1
Q
what are the 4 phases of an action potential?
A
initiation- depolarised to threshold voltage
upstroke- threshold reached causes voltage gated sodium ion channels open and causes an overshoot to a positive value
regeneration- thresh hold voltage also causes a more delayed openeing of voltage gated potassium ion channels brings voltage back to negative value
refactory period- absolute refactory period, no action potential can be fired, relative action potential, requires a larger action potential
2
Q
what are the 2 types of synapses?
A
electerical and chemical
3
Q
what are the features of an electrical synapse?
A
- bi-directional
- formed at gap junctions when the plasma membranes of two adjancent cells are with in 2-3 nm apart
4
Q
what are the features of a chemical synapse?
A
- unidirectional
- A synaptic cleft , a gap 30 nm wide, separates the presynaptic membrane of the terminal bouton and postsynaptic membrane of the target cell. The presynaptic terminal has synaptic vesicles , which contain the chemical neurotransmitter, and its membrane has an active zone where synaptic vesicles can dock and release the transmitter. The postsynaptic membrane opposite the active zone has a postsynaptic density packed with receptors capable of binding the transmitter
5
Q
what is the sequence of events that occur at a synapse?
A
1) action potential arrives at pre synaptic terminal
2) depolarisation causes voltage gated calcium ion channels to open in presynaptic membrane so calcium ions enter the terminal
3) this causes the release of transmitter from synaptic vesicles to synapse
4) diffuse across cleft and bind to receptors on post synaptic membrane
5) produces post synaptic potential
6) transmitter is transported back into the neurone
7) synaptic vesicles are reused and recycled
6
Q
what does it mean for a transmitter to be excitatory or inhibitory?
A
excitatory - increases the chance a postsynaptic neurone will fire an action potential
inhibitory - decreases the chance a neurone transmitter will fire an action potential
( a neurotransmitter can change which it is depending on receptors at post synaptic membrane etc)
7
Q
what are the two broad categories of neurone transmitters?
A
classical transmitters and peptide neurotransmitters
8
Q
what are the two types of cell surface receptors that neurotransmitters attach to?
A
Ligand-gated ion channels ( ionotropic receptors), G-protein-coupled (metabotropic ) receptors
9
Q
what is nociception?
A
transmission and transduction of noxious stimuli (an acctually and potentially tissue damaging event)
10
Q
nociceptive vs neuropathic pain
A
NOCICEPTION: NEUROPATHIC:
- impulses from nociceptors to brain -impulse caused by damaged
- feel as ache/throb. nerves
- identifiable stimulus -feels tingling/ burning
- mostly acute - unidentifiable stimulus
- responds to medication - mostly chronic
- poor response to medication
11
Q
what are the 3types of noxious stimuli?
A
mechanical, chemical and thermal
12
Q
what is the ascending pathways for pain?
A
spinothalamic
anterior - crude touch and pressure
lateral - pain and temprature
13
Q
what are the two types of the spinothalmic pathway to pain?
A
Spinoreticular (automatic responses to pain)
Spinoparabrachial (emotional/affective response to pain)
14
Q
describe the spinothalamic pathway
A
nociceptor afferent –> dorsal horn spinal cord –> spinothalamic tract –> thalamus —> somato sensory cortex
15
Q
describe the spinoreticular pathway for pain
A
nociceptor afferent –> dorsal horn spinal cord –> medulla, pons, midbrain –> thalamus –> somatosensory cortex
16
Q
describe the spinoparabrachial pathway of pain
A
nociceptor afferent –> dorsal horn spinal cord –> pons –> amygdala, hypothalamus
17
Q
what are two pain fibres and how do they differ in the pain they cause?
A
A delta fibres: Bright, sharp, stabbing,“Fast” pain, Cold stimuli
C fibres: Dull, throbbing, aching, “Slow” pain , Warm stimuli
18
Q
what are the 2 main cells that make up nerve tissue?
A
neurons- structural and functional unit of nervous system, rapid communication
neuroglia - non-neuronal, excitable cells, scaffolding
19
Q
what are the 4 types of neuroglia in the CNS?
A
astrocytes - blood brain
microglia - phagocytosis
ependymal cells - fluid
oligodendrocytes - myellin sheath in CNS
20
Q
what is the strucrure and function of sensory (afferent) nerve fibres?
A
structure: somatic and visceral nerve fibres
function: conducts impulses from receptors to the CNS
21
Q
what is the function of motor nerve fibres (efferent)?
A
- conducts impulses from the CNS to effectors (muscles and glands)
22
Q
what are the features of the autonomic nervous system?
A
- visceral motor (involuntary)
- conducts impulses from the CNS to cardiac muscles, smooth muscles and glands
23
Q
what are the features of the somatic nervous system?
