:))))))

Question 1

what are the majority of cells in NS?

Answer 1

glial cells

Question 2

what do glial cells do in PNS? & CNS?

Answer 2

• astrocytes: main cell type. star like process. control environment around neurons. form blood brain barrier: prevents substances entering and damaging cells.
• oligodendrocytes: cells put out processes that wrap around neighbouring axons. can myelinate multiple axons
• ependymal cells​: lining cells of ventricular system. they are epithelial boundary that regulate the movement of cerebral spinal fluid in/out brain tissue and ventricle system.
• macroglial cells - only active when pathogens come into brain - turn into macrophages

PNS

• Schwann cells: myelinate one axon
• Satelitte Cells: (similar role as astrocytes) - modulate environment around neuronal cell body

Question 3

what are the arterires like in the brain?

Answer 3

• arteries are thinner walled - less smooth muscle.
• can be distended (swollen due to pressure from inside; bloated)

Question 4

what type of cell is this?

Answer 4

astrocyte

Question 5

which is this?

role?

where?

Answer 5

ependymal cells

• function: ciliated. move cerebral spinal fluid (CFS) around CNS.
• located: lining central canal of spinal cord and ventricular system

Question 6

Answer 6

Question 7

which parts of the brain code for the following?

1. memory:
2. emotion:
3. coordination of complex movement:
4. language comprehension and production:
5. processing of multisensory information:
6. detection of visual stimuli:

Answer 7

1. memory: hippocampus
2. emotion: frontal lobe

3. coordination of complex movement: cerebellum

4. language comprehension and production: auditory area: temporal lobe. speeach production: frontal lobe
5. processing of multisensory information: primary somatosensory cortex
6. detection of visual stimuli: occipital lobe

Question 8

where is the starting point of cranial nerves?

how many pairs of cranial nerves are there?

which cranial nerves exit and enter the answer to 1.? what are there functions?1

Answer 8

1. brainstem!!
2. 12 pairs of cranial nerves -
3. cranial nerves III - XII -> provide main motor and sensory innervation to face and neck

Question 9

what is the reticular formation?

where?

Answer 9

Question 10

which cranial nerves DONT come from brain stem?

Answer 10

Cranial Nerve 1: Olfactory Nerve

Cranial Nerve 2: Optic Nerve

Question 11

role of each?

• CN III
• CN VII
• CN IX
• CN X

Answer 11

Parasympathetic Nervous System

• CN III: pupil size and lens focusing
• CN VII: saliva focusing, tear production
• CN IX: saliva production
• CN X: everything else (90% of parasympathetic nervous system)

Question 12

where does brain stem end / spinal cord start?

where does spinal cord end?

whats after spinal cord?

Answer 12

• brain stem continues till about C2/C3.
• here it turns into spinal cord: goes till to L1 vert.
• then forms cauda equina. typically L1-L5

Question 13

what do spinal cord white matter tracks code for?

Answer 13

ascending tracts:

• sensory: periphery to CNS (goes up to brain).
• located on outside

a) pain, temp, position,

descending tracts:

• motor - comes down from brain
• further in

Question 14

what is brown colour in brown adipose tissue samples from?

Answer 14

• brown colour from high levels of cytochrome oxidase in mitochondria

Question 15

what is cartilage made from?

is it vascular ?

Answer 15

cells: chondrocytes, ECM = 95%.

contains:

• avascular: ECM crucial for surivial
• glycosaminoglycans (GAGs)
• few type II collagen fibres

Question 17

how is cartilage made? (2)

Answer 17

• chondroblasts (immature chondrocytes): produce and deposit collagen type II and ECM.
• chondroblasts become trapped within matrix spaces (lacunae): become chondrocytes

2 mechanisms for formation of cartilage:
a) Interstitial growth - chondrocytes grow and divide and lay down more matrix inside the existing cartilage f

b) appositional growth: undiff. cells at the surface of the cartilage (perichondrium)

Question 18

where do you find hyaline, fibro and elastic cartilage?

