Chapter 5.1.3: Neuronal communication Flashcards
What’s one difference between relay neurones and motor neurones?
Relay neurones don’t have a myelinated sheath as faster transmission is not needed (Schwann cells minimise electrical loss)
What do the specialised cells on receptor organs do?
Detect energy changes in the surroundings - known as energy transducers
What are the axon and the axon hillock?
Axon = carries nervous impulses away from the cell body
Axon hillock = specialised region of tissue which triggers the production of nervous impulses
How are neurons specialised to their function?
They’re long so they can transmit messages over long distances, they’re surrounded by a fatty sheath to insulate neurones and they have numerous dendrites to connect to other neurones
What is the name of the receptor cell for touch and what form of energy is it received in?
Meissners corpuscles - kinetic
What is the name of the receptor cell for smell and what form of energy is it received in?
Olfactory cells - chemical
What is the name of the receptor cell for temperature and what form of energy is it received in?
Ruffins ending - thermal
What is the name of the receptor cell for pressure and what form of energy is it received in?
Pacinian corpuscles - kinetic
What is the name of the receptor cell for placement of limbs and what form of energy is it received in?
Proprioceptors - mechanical displacement
What is the name of the receptor cell for balance and what form of energy is it received in?
Semicircular canals hair cells - kinetic
What’s the resting potential of the neurone’s membrane?
-65mv
Define spatial summation
two or more presynaptic neurones converge and release their NT at the same time onto the same post synaptic membrane
Define temporal summation
two or more action potentials arrive in quick succession from the same presynaptic neurone
In six steps, outline the process of synaptic transmission
- action potential arrives = voltage gated calcium ion channels open
- Influx of calcium ions = presynaptic vesicles to move toward the membrane and fuse - releasing NT into synaptic cleft.
- NT diffuses across cleft and binds to subunits that bind to the receptor - opens sodium ion channels on post synaptic membrane.
- Sodium ions flood into post synaptic membrane - excitatory post synaptic membrane.
- NT broken down so that continual simulation of the PSM does not happen by enzyme
- Broken down NT re enter presynaptic membrane by diffusion - using ATP they are recombined in secretory vesicles
Define inhibitory
Hyperpolarise post-synaptic membrane - prevents AP being generated
Define excitatory
Depolarise post- synaptic membrane - trigger AP
Describe the 3 ways that drugs and poisons affect the synapse
- Blocking NT receptors so AP’s aren’t generated
- Preventing the removal of NT from the synaptic cleft
- Destroying enzymes which breakdown the NT
Name the poison obtained from plants, acting as a muscle relaxant and blocking Acetylcholine receptors
Curane
How does cocaine affect the Nervous system?
Causes Noradrenaline to persist in synaptic cleft - blocks reuptake channels
How does Sanin affect the Nervous system?
Destroys enzymes, inhibits Acetylcholinesterase - Acetylcholine builds up in cleft
Death occurs by asphyxiation
What is the name of the toxic chemical that is used in rat poison, destroys Acetylcholinerase - leading to continual AP’s generated = convulsions = death?
Strychnine
Name the 6 components of the nervous system
CNS, peripheral, autonomic, somatic, parasympathetic, sympathetic
What are the 2 components of the CNS?
Brain and spinal cord
What does the peripheral nervous system do?
Consists of sensory and motor neurones to carry impulses from receptors to CNS and impulses from CNS to effectors
What’s one difference between the somatic and autonomic nervous system?
Somatic = voluntary and autonomic = usually involuntary
What state should the body be in when resting/digesting?
Parasympathetic
What state does the sympathetic nervous system cause the body to be in?
Fight/flight
What’s the name of the membrane that surrounds the brain and what’s its purpose?
Meninges membrane - secretes cerebral spinal fluid to act as a shock absorber
What’s the purpose of neurones?
To transmit action potentials
Give an example of a glial cell
Schwann cells
What NT is used in the parasympathetic nervous system?
Acetylcholine
What two NTs are used in the sympathetic nervous system?
Noradrenaline and acetylcholine
Where in the spinal cord do nerves leave from when the sympathetic nervous system is activated
all the way down
Where is the medulla oblongata and what does it do?
Top of the spinal cord - Part of the brain that regulates breathing and HR
How does the medulla oblongata carry out its function?
Sends out messages via the autonomic nervous system which cause the diaphragm and intercostal muscles to contract and relax regularly
What is the cerebellum involved in?
control and coordination of movement and posture
Where does the cerebellum receive information from?
CNS and sensory neurones
What does the diencephalon consist of?
Hypothalamus and thalamus
What does the hypothalamus do and how?
connected to pituitary gland - controls temperature - sends messages to the autonomic nervous system to control shivering and sweating
Stating the stimulus, receptor, CNS response, effector and response, describe what happens to prevent damage to the eye
Stimulus - something touches the eye, receptor - sensory nerve endings in cornea, CNS - sensory neurone synapses with a relay neurone and then a motor neurone, effector - Orbicularis oculi muscles contract to shut the eyelid, response - eyelids close to protect eye
Stating the stimulus, receptor, CNS response, effector and response, describe what happens when testing the knee reflex
Stimulus - quad muscles stretched, receptor, stretch receptors, CNS - sensory neurone synapses directly with a motor neurone , effector - quads contract, response - lower leg straightens
What part of the brain do simple reflex arcs involve?
The unconscious part
Give three ways that reflexes benefit our survival
They’re innate, fast, involuntary
What are three physical responses of fight/flight?
Increase in HR/stroke volume, constricting of blood vessels near skin/digestive tract and relaxation of smooth muscle
