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Primary Physiology > Physiology Of The Nervous System > Flashcards

Physiology Of The Nervous System Flashcards

1
Q

Types of nervous system cell and function

A

Neurone - action potential generation and transmission
Astrocytes - support neurones and form bbb
Oligodendrocytes - insulate CNS neurones
Microglial cells - immune CNS response
Ependymal cells - line ventricles and spinal cord
Schwann cells - insulate PNS

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2
Q

Term for myelinated conduction down an axon?

A

Saltatory

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3
Q

Types of nerve fibre with example in order of decreasing size (with rough size)

A

Aalpha - proprioception and somatic motor - 12-20mm
Abeta - touch, pressure - 2-12mm
Agamma - muscle spindle 3-6mm
Adelta- pain, touch, temperature 2-5Mm
B - preganglionic ANS <3mm
C dorsal root - pain, temp, mechanoreceptors, reflex 0.4-1.2mm
C sympathetic - postganglionic ANS 0.3-1.3mm

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4
Q

Conduction speed of A type fibres

A

A alpha 70-120m/s
A beta 30-70m/s
A gamma 15-30m/s
A delta 12-30m/s

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5
Q

Speed of conduction in b and c type fibres

A

B 3-15m/s
C 0.5-2m/s (approx)

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6
Q

How is the neurone resting membrane potential set up?

A

NaKATPase 3:2 ratio
Both na and K diffuse back down their concentration gradient but membrane more permeable to K
Membrane impermiable to anions
Overall results in interior being more negative at -70mV

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7
Q

Term for the gaps in the myelin sheath

A

Nodes of Ranvier

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8
Q

What is the definition of ion conductance in relation to APs

A

The reciprocal of elctrical resistance of the membrane to a specific ion.

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9
Q

Key phases of a neuronal action potential

A

Slow rise to threshold
Spike potential - triggered by marked increase in Na permeability
After depolarisation
After hyperpolarisation

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10
Q

What limits the action potential depolarisation process

A

Na channels open only very transiently
Inside of cell becomes increasingly electropositive thus gradient that drives na influx disappears
K conductance also increases causing repolarisation

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11
Q

What is the after hyperpolarisation of an action potential

A

Slight but prolonged overshoot on repolarisation
Caused by slow return of k conductance to normal

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12
Q

What are the refractory periods of a neurone

A

Absolute refractory period - totally unresponsive to any stimuli regardless of strength - from time threshold is reached until repolarisation 1/3rd complete
Relative refractory period - period where stronger than normal stimuli may lead to excitation - from 1/3rd of repolarisation until start of after hyperpolarisation

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13
Q

What forms a synapse? Number per synapse?

A

Terminal buttons of a neurone (1-1000s) with cell body or axon of another neurone

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14
Q

What is the role of a synapse

A

UNIDIRECTIONAL impulse conduciton

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15
Q

What is an electrical synapse?

A

The synapse consists of the membranes meeting to form gap junctions allowing continued diffusion of ions

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16
Q

Width of a typical synaptic cleft

A

20nm

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17
Q

What are the three key organelles found in the synaptic button

A

Vesicles
ER
Mitochondira

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18
Q

Mechanism of synapse neurotransmitter release
Determining factor for amount released

A

Action potential reaches synaptic button.
Opening of voltage gated calcium channels - influx of calcium.
Proteins in vesicles bind to the calcium and spread apart allowing fusion with terminal membrane
Contents of vesicles released into cleft

Amount determined by calcium concentration

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19
Q

Why are post synaptic potentials transient

A

Reuptake of neuro transmitter
Enzymatic deactivation of neurotransmitter
Auto receptors on presynaptic membrane inhibit continued neurotransmitter release

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20
Q

What categories of effects can be mediated by neurotransmission

A

Excitatory (EPSP) eg opening of na channels causing depolarisation
Inhibitory (IPSP) eg opening of Cl or K channels causing hyperpolarisation

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21
Q

What are the main CNS neurotransmitters?

