7A.1 Structure Of Nervous System

CNS consist of …

brain and spinal cord

PNS consist of….

Cranial( are a set of 12 paired nerves that start in your brain)

and spinal nerves (31 pairs)

red is?

midbrain

blue is?

pons

green is?

medulla

structure thats not labelled and is next to the green is?

cerebellum

all together they are the???

brainstem

brain includes

cerebrum, cerebral hemisphere, brainstem and cerebellum

brain stem includes

midbrain, pons, and medulla

cerebrum

largest part of the brain, sits at the top of the head and has a left and right half (hemisphere)

forebrain is the…

cerebrum

midbrain is the

midbrain

hindbrain is the

pons

medulla

cerebellum

Lower motor neurons (LMN)

PNS efferent neurons that synapse and control skeletal muscle

motor unit

LMN + skeletal muscle

neuromuscular junction

synapse of LMN + skeletal muscle

signs of abnormalities and weakness of lower motor neurons

atrophy

fasciculations

hypotonia

hyporeflexia

atrophy

lost in size of muscle

fasciculations

involuntary twitches of skeletal muscle

hypotonia

decrease in tone of skeletal muscle— how much is contracted when person is relaxed (looks limp)

hyporeflexia

decrease muscle stretch reflex

mechanoreceptors

receptors for position, vibration, and touch

nociceptors

pain receptors

speed of mechanorecptors

fast

speed of nocireceptors and thermoreceptors

slow

image of type of receptors

which type of receptors have large diameter axons, thick myelin sheath?

the fast mechanoreceptors

the rest have small diameter axons,slower

Of the 5 samatosensation receptors (position vibration touch pain or temp) is both fast and slow depending on situtation?

touch receptors

receptors sends info through (afferent or efferent) axons

afferent

muscle stretch reflex consists of 2 parts…

afferent and efferent

somatosensory neurons in muscle spindles do what?

(it is an afferent neuron that ) form excitatory synapse in spinal cord with another neuron in spinal cord, which sends axon out back to same muscle that was stretched, and excite skeletal muscle cells to contract through lower motor neurons

The pathway

Muscle spindle (detects strech) → sensory neuron → spinal cord → α-motor neuron (LMN) → same muscle