A
- somatic motor (voluntary)
- conducts impulses from the CNS to skeletal muscles
24
Q
what are the two divisions of the autonmic nervous system?
A
sympathetic and parasympathetic
25
what makes up a spinal nerve?
dorsal rootlets - sensory nerve fiber
ventral rootlets - motor nerve fiber
--> join to form dorsal and ventral nerve roots and unite to form a spinal nerve
26
what are the two neuroglia cells in the peripheral nervous sytem?
schwann cells - myellin sheath
| satellite cells - support neuronal cell bodies in ganglia in PNS
27
what is a neurolemma?
a thin sheath around a nerve axon, and its formed by the cell membranes of schwann cells that immediatley surround the axon seperating it from others
28
what is the endomerium?
inner layer of connective tissue which surround the neurolemma (myellin sheath)
29
what is a fasicle?
a bundle of nerve fibres
30
where is perinerium found?
surrounding a fassicle
31
where is epinerium ?
very outter layer surrounding many fassicles
32
what are the two families of ganglia?
autonomic ganglia - belong to autonomic nervous sytem
| cerebro spinal ganglis - e.g. doral root ganglion
33
what is the structral difference between cerebro spinal ganglia and autonomic ganaglia?
autonomic ganglia have synapses where as cerbro spinal ganglia have no synpases just neuronal cell bodies
34
describe neuro transmitters in parasympathetic and sympathetic nervous system (post synaptic and pre synaptic nerurones)
presynaptic neurone always release acetylcholine (so is chollinergic),
where as in the sympathetic the post synaptic neurone releases noradrenaline and the post synaptic neurone in the parasympathetic continues to release acetylcholine
35
how do parasympathetic and sympathetic differ in where the nerves are coming from?
parasympathetic- cranio sacral
| sympathetic- tharaco lumbar
36
length of neurones difference between sympathetic and parasympathetic
sympathetic- short presynaptic, long postsynaptic
| parasympathetic - long presynaptic, short postsynaptic
37
what is somatic sensory afferent fibres function?
somatic sensory afferent fibres transmit signals relation to touch, pain, temp and position
38
what is somatic motor efferent fibres function?
somatic motor efferent fibres stimulate skeletal muscles by causing contractions- voluntary an reflex
39
what is the pathway of presynaptic sympathetic visceral efferent fibres?
leaves through anterior roots, enters anterior rami of spinal nerves and pass to sympathetic trunk
40
what are the 4 options for a visceral efferent (sympathetic) fibre after leaving lateral horn?
1) synapse immediatley
2) ascend and synapse
3) descend and synapse
4) leave without synapsing through splanchnic nerve
41
what are the 2 exit of the presynaptic parasympathetic visceral efferent fibres?
cranial - CN |||, V||, |X, X
| sacral - pelvic splanchnic nerves
42
what are the features of the cervical plexus?
- innervates some of the structures in the neck and trunk
- located in the posterior triangle of the neck and half way up the sternocleidomastoid muscle in the prevertabral layer of cervical fascia
- formed by the anterior rami of the cervical spine nerves C1 - C4
43
what are the muscular branches of the cervical plexus?
- Phrenic Nerve: C3-C5, motor innervation to diaphragm.
- Nerves to Geniohyoid and Thyrohyoid: C1, elevate/depress the hyoid bone.
- Ansa Cervicalis: C1-C3, supplies infrahyoids to depress the hyoid bone
44
what are the sensory branches of the cervical plexus?
- Greater Auricular Nerve: C2-C3, sensation to external skin and skin over parotid gland
- Transverse Cervical Nerve: C2-C3, sensation to anterior neck
- Lesser Occipital Nerve: C2 (+/- C3), cutaneous sensation to the posterosuperior scalp
- Supraclavicular Nerves: C3-C4, sensation to skin overlying the supraclavicular fossa and upper thoracic region and sternoclavicular joint
45
what are the features of the brachial plexus?
A network of nerve fibres that supplies the skin and musculature of the upper limb.
Formed by the anterior rami of C5, C6, C7, C8 and T1.
Divided into 5 parts: roots, trunks, divisions, cords and branches.
After their formation, the nerves pass between the anterior and medial scalene muscles to enter the base of the neck.
At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve then divides into anterior and posterior nerves.
46
what are the 5 terminal branches of the brachial plexus?
Musculocutaneous, Axillary, Median, Radial, Ulnar
47
what are features of the lumbar plexus?
- Network of nerve fibres that supplies the skin and musculature of the lower limb.
- Located within the substance of the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae.
- At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve then divides into anterior and posterior nerves.
- Formed from spinal nerves L1-L4.
48
what are the 6 branches of the lumbar plexus?
Iliohypogastric, Ilioinguinal, Genitofemoral, Lateral Cutaneous Nerve of the Thigh, Obturator, Femoral
49
what are the features of the sacral plexus?