A

ACh
NA
A
Dopamine
Serotonin

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22
Q

Location and function of ACh neurotransmitter in CNS

A

Cerebral cortex, thalamus, limbic - memory, perception, cognition, attention

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23
Q

Location and function of NA neurotransmitter in CNS

A

Locus coeruleus, cerebellum, hypothalamus - decending pain, inhibition of purkinje cells, regulation of anterior pituitary secretion

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24
Q

Location and function of adrenaline neurotransmitter in CNS

A

Medulla - uncertain

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25
Q

Location and function of dopamine neurotransmitter in CNS

A

Substantia nigra, hypothalamus - control of motor functions, regulation of prolactin secretion

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26
Q

Location and function of serotonin neurotransmitter in CNS

A

Neocortex, limbic system, hypothalamus, nucleus and phase Magnus, spinal cord

Mood and behaviour, increase prolactin secretion, pain modulation

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27
Q

What is a sensory receptor

A

A transducer that converts a stimuli eg mechanical or thermal energy into an electrical stimuli
Can be part of a neurone or separate structure that is capable of generating and transmitting action potentials to the neurone
Can be either visceral or somatic

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28
Q

What is the distinction between visceral and somatic sensory receptors

A

Visceral perceive changes to internal environment are are not usually consciously perceived e.g. chemoreceptors
Somatic receptors respond to external stimuli such as temperature or touch, usually consciously perceived

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29
Q

Route of pain perception to brain

A

Nerve ending
A and C fibres
Dorsal root ganglion
Dorsal horn
Spinothalamic tract
Ventral and medial nuclei of thalamus
Somatosensory cortex

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30
Q

Layers of the dura mater

A

Inner cerebral layer covering brain and spine,
Outer endosteal which merges with periosteum of skin at foramen magnum (only in head, no endosteal layer in spine, just vertebra periosteum)

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31
Q

Where does the dural sac end in adults?
How is it attached down the spine

A

Ends around S2
Attached to the edge of the vertebral canal except posteriorly where it is free

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32
Q

Areas of the frontal lobe

A

Precentral area - with anterior (pre motor) and posterior (primary motor) regions
Prefrontal cortex - with superior, middle and inferior frontal gryi

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33
Q

Where is Broca’s area

A

Inferior frontal gyrus of dominant hemisphere

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34
Q

Functions of frontal lobe

A

Personality
Initiative
Judgement
Insight
Control of emotions
Contra lateral motor function

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35
Q

Regions within the temporal lobe and function

A

Primary and secondary auditory areas - hearing (primary locates source of sound, secondary interprets sounds)
Wernickes area in dominant hemisphere - speech comprehension

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36
Q

Areas and functions of the parietal lobe

A

Postcentral gyrus - primary sensory - judgement of shape and form, pressure and weight, position sense, localisation of stimuli
Sylvian fissure - secondary sensory - relating sensory information to past experience and interpreting it

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37
Q

Areas and functions of the occipital lobe

A

Primary visual area

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38
Q

What determins level of consiousness?

A

Activities of cerebral cortex and the reticular activating system

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39
Q

What is the reticular activating system
Inputs and outputs

A

A network of neurones in the brain stem reticular formation
Receives sensory input from ascending tracts and head senses (eyes, hearing, taste, trigeminal Sensation)
Projects to the cerebral cortex directly and via thalamus

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40
Q

Types of EEG rhythm with frequency

A

Alpha - 8-12Hz, usually occipital in adult human at rest with eyes closed
Beta - 18-30Hz, frontal region of alert adult
Omaga - 4-7Hz, large amplitude usually very old or very young
Delta - <4Hz

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41
Q

Basic sleep patterns and EEG findings

A

NREM - four stages (from 1-4 light to deep) with progressive slowing of EEG and increased amplitude of waves
REM - nrem pattern replaced with fast low voltage activity similar to alert individual

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42
Q

What are the roles of wernickes and broccas areas? Pathology results in…
How do they communicate

A

Wernickes - comprehension of audible and visual information - receptive dysphasia
Communicate via arcuate fascicules
Broccas - output of speech and coordination of vocal aparatus - expressive dysphasia

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43
Q

Main types of memory and regions involved

A

Explicit memory - conscious retrieval and awareness, either episodic (memory of events) or semantic (memory of words, rules, languages etc). Involves hippocampus and medial temporal lobes

