Year 1 Flashcards
Descrive the nervous system.
The nervous system
Central nervous system - brain and spinal cord
Peripheral nervous system - autonomic NS (sympathetic and parasympathetic) and somatic NS
What is the brain and spinal cord responsible for?
Brain - centre of all conscious awareness
Spinal cord - responsible for reflex actions
What are the autonomic NS and somatic NS responsible for?
ANS - governs vital functions, e.g. HR.
SNS - controls muscle movement and receives information from sensory receptors.
What is the endocrine system?
Consists of a number of glands that send hormones throughout the blood stream.
List glands in the endocrine system.
- Pituitary gland - located in the brain and controls the release of hormones from all other endocrine glands in the body.
- Thyroid - releases thyroxine which affects cells in the heart.
- Ovaries, testes, adrenal, pancreas, hypothalamus.
Describe the fight-or-flight process.
- Perceived threat (stressor).
- Hypothalamus triggers activity in the sympathetic branch of the ANS.
- Adrenaline is released from the adrenal medulla.
- Triggers the physiological changes that are necessary for fight or flight, EG: increased HR, increased BR, inhibits digestion.
- Once the threat has passed the parasympathetic NS returns the body to its resting state, with the actions being antagonistic to the SNS.
- Decreases HR and BR, stimulates digestion.
What kind of the stress is the fight-or-flight response responding to?
Acute
How does the body deal with chronic stress?
HPA axis
What is the body’s reaction to chronic stress?
- Hypothalamus activates the HPA axis.
- Hypothalamus releases CRH which is released into the bloodstream.
- CRH causes the pituitary gland to produce and release ACTH which is transported through the bloodstream to its target site in the adrenal glands.
- ACTH stimulates the adrenal cortex which releases cortisol.
What 3 types of neurons are there?
Motor
Sensory
Relay
What do each of the types of neurons do?
Motor - carry messages from the CNS to muscles and glands.
Sensory - carry messages from the PNS to the CNS.
Relay - carry messages from sensory to motor neurone, or other relay neurons.
What is the structure of a neuron?
- Cell body - nucleus - genetic material of the cell.
- Dendrites - carry nerve impulses from neighbouring neurons.
- Axon - carries impulses away from the cell body.
- Myelin sheath - protects the axon and speeds up electrical transmission.
- Nodes of Ranvier - segmented gaps in the myelin sheath that speed up transmission.
- Terminal buttons - communicate with the next neuron.
Describe the process of synaptic transmission.
- Signals between neutrons are transmitted chemically across the synapse.
- When the electrical impulse reaches the presynaptic terminal it triggers the release of neurotransmitters from synaptic vesicles.
- Once the neurotransmitter crosses the synapse it is taken up by the post-synaptic receptor site.
- The chemical message is then converted back into an electrical impulse and the process of electrical transmission begins again.
What is excitation?
When a neurotransmitters increases the positive charge of the post-synaptic neuron and therefore increases the likelihood that the neutron will fire and pass on electrical impulses.
E.G. adrenalin
What is inhibition?
When a neurotransmitter makes the charge of a post-synaptic neuron more negative so decreases the likelihood that the neuron will fire.
E.G. serotonin
