Neuroscience and mental health

Question 1

What are the division of the nervous system?

Answer 1

Central nervous system
Peripheral nervous system:
- somatic PNS
- autonomic PNS: further divided into parasympathetic and sympathetic

Question 2

Put these in order of speed of onset, fastest to slowest.

Genetic, infection, trauma,degenerative, cerebrovascular accident, neoplastic, toxic, inflammatory

Answer 2

Trauma, cerebrovascular event, toxic, infectious, inflammatory, genetic, neoplastic, degenerative.m

Question 3

What is anterograde transport?

Answer 3

Transport of materials needed for neurotransmission and survival away from cell body. It uses micro tubule network and specific molecular motors requiring oxidative metabolism.

Question 4

What is retrograde transport?

Answer 4

Is for the return of organelles and movement of substances from extra cellular space (uses different molecular motors).

Question 5

Name the three types of the morphological subtypes seen in neurones.

Answer 5

Unipolar, pseudo-unipolar (e,g dorsal root ganglia sensory neurones have 2 fused axonal processes), bipolar

Question 6

What are Gogli type I multipolar neurones? Give examples.

Answer 6

Cells that are highly branched axons that extend over long distances.

• pyramidal cells in cerebral cortex
• purkinje cells of cerebellum
• anterior horn cells of the spinal cord

Question 7

What are Golgi type II multipolar neurones? Give an example

Answer 7

Cells with short axons terminating close to the cell body of origin. They use apparatus or glutamate transmitter
E.g stellate cells of the cerebral cortex and cerebellum

Question 8

What are the 3 types of functional neurones? Which areas do they conduct from to?

Answer 8

Sensory neurones: conducts from PNS to CNS

Motor neurones: conducts from CNS to PNS

Interneurons: transmits between cell bodies and processes remaining in the CNS. Make up most neurones in the CNS

Question 9

What are the 3 ways that neurones in the CNS tend to be collected in? Where each type may be found?

Answer 9

Laminae - layers of neurones of similar type and function e.g. Cerebral cortex

Ganglion - groups of neuronal cell bodies in the PNS that are encapsulated

Fibre tracts - groups or bundles of axons in the CNS

Question 10

What is the function of astroglia and where can they be found?

Answer 10

Make up 70% of grey matter and 50% of white matter. They have gap junctions allowing movement of ions between them.

Functions: scaffold for other cell types, formation of blood-brain barrier, k+ buffering, respond to injury by dividing, removal & degradation of neurotransmitters, release of neurotrophic factors

Question 11

What is an oligodendroglia? What is its function? Where is it found?

Answer 11

Found in the CNS and are the main myelin forming cells. They can produce myelin for multiple neurones also involved in maintenance.

Question 12

What are microglia cells? Where are they found and shay is their function?

Answer 12

Derived from early development from blood monocytes that invade the brain. They have dense lysosomes, lipid droplets and residual bodies, characteristic of phagocytic cells.

Function: act as immune cells, antigen presenting cells

Question 13

What are ependymal cells? What are their function and where are they found?

Answer 13

They line the ventricles and central canal of the cord. They have apical microvilli and cilia with prominent gap junctions between them but no tight junctions

Question 14

What are the 2 types of peripheral glia? What are their functions?

Answer 14

Schwann cell: envelop axons of neurones in PNS and produce myelin. 1:1 relationship with axon and Schwann cells also perform functions with astrocytes and repair

Satellite cells: each neuronal cell in spinal ganglia is surrounded by metabolically supportive satellite cells.

Question 15

What is the electrochemical equilibrium?

Answer 15

For an ion is reached when it’s concentration gradient is balanced by the electrical gradient across the membrane

Question 16

What is the Nernst equation? What are the 2 conditions needed to use this equation.

Answer 16

The Nernst equation related the size of the equilibrium potential of an ion to the size of its concentration gradient.

