Physiology

Question 1

the neuron is made up of which several components?

Answer 1

cell body/ soma

dendrites

axon

schwann cells

axon terminal

Question 2

what are astrocytes?

Answer 2

star-shaped glial cells wihin teh brain and spinal cord

store glycogen

remove exce potassion

removal of neurtransmitters

promote myelination by oligodendrocytes

Question 3

which cells produce myelin in the CNS?

Answer 3

oligodendrocytes

(schwann cells = PNS)

Question 4

where do microglial cells originate?

Answer 4

mesodermal origin

phagocytic and immunocompetent cellls

Question 5

what cells line the ventricular system of the brain and the spinal cord? what is their function?

Answer 5

ependymal cells: produce CSF

Question 6

how are ependymal cells attached and what covers their surface?

Answer 6

basal membranes are attached to astrocytes

surface covered with cilia and microvilli

Question 7

what is the function of cilia and microvilli located on the surfcae of ependymal cells?

Answer 7

cilia- circulation of CSF

microvilli- absorption of CSF

Question 8

which two groups of cells comprise the nervous system?

Answer 8

glial cells: support, noiurishment, insulation

nuerons: sensing changes and communication

Question 9

broadly speaking what is the function of the ascending and descending spinal tracts?

Answer 9

ascending: relayign sensory information from the PNS to the brain

descending: motor signals fron the brain to LMN

Question 10

how do astrocytes support the CNS?

Answer 10

break down excess neurotransmitter

store small amounts of glycogen

maintain low ionic environment

create BBB

Question 11

which cells are known as teh immune cells of the brain?

Answer 11

microglia

immunosuppressive and phagocytic functions

Question 12

what are the pH, osmolarity, protein and glucose levels in CSF compared to blood?

Answer 12

pH, lower

osmolarity, equal

protein, higher

glucose, lower

Question 13

where is CSF produced?

Answer 13

Choroid plexus

Question 14

what volume of CSF is produced each day?

Answer 14

around 500ml: 150-250ml is present in the body at any one time

Question 15

how does CSF move through ventricles?

Answer 15

lateral ventricles ⇒ third ventricle ⇒ fourth ventricle ⇒ subarachnoid space

Question 16

how is CSF drained?

Answer 16

drained into superior sagittal venous sinus through arachnoid villi

Question 17

functions of CSF?

Answer 17

bouyancy for the brain

shock absorbance

homeostasis: regulates distribution of metabolites

clears waste products produced by brain

Question 18

an abnormal increase in CSF volume within the ventricular system is known as what?

Answer 18

hydrocephalus: casues inc pressure within cranium and possible brain tissue damage

Question 19

what are the two types of hydrocephalus?

Answer 19

communicating: CSF not reabsorbed into dural venous sinuses due to functional impairment of arachnoid villi

non-communicating: obstruction to CSF outflow

Question 20

causes of communicating hydrocephlaus?

Answer 20

subarachnoid haemorrhage, meningitis

Question 21

how is hydrocephalus managed?

Answer 21

surgery: shunt placed from the ventricles to the atria of the heart of abdo cavity.

Question 22

how do neurotransmitters transmit signals?

Answer 22

across synapses

Question 23

what is a synapse?

Answer 23

junction through which a neuron relays information to another neuron

Question 24

what are the three main components of a synapse?

Answer 24

axon terminal/ presynaptic cleft (transmits info)

synaptic cleft

dendrite/ post synpatic cleft (receives info)

Question 25

at which 3 locatiosn can neurotrnamsitters transmit signals across a synapse?

Answer 25

one neuron to another neuromuscular junction (NMJ) neuron to target gland

Question 26

neurotransmitters can be grouped into one of two classes based on what?

Answer 26

structure or function

Question 27

neurotransmitters can be classed as the following based on structure?

Answer 27

monoamines amino acids peptides other: ACh, adenosine, NO

Question 28

neurotransmitters can be classed as what based on their function?