Answer 18

Hyaline - most common, found in the ribs, nose, larynx, trachea. Is a precursor of bone.

Fibro- is found in invertebral discs, joint capsules, ligaments.

Elastic - is found in the external ear, epiglottis and larynx.

Question 19

which type of collagen is found in fibrocartilage?

Answer 19

type I collagen. 3

Question 20

which type of cartilage doesnt have a perichondrium?

Answer 20

fibrocartilage

Question 21

what are the three archictetural patterns of bone?

what supplies blood to bones?

what connects ^?

Answer 21

1. circumferential outer layer

2. concentric - forms the osteons (looks like circles)
3. interstitial - between 1 & 2.

also have:

• harversion canal in the osteons: tubes where BV fill
• volkmann’s canals: connect the haversion canals

Question 22

what are the three mane types of bone cells?

Answer 22

1. osteoblasts: bone formation - immature bone cells
2. osteocytes: bone maintenance -
3. osteoclasts: - bone resorption / remodelling. multi nucleited (osteoclast, large multinucleated cell responsible for the dissolution and absorption of bone. Bone is a dynamic tissue that is continuously being broken down and restructured in response to such influences as structural stress and the body’s requirement for calcium)

Question 23

describe the intra and extracellular ion concentrations that sets up the cells resting membrane potential.

Answer 23

- Na+ greater outside cell

- K+ greater inside cell

• A- (proteins) greater inside cell

= creates a resting membreane potential: +ve outside, -ve inside = -70mV

Question 24

how do cells get over asymmetrical ionic charge distribution caused by proteins not being permeable?

Answer 24

* *Active Na/K diffusion** - 3Na+ from intracellular to extracellular - 2K+ from extracellular to intracelluar effects: - high Na+ conc in extracellular space, low intracellular - high K+ conc in intracellular space, low extracellular 32- results in +ve extraceullar space c.f. intracellluar space: sets up resting membrane potential * *membrane permeability:** * *-** - K+ (50:1 difference): more +ve charged ions move out of the cell: sets up more -ve charge inside cell. neuron plasma membrane is 50-100 times more permeable to K+ than Na= - resting membrane potential of cell: approx. **-70mV**

Question 26

what is the nernst equation?

Answer 26

the potential across the cell membrane at which the net diffusion of ions across thecell membrane due to conc. gradient stops equation: Em= 61.5 log ([C]0/[C]I)

Question 27

what is cell resting membrane potential a consequence of?

Answer 27

**- concentration gradients of ions across the plasma membrane** AND **- relative ion impermeabilities of the membrane**

Question 28

which cell types are voltage dependent ion channels found in?2

Answer 28

nerve cells muscle cells (skeletal, cardiac, smooth)

Question 29

describe the structure of Na+ voltage sensitive channels how does it work?

Answer 29

**2 channels:** _- activation gate: (in middle of channel)_ a) closed in resting state b) bridge in middle of channel stops Na+ being able to enter cell _- inactivation gate: (located intracellularly)_ a) open in resting state **_works by:_** open in response to depolarisation: _- activation gate_ a) v fast opens due to depol _-inactivation gate_ a) closes due to depol b) closes slowly after depol = Na+ go into cell - makes cell more postivie after repolarisation, channels return to resting

Question 30

explain whats going on at resting of AP - what reeastblishes resting membrane p?

Answer 30

- all Na and K+ pumps closed (activation gate of Na ion channels closed, inactivation gate of Na channels are open) **- Na/K ATPase pump, leak channels and proteins establish resting membrane potential**

Question 31

which part of AP is postive feedback and whch is negative feedback?

Answer 31

postive feedback: **depolarisation** negative feedback: **repolarisation**

Question 32

what do local anaesthetics do?

Answer 32

- bind to **open Na+ channel: become inactivated** - physically prevent Na+ reopening and generating AP: drugs stablises inactive state - cant depolarise cell - pain fibres cant send pain to brain

Question 33

name for jumping of conduction from node of ranvier to node of ranvier?