Conditions:
1. The membrane is selectively permeable to the one ion
The concentration of two ions are not equal on either side of the membrane

Question 17

What is the Goldman equation?

Answer 17

Describe the real resting potential as its influence by Na+, K+ and Cl-. The size of each ion concentration is proportional to membrane permeability.

Question 18

Why is the membrane potential closer to the potassium equilibrium point? Overall which is higher intracellular or extra cellular of sodium and potassium?

Answer 18

Sodium: intracellular extracellular

Real resting membrane is around -70mV. It is closer to the potassium equilibrium point because at resting the membrane is more permeable to k+. Diffuses out of cell via open channels. The membranes are slightly permeable to Na+ so some move into cell cancelling effect of the equivalent number of K+ ions meaning the potential is a little higher than the potassium equilibrium.

Question 19

What happens in stage 1 of the action potential? Stage 1: resting potential

Answer 19

The membrane potential -70mV . Permeability of the membrane is greater for potassium than sodium. Ungated channels are responsible for the resting potential. Ions diffuse through the membrane down their concentration gradient.

Question 20

What happens in stage 2 (stimulus depolarises the membrane potential) of the action potential?

Answer 20

Stimulus occurs and a small depolarisation in the membrane is sensed by the sodium channels in the membrane. At around -50mV they trigger the opening of others very quickly leading to an upstroke

Question 21

What happens in stage 3 (upstroke/depolarisation) of an action potential?

Answer 21

There is a massive increase in permeability to sodium so na+ enters the cell down their electrochemical gradient through voltage gated sodium channels.

Potassium voltage gated channels start to open but at a slower rate and k+ leaves the cell down electrochemical gradient, though fewer than na+ leaving.
This is why membrane potential doesn’t ever reach sodium equilibrium

Question 22

What happens in stage 4 (repolarisation phase) of the action potential? What are the 2 stages?

Answer 22

Sodium channel is inactivated meaning entry of sodium stops. Permeability to potassium increases as voltage-gates potassium channels open, so potassium ions leave the cell. As a restful membrane potential moves towards potassium equilibrium potential.

Early repolarisation: sodium channel activation gate closed, potassium channel open. Inactivation molecule moves into channel and blocks it sodium channels. opening of potassium channels allow repolarisation.
- blockage of sodium channel means restimulation cannot occur as large molecules blocks the channel.

Late repolarisation: na channel activation and inactivation gate closed, potassium open.

These two stages are known as the ABSOLUTE refractory period. There can be no action potential in this period.

Question 23

What happens in stage 5 (after-hyper polarisation phase) of the action potential?

Answer 23

This is known at the relative refractory period as a stronger than normal stimulus can result in an action potential.

Here the permeability to potassium is greater than at rest because potassium channels are still open. Post assist voltage gated channels close and membrane potential returns to resting where:

• na+ channel activation gate close
• na+ channel inactivation gate open
• potassium channel open

Question 24

What might cause reduced conduction velocity?

Answer 24

Reduced axon diameter

Reduced myelination (e.g. MS, diphtheria)

Cold, anoxia, compression and drugs

Question 25

What is a neurotransmission?

Answer 25

Information transfer across the synapse requires release of neurotransmitters and their interaction with post-synaptic receptors.

Question 26

What types of molecules act as neurotransmitters?

Answer 26

Neurotransmitters have a wide diversity in transmitters and been encoding receptors 1) amino acids 2) amines 3) neuro peptides

Question 27

What is the sequence of events that happens at a synaptic vesicles?

Answer 27

Action potential depolarises the nerve terminal ➡️ voltage-gated calcium channels open ➡️ Ca2+ influx ➡️ vesicles fuse to pre-synaptic membrane ➡️ exocytosis ➡️ transmitter release ➡️ binding to receptors on post-synaptic membrane ➡️ sodium enters post synaptic neurone (if threshold reached action potential occurs) ➡️ neurotransmitter is broken down and taken back up into original synapse

Question 28

What is electromechanical transduction?

