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Lab test 2 > #8: the nervous system > Flashcards

#8: the nervous system Flashcards

1
Q

What are the two main types of cells found in the nervous system?

A

Two main types of cells:
1) Neurons: cell body (contains the nucleus)/ dendrites (conduct impulses toward the cell body/ axons (conduct impulses away from the cell body)

2) Neuroglia (glial cells)
: supporting cells that carry out a variety of functions related to creating & maintaining an appropriate environment for neurons
1) ependymal cells (CNS)
2) oligodendrocytes (CNS)
3) astrocytes (CNS)
4) microglia (CNS)
5) satellite cells (PNS)
6) Schwann cells (PNS)

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2
Q

List the types of neuroglia in CNS and their locations/ structure/ functions

A
  1. ependymal cells
    - simple cuboidal epithelial cells
    - lining ventricles (in the brain) and central canal (in the spinal cord)
    > Assist in producing, circulating & monitoring cerebrospinal fluid
    > located in the gray matter
  2. oligodendrocytes
    - non-neural cells
    > produce myelin sheaths, which insulate axons and increase the speed of nerve impulses = myelinate CNS axons
    > Provide a structural framework
    > located in the white matter
  3. astrocytes
    - star-shaped cells in the brain and spinal cord
    [homeostasis/ synaptic support]
    > Support neurons by anchoring them to capillaries and protect them from harmful substances
    > Maintain blood-brain barrier (physically & chemically)
    > Provide structural support
    > Regulate ion, nutrient and dissolved gas concentrations
    > Absorb and recycle neurotransmitters
    > Form scar tissue after injury
    > regulating synaptogenesis
    » found both in the gray (protoplasmic astrocytes) and white matters (fibrous astrocytes)
  4. microglia
    - immune cells in the CNS (key cells in overall brain maintenance)
    - very small, bean-shaped cells
    [homeostasis/ phagocytosis]
    > help shape neural circuits by modulating synaptic transmission and sculpting neuronal synapses
    > Eliminate any kinds of infection aggregates that may endanger the CNS
    > can generate inflammation in response to infection
    » mostly in white matter (more elastic relative to those in the gray matter)
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3
Q

List the types of neuroglia in PNS and their locations/ structure/ functions

A
  1. Satellite cells
    - surround neuron cell bodies in ganglia
    > Regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in the ganglia
  2. Schwann cells
    - surrounds all axons in PNS
    > responsible for myelination of peripheral axons
    > Participate in the repair process after injury

*ganglion (plural: ganglia): a collection of neural cell bodies outside the CNS (i.e. in the PNS)

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4
Q

compare/ contrast the locations of gray matter and white matter to one another in spinal cord

A

Gray matter is found deeper in comparison to the white matter, resembles H or butterfly. White matter is surrounding in graymatter.

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5
Q

The steps of transmembrane potential or action potential

A
  1. resting state
  2. depolarization
  3. repolarization
  4. hyperpolarization
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6
Q

Explain the resting state

A

1) when the neuron’s membrane potential is stable and all gated sodium and potassium channels are closed

  • when the outtside the stimulation is large enough to bring the membrane potential in the neuron body up from -70mV to the threshold voltage of -55mV are higher (depolarization) > trigers the actional potential at the axon hillock, which the travel down the axon
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7
Q

Explain depolarization

A

when the cell membrane reaches the threshold (-55mv from -70mV) voltage, the voltage gated Na+ channel changes to an open position & Na+ rushes into the cell b/c of the electrochemical gradient
> makes the inside cell less negative
- when it reaches ‘0’ = depolarization

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8
Q

explain repolarization

A

up to +30mV = overshot
as the membrane potential becomes positive,
> sodium channel closed (inactivated)
> potassium channel open
= stop the flow of sodium ions into the cell, the poassium ions flow out of the cell b/c of its electrochemical gradient
> outside cell getting less negative relative to the inside cell (repolarization)

Absolute refractory period - prevents action potentials from happening again too quickly and from traveling backwards along the axons

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9
Q

Explain hyperpolarization

A

Because the potassium voltage gated channels take slower to close for a brief period
= membrane potential is hyperpolarized
> more negative than the resting potential (-90mV)
> the potassium channel close

Relatively refractory period - they’ll take a larger than usual stimulus (even tho the Na+ gate is opened (inactivated) b/c the cell is hyperpolarized due to K+ still leaving the cell

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10
Q

Explain after hyperpolarization

A

Becoming the resting state again, since the sodium-potassium pumps are still working
- the pump stores the chemical gradients by putting the sodium & potassium back in place
= more sodium out, mroe potassium in

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11
Q

compare/ contrast the locations of gray matter and white matter to one another in cerebrum