Answer 33

AP jumps from one to node to the next: aka **saltatory conduction**

Question 34

why do we have different conduction velocities and how do they achieve this? what are the names of different size fibres with different speeds?

Answer 34

fastest conduction velocities have widest axon diameter and myelination: (size goes down in order - see photo) **Aα fibres** are the fastest: motor neurons, muscle spindles, golgi tendon organs **Aβ fibres:** touch / mechanical pressure: **Aδ fibres:** pain (fast), temp **C fibres:** pain (slow), temp and itch. unmyelinated

Question 35

what is summation?

Answer 35

addition of excitatory and inhibtory signals

Question 36

name 4 important NT that are collectively called monoamines where each expressed?

Answer 36

**adrenaline**: fight or flight. PNS **noradrenaline**: concentration and arousal. PNS. undersupply can depress mood **dopamine**: pleasure, learning attention and momevent. CNS. XS: schizophrenia. depleted: Parkinsons **serotonin**: mood, hunger and arousal. CNS and gut. depression = collectively known as monoamines

Question 37

name three amino acid NTs? name a peptide NT

Answer 37

**_amino acids:_** **gaba**: calming. _major inhib NT._ CNS. undersupply: seizures, tremors **glutamate**: memory. _major excitatory NT._ XS: oversupply: overstimlate brain - migraines **glycine**: major inhibitory NT in spinal cord **_peptides_**: endorphins: euphoria

Question 38

which of gaba and glutamate are excitatory / inhibitory?

Answer 38

gaba: **inhibtory** gluatamate: **excitatory**

Question 39

what is temporal summation? what is spatial summation?

Answer 39

**temporal summation** - _post synaptic potentials at same syanpse (A&A)_ occur in rapid succession - first potential doesnt have time to dissipate: next potentials add to previous once **spatial summation** _- multiple postsynaptic potentials from different synapses (A+B)_ occur same time and add - alone, EPSP not strong enough to cause AP. reinforce each other = AP.

Question 40

which NT is most common in brain?

Answer 40

glutamate !!

Question 41

which type of synapse is the most common?

Answer 41

**axodendritic**: pre - post synaptic cleft

Question 42

how do inhibitory post synpatic potentials work? ## Footnote give an example of direct and indirect inhibitory post synaptic pontetial

Answer 42

- K+ permeability increased OR increased Cl- perm. * *indirect: Muscarinic ACh receptor:** - G-protein activated - acts via 2nd messenger - indirectly opens K+ channel * *direct: GABA_A receptor:** - opens Cl- channel BOTH: = hyperpolarisation

Question 44

which ACh receptor is ionotropic and which is metabotropic?

Answer 44

iontropic ACh receptor: **nicotonic receptors.** (PNS, bit in CNS) metabotropic ACh receptor: **muscarinic** **receptor**

Question 45

which is the main excitatory NT in CNS? use one or both type of receptors? how can the ionotropic receptors be classified?

Answer 45

**- glutamate** - both ionotropic and metabatropic receptores - 3 ionotropic receptors classified as: a) NMDA b) Non-NMDA i) AMPA ii) Kainate

Question 46

describe basic overview of glutamate G-protein coupled receptor response?

Answer 46

G-protein coupled receptor --\> G protein comple (intracellular) --\> enzyme (+/-) --\> 2nd messenger its the second messenger which causes varied responses: - e.g. cAMP released: inhibitory - IP3 or DAG released: excitatory

Question 47

how does receptor modulation by NTs occur?

Answer 47

**receptor modulation by other NTs:** - NTs influence accumulation of _opposite NTs_ on post-synaptic membrane e. g. ionotropic glutamate receptor fires excitatory response BUT also feedback to GABA receptor and causes to disperse (and vice versa) causes a balance of inhib and excitatory systems.

Question 48

what are the three main type of 2nd messengers of GPCR?

Answer 48

- hydrophilic water soluble (IP33, cAMP, Ca2+) - hydrophobic water insoluble (DAG and PIP3) - gases (NO, CO and ROS)

Question 49

what are: a) tonic adaptation b) phasic adaptation to stimuli?