Answer 28

Neurotransmission requires rapid transduction. Vesicles are permed and filled with neurotransmitter at active zone. Docked In synaptic zone (close to calcium channels). Calcium entry leads to rapid protein complex formation between vesicles, pre synaptic membrane and cytoplasmic proteins enable rapid response leading to exocytosis.

Question 29

Receptor action: what is ion channel receptors? How do they act and give some examples.

Answer 29

Fast excitatory and inhibitory transmission. CNS: glutamate, gamma amino butyric acid (GABA) Neuromuscular junction: acetylcholine at nicotine receptors They lead to a sodium influx

Question 30

Receptor action: what are g-protein couple receptors and give some examples?

Answer 30

Slow transmission. AMPA receptors : majority of fast excitatory, rapid onset leading to sodium influx NMDA: slow excitatory. Sodium and calcium influx, calcium acts as a secondary messenger

Question 31

How do seizures occur in epilepsy?

Answer 31

Decreased GABA inhibition so increased glutamate mediated excitability can lead to seizure activity.

Question 32

The drug valproate is used to treat epilepsy how does it work?

Answer 32

The cellular mechanism acts on GABA transaminase and on sodium channels. Used in most types in particular absences seizures

Question 33

Discuss GABA

Answer 33

Glutamate is synthesised from TCA cycle. After binding to GLUR it is removed from the synapse by excitatory amino acid transporter on pre synaptic new terminal and glial cell. Converted back into glutamine by glutamine synthetase. Reuptaken unto nerve cell. GABA transporter leads to reuptake in nerve terminal and glial cell. In the glial cell GABA transaminase converts GABA to succinate semi-aldehyde Terminal - repackaged, converted increase or enter TCA

Question 34

Phenobarbital is used to treat epilepsy how does it work?

Answer 34

Enhanced GABA action and inhibition of synaptic excitation. All types except absence seizures

Question 35

Benzodiazepines are used to treat epilepsy how do they work?

Answer 35

Enhanced GABA action. All types

Question 36

Vigabatrin is used to treat epilepsy how does it work?

Answer 36

Inhibits GABA transaminase All types. Seems to be effective in patients resistant to other drugs

Question 37

What make up the brain stem?

Answer 37

Midbrain, pons and medulla

Question 38

How many cervical vertebrae and nerves are there?

Answer 38

7 vertebrae and 8 nerves | - above and below each vertebrae

Question 39

How many thoracic vertebrae and nerves are there?

Answer 39

12 vertebrae, 12 nerves - nerves lying below vertebrae

Question 40

How many lumbar vertebrae and nerves are there?

Answer 40

5 vertebrae, 5 nerves | - nerves below vertebrae

Question 41

How many vertebrae and nerves are there in the sacral region?

Answer 41

5 vertebrae and 5 nerves | - nerves lie below vertebrae

Question 42

How many vertebrae and nerves are there in the coccyx region?

Answer 42

2 vertebrae, may be fused and one nerve associated with it

Question 43

In what region (specific vertebral levels) of the spinal cord can the lumbar puncture be safely performed?

Answer 43

Between L3 and L4 because there is no risk of da,age to spinal cord. Spinal nerves thin and move so little risk of damage from needle. - length of spinal cord is shorter than spinal column due to embryology. This means that the origins of nerves from the lumbar and sacral regions originate much higher up than the vertebral levels

Question 44

What are primary cortical areas where are they found and some examples of their functions?

Answer 44

Primary cortical areas are discrete areas with specific functions where damage leads to disability. Found in the forebrain (cerebral hemisphere). - e.g. Primary motor cortex, primary somatosensory cortex, primary visual cortex, primary auditory cortex

Question 45

What are associated cortical areas? Which area of the brain? What are examples of their functions?