A

Gray matter is the outter layer which is called the cerebral cortex, the white matter is more central to the gray matter.
- gray matter coating the white matter
- other gray matter structures, like the basal ganglia, are embeded within this white matter core.
- the brain’s fluid filled ventricles are also found within the white matter

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12
Q

Explain how reflexes work and how they are used in a clinical setting

A

Refelexes can be used in a clinical setting to assess the health of your nervous system.
e.g. they can test your reflexes by tapping your patellar tendon to see how well your knee-jerk reflex works (stretch reflexes)
> an overactive, weak or absent reflex could indicate a medical condition

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13
Q

Demonstrate how to test specific reflexes

A
  1. biceps reflex (stretch reflex)
    - elicited this reflex by holding the subject’s elbow with your thumb pressed over the tendon of the biceps branch
    - strike a sharp blow to your thumb with the reflex hammaar to stretch the tendon
    » this reflex functions through the C5 and C6 of cervical spinal nerves
  2. triceps reflex (stretch reflex)
    - have the subject flex his or her arm at the elbow, holding the wrist with the palm facing the body
    - strike the triceps branchii tendon above the elbow with the pointed end of the reflex hammar
    » this reflex functions through teh C7 and C8 spinal nerves
  3. patellar reflex
    (knee reflex, knee jerk reflex)
    - the subject should sit on the edge of a table with the leg suspended over the edge and completely relaxed.
    - strike the patellar tendon, to elicite the reflex
    »L2, L3, L4 of lumber spinal cord
    * clonus can occur: a manifestation of hyperreflexia and indicates damgae within the central nervous system (CNS)
  4. plantar reflex
    = superficial reflex
    - stroke the sole of the foot with a sharp object such as a key.
    - With certain types of damage to the pyramidal tract, however, the response to plantar stimulation is dorsiflection of the great toe and spreading of the other toes = Always pathological in adults, but normal in infants (Babinski’s sign)
    » S1 and S2 of sacral spinal nerves
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14
Q

describe the relationship between the structure and function of nervous system cells and tissues

A

You are good if you know the locations/ functions/ structures of neurons and neuroglia

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15
Q

2 types of clinical reflexes

A

1) stretch reflexes: elicited by sharply tapping (percussing) an appropriate tendon or muscle. Also called jerk or myotactic reflexes
- the receptors (spindles) for these reflexes are located in the muscle, not the tendon.
- tapping a tendon stretches the muscle, which, activates the muscle spindle and triggers the reflex response
2) superficial reflexes (cutaneous reflexes): withdrawal reflexes elicited by noxious or tactile stimulation. Instead of using percussion, stroking or scratching the skin induces the reponse.

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16
Q

Explain the three ways that damage to the nervous system may affect reflexes in

A
  1. hyporeflexia:
    - diminished/ absent reflex
    - due to loss of muscle or of afferet/ efferent neurons or diminished muscle tone caused by aging, malnutrition or deliberate relaxation
  2. hyperreflexia
    - the loss of inhibitory control of the motor cortex and upper motor neurons of the pyramidal tracks often accompanied by increased muscle tone
  3. pathological reflex
    - the reflex response occurs in one or more muscles other than the one where the stimulus originates

accompanied: go along with

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17
Q

What is biceps reflex

A

this strech reflex causes flexion of the forearm.

  • elicited this reflex by holding the subject’s elbow w/ your thumb pressed over the tendon of the biceps branchii.
  • strike a sharp below to your thumb with the reflex hammer to stretch the tendon.
  • this reflex functions through the fith and sixth cervical spinal nerves (C5 and C6)
18
Q

What is triceps reflex

A

this reflex causes extension oft he forearm in normal individual. to demondrate this reflex, have the subject flex his or her arm at the elbow, holding the wrist with the palm facing the body. The arm must be completely relaxed..
- strike the tricpes branchii tendon above the elbow with the pointed end of the reflex hammer.
- this reflex functions through the C7 and C8 spincal cord

19
Q

What is patellar reflex

A

(also known as the knee reflex, knee jerk, or quadriceps reflex)
- to elicit the typical response, strike the patellartendon, which is just below the knee cap
- when testing for this reflex, a phenomenon called clonus can sometimes occur.
(clonus: a succession of jerk-like contractions that follow the normal reponse and persist for ashort time)
- this reflex functions through the second, third and fourth lumbar spinal nerves (L2,L3, L4)

20
Q

WHat is plantar reflex

A

differs from the other int hat it is a superficial reflex
- in adult, stroking the sole of the foot elicits plantar flexion of the toes
> in a healthy adult, the big toe will flex downward.
> anormal response occurs when the big toe extends upward and the other toes fan out = the Babinski sign (always pathological in adults, but is normal in infants)
- Babinski sign will disappear as teh infant frow and myelinization of the nerve fibers is completed
- this reflex funtions through first and second sacral spinal nerve (S1 andS2)

