2. Homeostasis pt1 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 & external changes
(Maintains optimum conditions for enzyme action and all cell functions)
What do we control and why in our internal environment?
- Temperature (for correct enzyme activity)
- blood glucose concentration (for constant energy supply)
- water levels (to control osmosis and chemical reactions)
What are the 3 components of an effective control system and what do they do?
- Receptors, to detect the change in conditions
- Coordination’s centres, to process the information
- Effectors, to bring about the correct response
What’s the change in the environment called?
Stimulus
What do we call the specialised nerve endings that detect the stimuli?
Receptors
And when grouped together form a sense organ
List 7 of your receptors
- eyes
- nose
- ears
- tongue
- skin
- muscles
- joints
Describe the type of receptor your eye has?
Receptors for light
Describe the type of receptor your nose has?
Receptors for chemicals forming smell
Describe the type of receptor your ears has?
For sound and detecting changes in position (balance)
Describe the type of receptor your tongue has?
Receptors for chemicals forming taste
Describe the type of receptor your skin has?
Receptors for touch, pressure, pain and temperature
Describe the type of receptor your muscles and joints have?
Receptors for changes in position
What is the name of the specialised cells in the nervous system?
Neurones (which work in groups called nerves)
What does the nervous system do?
It enables the body to respond to changes in the environment to trigger the appropriate response
Describe how a response in coordinated through the neurones
- Once the receptor detects the stimulus, it sends a nerve impulse along a sensory neurones
- This cell takes the impulse towards the central nervous system
- The CNS can then coordinate an effective response
What’s the central nervous system made up of?
The brain and spinal cord
How would the neurones respond to the change?
- Once the brain/spinal cord has determined an appropriate response, it sends another nerve impulse out along a motor neurone
- This takes the impulse to an effector organ, which carries out the response
- This organ can either be a muscle, that contracts/relaxes or a gland that’s triggered to secrete hormones as part of the endocrine system
Name all 5 of the main parts of coordinating a response
- Receptor
- Sensory neurone
- Coordinator (CNS)
- Motor neurone
- Effector
Define a reflex
A reflex is a fast, automatic response that occurs without conscious thought
They control basic body functions such as breathing and digestion and help you avoid harm or danger
Explain how a reflex occurs
- The sequence of events is the same as other responses but only 1 neurone is use in the CNS instead of hundreds
- this is called a relay neurone, which connects the sensory neurone to the motor neurone through the spinal cord (sometimes in the unconscious part of the brain)
Explain the purpose of the reflex arc
- As it bypasses the brain it reduces the time between the stimulus and response
- This minimises damage caused by stressful stimulus
- the reflex arc will send another impulse to the conscious brain so you’re aware, but only after the reflex action has happened
What’s the junction between each neurone called?
Synapse
Explain how synapses work
- 2 neurones aren’t connected, so to transmit a nerve impulse, the neurone realises a chemical into the gap
- the chemical diffuses across the gap
- binds the receptors on the next neurone
Explain the brain
The brain controls complex behaviour. It’s made up of billions of interconnected neurones that receive sensory inputs from your receptors (sensory neurones deliver impulses), and then coordinate the appropriate response through the effectors (motor neurones deliver impulses)
And it has different regions that carry out different functions
What are 5 parts of the brain?
- cerebral cortex
- cerebellum
- medulla
- pituitary gland
- hypothalamus
What does the cerebral cortex do?
Conscious
Intelligence
Memory
Language
What does the cerebellum do?
Coordinating muscles
Balance
What does the medulla do?
Unconscious activities
Eg. Heartbeat, breathing, digestion
What does the pituitary gland do?
Secrets hormones
What does the hypothalamus do?
Controls homeostatic functions
Eg. Temperature
