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Paper 2 - Homeostasis and Response - Coggle Diagram
Paper 2 - Homeostasis and Response
Homeostasis and the Nervous System
Control Systems
All
control systems iclude:
Cells called
recptors
, whitch detect stimuli (changes in the environment)
Coordination centres (such as the brain, spinal cord and pancreas), whitch receive and process information from receptors
Effectors
(mucles or glands), whitch bring about reponces that restor optimun levels
THe control system
may
involve:
responces using nerves
Chemical responces using hormones
The Nervous Systems
The nervouse system enables humans to react to their suroundings andcoordenate their behaviour
Information from receptors passes to the central
nervous system (CNS)
The CNS coordenates the responce of effectors, i.e. muscles contracting or glands secreting hormones
Relfex actions are automatic and rapid so they can protect the body. They do not involve the conscious part of the brain
Neurones
Neurons are not directly connected to to each other
They are conected to eachother by
synapses
(gaps between nerones)
When an eletrical impulse reaches a synapse, a chemical is released that diffuses across the gap between the two neurons
This causes an eletrical impulse to be generated in the second neurone
The Importance of Homeostasis
Homeostaisis
is the regulation of internal conditons of a cell or oragnism in responce to internal and external changes
It keeps condditions constant for enzyme action and cell functions
It includes control of:
Blood glucose concentraction
Body temprature
Water and Ion levels
Hormones and Homeostasis
The Endocrine System
The
endocrine system
is made up of glands that secreate hormones directly into the bloodstream
Hormones
are chemical messengers that are carried in the blood to a traget organ where they produse an effect
Compared with effects of the nervous system,the effects o hormones are slower and act for longer
The
pituitary gland
in the brain is the 'master gland'
It secreats several hormones in responce to body conditions
Some of these hormones act on other glands to stimulate other hormones to be released and bring about effects
Control of Blood Glucose
Blood glucose concentation is monitored by the pancreas
If the blood glucose concentation is too high:
The pancreas releses more of the hormone insulin
Insulin causes glucos to move from the blood into the cells
In liver amd muscle cells, excess glucose is converted to glycogen for storage
Hormones and Reproduction
Reducing Fertility
Increasing Fertility (HT)
Control of the menstrual Cycle
The Sex Hormones
Hormones play many roles in controling human reprodution
During puberty, the sex hormones cause secondary sexual characteristics to develop
Females
In females, at puberty, eggs begin to maure and be released. This is called
ovulation
Oestrogen
, from the ovaries, is the main female sex hormone
Males
Testosterone
is the main male sex hormone. It is produced by the testes and stimulates sperm production
After puberty, men produse sperm continuously, but women have a monthly cycle of events called the
menstrual cycle
Several other hormones are involved in the women's menstrual cycle