Answer 45

Primarily involved in higher functions, but much more unpredictable. Found in forebrain - cerebral hemispheres. - e.g. Broca's area (speech) and wernicke's area (understanding language)

Question 46

What does the basal ganglia control?

Answer 46

Movement

Question 47

What does the cerebral cortex do?

Answer 47

Involved in all functions

Question 48

What does the corpus callosum do?

Answer 48

Interconnects corresponding parts of the 2 hemispheres across midline

Question 49

What is the cerebellum involved in?

Answer 49

Co-ordinates movement and involved in learning motor skills

Question 50

What are the four cortical lobes?

Answer 50

Frontal lobe (most anterior), parietal lobe, occipital lobe (most posterior) and temporal lobe.

Question 51

Where is the Diencephalon found in the brain? What are the 2 parts of the diencephalon and what do they do?

Answer 51

Lies between hemispheres and has 2 main structures: - thalamus which is involved in relaying information between brain stem/lower structure and cerebral cortex - hypothalamus involved in homeostasis

Question 52

What are the three layers of the meninges? Where is CSF found in the meninges?

Answer 52

Dura mater: tough membrane attached to SKULL BONE or forming partitions (dural folds) with genius sinuses in their margins Arachnoid membrane: thin membrane attached to dura underside Pia mater: delicate membrane closely adherent to surface of brain or spinal cord CSF flows into sub-arachnoid space.

Question 53

What is a ventricle? What are the different ventricles found in the brain?

Answer 53

Ventricles are interlocking pace filled with CSF lateral ventricle: 2 c shaped either side of corpus callosum. Horn connects to single third ventricle Third ventricle: bisect Diencephalon, lower end forms aqueduct going through midbrain to fourth ventricle Fourth ventricle: posterior to brain stem anterior to cerebellum. Forms central Canal which runs down the spinal cord

Question 54

What are the functions of cerebrospinal fluid? Where is it formed and its subsequent "life cycle"?

Answer 54

It acts as a CARRIER - oxygen, glucose and other substances Provides optimal chemical environment Provides MECHANICAL PROTECTION (shock absorber) It is formed in CHOROID PLEXUS of each lateral ventricle. Travels to third ventricle where more CSF added by plexus ➡️ aqueduct ➡️ 4th ventricle ➡️ circulation in subarachnoid space ➡️ reabsorbed into blood via ARACHNOID VILLI that project into dural venous sinus

Question 55

What is hydrocephalus? What are the 2 main causes? How do you treat?

Answer 55

Accumulation of CSF in ventricle leading to increased pressure. Main causes: - communicating block (subarachnoid bleed) in CSF absorption or flow (meningitis, trauma) - non-communication block: caused by aqueduct stenosis or ventricular/paraventicular tumour Relieved by drainage of excess via a shunt from lateral ventricle to superior vena cava or abdomen. As well removal of causative agent.

Question 56

Define an epidural/ extramural haemorrhage.

Answer 56

Is due to damaged meningeal artery between skull and dura post trauma. It is a fast bleed due to arterial cause.

Question 57

Define a subdural haemorrhage.

Answer 57

Due to damaged vein between dura and subarachnoid spaces. Slower bleed due to venous cause.

Question 58

Through what cranial fossa does the brain stem leave the skull into the spinal cord?

Answer 58

Foramen magnum

Question 59

What is an endonerium?

Answer 59

Individual axons and associated Schwann cells surrounded by delicate, loose connective tissue (important for regeneration) to prevent damage.

Question 60

What is the perneurium?

Answer 60

A fascicle surrounded by dense connective tissue. Prevent damage to neurones

Question 61

What is an epineurium?

Answer 61

Whole nerve surrounded by loose connective tissue to prevent damage.

Question 62

What does the dorsal rami and ventral rami innervate? What does the rami communicantes do?

Answer 62

Dorsal rami: innervate muscle and skin of back Ventral rami: innervate muscle and skin of rest of body and limbs Rami communicantes provide interconnections between some spinal nerves and ganglia of the sympathetic nervous system

Question 63

What do you call a specific band of skin innervated by a spinal nerve? And a muscle?

