GCSE AQA BIOLOGY [PAPER 2] -
Homeostasis and Response (HIGHER
SEPARATE SCIENCE)
Homeostasis - ANS- -HOMEOSTASIS is the regulation of the internal conditions of a cell
or organism to maintain optimum conditions for function, in response to internal and
external changes.
-The aim of homeostasis is to maintain optimum conditions for cells to function.
-Enzymes only work best in their specific conditions of temperature and pH. It is
important for to respond to changes in the internal and external environment to maintain
the conditions for the cellular organisms so that they can correctly and not denature.
Examples of internal conditions that are controlled by homeostasis - ANS- -Blood
glucose concentration
-water content of the body
-body temperature
[e.g] During exercise, the human body uses homeostasis to keep the blood glucose
concentration, body temperature and water levels constant.
Automatic control systems (negative feedback) - ANS- -AUTOMATIC CONTROL
SYSTEMS in the human body can involve the nervous system or hormones.
-RECEPTOR CELLS detect changes in the environment by a STIMULUS.
-RECEPTOR CELLS now pass information to a COORDINATION CENTRE (e.g- the brain).
-The COORDINATION CENTRE receives and processes the information from the
RECEPTOR CELLS.
-The COORDINATION CENTRE now sends instructions to the EFFECTOR.
-The EFFECTOR is a muscle or gland that carries out a RESPONSE to the optimum level.
Human Nervous System - ANS- The human nervous system uses electrical impulses to
enable humans to react to their surrounding quickly and coordinate their behaviour.
Compared to the endocrine system, the effects are faster but don't last long.
Receptors - ANS- Are cells that detect changes in the internal or external environment.
These changes are known as stimuli.
Coordination Centres - ANS- Are areas that receive and process information from
receptors. They send out signals and coordinate a response of the body.
, Effectors - ANS- Are muscles or glands that bring about a response to the stimulus that
has been recieved. The responses restore conditions in the body to optimum levels.
How the nervous system works - ANS- -A stimulus is detected by repceptor cells
-Information is passes along neurones as electrical impulses to the central nervous
system (CNS). The CNS includes the brian and spinal cord.
-The CNS coordinates a response by passing the information along nurones to an
effector.
-The effector carries out the response by secreting hormones or by contracting a muscle.
stimulus --> receptor --> coordinator --> effector --> response
Reflex arc - ANS- -The receptors detect a stimulus due to a change in the environment
(hot surface).
-The receptor send an impulse along a sensory neurone.
-The information is then sent to the coordinator (CNS) to process what response to carry
out.
-The coordinator sends impulses down relay neurons in the brain and is then passed
along to a motor neuron when the electrical impulse reaches the synapse of the relay
neurone.
-An electrical impulse travels through the motor neuron to the effector to stimulate a
response.
stimulus --> receptor --> sensory neurone --> relay neurone --> motor neurone --> effector
--> response
Reflex Actions - ANS- Reflex actions are automatic and do not involve the conscious
part of the brain.
Synapses - ANS- -Are tiny gaps between dentrites and axons of different neurons.
-Electrical impulses travelling along the neurons travel along the synapse by releasing a
chemical which diffuses the electrical signal to the next neuron.
Cerebral cortex - ANS- The outermost layer of the brain which is concerned with
consciousness, memory and language.
Cerebellum - ANS- A large structure of the hindbrain that controls muscular activity,
movement and balance.
Medulla - ANS- The base of the brain stem that controls heartbeat and breathing
(unconscious activities).
The Brain - ANS- -The brain controls complex behavior.
Homeostasis and Response (HIGHER
SEPARATE SCIENCE)
Homeostasis - ANS- -HOMEOSTASIS is the regulation of the internal conditions of a cell
or organism to maintain optimum conditions for function, in response to internal and
external changes.
-The aim of homeostasis is to maintain optimum conditions for cells to function.
-Enzymes only work best in their specific conditions of temperature and pH. It is
important for to respond to changes in the internal and external environment to maintain
the conditions for the cellular organisms so that they can correctly and not denature.
Examples of internal conditions that are controlled by homeostasis - ANS- -Blood
glucose concentration
-water content of the body
-body temperature
[e.g] During exercise, the human body uses homeostasis to keep the blood glucose
concentration, body temperature and water levels constant.
Automatic control systems (negative feedback) - ANS- -AUTOMATIC CONTROL
SYSTEMS in the human body can involve the nervous system or hormones.
-RECEPTOR CELLS detect changes in the environment by a STIMULUS.
-RECEPTOR CELLS now pass information to a COORDINATION CENTRE (e.g- the brain).
-The COORDINATION CENTRE receives and processes the information from the
RECEPTOR CELLS.
-The COORDINATION CENTRE now sends instructions to the EFFECTOR.
-The EFFECTOR is a muscle or gland that carries out a RESPONSE to the optimum level.
Human Nervous System - ANS- The human nervous system uses electrical impulses to
enable humans to react to their surrounding quickly and coordinate their behaviour.
Compared to the endocrine system, the effects are faster but don't last long.
Receptors - ANS- Are cells that detect changes in the internal or external environment.
These changes are known as stimuli.
Coordination Centres - ANS- Are areas that receive and process information from
receptors. They send out signals and coordinate a response of the body.
, Effectors - ANS- Are muscles or glands that bring about a response to the stimulus that
has been recieved. The responses restore conditions in the body to optimum levels.
How the nervous system works - ANS- -A stimulus is detected by repceptor cells
-Information is passes along neurones as electrical impulses to the central nervous
system (CNS). The CNS includes the brian and spinal cord.
-The CNS coordinates a response by passing the information along nurones to an
effector.
-The effector carries out the response by secreting hormones or by contracting a muscle.
stimulus --> receptor --> coordinator --> effector --> response
Reflex arc - ANS- -The receptors detect a stimulus due to a change in the environment
(hot surface).
-The receptor send an impulse along a sensory neurone.
-The information is then sent to the coordinator (CNS) to process what response to carry
out.
-The coordinator sends impulses down relay neurons in the brain and is then passed
along to a motor neuron when the electrical impulse reaches the synapse of the relay
neurone.
-An electrical impulse travels through the motor neuron to the effector to stimulate a
response.
stimulus --> receptor --> sensory neurone --> relay neurone --> motor neurone --> effector
--> response
Reflex Actions - ANS- Reflex actions are automatic and do not involve the conscious
part of the brain.
Synapses - ANS- -Are tiny gaps between dentrites and axons of different neurons.
-Electrical impulses travelling along the neurons travel along the synapse by releasing a
chemical which diffuses the electrical signal to the next neuron.
Cerebral cortex - ANS- The outermost layer of the brain which is concerned with
consciousness, memory and language.
Cerebellum - ANS- A large structure of the hindbrain that controls muscular activity,
movement and balance.
Medulla - ANS- The base of the brain stem that controls heartbeat and breathing
(unconscious activities).
The Brain - ANS- -The brain controls complex behavior.