Implicit memory - does not require conscious awareness, eg skills for day to day activities and habits e.g driving once a routine task (not learning). Does not involve hippocampus

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44
Q

Where is short term explicit memory processed

A

Hippocampus

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45
Q

Functions of the basal ganglia

A

Movement control and posture control

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46
Q

Which side of the body does the left cerebellar hemisphere control

A

Left! Ipsolateral not controlateral

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47
Q

Functions of cerebellum

A

Gait and balance

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48
Q

Which cranial nerves have the nuclei outside of the brain stem

A

I and II

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49
Q

Contents of the brain stem

A

Nuclei of cranial nerves III - XII
RAS
Ascending and decending tracts
Centres for respiratory, cardiovascular and gastrointestinal function
Centres for eye movement, balance and equilibrium

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50
Q

What are the metabolic requirements of the brain %
Cerebral blood flow

A

20% basal oxygen
25% basal glucose
700ml/min cerebral blood flow (around 14%)

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51
Q

Where in the brain receives most blood flow

A

Grey matter receives around 5x that of white matter

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52
Q

What is cerebral perfusion pressure e

A

CPP = MAP - ICP - Venous pressure

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53
Q

What factors control cerebral blood flow

A

Pressure auto regulation
Flow metabolism coupling
PaO2
PaCO2

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54
Q

What does the brain closely regulate to maintain constant oxygen and nutrient delivery
How?
In what range of CPP is It maintained

A

Cerebral blood flow
When CPP varies vascular resistance altered to maintain blood flow.
Between around 50-150mmHg

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55
Q

What is pressure auto regulation of cerebral blood flow?

A

As MAP increases cerebral vasculature constricts and viva versa

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56
Q

What is the effect of chronic hypertension on cerebral pressure auto regulation

A

Shifts curve to right (maintains in higher range)

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57
Q

What is the effect of voletile anaesthetics on cerebral auto regulation

A

Dose dependant vasodilation of cerebral vessels impairing auto regulation.

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58
Q

What is flow metabolism coupling in cerebral auto regulation

A

Increase in cerebral metabolic rate (e.g. seizure, fever)
Mediator release such as ach, no, substance p, serotonin (all possibly)
Cause increase in cerebral blood flow.

Opposite effect with decreased metabolic rate eg anaesthetics!

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59
Q

Effect of carbon dioxide on cerebral blood flow

A

Cerebral vasodilation increasing flow
In physiological range roughly linear
Outside normal range 1kpa increase in pCO2 increases cbf by 30%
No further effect above 10kpa or beneath 2.5kpa as max dilation/restriction reached

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60
Q

Why does co2 increase cerebral blood flow

A

Increased h+
As ph compensated for with time then cerebral blood flow returns to normal

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61
Q

Effect of oxygen on cerebral blood flow

A

Little change in physiological range but when PaO2 <6.7 or 92% then there is some vasodilation

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62
Q

What are the effects of the ans on cerebral blood flow

A

Mainly on larger vessels
B1 vasodilates
A2 vasoconstriction
Significant vasoconstriction can occur at very high concentrations of catecholamines.

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63
Q

Spinal cord end point at birth and adult hood

A

Birth lower border of l3
Adult l1/2 gap

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64
Q

Where is the spinal cord enlarged in diameter, why

A

Cervical and lumbar corresponding to brachial and lumbosacral plexuses

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65
Q

Spaces and potential spaces around the spinal cord

A

Subarachnoid space
Subdural space - potential
Extradural space

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66
Q

What traverses the subarachnoid space in the spine

A

3 incomplete trabeculae , 1 posterior subarachnoid septum and bilateral ligamentum denticulatum

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67
Q

What are the boundaries of extramural space around the spine

A

Between dura and spinal canal extending from foramen magnum ending at sacral hiatus

68
Q

Contents of extradural space around spine

A

Lymphatics, fat, vasculature,
Includes vein outs plexus of Bateson communicating between pelvic and cerebral veins

69
Q

What are the coverings of spinal nerves

A

Emerge from cord covered in pia and arachnoid mater, pierce the dura which then fuses with them forming the epineurium

