Neurobiology 2/2 Flashcards
(44 cards)
how many spinal nerves do we have
31 each side
where do upper motor neurons come from and what do they do
come from the brain and control the lower motor neurons
what is the special section of the brain that stimulates body movement
pre central gyrus
what is the role of the lower motor neurons
connects to multiple muscle fibres, controls the muscles
what is a motor unit and how do they vary
- motor neuron and and the muscle fibres it’s connected to
- fine control (6-10 muscle fibres) coarse control (up to 2000)
what is at a neuromuscular junction
- presynaptic Ca2+ channels
- post synaptic nicotinic Ach receptors
- junction fold to increase SA
describe what happens after the motor neurone fires
1, increase of calcium in the terminals
2. Ach released and binds to receptors on muscle cells
3. muscle cells fire action potential
how do we increase muscle contraction
- recruiting more motor units (more muscle fibres contract)
- temporal summation (keep stimulating muscle before it has time to relax)
what is a twitch
response to a single muscle contraction
what are some reasons muscles show fatigue
(stimulated but nit performing)
runs out of fuel
- glycogen depletion
- accumulation of K+ / lactate / ADP + Pi
- central fatigue
what are the two types of receptors and where are they
- golgi tendon organs (end of muscle, measure how much muscle contracts)
- muscle spindles (middle of muscle, how stretched muscles are)
how does sensory transduction work
- stimulus
- receptor
- nerve ending changes in permeability
- then membrane potential
- action potential generated and travels to CNS
- CNS integrates info
what is the difference between slowly and rapidly adapting mechanoreceptors
slow - spikes are more frequent, generator potential doesn’t decrement
fast - spikes die off. generator potential decrements
what are the functions of the autonomic nervous system?
- contraction/ relaxation of smooth muscle
- exocrine and endocrine secretion
- control of heartbeat
- intermediary metabolism
what is the difference between a motor neuron in somatic vs autonomic nervous system
SOMATIC - cell body, axon, NMJ
AUTONOMIC - cell body, preganglionic neuron, postganglionic neuron
what are the two branches of the autonomic nervous system
- sympathetic
- parasympathetic
what is the difference between the sympathetic and parasympathetic nervous system
(NEUROTRANSMITTERS)
- sympathetic
preganglionic releases acetylcholine, post ganglionic neuron releases noradrenaline
(except adrenal/ sweat glands) - parasympathetic
preganglionic releases acetylcholine, post ganglionic releases acetylcholine
what is the difference between sympathetic and parasympathetic nervous system
(RECEPTORS )
- both nicotinic Ach receptors
SYMPATHETIC - alpha and beta adrenoreceptors
PARA - muscarinic Ach receptors
where do preganglionic neurones sit in the body in sympathetic nervous system
intermediate area of the spinal chord, in the lateral horn
give examples of actions the parasympathetic NS is responsible for
- constricts pupil and ciliary muscle
- secretion in salivary glands
- decreases heart rate
- relax sphincters, increases secretion
what controls the autonomic nervous system
sensory fibres -> interneurons (processing in the brain) -> sympathetic and parasympathetic post ganglionic neurones -> effector organ
give examples of autonomic reflexes
- baroreceptor reflex
- lung inflation
- saliva
- vomiting
- defecation
- micturition (peeing)
- defence
how is the parasympathetic nervous system involved with the eye
Parasympathetic - (controls how much light enters the eye) sensory input comes in via optic nerve, reaches autonomic nuclei, then ganglions, then pupil constricts
contracts and relaxes ciliary muscle, makes lens thicker or thinner to switch between near and far vision
how is the sympathetic nervous system involved with the eye
causes the pupil dilate via the limbic system involved with emotional control
