Homeostasis Flashcards
Define homeostasis
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
What does homeostasis maintain optimum conditions for
Homeostasis maintains optimal conditions for enzyme action and all cell functions.
What is homeostasis used to do in the human body/puropse of homeostasis in human body
Used to keep /control of
- blood glucose concentration
- body temperature
- water levels.
Constant
What does homeostasis consist of
Homeostasis consists of automatic control systems making sure them at the internal conditions of the body stay as constant as possible
What can the automatic control systems in the human body involve
The automatic control systems in the human body can involve the nervous responses (nervous system ) or chemical responses (hormones)
what do all control systems include:
general features of automatic control system
All control systems include:
Cells called receptors
Coordination centres
Effectors
(they also have stimulus + response)
What is the purpose of the receptors
receptors detect stimuli (changes in the environment)
Environment could mean the body’s internal conditions e.g. concentration of glucose in the blood or also the body’s external conditions e.g. temperature of the skin
Examples of coordination centres
Brain
Spinal cord
Pancreas
Purpose of coordination centre
Coordination centres receive and process information from receptors (receptor cells)
Examples of effectors
Muscles or glands are example of effectors
What is the purpose of the effectors
Effectors bring about responses which restore optimum levels.
Describe the stages of the automatic control system
Cells called receptors, detect stimuli (changes in the
environment)
The receptor cells now pass information to a co-ordination centre e.g. the brain, the spinal cord or the pancreas
coordination centres (such as the brain, spinal cord and pancreas)
receive and process information from receptors
The coordination centre now sends instructions to the effector
Effectors are muscles or glands, which bring about responses which
restore optimum levels
State the two parts which the nervous system consists of
which make up the nervous system
The nervous system consists of two parts:
Central Nervous System (CNS) - the brain and the spinal cord
Other nerves running to and from the central nervous system
Describe the actions that take place, when a stimulus is detected
Receptors detect a stimulus and send electrical impulses along
sensory neurones to the central nervous system
The central nervous system is the coordination centre - The CNS makes a decision
The CNS coordinates the response of effectors
This now sends information as electrical impulses down motor neurones to effectors and the effectors bring about a response
Effectors are usually a muscle which contracts or a gland which secretes a hormone
Information from receptors passes along cells (neurones) as electrical
impulses to the central nervous system (CNS). The CNS is the brain and
spinal cord. The CNS coordinates the response of effectors which may
be muscles contracting or glands secreting hormones (or sweat).
Role of the nervous system
The nervous system enables humans to react to their surroundings and
to coordinate their behaviour.
Describe how the structure of the nervous system is related to its functions
The nervous system enables humans to react to their surroundings and
to coordinate their behaviour.
One way that this is done is through the reflex arc
Describe the actions that take place, when a reflex occurs e.g. when you touch a hot object
The stimulus is detected by a receptor (the stimulus is heat and the receptors are in the skin)
Electrical impulses now pass from the receptor along a sensory neurone to the central nervous system (sensory neurones are connected to receptors, receptors allow us to sense our environment)
At the end of the sensory neurone is a junction called a synapse
At the synapse, a chemical is released
This chemical now diffuses across to a relay neurone in the central nervous system where it triggers an electrical impulse.
The electrical impulse now passes across the relay neurone and reaches another synapse
Once again a chemical is released
This chemical triggers an electrical impulse in a motor neurone
The electrical impulse now passes down the motor neurone to an effector
In this case the effector is a muscle. The muscle now contracts and pulls the hand away from the heat.
Pulling the hand away from the heat is called the response
purpose of brain as a coordination centre
The brain makes decisions about what action to make
How are reflexes different to normal actions
The brain makes decisions about what action to make for regular actions
However, in the case of reflexes, there is no decision making by the conscious part of the brain
This makes reflexes automatic and rapid
Reflex actions are automatic and rapid; they do not involve the
conscious part of the brain.
Explain why reflex actions are important
For reflexes, there is no decision making by the conscious part of the brain
This makes reflexes automatic and rapid
So because they are rapid, reflexes help to protect us from danger
adv. of this is speed. The faster you get your hand away from the flame, the less damage it will do to your tissue
order these stages
receptor
coordinator
response
stimulus
effector
stimulus -> receptor -> coordinator -> effector -> response
purpose of sensory neurone
the neurones which carry information as electrical impulses from the receptor to the CNS
what are the motor neurones
The neurones that carry electrical impulses from the CNS to the effectors
Examples of receptors
taste receptors on the tongue
Sound receptors in the ears
Light receptors in the retina of the eye
What is a synapse
A synapse is the connection between two neurones.
What occurs at the synapse
The nerve signal is transferred from one end of one neurone to the start of another by chemicals which diffuse across the gap
These chemicals trigger a new electrical signal in the next neurone