70
Q

What are the gaps in the shape of the spinal cord in cross section

A

Anterior median fissure
Posterior median sulcus

71
Q

Where is csf located in the spine

A

In the sa space
In the central canal

72
Q

What neurones make up most decending tracts

A

First order neurones from cerebral cortex
Synapse with second order neurones in anterior grey column of spinal cord
Second order neurone synapse with third order neurone (lower motor neurone) again in the anterior grey column of the spinal cord.
Third order neurone heads peripherally through the anterior root of the spinal nerves innervating skeletal muscle

73
Q

What are the key descending tracts of the spinal cord? Brief function

A

Corticospinal - skeletal motor
Reticulospinal - alpha and gamma motor neurones
Tectospinal - reflex postural movements due to vision
Rubrospinal - posture and balance activating flexor and inhibiting extensor action
Vestibulospinal - posture and balance activating extensor and inhibiting flexor action
Olivospinal
Descending autonomic fibres

74
Q

Route of corticospinal tract
Role

A

First order - motor cortex, medulla. 80% decussate forming lateral corticospinal tract, 20% remain ipsolateral forming anterior corticospinal tract
Skeletal muscle innervation

75
Q

Neuronal structure of ascending spinal tracts

A

First order neurones posterior root ganglion - peripheral process receives sensory information from receptor, central process into spine vi posterior root and synapse with second order neurone in posterior grey column.
Second order neurone decussate and ascends to thalamus synapsing with third order neurone,
Third order neurone projects from thalamus to sensory cortex

76
Q

Key ascending spinal pathways and what they carry,

A

Spinothalamic tract - pain and temp from 1st order Adelta and C fibres,
Gracile and curate tracts - touch, vibration and proprioception
Ant and post spinocerebellar tract - muscles and joint reception
Spinotectal - pain temp and touch facilitating spinovisual reflex
Spinoreticular tract - info effecting consciousness
Spinoolivary tract

77
Q

Effect of a complete spinal cord transaction

A

Initially
All spinal reflexes depressed or absent
All muscle innervation below level paralysed
All sensation below level paralysed

Slow recovery of involuntary reflexes over several weeks but not voluntary

78
Q

What is the recovery pattern of spinal reflexes post a complete cord transection

A

Initially flexor response to touch and anogenital reflexes
Last are tendon reflexes

Reflexes initially hyperactive when initially recovered
Can have mass reflex response to minor noxious stimuli with significant blood pressure changes.

79
Q

Effect of hemisection of spinal cord

A

Ipsolateral loss of muscle power, fine touch, pressure and joint/vibration sense
Contralateral pain and temperature loss

80
Q

Where do the spinothalamic and gracile/cuneate tracts decusate

A

Spinothalamic 2nd order neurones decusate at spinal level or one above/below
Gracile/cuneate - second order neurones decusate in above the gracile/cuneate nuclei I;the medulla

81
Q

What is the basic blood supply to the spine and derivation

A

Single anterior spinal artery - union of branches from each vetebral artery, also from radicular arteries arising from deep cervical, intercostal and lumbar arteries
Two small poster spinal arteries - from posterior inferior cerebellar arteries

82
Q

What is the effect of thrombosis of the anterior spinal artery

A

Anterior spinal artery syndrome With paralysis due to ischaemia of pyramidal tracts but continued sensation due to posterior supply of posterior columns

83
Q

What connects anterior and posterior arteries of the spine

A

Vasa coronae

84
Q

What is the main derivation artery of the anterior spinal artery

A

The arteria radicularis magna

85
Q

What sort of reflex in the stretch reflex? How does it work

A

Monosynaptic
Spindle fibre stretched
Afferent conduction via 1a fibre through dorsal horn.
Synapse with efferent Aalpha motor neurone
Contraction of muscle

86
Q

Example of polysynaptic muscle reflex

A

Withdrawal reflex
Noxious stimuli sensed
Afferent sensory signal activates 2 interneurones in spine
interneurone activates one muscle and other inhibits the antagonistic muscle
Limb withdraws from stimuli

87
Q

What sort of muscle fibres do motor neurones control? What basis in the number of these fibres to number of neurones decided

A

Extrafusal fibres
Depends on how fine a action is required (ie one nerve to a finger supplies far fewer extrafusal fibres than a nerve to the thigh)

88
Q

What are intrafusal muscle fibres

A

Form muscle spindle

89
Q

Function of a muscle spindle

A

Detect muscle length

Central bag or chain of noncontractile fibres supplied by either Ia (both) or II (chain) afferents
Either end has a contractile region supplied by Agamma efferents

When muscle contracts spindle relaxes and afferent firing stops - opposite occurs on muscle relaxation or on passive stretching.

