Module 5 Flashcards
(62 cards)
Describe sensory neurones
Transmit impulses from a sensory receptor to relay neurone, motor neurone or brain.
1 dendron, cell body and 1 axon
Describe relay neurones
Transmit impulses between neurones
Many short axis and dendrons
Describe motor neurones
Transit impulses from really/sensory neurones to an effector
1 long axon and many short dendrites
What happens in the membrane of the sensory receptor in response to pressure
Pascinian corpuscle changes shape Na+ channels open Na+ ions enter depolarisation (+40mV) generator potential creates an action potential
Outline two roles of synapses in the nervous system.
transmit information between neurones
ensure one way transmission of impulses (unidirectional)
Describe how a resting potential occurs
=Na+ are actively transported out of the axon , K+ actively transported into the the axon by sodium-potassium pumps. (3 sodium for every 2 potassium)
=Na+ diffuse back into, K+ diffuse out of axon down an electrochemical gradient
=However most of the sodium channels are closed and most of the potassium channels are open, allowing potassium out.
=This creates an resting potential of -70mV, with the inside negative to the outside
What is an action potential?
A depolarisation of the cell membrane so it becomes more positive on the inside than outside, creating a nerve impulse
Describe how an action potential is created
- Energy of stimulus triggers some sodium channels to open, making the membrane more permeable to Na+ ions, Na+ diffuse into the axon down an electrochemical (inside is less negative)
- More sodium ion channels open (positive feedback)
- When potential difference reaches +40mV sodium ion channels close and potassium ion channels open (depolarisation)
- Potassium ions diffuse down an electrochemical gradient, causing the inside to become more negative (hyperpolariation) Axon turns to resting potential
What is the refractory period?
A short period of time when the axon can’t be excited again
What is saltatory conduction?
Where the action potential jumps from one node to another
What is the all-or-nothing principle?
if the threshold is reached an action potential is always created
What are the 2 types of neurotransmitters?
1 ) Excitatory= result in depolarisation and an action potential if the threshold is reached (e.g.. Acetylcholine)
2 ) Inhibitory= result in hyperpolaristion, prevents action potential (e.g. GABA)
Describe the transmission of impulses across a synapse
- Action potential reaches the end of the presynaptic membrane
- Depolaristion. Calsium channels open and calcium ions diffuse into the presynaptic knob
- Neurotransmitters are release into the synaptic cleft via vesicles by exocytosis
- Sodium ion channels open and sodium ions diffuse into the post synaptic neurone.
- Action potential is created
What is spatial summation?
Where many presynaptic neurones connects to one post synaptic neurone
What is temporal summation?
Where a single presynaptic neurone releases neurotransmitter several times
What is the somatic nervous system?
This system is under conscious control (voluntary)
What is the autonomic nervous system?
This system works constantly and is under subconscious control (involuntary)
What are the 5 main areas of the brain?
Cerebrum, cerebellum, medulla oblongata, hypothalamus, pituitary gland
Describe the cerebrum
Controls voluntary actions (e.g. memory)
-Highly convoluted, which increases SA so theres greater capacity for complex activity
Describe the cerebellum
Controls unconscious actions (e.g. balance)
Describe the medulla oblongata
Used in autonomic control (e.g. heart rate)
Describe the hypothalamus
Regulatory centre for temperature and water balance
- controls complex behavioural patterns (sleeping)
- monitors composition of blood plasma
- produces hormone, endocrine gland
Describe the pituitary gland
Stores and releases hormones
What is the adrenal cortex responsible for?
Outer region- produces hormones that are vital to life (glucocorticoids, mineralocorticoids, androgens)