homeostasis etc
- 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.
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
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.
Reflex Response
A reflex action is a rapid, automatic and protective response to a stimulus that doesnt involve the concious part of the brain.
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
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
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.
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.
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
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
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
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
Contraception
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
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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