21
Q

Macroanatomy and function of the mammalian eye

A

The photoreceptor neruons (rods and cones)are located in retina
> these along w/ other neruons transmit the potential generated int he receptor cells to the optic nerve
* optic nerve: to send visual information fromt he eye to the brain, which then processes the signals to create the images we see (transmits visual info/ conducts visual reflexes)
* cornea: light enters our eyes through the cornea, which bend the light towards teh iris
* iris: a muscular ring that controls how much light enters the eye through the pupil
* lens: the light passes through the lens, which focuses the light ont he retina

the photoreceptor neurons (rods and cones): the functioanl units of mammalian sight, detecting the light entering the eye and transmitting the potentail generated to the optic nerve which carries the information to the brain

22
Q

What are the rods and cones

A

cones associated with colour vision under well-lit conditions
rodes: are associated with black and white vision udner dimly lit conditions

  • each photopigment is a combination of two diff light absorbing pigments:** retinal and opsin**
    > each photoreceptors contain the same retinal but there are four different types of opsin in humans: three in cones and one in the rods
  1. When a photopigment absorbs a photon of light, the retinal portion of the compound changes shape and detaches from the opsin.
  2. This detachment triggers a series of reactions that leads to the release of a neurotransmitter, which initiates an action potential in a neuron and sends a signal to the brain.
  3. After a few minutes, enzymes will cause the retinal to revert to its original shape, allowing it to bind to the opsin again and halting the release of the neurotransmitter.
23
Q

How does the eye works with brain

A
  1. When a photopigment absorbs a photon of light, the retinal portion of the compound changes shape and detaches from the opsin.
  2. This detachment triggers a series of reactions that leads to the release of a neurotransmitter, which initiates an action potential in a neuron and sends a signal to the brain.
  3. After a few minutes, enzymes will cause the retinal to revert to its original shape, allowing it to bind to the opsin again and halting the release of the neurotransmitter.

important**

24
Q

Macroanatomy and function of the ear

A

The sensory nerve used here is cranial nerve 7, the vestibulocochlear
- the pinna (external auditory canal): directs sound waves through the tympanic memrbane
- the tympanic membrane: medical term for ear drum
- the middle ear ossicles (the malleus, incus, and stapes): carry these vibrations throught he middle ear to the surface of the oval window
- the oval window & the round window = membrane-covered openings into the bone that houses the inner ear
- the vibrations of the oval window produce pressure waves in the fluid within the snail-shaped cochlea
- - the vibrations of the oval window produce pressure waves in the fluid within the snail-shaped cochlea
> these pressure waves vibrate a membrane with hair cells attached to it
> the deflection of these hairs converts these pressure waves into nerve impulses that the brain perceives as sound
- the Eustachian tube: connects the throat to the middle ear
> equalizing air pressure in your middle ear with the air pressure outside (opens when you swallow, yawn or chew)
> drains fluid from the middle ear which reduces the risk of ear infections
> (when swallowing or yawning) the tube closes to protect your middle ear from bacteria and viruses

Not actually important (skip it)

25
Q

How the sound is delivered to the brain nerve (ear)

A
  • the vibrations of the oval window produce pressure waves in the fluid within the snail-shaped cochlea
    1. these pressure waves vibrate a membrane with hair cells attached to it
    2. the deflection of these hairs converts these pressure waves into nerve impulses that the brain perceives as sound
    3. louder sounds cause a greater deflection of the hair
    4. the base of the cochlea is wider than the apex, therefore the membrane in that region responds to lower frequency sounds where as those near the apex of the cochlea respond to higher frequency sounds

important***`

26
Q

2 different types of equilibrium

A

1) static equilibrium: the orientation of the head relative to the ground its linear acceleration
- hair cells in the saccule and utricle (cochlea) monitor our static equilibrium
2) dynamic equilibrium: the maintenance of body position (mainly that of the head) in response to sudden movements or to changes in rate or direction of movement
- hair cells in the ampullae of the three semicircular canals detect this motion

27
Q

What is tactile (Meisnner’s) corpuscles (DEMO)

A

the sensory receptors specialized for light touch sensation
- located at the upper most part of teh dermis in the ridgesbetween the dermis and epidermis (dermal papillae)

28
Q

What is the lamellar (Pacinian) corpuscles?