Answer 28

exicitatory: inc electrical excitability on post-synaptic side inhibitory: decrease excitatory excitability neuromodulators: alter strength of transmission between neurons by affecting porduction/ release of neurotransmitters

Question 29

which is th most abundant neurotransmitter within the brain?

Answer 29

glutamate

Question 30

what class of neurotransmitter is glutamate?

Answer 30

excitatory

Question 31

what 4 receptors does glutamate bind to?

Answer 31

NMDA receptors AMPA receptors Kainate receptors Metabotropic G-protein couples receptors

Question 32

glutamate is thought ot have an essential role in which neurological processes?

Answer 32

**learning and memory**, particularly in the process of long-term potentiation

Question 33

Acetycholine (ACh) is synthesised in neurons from which two substances?

Answer 33

acetyl-CoA and choline

Question 34

ACh binds to which to receptor types?

Answer 34

**Nicotonic**: found at the NMJ, CNS, autonomic nervous system, pre-synaptically in brain **Muscarinic**: G protein coupled receptors fround in CNS and within post-ganglionic parasympathetic neurons

Question 35

which neurotransmittor is synthesised from glutamate?

Answer 35

GABA: inhibitory neurotransmitter

Question 36

GABA binds to which receptor types?

Answer 36

**GABA A receptors**: permeable to chloride and bicarbonate ions **GABA B receptor**s: G protein coupled receptors

Question 37

is glycine an inhibitatory or excitatory neurontransmitter?

Answer 37

both inhibibitory: ihibition of antagonistic muscles in spinal reflexes excitatory: co-agonist at glutamatergic NMDA receptors in CNS

Question 38

which neurotransmitter receptor do benzodiazepines bind to?

Answer 38

GABA receptors

Question 39

the peripheral nervous system is classified into which two systems?

Answer 39

somatic nervous system autonomic nervous system

Question 40

describe the afferent and efferent arms of the PNS

Answer 40

afferent: sensory neurons running from receptors to teh CNS efferent: motor neurons runnign from CNS to the effector organ

Question 41

how do efferent nerves differ in fucntion between the somatic and autonomic nervous system?

Answer 41

efferent nerves of **somatic system** is responsible for **voluntary, conscious control** of skeletal muscle efferent nerves of **autonomic system** **control visceral functions** i.e. heart rate, digestion, salivation, urination etc (can be further subdivided into parasympathetic or symapthetic)

Question 42

where does the symapthetic nervous system arise and what length of pre/post ganglionic neurons does it use?

Answer 42

orignates from the **throacolumbar segments** of the spinal cord **short pre**ganlgionic neuronsand **long post**ganglionic neurons

Question 43

which neurotransmitter do the preganglionic and postganlgionic neurons of the sympathetic nervous system use?

Answer 43

preganglionic- ACh postganglionic- noradrenaline Exception to this is the innervation of the sweat glands and chromaffin cells of teh adrenal medulla: cholinergic so use ACh

Question 44

where does the parasymapthetic nervous system arise and what length of pre/post ganglionic neurons does it use?

Answer 44

arises from the **craniosacral segments** of the spinal cord **long pre**ganglionic neurons and **short post**ganglionic neurons

Question 45

which neurotransmitter do the preganglionic and postganlgionic neurons of the parasympathetic nervous system use?

Answer 45

both use acetylcholine

Question 46

which nervous sytem is found within the lining of the GI tract?

Answer 46

enteric nervous system

Question 47

the enteric nervous sytem consists of which two plexuses and where are they located?

Answer 47

**Myenteric plexus**: found between inner and outer layers of muscularis externa **Submucosal plexus**: found in submucosal layer

Question 48

what is teh function of the myenteric and submucosal plexus of the enteric nervous system?

Answer 48

Myenteric- responsible for increasing tone of gut, controls velocity and intensity of contractions Submucosal: responsible for secretions and absoprtion in the gut, controls local muscle movements as well