Answer 63

Skin: dermatome Muscle: myotome

Question 64

How are limbs innervated? What is a plexus? What are the 2 main plexuses (one for the upper limbs and one for the lower limbs)?

Answer 64

To innervate limbs spinal nerves need to combine to form peripheral nerves. They combine to form a plexus = network of fir red originating from different levels associated with an organ C5-T1 innervate arm via BRACHIAL PLEXUS L2-S2 innervate leg via LUMBOSACRAL PLEXUS

Question 65

What happens when a nerve has been damaged? (Five steps)

Answer 65

1. Normal neurone contained in endonerium. A compression injury which break as continuity of axoplasm so action potentials stop. 2. Distal part of nerve degenerates, proximal stump remains intact (unless injury close to soma). Macrophages phagocytose axonal and myelin debris. 3. Proximal part of axon and soma usual survive and undergo meta block changes (CHROMATOLYSIS) leading to outgrowth of axonal sprouts from proximal stump which are guided down scaffold by proliferating Schwann cells. 4. When first axonal sprout reaches target site growth and myelination occurs. All other axonal sprouts retract into stump. - successful regeneration depends on extent of damage to axons and connective tissue sheaths and distance from target - failure to reconnect ➡️ neuroma (containing trapped nerves) 5. Nodes of ranvier closer together than normal

Question 66

What are peripheral neuropathies? What are causes? | What is segmental demyelination? What is axonal degeneration?

Answer 66

Peripheral neuropathies are progressive degeneration of peripheral nerves. Causes: metabolic disorder (e.g diabete), infection, hereditary Segmental demyelination: Schwann cells eventually die therefore continuous conduction replaces saltatory leading to reduced conduction velocity Axonal degeneration: complete conduction block (may be due to increased/prolonged segmental demyelination)

Question 67

Describe the normal physiology at neuromuscular junction initiating muscle contraction. Describe the activation and relaxation process.

Answer 67

Action potential opens Ca2+ voltage gated channels ➡️ influx of Ca2+ ➡️ Ca2+ triggers exocytosis of vesicles containing neurotransmitters ➡️ acetylcholine diffuses across cleft and finds to receptors opening channels ➡️ local currents flow from depolarised region and action potential triggered which spreads along surface membrane ➡️ acetylcholine is broken down by the enzyme acetylcholine ester are (enzyme) AP propagates along membrane of t-tubule ➡️ dihydropyridine receptor opens ➡️ ryanodine receptors open ➡️ calcium released from sarcoplasmic reticulum ➡️ calcium binds troponin and tropomyosin moves allowing crossbridges to attach to actin ➡️ calcium is activel transported into SR continuously while AP continues ➡️ calcium dissociates when free calcium declines. Tropomyosin block preventing cross bridges and active force declines

Question 68

Name three neuromuscular junction disorders that can lead to muscle weakness

Answer 68

Botulism toxin: irreversible disruption in stimulation-induced acetylcholine release by presynaptic nerve terminal Myastenia gravis: autoimmune Lambert-Eaton myasteric syndrome : associated with lunch cancer. Autoimmune attack on voltage gated calcium channels

Question 69

What are causes of lesions in the nervous system?

Answer 69

Spinal roots and spinal nerve damage occurs usually due to trauma or strenuous activity. Peripheral nerves may be affected by trauma or disease

Question 70

What does damage to the dorsal root lead to?

Answer 70

Leads to loss of sensation in dermatome supplied by the corresponding spinal nerve. This may be not detected as there is considerable overlap between innervation of dermatome

Question 71

What symptoms may occur due to damage to the central root?

Answer 71

Leads to weakness in the muscle supplied by the corresponding spinal nerve

Question 72

What is the thoracolumbar outflow?

