kaap309 exam 2

define afferent nerves

associated with sensory. info coming TO spinal cord, CNS and brain (input)

define efferent nerves

associated with motor. spinal cord sends info DOWN to organs, muscles, etc

define somatic nerves

controls muscles, voluntary

define visceral nerves

controls organs, involuntary, automatic

describe sensory input

afferent, sensory receptors monitor changes throughout the body. when they detect the change that theyre specialized for, they send the signal to the brain

describe integration

processing of afferent info, interpretation, and decision on what should happen next

describe motor output

efferent, acts of organs, glands, muscles. coming from spinal cord to our target muscles

CNS vs PNS name for a group of cell bodies

CNS: nucleus

PNS: ganglia

CNS vs PNS name for a group of axons

CNS: tract

PNS: nerve

what are the 3 parts of a neuron

cell body: spherical, large nucleus, metabolic center of neuron

dendrite: extending off cell body, lots of variability, motor neurons typically contain more

axon: 1 axon, arises from cell body

what are the 4 structure types of neurons

multipolar, unipolar, bipolar, anaxonic

describe multipolar neurons

most common type, contains LOTS of dendrites.

most are interneurons that conduct impulses within the CNS

describe bipolar neurons

less common, found in retina of eye, receptors or nose, ear.

2 process extend from the cell body, one is a dendrite the other is an axon.

all bipolar neurons are sensory neurons located in special sene organs

describe unipolar neurons

cell body sits up and floats on its own, peripheral process is usually long, central process is short

starts bipolar in embryonic development

usually found in dorsal root ganglion areas of PNS

describe anaxonic neurons

do not contain axons nor deal with APs.

send signals between other neurons

found in networks within the brain, retina of eye, adrenal medulla

describe variations of structure of multipolar, bipolar, and unipolar neurons

mulitpolar: purkinje of the cerebellum, pyrimidal cell

bipolar: olfactory and reitnal cells

unipolar: dorsal root ganglion cell

describe the 3 types of neurons

sensory: afferent, pick up info from receptor in PNS and bring it to CNS

interneuron: only in CNS< relay info to appropriate motor neurons, 90% of neurons

motor: sneds info to muscles and organs

what are the 4 supporting cells of nervous tissue in CNS?

oligodendrocytes, ependyma,microglia, astrocytes

what are the 2 supoporting cells of enrovus tissue in the PNS?

satellite and schwann cells

describe oligodendrocytes

found in CNS, branching cells, can help on multiple axons at once

F: wrap around axons of CNS neurons, creating an insulating layer known as the myelin sheath in brain and spinal cord

describe ependymal cells

found in CNS, wrapping garment, typically columnar or squamous, containing cilia

F: line cavities of brain and spinal cord, circulate CSF, create a fairly permeable barrier

describe microglia

found all over CNS, small ovoid shape

F: monitor health of neurons(migrate to neurons in distress), transform to macrophages

describe astrocytes

found in CNS, star cells, most abundant and versatile neuroglia

F: everything, exchanges between capillaries and neurons, control chemical environment (mop up leaked K+)

describe satellite and schwann cells

found in PNS

satellite = astrocytes of PNS

Schwann = oligodendrocytes of PNS, only covers one segment of an axon with myelin

describe myelin

fatty protein lipid, develops rapidly within the first 2 years of life

F: insulation and increase the speed of electrical impulse

describe the nodes and ranvier

gaps found about every 1mm on axon, first gap is known as initial segment

describe unmyelinated axons

many within both CNS and PNS but in PNS, axons are still within a schwann cell, just not wrapped around

describe 3 types(size) of nerve fibers

large diameter: sensory and motor fibers for skin, muscles, joints; thick myelin sheaths, fastest

intermediate diameter: lightly myelinated, ANS and pain

small diameter: non myelinated, ANS and pain, slowest

how can you change a resting membrane potential?

alter ion concentrations or change the permeability to an ion

what can changing the resting membrane potential produce?

graded potential: short distance

action potential: long distance

what is the resting membrane potential?

-70 mV

changing resting membrane potential: leaks/voltage-gated channels

Na+ leaks in while K+ leaks out, happens naturally, Na+/K+ pump compensates for this to maintain homeostasis, working constantly

changing resting membrane potential: ligand (chemcial) gated

ligand binds to a receptor, channel opens and Na+ floods into the neuron, shifts the membrane to depolarization

changing resting membrane potential: mechanically gated

ion channels that open under mechanical stress

what are the 4 types of local potentials?