A

the sensory receptors specialized for firm touch or deep pressure sensations.
- in the dermis of the skin and in many internal organs

29
Q

Explain the anatomy of the outer brain

A

Outer:
1) cerebrum
- frontal lobe
- parietal lobes
- temporal lobes
- occipital lobe
- longitudinal fissure
- central sulcus (between frontal and parietal lobes)
- sylvial fissure (lateral sulcus) (where the temporal lobes seperate)
- Gyrus or gyri (looks like a mountain on the line)
- sulci or sulcus (the typical brain line)
2) cerebellum
3) spinal cord
4) pons

30
Q

The connective tissue membrane inside the skull

A

menings (sing. meninx)
- cover and protect the brain

1) dura matar (outermost meninx, the tough leathery)
2) arachnoid: a thin delicate membrane that bridges the sulci
- covers many small blood vessels
3) piamater: a thin vascular membrane applied closely to the surface of the brian
- the innermost meninx and lies deep to the blood vessels, whithin the folds of the sulci
-* is difficult to identify
*

31
Q

what is the largest portion of the brain and explain its structure

A

cerebrum
1) the cerebral cortex (the outer part of the brain)
- convoluted, or folded
- consists of gray matter
2) Gyri: the folds consist of raised section (a mountain-like)
3) fissure; sylivial fissure: deep depressions
4) sulci; sulcus: shallow depressions
5) **longitudinal fissure **: divides the two celebral hemispheres
6) celebral hemispheres: joined by a bridge of nerve fibers called corpus callosum

32
Q

Identify structures on the ventral surfaces of the brain

A

1) olfactory bulbs and tracts:
concerned with* the sense of smell*.
- the olfactory bulbs are extensions of the brain that lie above the nasal cavity
2) optic chiasma: vision; a white cross, posterior to the olfactory tracts. - some of the fibers from each optic nerve cross over tot he opposite side of the cerebrum
3)the pituitary stalk: connects to the main body of the brain tot he pituitary gland; *part of the endocrine system *
- lies posterior to the optic chiasma
- you may find some of the sphenoid bone still connected ot the pituitary

4) the ponse: a rounded bulge in the brain sem, posterior to the pituitary gland
- a bridge connecting the spinal cord with the brain and parts of the brain with each other

5) the medulla oblongata: regulates heart rate, respiratory rate, and other basal functions
- the area of the brain stem immediately posterior to the pons

not neccessary

33
Q

What is cerebral cortex

A

contains…
- sensory areas that interpret sensory impulses
- motor areas that control muscular movement
- association areas that regulate emotional and intellectual process

34
Q

What is corpus callosum

A

contains transverse connections between the left and righ cerebral hemispheres

35
Q

What is the thalamus?

A

“a central sorting area”
- receives sensory imppulses
- relays them to the apppropriate regions of the brain

36
Q

What is the pineal gland

A

a small mass of tissue attached to the thalamus
- secretes the hormone melationin in response to changing day length

37
Q

What is the hypothalamus

A

plays a major role in…
- maintaining homeostasis
- regulating hunger, thirst, circaain rhythms, emotions and behaviours
- secreting the hormones ADH and oxytocin
- also controls and integrates the autonomic nervous system

38
Q

What is optic chiasma

A
  • the place in the brain where some of the optic nerve fibers coming from an eye cross optic nerve fibers from the other eye
  • anterior to the pituitary gland
39
Q

What is pons

A

a relay centre for impulseswithin the brain and between parts of the brain and spinal cord

40
Q

What is medulla oblongata

A

the myelinated nerve fibers of the cerebellum lead to the cerebellar cortex
- form a white ‘tree-like’ pattern called the arbor vitae
- the cerebllum controls skeletal muscle contractions required for coordination, posture, balance and fine motor coordinations

41
Q

what’s the name for the four, fulid-filled cavities inside the brain and its locations/ functions?

A

Ventricles
- in the brain that are continuous with one another and with the central canal of the spinal cord)
1) one lateral ventricle: extends through each hemisphere of the cerebral cortex
2) third ventricle: at the level of the thalamus
3) fourth ventricle: anterior tot he cerebellum in the brain stem

= to protect the human brain from trauma (via cushioning effect) and to help from the central canal, which runs the length of the spinal cord

  • each of them contains: cerebrospinal fluid

ependymal cells is responsible for cerebrospinal fluid

42
Q

What is the cerebrospinal fluid (CSF)

A

circulates around and within the entire central nervous system (CNS)

has many functions in the CNS…
- providing physical support, protection from trauma
- distrubtes nutrients wastes, and chemical signals

If obstruction of CSF circulation and/ or drainage occurs, CSF volume can increase, leading to increased intracranial pressure (hydrocephalus)

Hydrocephalus?
: casues enlargement of the head of newborns as the skull bones have not fully formed and fused

In adults, causes damge to the brain tissue

Lab test 2 (5 decks)

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