Answer 72

The preganglionic fibres of the sympathetic system which are found in the thoracic (t1-t12 and upper lumber (L1-L3)

Question 73

What is the craniosacral outflow?

Answer 73

The preganglionic fibres of the parasympathetic system found in the cranial and sacral spinal nerves

Question 74

What is the sympathetic trunk?

Answer 74

A chain of ganglia and connecting fibres lying next to the vertebrae for the entire length of the vertebral column which allows dispersion of the sympathetic outflow from a small region in the spinal cord (T1-L3) to peripheral via spinal nerves

Question 75

What are the sympathetic and parasympathetic known as?

Answer 75

Fight or flight = sympathetic. | Rest and digest = parasympathetic

Question 76

What features does the parasympathetic system have? | I.e. Where are the ganglia, where do the preganglionic neurones originate.

Answer 76

Ganglia are close to the effector organs. Preganglionic neurones originate from craniosacral regions of spinal cord Preganglionic neurones are long and post ganglionic are short

Question 77

What neurotransmitter does parasympathetic pre-ganglionic neurones secret?

Answer 77

Acetylcholine

Question 78

What neurotransmitter does post-ganglionic parasympathetic neurones secrete?

Answer 78

Acetylcholine

Question 79

What response does the sympathetic nervous system evoke in the eye?

Answer 79

Dilation of pupil

Question 80

What response does the sympathetic nervous system evoke in the trachea & bronchioles?

Answer 80

Dilation

Question 81

What response does the sympathetic nervous system evoke in the liver?

Answer 81

Glycogenolysis and gluconeogenesis

Question 82

What response does the sympathetic nervous system evoke in adipose tissue?

Answer 82

Lipolysis

Question 83

What response does the sympathetic nervous system evoke in the kidney?

Answer 83

Increased renin secretion

Question 84

What response does the sympathetic nervous system evoke in the salivary glands?

Answer 84

Thick viscous secretion

Question 85

What response does the sympathetic nervous system evoke in the skin?

Answer 85

Piloerection, increased sweating

Question 86

What response does the sympathetic nervous system evoke in the heart?

Answer 86

Increased heart rate and contractility

Question 87

What response does the sympathetic nervous system evoke in the GI tract?

Answer 87

Decrease motility and tone, sphincter contraction

Question 88

What response does the sympathetic nervous system evoke in blood vessels?

Answer 88

Dilation of those in skeletal muscle | Construction of skin, mucous membrane and splanchnic Area

Question 89

What response does the parasympathetic nervous system evoke in the eye?

Answer 89

Construction of pupil and ciliary muscle

Question 90

What response does the parasympathetic nervous system evoke in the eye?

Answer 90

Constriction

Question 91

What response does the parasympathetic nervous system evoke in the bladder?

Answer 91

Contraction of destructor. Relaxation of internal sphincter

Question 92

What response does the parasympathetic nervous system evoke in the salivary glands?

Answer 92

Copious watery secretion

Question 93

What response does the parasympathetic nervous system evoke in the heart?

Answer 93

Decreased rate and contractility

Question 94

What response does the parasympathetic nervous system evoke in the GI system

Answer 94

Increased motility, tone and secretions

Question 95

What are features of the sympathetic neurones?

Answer 95

Arise from thoracic and lumbar regions. Pre ganglionic are short, post are long. Ganglia chain near vertebral column allows mass innervation

Question 96

There are three routes seen in the sympathetic: one general, one via the adrenal medulla and the other involving specific effector organs. What are the preganglionic neurotransmitter and post ganglionic neurotransmitter?

Answer 96

General: pre ganglionic = acetylcholine, post ganglionic = noradrenaline Via adrenal medulla: pre ganglionic = acetylcholine, post ganglionic = not exists instead adrenaline (and some noradrenaline) is secreted into the bloodstream fro, adrenals Special cases e.g. To sweat glands: pre ganglionic = acetylcholine , post ganglionic = acetylcholine

Question 97

How is control of cardiac output controlled by autonomic system?