-graded

-decremental: as we move away from stimulus, it will have less effect

-reversible: when stimulus ends, cell goes back to normal

-excitatory/inhibitory

what are the 3 types of action potentials?

- all or none

-nondecremental: once it starts, same level you have is going to continue all the way down

-irreversible

what are the 7 steps of action potentials?

1. A local current arrives at the axon hillock, depolarizing the area

2. A minimum threshold (critical voltage) of -50mV must be reached

3. Voltage gated channels open (Na+ fast, K+ slower). Na+ channels continue to open

4. At 0 mV the Na+ channels close, and final voltage peaks between +35-50mV

5. At the peak, K+ gates are open and K+ floods out of the cell

6. K+ channels stay open, resulting in more K+ leaving than Na+ entering. Voltage is now 1-2 mV more negative than RMP

7. Na+ begins to re-enter the cell, returning to normal RMP

describe the propagation of an action potential

they are sefl propagating away from the point of origin, continue as a consistent velocity. NOT the same as conduction

what influences impulse propagation?

axon diameter(larger=faster) and degree of myelination(present=faster)

continous vs saltatory propagation

myelinated: continuous, APs are triggered in nodes, only change seen in resting MP is seen in gaps

nonmyelinated: saltatory

what is a synapse and their 3 locations?

a junction that mediates info from one neuron to another

L: axosomatic, axodendritic, axoaxonal

what are neurotransmitters?

molecules synthesized by a neuron, released when a nerve signal reaches an axon terminal, have a specific effect on physiology

describe acetylcholine

L: neuromuscular junctions, most synapses of ANS, retina, aprts of brain

F:excites skeletal muscles, inhibits cardiac muscle

describe glutamate

L: cerebral cortex and brainstem

F: accounts for about 75% of all excitatory synaptic transmission in the brain, involved in learning and memory

describe aspartate

L: spinal cord

F: effects similar to glutamate

describe glycine

L: inhibitory neurons of the brain, spinal cord, retina

F: most common inhibitory neurotransmitter in the spinal cord

describe GABA

L: thalamus, hypothalamus, cerebellum, occipital lobe, retina

F: most common inhibitory neurotransmitter in the brain

describe norepinephrine

L: SNS, cerebral cortex, hypothalamus, brainstem, cerebellum, spinal cord

F: involved in dreaming, waking, mood; excites cardiac muscle; can excite or inhibit smooth muscle and glands depending on location

describe epinephrine

L: hypothalamus, thalamus, spinal cord, adrenal medulla

F: similar to norepinephrine

describe dopamine

L: hypothalamus, limbic system, cerebral cortex, retina, substantial nigra of midbrain

F: involved in elevation of mood and control of skeletal muscles

describe serotonin

L: hypothalamus, limbic system, cerebellum, retina, spinal cord, also secreted by platelets and intestinal cells

F: involved in sleepiness, alertness, thermoregulation, mood/behavior

describe histamine

L: hypothalamus, a potent vasodilator released by mast cells of CT and basophils

F: causes allergy symptoms

describe substance P

L: basal nuclei, midbrain, hypothalamus, cerebral cortex, small intestine, pain receptor neurons

F: mediates pain transmission

describe enkephalins

L: hypothalamus, limbic system, pituitary, pain pathways of spinal cord, nerve endings of DT

F: act as pain relievers by inhibiting substance P, inhibit intestinal motility, modulate immune responses

describe beta endorphin

L: digestive tract, spinal cord, parts of brain, also secreted as a hormone by the pituitary

F: surpasses pain, secretion rises sharply during labor and delivery

describe cholecystokinin

L: cerebral cortex and small intestine

F: suppresses appetite

what are the 4 primary regions of the brain?

cerebrum, diencephalon, brain stem, cerebellum

describe white matter

myelinated neurons, found mainly on internal of brain

describe gray matter

short, unmyelinated neurons, external aspect of brain but some clusters internally

describe the cerebral cortex

2 hemispheres, divided into 5 lobes. accounts for 83% of brain mass

gyri: "twisters"(elevated ridges)

sulci: "furrows"(shallow grooves)

describe the frontal lobe

motor areas(efferent somatic)

prefrontal cortex: controls personality, critical thinking, spatial memory

describe parietal lobe

sensory areas: where afferent neurons end up

describe the insula

found deep in the brain, controls taste and equilibrium

describe motor areas of the brain

primary motor cortex: pre central gyrus

premotor cortex: process thinking about movement patterns

brocas areas: deals with speech production

frontal eye field

describe sesnory areas

primary sensory cortex: post central gyrus

somatosensory association cortex

visceral sensory area

frontal eye field

what is the main purpose of basal nuclei (ganglia)?

primarily involved in control of movement

"who" is basal nuclei?

caudate nucleus, putamen, globus pallidus

who helps out basal nuclei?

subthalamic nuclei, substantia nigra

what neurotransmitters do basal nuclei primarily use?

