Neurobiology 5 Flashcards
what are mechanoreceptors?
- activated by mechanical forces (touch, stretch, pressure, vibration, sound waves)
what are photoreceptors?
- activated by light
what are nociceptors?
- activated by potential/ actual tissue damage
what are chemoreceptors?
- activated by binding of chemicals
what are thermoreceptors?
- activated by heat or cold
what are the receptors in retina for light?
- photoreceptor
- rods and cones
what are the receptors in inner ear for sound wave?
- mechanoreceptor
- auditory hair cells
what are the receptors in olfactory epithelium for airborne chemicals?
- chemoreceptor
- free nerve endings
what are the receptors in the tongue for food chemicals?
- chemoreceptor
- taste cells
what are receptors in skin and viscera for pressure/touch/vibration?
- mechanoreceptor
- pacinian corpsucles
what are receptors in skin and viscera for pain?
- nociceptor
- free nerve endings
what are receptors in skin for temperature?
- thermoreceptor
- temperature receptors
what are the receptors in tendon and muscle for stretch?
- mechanoreceptor
- golgi tendon organ and muscle spindle
what are the receptors in aortic arch and carotid artery for blood pressure?
- mechanoreceptor
- nerve endings
what are the receptors for blood pH, glucose, CO2, and O2 in brain and blood vessels?
- chemoreceptors
what are the two forms of sensory receptors
- cells send a chemical signal to sensory neuron
- specialized terminal of the sensory neuron
how does the sensory epithelium work in the ear?
- hair cells in ear have cilia that are displaced by the sound which causes ion channels to open and propagate down the cell and ion channels open causing signal to spread
what is a cervical spinal cord segment like?
- more white matter than grey matter
what is a thoracic spinal cord segment like?
intermediolateral horns for sympathetic motor neurons
what is a lumbar and sacral spinal cord segment like?
- more grey matter than white matter
what is the basic pathway for neurons?
- sensory neurons travel spinal cord to brain and then the brain sends a motor signal to the necessary part of the body
where is the dorsal funiculus?
see picture
where is/are the lateral funiculus
see pic
what information do the dorsal somatosensory pathways relay?
- touch, position, vibration
where is the location of first neuron in dorsal somatosenosry pathway?
- cell body in dorsal root ganglion
- axon ascends in dorsal funiculus
- synapses in brainstem
where is the second neuron located in dorsal somatosensory pathway?
- cell body if brainstem nucleus
- axon crosses midline of medulla
- synapses in thalamus
where is the location of third neuron in dorsal somatosenosry pathway?
- cell body in thalamus
- synapses in cerebral sensory cortex
what information does the lateral somatosensory pathway relay?
- pain and temperature
where is the location of first neuron in lateral somatosenosry pathway?
- cell body in dorsal root ganglion
- synapses in dorsal horn of spinal cord
where is the location of second neuron in lateral somatosenosry pathway?
- cell body in dorsal horn of spinal cord
- axon crosses midline
- ascends in lateral funiculus
- synapses in thalamus
where is the location of third neuron in lateral somatosenosry pathway?
- cell body in thalamus
- synapses in cortex
what are the pyramids?
- external landmarks on ventral medulla
- correspond to tracts composed of axons running from motor cortex to spinal cord
what do the lateral corticospinal tracts do?
- voluntary control of skeletal muscle in distal limbs
how many neurons are in the lateral corticospinal tract?
- 2 motor neuron pathway
where is the location of the upper motor neuron in lateral corticospinal tract?
- cell body in primary cerebral motor cortex
- axons cross midline in ventral medulla (pyramids)
- axon descends in lateral corticospinal tract
- synpases in ventral horn
where is the lower motor neuron in lateral corticospinal tract?
- cell body in ventral horn
- innervates skeletal muscle
what does the ventral corticospinal tract control?
- voluntary control of skeletal muscle in proximal limbs and trunk
where is the upper neuron in the ventral corticospinal tract?
- cell body in primary cerebral motor cortex
- axon passes through ventral medulla (pyramids) and descends in the ventral corticospinal tract
- axon crosses midline at level of second neuron (so spinal cord injury would cause problems on contralateral side)
- synapses in ventral horn
where is the lower motor neuron in ventral corticospinal tract?
- cell body in ventral horn
- innervates skeletal muscle
what are the extrapyramidal tracts?
- motor pathways other than the corticospinal tracts
- axons do not travel in pyramids of medulla
what functions do extrapyramidal tracts control?
- alternative route of transmission from motor cortex to spinal cord
- control of postural reflexes
- control of eye movements
- control of head movements in response to sound or light
- regulate muscle tone
what happens at the neuromuscular junction?
- synapse between motor neuron and muscle cell
how does the neuromuscular junction work in somatic nervous system?
- neurotransmitter acetylcholine crosses cleft binds to nicotinic cholinergic receptor
- in response to binding channels open and Na+ flows into cell causing depolarization
- calcium releases from sarcoplasmic retic.
- calcium promotes muscle contraction
what is in the ascending reticular activating system of consciousness?
- composed of multiple CNS structures
- thalamus, hypothalamus, midbrain, pons, medulla
what structures are involved in memory?
- hippocampus important in memory formation
- memory storage distributed throughout cerebral cortex
- learning = strengthening of synapses between neurons