Answer 97

CO = stroke volume x heart rate Sympathetic stimulation of the heart leads to inotropic (increased force leading to increased Stoke volume) and chronotropic effect (increase heart rate)

Question 98

How is the total peripheral resistance regulated by autonomic system?

Answer 98

Achieved by controlling the sympathetic tome of vessels. Increased activity leads to generalised vasoconstriction and TPR is increased. Reduced sympathetic activity leads to dilation. Increasing TPR will increase cardiac output

Question 99

Vasodilation usually occurs due to reduced sympathetic activity but there are some exceptions. What are they?

Answer 99

- increase sympathetic activity in skeletal muscle leads to dilation - localised vasodilators (products of metabolism) - increased parasympathetic activity to certain blood vessels leads to dilation e.g. Certain gland and organs such as penis

Question 100

How does the autonomic system control the penis during arousal?

Answer 100

Parasympathetic is essential for election Sympathetic involved in penis flaccidity and ejaculation. Both needed for reproduction

Question 101

How is the bladder regulated by the autonomic system?

Answer 101

Smooth muscle (detrussor) surrounds the bladder. Parasympathetic is main influence, but sympathetic controls internal sphincter. Increased pressure in bladder ➡️ increased after net activity to spinal cord ➡️ increased parasympathetic via pelvic nerve so detrussor muscle contracts ➡️ decreased sympathetic activity via hypogastric nerve relaxes internal sphincter ➡️ central inhibition of voluntary control via pudenal nerve relaxing external sphincter and decreased pressure in bladder

Question 102

What is the receptor for acetylcholine (cholinergic neurones) released from pre ganglionic neurones in all of the autonomic ganglion? What blocks it?

Answer 102

Nicotine receptor is ligand ion channel and is very fast. | Stimulated by nicotine and acetylcholine. Blocked by hexamethonium

Question 103

At effector organs of the autonomic system what receptors does acetylcholine secreted by post ganglionic neurones bind to? Which branches does this occur? What is the receptor blocked by? Is it a fast or slow response?

Answer 103

Muscarinic receptor - G protein coupled Relatively slow - parasympathetic and sympathetic in specific cases such as effector organs e.g. sweat glands - stimulated by muscarine and acetylcholine - blocked by atropine

Question 104

What receptor does noradrenaline released by sympathetic nexus system bind to?

Answer 104

Adrenoceptors - there are different forms - stimulated by adrenaline and noradrenaline - G protein coupled

Question 105

Describe the biosynthesis and metabolism of acetylcholine.

Answer 105

Formation inside pre-synaptic neuron: acetyl CoA + Choline is converted into acetylcholine and CoA by enzyme choline acetyl transferase. acetylcholine is then released via exocytosis at depolarisation. removal: acetylcholine is converting into choline and acetate by acetylcholinesterase in the synaptic space. the Choline is taken up by the pre-synaptic neruoneto be recycled

Question 106

Describe the biosynthesis and metabolism of noradrenaline

Answer 106

Formation: tyrosine is taken up by pre-synaptic neuron. Tyrosine -> DOPA (tyrosine hydroxylase) DOPA -> Dopamine (DOPA decarboxylase) the dopamine is stored in vesicles allowing with the enzyme dopamine beta-hydroxylase. The dopamine in the vesicles is converted into noradrenaline. Removal: ROUTE 1: reuptake into neurone and then conversion into metabolites by monoamine oxidase A (MAO-A). ROUTE 2: uptake into effecter cell and degradation by COMT some of the metabolites are excreted in urine.