90
Q

What happens to spindle sensitivity on muscle contraction

A

Spindle contacts and also becomes more sensitive

If muscle met with resistance intrafusal fibres shorten more than extrafusal fibres stretching the centre of the spindle and causing increased motor contraction.

91
Q

What do golgi organs sense

A

Muscle tension
Detect stretch and provide inhibitory feedback to prevent muscle damage

92
Q

Main function of pre motor cortex

A

Postural adjustment at the beginning of voluntary motion

93
Q

What is the function of the supplemental motor area of the cortex

A

Planning of complex movements

94
Q

How are motor signals passed to the spinal cord

A

Directly through corticospinal tract
Indirectly via accessory pathways through cerebellum, basal ganglia and brainstem nuclei

95
Q

Three key functional parts of cerebellum and their function

A

Vestibulocerebellum - equilibrium during motion
Spinocerebellum - proprioception and coordination of motor actions
Neocerebellum - planned execution of voluntary movements esp rapid ones

96
Q

Parts of basal ganglia

A

Caudate nucleus
Putamen
Globes pallidus
Subthalmic nucleus
Substantia nigra

97
Q

Function of basal ganglia

A

Forms a loop with the cortex via the thalamus
Helps coordinate action with subconscious movements that are required to carry out the voluntary action.

98
Q

Factors involved In posture control

A

Spinal cord - stretch reflex, proprioception transmission
Brainstem - facilitation and inhibition of stretch reflex,
Midbrain - tonic reflexes controlling head and neck position
Cortex - Agamma discharge to muscle spindle with physical postural reflexes

99
Q

Where is csf produced

A

70% in choroid plexuses of ventricles

100
Q

What are choroid plexuses
Function

A

Vascular invagination of highly vascular pia mater covered by single layer of ependymal epithelium
Secretion and filtration of plasma to form csf

101
Q

How does ICP effect csf volume

A

No effect on production but increased ICP increases with increasing pressure

102
Q

What is the route of csf

A

Lateral ventricles
Foramen of monro
Third ventricle
Aqueduct of Sylvius
Fourth ventricle
Formen of megendie and luschka
Subarachnoid space
Arachnoid villi Reabsorb into venous sinus

103
Q

Why do large molecules not enter the csf

A

Tight junctions between endothelium of cerebral capiliaries

104
Q

What agents easily pass the bbb

A

Water
Co2
Oxygen
Ions
Lipid soluble molecules such as voletile anaesthetics.

105
Q

Total csf volume
Amount produced per day in typical adult

A

150ml
550ml

106
Q

Normal ICP values

A

5-15mmHg

107
Q

What is the monro Kellie doctrine
Regions discussed and %s

A

Change in volume of one intracranial compartment is accompanied by a reciprocal change in the other
Solid 10%’
Tissue Water 75%
Csf - 10%
Blood 5%

108
Q

How can high ICP cause damage

A

Direct pressure of brain tissue
Distortion and herniation of intercranial contents

109
Q

What is the effect of increasing volume of intercranial contents on ICP

A

Initially compensatory mechanisms keep in normal range then exponential increase as they fail.

110
Q

Autoregulatroy Compensatory mechanisms for increased intercranial contents volume

A

Reduction in csf volume
Reduction in cerebral blood volume
Cerebral vasoconstriction
Increased arterial pressure

111
Q

What therapeutic measures can be taken to control ICP by triggering auto regulatory changes

A

Reduction in cerebral metabolic rate (eg seizure termination, anaesthetic)
Reduced pCO2
Avoidance of low PaO2
Avoid raised JVP

