Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 373 Human Physiology 2 > Unit 2 > Flashcards

Unit 2 Flashcards

1
Q

how did the vertebrate central nervous system develop

A

-neural plate bends
- is joined together at the neural fold
- epidermis forms on top
- neural crest cells migrate through body to form peripheral nervous system
- neural tube is formed which is the precursor of the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

development of the human CNS

A

4 weeks:
- anterior end of neural tube specialized into three regions (forebrain, midbrain, hindbrain)
6 weeks:
- neural tube differentiated into major brain regions present at birth (Medulla oblongata, Cerebellum and Pons, midbrain, Diencephalon, Cerebrum
11 weeks:
- growth of cerebrum much more rapid than that of other regions
Birth:
- cerebrum covers most of other brain regions; convoluted surface due to rapid growth in confined space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how is the CNS protected and supported

A
  • surrounded by bony cage – cranium, vertebrae
  • three layers of connective tissue - meninges
  • fluid between layers – cerebrospinal fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the 3 meninges

A
  1. dura mater
  2. arachnoid mater
  3. pia mater
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the fluid filled ventricles in the brain

A
  • ventricles within brain, hollow central canal within spinal cord
  • two lateral ventricles, two descending ventricles that extend through in brain stem
  • CSF in ventricles continuous with fluid in central canal of spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is choroid plexus

A

where CSF is created in each ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are ependymal cells

A

cells that line the choroid plexus and determine the composition of CSF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is interstitial fluid

A

surrounds neurons and glial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is plasma

A

within cerebral blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is CSF

A
  • within ventricular system
  • bathes external surfaces of brain, between meninges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

compared to plasma, CSF has

A
  • lower K+, Ca2+, HCO3- , glucose, pH similar Na+
  • very low protein, no blood cells
  • increase presence of blood cells or elevated protein in CSF collected via lumbar puncture (sampling of fluid from subarachnoid space between vertebrae) suggests infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how much CSF is removed daily

A
  • removed and replaced about 4 times daily
  • produce about 500ml of CSF daily
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how is CSF removed

A
  • flows through arachnoid villi back into venous blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

circulation of CSF

A

lateral ventricles <–> Third ventricle <–> fourth ventricle –> subarachnoid space –> arachnoid villi –> superior sagittal sinus –> venous return to heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

special features of cerebral vasculature

A
  • very tight junctions
  • not many things get through
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

blood brain barrier

A
  • lipid soluble molecules cross readily
  • hydrophilic substances (ions, amino acids, peptides) will only cross if specific transporters / carriers are present on endothelial cells of capillaries within CNS
  • considerations for drugs that are and are not wanted to reach the
    CNS:
    – antihistamines
    – treating diseases of the CNS
17
Q

metabolic needs of neural tissue

A
  1. oxygen requirement:
    - neurons are ‘obligate aerobes’
    – unable to switch to anaerobic metabolism
    – O2 readily crosses blood-brain barrier
  2. glucose requirement:
    - capillaries of CNS express high levels of glucose transporters to provide adequate levels of glucose
    - brain responsible for approximately half of body’s glucose consumption
    vasculature to deliver oxygen and glucose:
    - approximately 15% of cardiac output received by brain
    – critically dependent on adequate O2, glucose (and therefore blood flow)
    - hypoglycemia = confusion, loss of consciousness, death
18
Q

spinal cord

A
  • major path for information flow between CNS and skin, joints, muscles
  • contains neural networks involved in locomotion
  • divided into four regions (cervical, thoracic, lumbar, sacral), each of which is divided into segments
  • each segment gives rise to pair of spinal nerveswh
19
Q

what are the ascending tracts for

A
  • dorsal columns : touch/pressure, proprioception
  • spinocerebellar: proprioception (posture, coordination)
  • spinothalamic: pain, temp
20
Q

what are the descending tracts for

A
  • corticospinal tracts: voluntary movement
21
Q

brainstem

A
  • oldest and most primitive part of brain
  • contains structures derived from
    embryonic hind and midbrain
  • organized much like spinal cord
  • most (10 of 12) cranial nerves
    originate from here
  • carry sensory and motor info for
    head/neck
  • cranial nerve X = vagus
  • contains nuclei associated with reticular formation
  • diffuse network of neurons involves
    in processes such as arousal/sleep, muscle tone, coordination of breathing, blood pressure, et al
22
Q

functions of brain stem structures

A
  1. midbrain:
    - coordination of eye movement, visual and auditory reflexes
  2. pons:
    - relay station between cerebrum and cerebellum
    – works with medulla to regulate breathing
  3. medulla:
    - gray matter involved in control of many involuntary functions – blood
    pressure, breathing, swallowing, vomiting
    – white matter – ascending somatosensory tracts, descending corticospinal tracts
    – site of decussation (crossing over) for most neurons in corticospinal tract
23
Q

diencephelon

A
  • between brain stem and cerebrum
    1. thalamus:
  • relays and integrates sensory info from lower parts of CNS, ears, eyes, motor info from cerebellum
    2. hypothalamus:
  • tiny region of brain yet major centre for homeostasis
  • contains centres that drive behaviour related to hunger, satiety, thirst
  • influences autonomic responses, endocrine systems
    3. pituitary gland:
  • regulated by hypothalamus (more later in course)
    4. pineal gland:
  • secretes hormone melatonin - involved in circadian and seasonal rhythms
24
Q