Question 107

Describe the biosynthesis and metabolism of adrenaline.,

Answer 107

Occurs in adrenal medulla and adrenaline is released into the blood. cell takes up tyrosine. Tyrosine -> DOPA (tyrosine hydroxylase) DOPA -> dopamine (DOPA decarboxylase) domapine is packaged into vesicles with dopamine beta-hydroxylase forming noradrenaline. the noradrenaline is release from vesicles and converted into adrenaline by phenylethanolamine methyl transferase. Adrenaline is packaged into vesicles Some of the metabolites of adrenaline are excreted in urine

Question 108

What is the fight or flight response? give some examples of changes to physiology that it mediates? what does it stimulate the release of?

Answer 108

is a mass sympathetic discharge in response to alarm of stress. E.g. increased BP, glucose concentration, awareness, more blood to muscle and respiration Stress acts on hypothalamus and brain stem leading to release of CATECHOLAMINES from adrenal medulla (e.g. adrenaline. leads to effects such as tachycardia, pupil dilation, etc.

Question 109

What is a baroreceptor and where are they found?

Answer 109

They have modified nerve endings that respond predominantly to stretch of blood vessels due to pressure. Found in carotid sinus and aortic arch

Question 110

Describe what happens when there is an increase in arterial blood pressure and when there is a decrease.

Answer 110

Increase arterial BP: increased stretch of barorecepetors -> increased afferent nerve activity to brain -> increased inhibition of sympathetic nervous system leading to - decreased vasomotor tone, so TPR reduces -decreased heart rate and force of contraction - decreased circulating catecholamines these combined effects lower BP Decrease arterial BP: reduced stretch from baroreceptors -> reduced afferent nerve activity to brain -> reduced inhibition of sympathetic nervous system leading to: - increased vasomotor tone, increased TPR -increased heart rate and contraction - increased catecholamines circulating combined effects lead to an increased in BP

Question 111

What occurs when standing up regarding the nervous system in order to maintain BP?

Answer 111

On standing there is reduced venous return as blood pools in the leads so CO reduces as does BP. baroreceptors and cardiopulmonary receptors are stimulated. there is an increase in sympathetic activity. increasing TPR allowing sufficient BP to be maintained so as not to faint

Question 112

What is postural hypotension?

Answer 112

impaired sympathetic response leading to little change in cardiac output and BP is not maintained. this leads to symptoms of feeling faint, dizzy and passing out.

Question 113

What are the 4 general splanchic nerves and what do they innervate?

Answer 113

greater: thoracic aorta supply, passes through diaphragm entering abdominal plexus around greater vessels of the gut lesser: passes through diaphragm and enters abdominal plexus around aorta least: passes through diaphragm and enters abdominal plexus around gut lumbar: has 4 ganglia and nerves are part of all plexi of SNS in abdomen and pelvic region

Question 114

What are the types of generalised epileptic seizures? | What does generalised seizure mean?

Answer 114

Tonic-clonic Absence Myoclonic Atonic The whole brain is involved/effected by the excitatory pathways

Question 115

What types of partial epileptic seizures are there? | What are partial seizures?

Answer 115

Simple, complex and secondary generalised They are localised to one lesion or area of the brain

Question 116

What is a tonic-clonic seizure?

Answer 116

Typical seizure, full body contractions

Question 117

What are absence seizures?

Answer 117

Short seizures often seen in children. As damaging to brain as tonic clonic despite not appearing as dangerous

Question 118

What is an atonic seizure?

Answer 118

Loss of muscle tone in the body. People tend to fall forwards onto their face

Question 119

What is a simple partial seizure?

Answer 119

Symptoms will depend on the area of the brain effected. Often involve motor regions and can be detected as twitching. Consciousness is maintained

Question 120

What is a complex partial seizure?

Answer 120

Concours nests is not maintained, often display stereotypical behaviours such as lip smacking. Often related to the temporal lobe

Question 121

What is myoclonus seizure?

Answer 121

Jerks are normally repeated - series of jerks that can last for hours and as time progresses consciousness diminishes

Question 122

What is secondary generalised seizures?

Answer 122

When a partial seizure develops into a generalised seizure