112
Q

What can cause realised jvp

A

Jv obstruction
Increased interthoracic pressures
Raised cvp
Head down position

113
Q

Outer layer of the eye

A

Sclera with transparent cornea

114
Q

Pathway of aqueous humour

A

Produced by ciliary processes catalysed by the action of carbonic anhydrase
Passes from posterior chamber to anterior chamber via the pupil
Drains through canal of schlemm into venous syste:

115
Q

Which muscles cause what pupillary changes

A

Iris muscles
Constriction of circular muscles cause constriction
Constriction of radial fibres cause dilation

116
Q

Terms for pupillary constriction and dilatation

A

Constriction - miosis
Dilatation - mydriasis

117
Q

Which muscle controls lens accomodation

A

Ciliary muscle via suspensory ligaments

118
Q

What is the blood supply to the photoreceptive cells of the eye

A

From the choroid, not the vessels on the retina surface

119
Q

What pigments are contained in rods and cones
Where are cones concentrated

A

Rods - rhodopsin
Cones - red green and blue sensitive opsins
Cones are located at the fovea

120
Q

Visual pathway up to point of optic nerve

A

Light stimulates photoreceptors causing electrical potential
Transmitted to ganglion cells via bipolar/horizontal and amicrine cells
Axons from ganglia converge forming optic nerve

121
Q

Visual pathway from optic nerve onwards

A

Nasal retina axons (temporal vision) deccusate at optic chiasm
Temporal retina axons (nasal vision) continue ipsilatral
Follow optic tract back to lateral geniculate body where they synapse
Axons follow optic radiations back to primary visual cortex

122
Q

Effect on vision of a lesion to the optic nerve

A

Loss of vision in one eye

123
Q

Effect on vision of a lesion to the optic chiasm

A

Bitemporal hemianopia (damage to decussating fibres only)

124
Q

Effect on vision of a lesion to the optic radiation

A

Homonymous hemianopia (effecting opposite side of vision to side of lesion)

125
Q

Structure of the cochlear

A

Coiled tube divided into three canals lengthways - scala vestibuli, scala media and scala tympani separated by the reissners and basilar membranes.

126
Q

What do the oval and the round window of the middle ear connect to

A

Oval window to stapes
Round window to scala tympani of cochlea

127
Q

What fills the canals of the cochlea

A

Scala media filled with endolymph
Scala tympani and vestibuli with perilymph

128
Q

Where are sound receptors located in the inner ear

A

Organs of corti located on basilar membrane in scala media

129
Q

Mechanism of hearing

A

Sound wave vibrates tympanic membrane
Ossicles vibrate vibrating oval window
Pressure waves in scala vestibuli displace endolymph and then tectorial membrane displaced with respect to basilar membrane
Hair cells in organ of corti stimulated triggering a depolarisation And AP
Transmitted via ganglion cells to cochlear nerve
Cochlear nerve to cochlear nucleus in brainstem
Second order neurones transmit to Contralateral inferior colliculus
Then to the medial geniculate body
Then to primary auditory complex in temporal lobe

130
Q

Where are most taste buds

A

Papillae at back of tongue

131
Q

How long is the t1/2 of taste cells

A

2 weeks

132
Q

Four taste modalities

A

Sweet sour salt bitter

133
Q

Innervation of taste buds

A

Chorda tympani (anterior 2/3) - branch of facial nerve
Glossopharyngeal (posterior 1/3)
Greater petrosal (soft palate) - branch of facial

134
Q

Where do the nerves supplying taste buds run too

A

Tractus solitarious in medulla then thalamus and cortex

135
Q

What is special about olfactory cells

A

Only neuronal cells in body to robe replaced continually by division of underlying basal cells

136
Q

Pathway of smell

A

Odoriferous compounds dissolve in mucus
Chemical interaction with chemoreceptors on olfactory cells cilia
Action potential spreads through neurone passing through cribiform plate to olfactory bulb.
Second order neurone project to olfactory cortex and also thalamus and limbic system

137
Q

Definition of autonomic nervous system

A

The part of the nervous system that provides neurological control over the cviceral activities of the body. It is involuntary and allows the body to adjust to varying demands.

138
Q

Where does the SNS arise
Route of nerves (general)
Exceptions?