GABA, dopamine, glutamate

what is parkinsons disease?

-results from a degeneration of the dopamine-releasing neurons from the substantia nigra

-basal nuclei become overactive, results in persistent tremors and slow initiation of movement

describe the diencephalon

central core, paired structures: thalamus, hypothalamus, epithalamus

describe the thalamus

bilateral egg shaped nuclei where info is sorted and relayed, accounts of 80% of diencephalon

describe the hypothalamus

vital for homeostasis

some functions include: body temp, thirst, sleep/wake cycles, control ANS, response to emotion, food intake

describe the epithalamus

visible as pineal gland, secretes melatonin

describe the midbrain

1.superior cerebellar peduncles

2. superipr colliculi: vision reflexes

3. inferior colliculi: auditory reflexes

4. substantia nigra

5. red nuclei: limb flexion pathways

describe the pons

composed of mainly tracts: longitudinal(brain to spinal cord) and transverse(pons to cerebellum)

describe the medulla

crucial for ANS, site of decussation(crossing), inferior cerebellar peduncle controls spatial awareness

important nuclei: cardiac and respiratory center, cochlear nuclei

describe the cerebellum

provides the precise timing and appropriate patterns of muscle contraction (subconscious)

primarily made of gray matter and ipsilateral

describe the 4 steps of cerebellar processing

1. motor cortex relays info to the cerebellum their intention for movement

2. cerebellum is simultaneously receiving info from the proprioceptors throughout the body

3. cerebellum calculates the best way to coordinate the force, direction, and extent of muscle contraction

4. cerebellum dispatches a blue print of movement to the cerebrum

what are meninges?

layers(from superficial to deep): dura mater, arachnoid mater, pia mater

what are the functions of meninges?

protect CNS, protect vasculature, house CSF, form partition in the skill

describe the dura mater

2 layers of fibrous CT: periosteal and meningeal

encloses the dural venous sinuses

describe the dural foldings of the dura mater

falx cerebri: separates right and left hemis of cerebellum, sits in longitudinal fissure

falx cerebelli

tentorium cerebelli: separates cerebrum from cerebellum

describe arachnoid mater

spider like, fine elastic CT

describe pia mater

gentle, direct contact with brain tissue

describe the 3 meningeal spaces

dura: 1. under epidural space, only found in some sections (real/potential) 2. above subdural space(potential)

arachnoid: subarachnoid, CSF flowing through it (real)

what does CSF do for us?

provides nutrients and reduces brain weight by 97%

where does CSF come from

choroid plexuses, about 500mL of CSF is formed daily and about 50mL is replaces every 8 hours

what is the pathway of CSF?

1. the choroid plexus of each ventricle produces CSF

2. CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures

3. CSF flows through subarachnoid space

4. CSF is absorbed into the dural venous sinuses

describe hydrocephalus

water on the brain, CSF is produced faster than it drains. treatment options include a shunt to reduce pressure

what is included in the limbic system

amygdala, cingulate gyrus(express emotion thru gestures), hypothalamus, hippocampus

what does the limbic system control

-why we react emotionally to things we understand to be happening(emotion> logic)

-aware of our emotions(logic>emotion)

describe language in regards to the brain

originally though to be entirely left sided

includes brocas area and wernickes area

what is the spinal nerve composed of?

ventral root and dorsal root

describe ventral and dorsal roots

ventral: motor, skeletal muscle

dorsal: sensory, receptors

describe spinal nerve rami path

afferent info enters through the dorsal rami, then travels to the spinal nerve, then to the dorsal root, then finally the spinal cord.

efferent info leaves the spinal cord and goes into the ventral root, then the spinal nerve, then exits through the ventral rami to go to muscles

how many pairs of spinal nerves are there

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

how many vetebrae each are there?

7 cervical, 12 thoracic, 5 lumbar (breakfast at 7, lunch at 12, dinner at 5)

how are spinal nerves named in regards to their location?

cervical region: spinal nerve is named for vertebrae below

thoracic and lumbar region: spinal nerve is named for vertebrae above

what are the 5 PNS stimulus receptors and what do they detect?

-mechanoreceptors: physical change(stretch, vibration, pressure)

-thermoreceptors: temp changes

-photoreceptors: changes in light

chemoreceptors: chemical changes

nociceptors: pain