B5 Flashcards
What is homeostasis?
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 do?
- It maintains optimal conditions for enzyme action and all cell functions
- In the human body these include the control of blood glucose concentration,body temperature and water levels
What do automatic control systems involve?
Nervous responses or chemical responses
What do all control systems include?
- Cells called receptors, which detect stimuli (changes in the environment)
- Coordination centres (such as the brain, spinal cord and pancreas) that receive and process information from receptors
- Effectors, muscles or glands, which bring about responses which restore optimum levels.
What is the structure of the nervous system?
- The nervous system consists of the brain and spinal cord, which together form the central nervous system (CNS)
- The CNS is linked to sense organs by neurones, which form the peripheral nervous system (PNS)
- Neurones (nerve cells) are specialised cells which carry electrical impulses
How is the structure of the nervous system adapted to its functions?
- A bundle of neurons is called a nerve
- The features of neurons help them to carry out their function efficiently: they have a long fibre (axon ) so they can carry messages up and down the body over long distances
- In a stimulated neuron, an electrical nerve impulse passes along the axon
Structure of the nervous system in symbol equations
Stimulus –> receptor –> coordinator –> effector –> response
What does the nervous system enable humans to do?
- React to their surroundings
- Co-ordinate their behaviour
What are the structures in a reflex arc?
- Sensory neurone
- Sypnapse relay neurone
- Motor neurone
What is the structure of a sensory neurone?
Contains a cell body, axon and dendrites
What is the structure of a sypnapse relay neurone?
Contain lots of short dendrites, a cell body and a long axon
What is the structure of a motor neurone?
Contains a cell body, axon and dendrites
How is te structure of the sensory neurone related to its function?
The neurones that carry information as electrical impulses from the receptors to the CNS
How is the structure of the sypnapse relay neurone related to its function?
- Relay neurons connect various neurons within the brain and spinal cord and are easy to recognize due to their short axons
- Alike to motor neurons, interneurons are multipolar
- This means they have one axon and several dendrites
How is the structure of the motor neurone related to its function?
- The dendrites use these structures to send and receive information from other neurons
- The axon is the long extension structure stemming from the soma
- The axon works to transmit the information it receives down its body to the dendrites at the end of the neuron
What are reflex actions?
- Reflex actions are automatic and rapid
- They do not involve the conscious part of the brain
Note:
AQA says that students should be able to:
- Extract and interpret data from graphs charts and table about the functioning of the nervous system
- Students should be able to translate information about reaction times between numerical and graphical forms
Practical 6:
AAA