A

Arise T1-L2 - the thoracolumbar outflow
Synapse in the paired sympathetic chain ganglia either side of vertebral column then postganglionic fibres to organs.
Some preganglionic fibres run straight through the sympathetic chain ganglia to ganglia close to effector site such as the coeliac and mesenteric ganglia or adrenal medulla (which is unique in having no postganglionic fibres)

139
Q

Which nerves contribute to PNS outflow?

A

CN III, VII, IX, X
S2,3,4

140
Q

What percentage of total PNS outflow is accounted for by the two vagus nerves

A

75%

141
Q

Location of parasympathetic ganglia

A

In the effector organs thus short postganglionic neurones

142
Q

Neurotransmitters for ANS preganglionic fibres

A

Ach

143
Q

Neurotransmitters for PNS postganglionic neurones

A

Ach
Rarely vasoactive intestinal polypeptide

144
Q

Neurotransmitter for postganglionic SNS neurones

A

Noradrenaline
Except sweat glands, piloerector muscles and some blood vessels (those supplying skeletal muscle) that use ach

145
Q

Release from adrenal medulla on stimulation by sns with percentages

A

Adrenaline 80%
Noradrenaline 20%

146
Q

Main receptors activated by noradrenaline

A

Alpha

147
Q

Main receptors activated by adrenaline

A

Alpha and beta

148
Q

Type of ach receptor in ans ganglia

A

Nicotinic

149
Q

Type of ach receptor at PNS effector site (postganglionic PNS synapse)

A

Muscurinic

150
Q

Types of muscurinic ach receptor and locations

A

M1 - CNS
M2 - heart
M3 - exocrine glands and vascular endothelium

151
Q

What is a nicotinic ach receptor (receptor type)

A

Ligand gated ion channel

152
Q

What is a muscurinic ach receptor type

A

G protein linked

153
Q

Type of ach receptor at skeletal muscle

A

Nicotinic

154
Q

Alpha 1 receptors found at

A

Blood vessels supplying salivary glands, skin, mucus membranes, kidneys, abdominal vicera, radial muscles of iris, urinary bladder sphincter
Salivary glands
Sweat glands in palms and soles

155
Q

Alpha 2 receptors found at

A

Smooth mucslce of some blood vessels
Pancreatic islets for insulin (beta cells)
Pancreatic acinar cells

156
Q

Beta one receptors found at

A

Cardiac muscle
Juxtaglomerular cells in kidneys
Posterior pituitary
Adipose tissue

157
Q

Beta 2 receptors found at

A

Airways
Ciliary muscles of eye
Hepatocytes of liver

158
Q

Beta 3 recptors found at

A

Brown adipose tissue

159
Q

Components of limbic system
Functions

A

Hypothalamus - endocrine function, homeostasis
Amygdala - behavioural response to stimuli
Hippocampus - memory

All - behavioural, emotion

160
Q

How does the hypothalamus contribute to temp homeostasis

A

Recieves afferent input of temp data from peripheral receptors and from receptors in anterior hypothalamus
Initiates physiological response to temp eg shivering, vasoconstriction and also behavioural changes eg extra clothes

161
Q

How does the hypothalamus control anterior pituitary

A

Secretion from nerve endings in median eminance of hypothalamus of releasing and inhibiting hormones into the portal hypophyseal vessels

162
Q

What are the hormones released by the hypothalamus that control anterior pituitary secretions

A

Adrencorticotrophic hormone releasing hormone
Thyrotropin releasing hormone
Growth hormone releasing hormone
Luteinising hormone releasing hormone
FSH releasing hormone
Prolactin releasing hormone
Prolactin inhibiting hormone

163
Q

What hormones are secreted by posterior pituitary
Where are they produced

A

Oxytocin
Vasopressin

Produced in neurones of supraoptic and paraventricular nuclei of the hypothalamus - transported down the axons to endings in the posterior pituitary

164
Q

Effects of oxytocin

A

Milk ejection
Uterine contraction

165
Q

How is thirst sensation mediated

A

High osmolality and low volume detected by hypothalamus
Triggers vasopressin release and RAAS

166
Q

How does the hypothalamus control food intake

A

Two centres feeding centre and satiety centre
Likely feeding centre constantly active and inhibited by saitity centre itself triggered by raised bm

Primary Physiology (15 decks)

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