Week 6 Flashcards
what are afferent and efferent nerves?
afferent- carries signals towards the CNS (sensory)
efferent- carries signals away from the CNS (motor)
what are the functions of somatic and autonomic branches of the nervous system?
both efferent nerves
somatic- voluntary, skeletal muscle movement
autonomic- involuntary, reflexes, heart rate, digestion, smooth muscles (parasympathetic/sympathethic)
what is the general role of the glial cells and what are the different types found in the CNS and PNS?
glial cells support functions
CNS
- astrocytes (links capillaries to neutrons, controls chemical environment)
- microglia (dispose dead cells and bacteria)
- ependymal cells (protect spinal cord and brain cavities)
- oligodendrocytes (myelin around multiple axons)
PNS
- Schwann cells (myelin around one axon segment)
- satellite cells (cushioning)
describe the anatomy of a neutron and its parts
cell body- contains nucleus/mitochondria
dendrites- branch off cell body, receives/transmits signals)
axons- transmits info
myelin sheath- enhance impulse rate (Schwann cells, nodes of ranvier/oligodendrocytes)
white matter- axons with myelin sheath
grey matter- nerve fibres without myelin sheath
axon terminals- connect other neurons/muscles, contain neurotransmitters to convey information
how is an action potential/nerve impulse generated?
at rest- inside of neuron is polarised (negative) due to K+ ions inside and Na+ ions outside
depolarisation- stimulus (light, touch, pain) opens sodium channels, causing inflow (inside becomes more positive)
action potential- wave through neuron
depolarisation- K+ diffuse out, restoring polarised state
refractory period- neuron is temporarily fatigued, cannot respond to another stimulus
describe the anatomy of unipolar, bipolar, and multipolar neurons
unipolar- one axon, cell body branches off axon
bipolar- one axon, one dendrite(straight line)
multipolar- one axon, multiple dendrites
what are the factors that influence the speed of neural impulse transmission?
myelin sheath presence
- myelinated axons have a faster impulse
- impulse jumps at nodes of Ranvier (faster)
axon diameter
- larger diameter means faster impulse conduction, more ions conduct current
body temp
- warmer temp accelerates ion diffusion
how are impulses transmitted across the synapse?
- electrical energy -> chemical energy
- between neuron-neuron or neuron-muscle
- impulse reaches axon terminal, depolarisation occurs
- calcium gates are opened, ions diffuse in
- vesicles with neurotransmitters open and merge with presynaptic membrane
- neurotransmitters diffuse into synaptic cleft and bind to receptors on receiving cell (inhibits/excites receiving cell)
- neurotransmitters removed by enzymes to prevent ongoing stimulation
what are the two types of reflexes and how do each work?
somatic reflexes- stimulation of skeletal muscles, rapid response (hot surface etc)
autonomic reflexes- involuntary stimuli to cardiac and smooth muscles, regulation (digestion, blood pressure)
lobes of brain and functions
divided into left and right hemispheres
frontal lobes
- skeletal muscle motor cortex (muscle control)
- involved in speech and intellect
parietal lobes (mid)
- somatic sensory cortex
- neural input (fingertips, lips)
occipital lobes (back)
- vision
temporal lobes (sides)
- speech
- hearing
- vision
- memory
- emotion
what are gyri and sulci in the cerebrum?
gyrus- raised bumps on brain surface
sulcus- grooved part, deep fissures that further divide the brain
how is grey matter and white matter orientated in the cerebrum?
non-myelinated grey matter on the surface, white matter on the inside
describe the location, structures, and functions of the diencephalon
inside cerebral hemispheres
thalamus
- relays sensory and motor information
- regulates sleep/wakefulness
hypothalamus
- controls metabolism
- heart rate
- temperature
- sex
- hunger
- pain centres
epithalamus
- regulates sleep cycle hormones (pineal gland)
what are the structures, and functions of the brainstem?
midbrain
- relays vision
- hearing
- motor info
pons
- regulates breathing
medulla oblongata
- regulates heart rate, blood pressure
- controls reflexes (coughing, vomitting)
what is the role of the cerebellum?
back bottom of brain
- coordinates body movements
- balance
- receives info from eyes, ears, sensory receptors around body
what membranes comprise meninges and their purposes?
3 protective layers:
dura mater
- outermost membrane under the skull
- tough
arachnoid mater
- under dura mater
- web-like
pia mater
- innermost layer
- delicate
how are capillaries in the brain different and what is the significance of this?
impermeable to many substances (to protect against fluctuations in hormones and ions) but permeable to essential substances like water, glucose, amino acids, also alcohol and nicotine
what is the location, functions, and structure of the spinal cord?
extends from brainstem to start of lumbar spine
functions:
- pathway for sensory and motor impulses
- encased by meninges and cerebrospinal fluid
structure:
- exterior: myelinated white matter
- core: grey matter (neuron cell bodies and interneurons)
describe the structure of a nerve
axons and blood vessels bundled in protective sheaths
3 layers:
endoneurium- encases one axon
perineurium- encases many endoneuriums
epineurium- encases a few perineuriums
explain the organisation of the spinal nerves
- 31 pairs
- mixed (sensory+motor)
- 4 main plexuses (splits): cervical, brachial, lumbar, sacral
explain the organisation of the cranial nerves
- 12 pairs
- communicates between left/right hemispheres
- either afferent, efferent, or mixed
- most originate in brainstem
describe the location, structure, and function of ganglions
- found in PNS
- clusters of neuron cell bodies
autonomic ganglia
- preganglionic neuron starts in CNS and synapses with one or more postganglionic neuron that connect with target organ
sensory ganglia
- send information to CNS
- no synapsing here
what are the differences between the sympathetic and parasympathetic nervous systems?
part of the autonomic nervous system
sympathetic
- flight or fight
- preparation for stress
- increases heart rate, dilates pupils
parasympathetic
- rest and digest
- conserves energy
- returns balance
- stimulates digestion
