstream where they travel in the blood plasma.

-The blood carried the hormones to a target organ where it produces an effect compound to the nervous system. The effects are slower but act for longer. Some hormones stimulate others to be secreted

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The Endocrine System: Controlling Blood Glucose

Carbohrdrates are large insoluble molecules.  An enzyme called carbohydrase breacks the carbohydrate molecules into smaller soluble molecules of sugar (glucose). Theese can then be absorbed into the blood stream.

The adaptions of the villi are: A large surface area, thin walls and are close to cappilaries (bloodstream)

blood glucose levels regulate in concentration

Increasing blood glucose can be done by carbohydrate intake and can be reduced by exercise and metabolism

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The Use Of Insulin

If the blood glucose is to high then insulin is added.

-Excess glucose travels through blood and receptors on the pancreas tell the pancreas to release insulin.

-Excess glucose and the insulin travel to the liver and muscles

-Glucose (soluble) is coverted into glycogen (insoluble) and stored

-Glyogen is then broken down into glucose when we need to increase the amount off sugar we have in or blood.

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The Use Of Glucagon

-If the body has a low glucose concentration the pancreas secretes the hormone glucagon

-This then travels round the body in the blood plasma through the muscles and liver.

-The liver then breaks down the glucogon into glycogen which is the broken down again into glucose.

-This is then released back into the bloodstreame and bloodglucose levels are back at optimum levels.

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Controlling Blood Glucose Concentration: Diabetes

Type 1:

Pancreas produces little or no insulin

insulin is injected

born with it

Treatment:

Insulin therapy

Limit food rich in simple sugars

Regular exercise

Pancreas transplant

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Controlling Blood Glucose Concentration: Diabetes

Type 2:

-Resistant to own insulin

-Pancreas does produce insulin but the body does not espond properly to the hormone

-Glucose can be converted into glycogen in the muscles and liver.

Treatment:

-Limit food rich in simple carbohydrates

-Regular exercise

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The Menstrual Cycle

An agg is released from the ovaries on day 14 of your period.

The average period can last from 4-6 days plus

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FSH, Oestrogen, LH And Progestrone

Follicle stimulating hormone (FSH):

Secreted from pitruitry gland and causes the egg to mature (maturation) in a follicle (ovary)

Oestrogen

Produced in ovaries and causes the lining of he uterus to grow and inhibits the production of FSH

LH

Secreted from the pitruity gland and stimulates the egg being released from the follicle in ovary

Progestrone

Produced in the ovaries and maintains the lining of the uterus and stops the release of FSH and LH

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Contraception

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Menstrual cycle hormones

FSH- produced in pitruitry gland- matures egg

Oestrogen- produced in ovaries- builds lining of the uterus

LH- produced in pitruitry gland- releases egg

Porgestrone- produced in ovaries- maintains lining uterus.

When LH is high FSH is inhibited.

When LH decreases FSH increases

When porgestrone and oestrogen is high it inhibits FSH and LH

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Adrenaline And Thyroxine

Fight or flight:

Adrenaline is released from adrenal gland.

Heart beats faster, pupils dilate and heart beats faster

increased glucose and oxygen go to the muscles brain.

adrenal gland are located at the top of the kidneys

Thyroxine

-Metabolism

-The speed of which chemiccal reactions happen.

-Regulates basal metabolic rate

-Stimulates protien synthesis - growth and development

When thyroxine is low Thyroid stimulating hormone is released.

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supergirl4

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The slide on contraception appears to be blank... great resource though!

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