nervous system

Question 1

what are the general functions of the nervous system?

Answer 1

• gather sensory input to monitor changes occurring inside and outside the body
• process and interpret sensory input
• respond to sensory input
• helps maintain homeostasis
• mental activity (thinking, memory, emotions)

Question 2

compare and contrast oligodendrocytes and schwann cells

Answer 2

oligodendroytes:
- wrap their processes around nerve fibers in the CNS to form a myelin sheath
- one oligodendrocyte can wrap around several axons

schwann cells:
- form a myelin sheath around larger nerve fibers of the PNS
- one schwann cell can only wrap around one portion of one axon

Question 3

what are the structural divisions of the nervous system?

Answer 3

CNS:
- brain and spinal cord
- integration, command center
PNS:
- outside of the CNS
- cranial nerves, spinal nerves

Question 4

describe early brain development in a general sense

Answer 4

• a neural tube is formed, which will eventually become the CNS
• then, three primary brain vesicles form around the tube: prosencephalon, mesencephalon, rhombencephalon.
• two of the three primary brain vesicles further develop, forming five secondary brain vesicles: telencephalon, diencephalon, mesencephalon (did not further divide), metencephalon, myelencephalon.

Question 5

what are the adult brain structures that the developmental brain will ultimately develop into?

Answer 5

telencephalon and diencephalon=forebrain
mesecephalon=midbrain
metenscephalon=pons and cerebellum
myelencephalon=medulla oblongata

Question 6

name the four brain ventricles and describe their location relative to other brain structures

Answer 6

lateral ventricles: cerebrum, specifically right and left hemispheres
third ventricle: in the diecephalon
fourth ventricle: posterior to pons and medulla oblongata, anterior to cerebellum

Question 7

what cells are the brain ventricles lined by?

Answer 7

ependymal cells

Question 8

describe the overall structure of the cerebrum

Answer 8

• the surface of the cerebrum has gyri (ridges) and sulci (grooves)
• cerebral cortex (the outer surface) made up of grey matter
• cerebral medulla (between cortex and basal nuclei) made up of white matter

Question 9

lobes of the cerebrum and general functions?

Answer 9

1. frontal lobe
   - contains primary motor cortex; initiates volunatry motor impulses. also contains prefrontal cortex, which plays a role in predicting consequences of events or actions
2. parietal lobs
   - contains the primary somatosensory cortex; receives sensory input from the general senses and performes concious perception of touch , pressure, temperature, pain, and vibration
3. occipital lobe
   - contains primary visual cortex, performes concious perception of visual stimuli
4. temporal lobe
   - contains primary auditory and olfactory cortex. performes concious perception of hearing and smell/olfaction
5. insula
   - integration of some sensory info, mostly gustatory

Question 10

name and define the three main types of nerve tracts in the white matter of the CNS

Answer 10

1. association fibers
   - connect different areas within the same hemisphere, allowing for communication between regions in one hemisphere
2. commissural fibers
   - connect the two hemispheres, allowing for communication and integration of info between them
3. projection fibers
   - connect the cerebrum to other parts of the CNS, like brainstem and spinal cord.

Question 11

describe the composition, location, and function of the basal nuclei of the cerebrum

Answer 11

composition:
- caudate nucleus
- lentiform nucleus
- amygdaloid body
location:
- deep to the grey matter
function:
- involved in control of motor function

Question 12

describe the location and functions of the three regions of the diencephalon: thalamus, hypothalamus, and epithalamus

Answer 12

thalamus:
location=inferior to cerebral cortex, superior to brainstem
function=”relay station” receives, filters, and relays sensory and motor information to appropriate areas of the brain

hypothalamus:
location=inferior/anterior to thalamus
function=maintenance of homeostasis, controls pituitary gland

epithalamus
location=most dorsal part of diencephalon
function=contains pineal gland

Question 13

location and function of corpora quadrigemina?

Answer 13

located on the posterior midbrain.
functions:
superior colliculus=contains visual reflex centres
inferior colliculus=contains auditory reflex centres

Question 14

general functions and location of pons, medulla, and cerebellum

Answer 14

pons:
location=anterior portion of brainstem
function=relay station between cerebrum, cerebellum, and spinal cord

medulla oblongata:
location=inferior to pons
function=contains cardiovascular centre, respiratory centre, and centres to regulate hiccuping, swallowing, coughing, sneezing, etc.

cerebellum:
location=posterior to brainstem
function=maintains balance, allows for fine motor skills

Question 15

general location and function of limbic system

Answer 15

location: deep within cerebrum, surrounds brainstem
function: involved in emotions (esp. amygdala) and memory/ learning (esp. hippocampus)

Question 16

describe the general structure and location of the spinal cord

Answer 16

1. structure:
   grey matter: centrally located, shaped like a butterfly; contains neuron cell bodies.
   - dorsal horns: sensory neurons.
   - ventral horns: motor neurons.
   - lateral horns: autonomic neurons (in some regions).
   white matter: Surrounds grey matter; contains myelinated axons forming nerve tracts.
   - divided into dorsal, lateral, and ventral columns.
   centra canal: fluid-filled space in the centre, filled with cerebrospinal fluid (CSF).

location:
- extends from the medulla oblongata (brainstem) through the vertebral column.
- ends at L1-L2 (lumbar vertebrae) in adults.
- protected by the vertebrae, meninges, and CSF.
- divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.