Cerebrum

A
  • site of ‘higher’ brain functions
    – largest and most distinctive part of brain in higher primates
  • each cerebral hemisphere divided into four lobes: frontal, occipital, parietal, temporal
  • furrow or groove = sulcus (pl sulci)
  • convolution = gyrus
25
Q

organization of cerebrum

A
  • three regions of cerebral gray matter:
    1. ‘basal ganglia’ (more correctly - basal nuclei)
  • coordination of movement
    2. limbic system
  • linking emotion/fear with higher cognitive functions
    3. cerebral cortex
26
Q

functional areas of cerebral cortex

A
  1. Sensory areas:
    – sensory input translated into perception (awareness)
  2. Motor areas:
    – control skeletal muscles
  3. Association areas:
    – integrate information from sensory and motor areas
27
Q

Primary Motor and Somatosensory contexes

A
  1. primary motor cortex
    – on ridge just anterior to central sulcus
    - aka precentral gyrus
    – cell bodies of descending ‘upper’ or ‘first order’ motor neurons
  2. primary somatosensory cortex
    – on ridges just posterior to central sulcus
    - aka postcentral gyrus
    – terminals of ascending sensory pathways from skin,
    musculoskeletal system, viscera
    - information about touch/pressure, pain, temperature, body
    position
  3. ‘special senses’ have devoted regions
    – visual cortex, auditory cortex, olfactory cortex, gustatory cortex
  4. neural pathways extend from sensory areas to association areas, which integrate stimuli into perception
28
Q

usually conscious stimulus processing

A
  • touch
  • temperature
  • pain
  • itch
  • proprioception
29
Q

usually unconscious stimulus processing

A
  • blood pressure
  • distension of gastrointestinal tract
  • blood glucose concentration
  • internal body temperature
  • osmolarity of body fluids
  • lung inflation
  • pH of cerebrospinal fluid
  • pH and oxygen content of blood
30
Q

sensory pathway

A

Stimulus – (acts on receptor) –> receptor transduces stimulus into intracellular signal (typically Δ in membrane potential, MP) – (if Δ in MP reaches threshold) –> action potentials (APs) travel along afferent neuron – (decoding: frequency of APs, pattern, travelling on which fibre) –> information reaches subcortical integrating / relay centres
(e.g. thalamus, medulla, …) – (subconscious processing) –> information reaches appropriate regions in cortex – (conscious processing)

31
Q

types of receptors

A
  • Chemoreceptors
  • mechanoreceptors
  • photoreceptors
  • thermoreceptors
32
Q

how does signal transduction get turned into a graded potential

A
  • each sensory receptor has an adequate stimulus (type of energy to which it responds best)
    – thermoreceptors- respond best to increase in temp (vs pressure)
    – mechanoreceptors- deformations of membrane that open ion channels
    – photoreceptors of eye- light
  • stimulus opens or closes ion channels in receptor cell membrane
  • directly or via second messenger systems
  • mostly: open cation channels –> influx of Na or Ca –> depolarization
    sometimes: efflux of K –> hyperpolarization
  • Δ in membrane potential (graded potential) = receptor potential
33
Q

what are receptive fields

A
  • somatosensory neurons and visual neurons are activated by stimuli that fall within a certain physical area
    – cutaneous receptors – patch of skin
    – photoreceptors – light falling on area of retina
  • at least two afferent neurons in pathway to brain:
    – first order (primary) sensory neuron
  • directly associated with stimuli

– second order (secondary) neuron
- relays information from first neuron

  • receptive field often defined by neurons further up the pathway
    – sensory input can then be gathered from more than one primary sensory neuron
34
Q

overlapping of primary sensory neurons

A
  • several primary neurons converge onto a secondary neuron
  • convergence allows summation of multiple stimuli
  • creates larger receptive fields
35
Q

convergence of sensory receptors

A
  • The receptive fields of three primary sensory neurons overlap to form one large secondary receptive field
  • Convergence of primary neurons allows simultaneous subthreshold stimuli to sum at the secondary sensory neuron and initiate AP
  • two stimuli fall within same secondary receptive field –> only one signal goes to brain –> perceived as a single point
  • no two point discrimination
36
Q

smaller receptive fields

A
  • The two stimuli activate separate pathways to the brain
  • The two points are perceived as distinct stimuli
  • two point discrimination
37
Q

sensory pathway to CNS

A
  • somatic senses, hearing, vision, taste: to appropriate cortex after processing in thalamus
  • olfactory: direct to brain (olfactory bulb –> olfactory cortex)
  • equilibrium: mostly to cerebellum, minor input to thalamus
  • What about visceral sensory information?
  • mostly integrated in brain stem and spinal cord
  • does not usually reach conscious perception
  • completely subconscious –> blood pressure
  • can reach consciousness –> ‘fullness’ (pressure), pain
38
Q

what happens to stimuli

A
  • all stimuli converted to graded potentials –> APs
  • all APs are identical
39
Q

So how are different sensations distinguished?

A
  • CNS must be able to decode:
    – type of stimulus –> modality
    – location
    – intensity
    – duration

BIOL 373 Human Physiology 2 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions