Med anatomy chapter 2

nervous system

nervous system

controls muscles and glands, receives sensory input, integrates information, establishes and maintains mental activity

what is skeletal muscles controlled by?

the somatic system of the PNS

what are smooth muscles and cardiac muscles and glands controlled by?

autonomic division of the PNS

what are the divisions of the nervous system

central and peripheral nervous system

what are the division of the CNS

brain and spinal chord

what are the divisions of the PNS

motor and sensory

what are the division of the motor PNS system

somatic and autonomic

what are the divisions of the motor autonomic PNS system

sympathetic and parasympathetic

parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy

systematic nervous system

fight or flight; nervous system that we DO control; controls voluntary movements of skeletal muscles

external stimuli

5 senses, temperature

what is the external stimuli controlled by

the somatic part of the PNS that leads to conscious feeling

somatic nervous system

A subdivision of the peripheral nervous system. Enables voluntary actions to be undertaken due to its control of skeletal muscles

autonomic nervous system

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

internal stimuli

muscle length and tension, blood pH, pressure, blood glucose level, hormone control

Acetylcholine

A neurotransmitter that enables learning and memory and also triggers muscle contraction

myelinated axons

axons covered with myelin sheaths

dendrites

Branchlike parts of a neuron that are specialized to receive information.

splitting of dendrites

arborisation

cell body of axons

contains the nucleus and nissi bodies runs the processes houses DNA organelles rough endoplasmic reticulum and produce protein and neurotransmitters

nissi body

membranous sacs within cytoplasm of nerve cells that have ribosomes attached to their surfaces

axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

myelin sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Nodes of Ranvier

a gap in the myelin sheath of a nerve, between adjacent Schwann cells. which allow conduction of electricity

axon terminals

Branches at the end of the axon that contain tiny pouches, or sacs, called synaptic vesicles.

synaptic bouton

A swelling specialized for the release of neurotransmitter that occurs at the end (or along) an axon - pre-synaptic (before the synaptic cleft)

Also known as an axon terminal or terminal boutons

what is 1 in this image

unipolar

what is 2 in this image

bipolar

what is 3 in this image

multipolar

what is 4 in this image

pseudo uni polar

bipolar axons

neuron two poles one dendrite and one axon. Rare found for special senses

pseudo uni polar

peripheral axon and the central axon, they do not have dendrites. In sensory neurons. efferent

multipolar neuron

A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system. stimulate muscles.

axon hillock

Cone shaped region of an axon where it joins the cell body.

schwann cell

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

nissl body

Rough ER

chemicals released in synaptic boutons

neurotransmitters

action potentional

a neural impulse; a brief electrical charge that travels down an axon

synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

neuromusclar junction

point of contact between a motor neuron and a skeletal muscle tissue

neuroglandular junction

synapse between neuron and gland

How does action potential work?

1. When an axon is not stimulated, its membrane has resting potential.

2. An action potential excites the neuron's membrane. If the excitation reaches the threshold of the axon, some gates/channels open at the start of the axon. Sodium ions, concentrated outside the membrane, rush into the cell, attracted by the negative charge. The influx of positively charged sodium ions is the action potential. As the positive charge enters the axon at one point, it stimulates the next point along the axon, which then starts opening sodium channels and repeats the process.

3. The sodium gates snap shut after being opened for a few milliseconds. The potassium gates remain open. Potassium does not flow as rapidly as sodium, but continues longer. The potassium ions carry a positive charge. Their exit drives the inside of the axon back to resting potential.

4. Eventually, the sodium-potassium pump removes the extra sodium ions and recaptures escaped potassium ions.

lipid found in myelin sheath

cholesterol

afferent

sensory towards the CNS

efferent

motor away from the CNS

Oligodendrocytes

Type of glial cell in the CNS that wrap axons in a myelin sheath.

white matter

Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.

grey matter

The portions of the central nervous system that are abundant in cell bodies of neurons rather than axons. Unmyelinated.

histology of an axon

axon, surrounded by a myelin sheath, covered in schwann cells and the nodes of ranvier

histology of the axons (p.e.e)

axons, myelin sheath, endoneurium, fascicle, perineurium, epineurium

Cell body collection in CNS

nucleus

cell bodies in PNS

ganglion

axons in CNS

tract

axons in PNS

nerve

CNS

lies in the vertebral column in the dorsal cavity of the back

where is grey and white matter stores in the brain

grey peripherally, white centrally

where is grey and white matter located in the spinal chord

grey centrally white peripherally

dorsal

sensory information

ventral

motor information

what does the dorsal root ganglion contain

cell bodies for sensory axons

do the ventral and dorsal primary rami carry sensory motor or mixed info

mixed

are the rootlets roots and rami part of the CNS or PNS

PNS

Meninges

three protective membranes that surround the brain and spinal cord

meninges layers

1. dura mater

2. arachnoid

2.5. subarachnoid space

3. pia mater

4. cranium

5. periosteum

6. skin

where does the spinal chord end

L1-L2 or at the conus medullaris

what does the central canal and subarachnoid space contain

CSF

are tracts located in white or gray matter

white

difference between nerve and axon

nerve a group neuron an individual cell

fascicle

bundle of axons surrounded by perineurium

endoneurium

surrounds an axon

epineurium

surrounds the entire nerve

difference between cranial and spinal nerves

cranial originate through foramen at base of the skull and spinal originate through the foramen of the spinal column

paires of spinal nerves

31

spinal nerves type

mixed

number of cervical

8

number of thoracic

12

number of lumbar

5

number of sacral

1

number of coccygeal

1

C1-4

cervical

C5-T1

brachial

T2-12

remain segmented

L1-S4

lumbosacral

dorsal ramus

innervates the skin of the back and spinal muscles

C5

shoulder abduction

C6

elbow flexion, wrist extension, thumb

C7

elbow extension, wrist flexion

C8

finger flexion

T1

medial forearm

T2

medial side of upper arm to medial elbow, pectoral and midscapular areas

L2-L4

Quadriceps

S1

achillies

tricepts reflex

C7 radial nerve

bicepts reflex

C5, musculocutaneous

Brachioradialis reflec

C6 radial

Patellar reflex

L2-L4 femoral

achillies reflex

tibial S1

plantar reflex

Position the thigh in a slight external rotation.

With the reflex hammer, draw a light stroke up the lateral side of the sole of the food AND inward across the ball of the foot like in an upside down J shape.

Normal Response: Plantar flexion of the toes (toes curl) and inversion and flexion of the forefoot.

abdominal reflex

causes lateral movement of umbilicus as abdominal muscles on one side contract

neuropraxia

Neuropraxia is the mildest form of traumatic peripheral nerve injury. It is characterized by focal segmental demyelination at the site of injury without disruption of axon continuity and its surrounding connective tissues. This condition results in blockage of nerve conduction and transient weakness or paresthesia.