Question 17

what is the order of the meninges from deep to superficial?

Answer 17

pia mater, arachnoid mater, dura mater

Question 18

describe the location and function of the meninges, including the names and relative locations of the three different layers

Answer 18

dura mater
location: most superficial layer
function: structural support and protection. also anchors brain to skull

arachnoid mater
location: middle layer
function: cushioning barrier

pia mater
location: most deep layer
function: nourishes CNS by allowing blood vessels to pass through it

Question 19

describe the function, production, and circulation of CSF

Answer 19

function: provides a protective cushion, plus some nutrients to CNS tissue
production: produced by specialized ependymal cells
circulation: fills the ventricles, subarachnoid space, and central canal of spinal cord

Question 20

what is the blood brain barrier? role of astrocytes?

Answer 20

endothelial cells of the blood vessels in the brain are held together by tight junctions and don’t allow the majority of substances to pass through and into the brain. astrocytes promote development of tight junctions

Question 21

what are the two main subdivisions of the PNS and the subdivisons of those subdivisions?

Answer 21

• afferent and efferent
• efferent=somatic and autonomic

then

• autonomic=sympathetic and parasympathetic

Question 22

affarent vs efferent? (sensory or motor, carries impulses to and from where)

Answer 22

afferent:
- sensory
- carries impulses from sensory receptors to CNS
- can be from skin, skeletal muscles, joints, etc

efferent:
- motor
- carries impulses from CNS to effectors
- has 2 subdivisions

Question 23

somatic vs autonomic (where do the nerve fibers carry impulses to and from)

Answer 23

somatic:
- voluntary
- motor nerve fibers that carry impulses from CNS to skeletal muscles

autonomic:
- involuntary
- motor nerve fibers that carry impulses from CNS to smooth muscles, cardiac muscles, and glands
- has 2 functional subdivisions

Question 24

sympathetic vs paRasympathetic

Answer 24

sympathetic:
- mobilizes body during activity
- fight or flight
- think E!! exercise, excitement, emergency, embarrassment

paRasympathetic:
- promotes maintenance and conserves energy
- resting and digesting
- think D!! digestion, defecation, diuresis

Question 25

what are the names and numbers of the 12 cranial nerves, including basic functions

Answer 25

1. olfactory nerve - detecting chemicals in the air 2. optic nerve - detecting light 3. oculomotor nerve - constricting pupils 4. trochlear nerve - moving eyes down and to the side 5. trigeminal nerve - experiencing a toothache 6. abducens nerve - moving eyes side to side 7. facial nerve - scrunching the face 8. vestibulocochlear nerve - listening to music 9. glossopharyngeal nerve - sensing blood pressure 10. vagus nerve - slowing heart and increasing GI activity 11. accessory nerve - shrugging shoulders 12. hypoglossal nerve - sticking tongue out

Question 26

structure of a nerve?

Answer 26

each axon is myelinated by schwann cells and covered by a layer of endoneurium, creating a nerve fibre. nerve fibers are grouped together and covered by a CT layer of perineurium, creating a fasicle. fasicles are grouped together and covered by an outer layer of epineurium, creating a nerve.

Question 27

compare and contrast spinal and cranial nerves

Answer 27

cranial: - 12 pairs - arise from brain or brainstem - can be sensory, motor, or mixed nerves spinal: - 31 pairs - arise from spinal cord - mixed nerves

Question 28

compare and contrast the autonomic motor division of PNS and somatic motor division of the PNS

Answer 28

autonomic: - effectors=cardiac and smooth muscle, glands - light or no myelination - neurotransmitters not always excitatory somatic: - effectors=skeletal muscle - axons are heavily myelinated - neurotransmitters always excitatory

Question 29

compare and contrast the sympathetic and parasympathetic divisions of the autonomic nervous system (what NT do they have, how are the effects?)

Answer 29

sympathetic: - fight or flight function - ACh and NE neurotransmitters - widespread and long lasting effects parasympathetic: - rest and digest function - ACh neurotransmitters - localized and short-lasting effects