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
Identify two glands that form part of the endocrinal system and outline their functions.
Pituitary gland - releases ACTH in the HPA axis for chronic stress and controls the release of hormones from all of the endocrine systems glands.
Adrenal medulla - releases adrenalin during the fight or flight response which produces physiological adaptations necessary for the fight or flight response.