Answer 49

Tonic receptors adapt slowly and inform about the presence and strength of a stimulus. phasic - rapid adaption

Question 50

give skin sensory receptors example that do rapidly adapting slowly adapting

Answer 50

**rapidly adapting**: Meissner corpuscles (light touch), Pacinian corpsucles (vibration) s**lowly adapting:** Merkel cells (pressure, texture), Ruffini endings (stretching of skin)

Question 51

what do the 4 skin receptors detect?

Answer 51

Meissner corpuscles – Light touch * Merkel cells – Pressure, texture * Pacinian corpuscles – Vibration • Ruffini endings – Stretching of skin

Question 52

what do enteric neurons use as their major NT?

Answer 52

Ach, NO and seratonin

Question 53

where do the autonomic output signals go via from the hypothalamus? what does hypothalamus maintain homeostasis of ?

Answer 53

**_integration centre for ANS: hypothalamus:_** - Receives sensory stimuli and visceral sensations from the periphery (input signals, afferent fibers) - output signals go via **medulla oblongata and pituitary to target organ**s (smooth & cardiac muscles, exocrine glands) - maintains homeostasis of: **BP, body temp and electrolyte balance**

Question 54

where in the spinal cord do the neurons leave from for SNS? - which part of the spinal cord? where are cell bodies of SNS found? where do SNS preganglionic fibres synapse (3)

Answer 54

**_thoracolumbar (T1-L2) outflow:_** - cell bodies in lateral horn of the spinal cord - (short preganglionic nerves, long post-ganglionic nerves) **preganglionic fibres synapse in:** i) _paravertebral ganglia of the sympathetic chain: (_T1-4 sympathetic chain). ii) p_revertebral ganglia: T5-L2_ the nerve fibres from the spinal cord pass through the sympathetic ganglia and synapse outside the sympathetic trunk (prevertebral or collateral ganglia).) iii) _chromaffin cells of the adrenal medulla_ (pass independently)

Question 55

where are sympathetic postganglionic neurons that innervate abdominal viscera located? what do they both synapse at?

Answer 55

**_in prevertebral ganglia:_** **T5-T9 = great splanchnic nerve** (The greater splanchnic nerve is formed from the preganglionic fibres of T5–T9, which traverse the paravertebral ganglion and terminate in the coeliac and superior mesenteric ganglia) Function: Sympathetic supply of foregut and adrenal medulla **T10-T12 = lesser splanchnic nerve** Function: Sympathetic supply of midgut BOTH SYNAPSE ON POSTGANGLIONIC NEURONS IN THE CELIAC GANGLION - postganglionic fibres innervate smooth muscle and glands in stomach, small intestines, liver, kidney and spleen

Question 56

which sympathetic preganglionic fibres pass through the sympathetic chain and travel in lumbar splachnic nerves? what do they synapse on?

Answer 56

- **L1-L2 sympathetic preganglionic fibres** - Synapse on postganglionic neurons in **inferior mesenteric ganglion: innervates colon, rectum, bladder and genital**

Question 57

how is the PNS organised? do nerve fibres orginate at differe or same levels of spinal cord? most organs recieve dual or single innervation?

Answer 57

Craniosacral outflow: a) **Cranial nerves:** III, VII, IX, X: organs in head b) **Sacral nerves:** S2-S4: rectum, bladder and genitals 2. nerve fibres originate different levels of spinal cord 3. dual innervation

Question 58

How is the enteric NS organised? what does ENS control?

Answer 58

organisation: two major plexuses: **a) Myenteric plexus:** _located_: between circular and long. muscle layers _function_: motility **b) submucosal plexus:** _located_: between submucosal and circular muscle layer _function_: controls secretion and muscle function in the mucosal layer controls: **motility of intestine, exchange of fluids across mucosal surface, blood flow and secretion of gut hormones** (The enteric nervous system (ENS) controls effector systems of the digestive tract, consisting of the musculature, secretory glands, and blood vessels)