- Network of nerve fibres that supplies the skin and muscles of the pelvis and lower limb.
- Formed by the anterior rami of the sacral spinal nerves S1, S2, S3 and S4. It also receives contributions from the lumbar spinal nerves L4 and L5.
- At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve then divides into anterior and posterior nerves.
50
what are the branches of the sacral plexus?
Superior Gluteal Nerve, Inferior Gluteal Nerve, Sciatic Nerve, Posterior Femoral Cutaneous, Pudendal Nerve, (Other Branches: Nerve to piriformis, obturator internus, quadratus femoris )
51
what is the therapeutic index?
A ratio that compares the blood concentration at which a drug becomes toxic and the concentration at which the drug is effective. The larger the therapeutic index (TI), the safer the drug is. If the TI is small (the difference between the two concentrations is very small), the drug must be dosed carefully and the person receiving the drug should be monitored closely for any signs of drug toxicity.
52
what is the formula for therapuetic index?
median lethal dose / median effective dose
53
what is the definition of addiction?
the fact or condition of being addicted to a particular substance or activity.
54
what are the 3 functions of the lymphatic system?
1) picks up lymph
2) waste removal
3) deliver nutrients
(lymph is cleansed at lymphnodes)
55
how is lymph formed?
- proteins and fluids are able to move out the capillaries via the capillary pores
- this fluid is now in the interstitial fluid, and most of it is reabsorbed into the capillary
- the rest is then taken into the lympathics and forms lymph
56
where does lymph go when it leaves lymphatic system?
dumped in the veins through lymphatic capillaries
57
describe the structure of lymphatic capillaries
- found in the intersistital space
- extremely permable cells loosely overlap
- forms one way mini valves
- collagen filaments provide flexability but retain its overall shape
58
how is movement of lymph into lymphatic capillaries controlled?
- when the the pressure in the interstitial space is higher the mini valves open
- when the pressure in the interstitial space is lower the mini valves will close
59
how does lymph move through the lymphatic system?
capillaries -> vessels -> trunks -> ducts
- no pulses, instead smooth muscle reacts to arterial pulse and skeletal muscle provide external pressure to keep the lymph moving
60
how is lymph stopped from moving backwards?
- valves
61
what are 5 different lymphatic trunks?
1) lumbar (x2)
2) bronchomediastinal (x2)
3) subclavian (x2)
4) jugular (x2)
5) intestinal (x1)
62
what are the 2 ducts of the lymphatic system and where do they dump lymph?
1) thoracic
2) right lymphatic
- -> both dump into jugular and subclavian veins (on each side)
63
what are two lymphoid organs and what is their function?
- diffuse lymphoid tissue
- lymph nodes
- -> remove foreign material in lymph (look outs for immune system)
64
describe lymph nodes their structure and function
- balls of lymphoid cells and protein
- where they are concentrated in the lymph trunk they can be felt: neck, armpit and groin
- found in intestinal wall and called peyers patches
- lymph is filtered into lymph nodes where dendritic cells then identify a pathogen
65
what happens when lymph is drained into a lymph node and a pathogen is present?
- dendritic cells, becomes an antigen presenting cell
- come across B cells which are types of lymphocytes, when it detects a foreign antigen it becomes a plasma cell and produces specific antibodies
- antibodies exit lymphnode, become part of the lymph
- T cells circulating in the lymphatic system on look out for foreign cells
66
what is the role of the thalamus?
destroys T cells which reacts to self antigens
67
what is edema?
the build up of fluid in the interstitium (extracellular fluid)
68
what are the reasons oedema can occur?
1) increased hydrostatic pressure in interstitium
2) decreased osmotic pressure in interstitium
3) lymphatic destruction
4) increased permeability of vasculature
5) water retention (reduced lymphatic drainage)
69
what are the features of gram positive bacteria?
- They have a thick peptidoglycan layer and cytoplasmic lipid membrane.
- These bacteria lack an outer membrane
- Have a lower lipid content
- They move around with the help of locomotion organs such as cilia and flagella
70
what are the three functional layers of the skin?
- epidermis
- dermis
- subcutaneous tissue ( hyodermis)
71
what seperates the epidermis and the dermis?
semipermable basement membrane seperates the epidermis and dermis
72
what are the layers of the epidermis? (Come Lets Get Sun Burnt)
- corneum
- lucidum
- granulosum
- spinosum
- basale
73
what are the features of the stratum corneum?
- dead keratinocytes that are continuosly shed and replaced
| - it protects deeper layers from injury
74
what is the feature of the stratum lucidum?
- present in finger tips, palms and soles of the feet
| - 4-6 rows of clear flat dead keratinocytes that provide an extra layer of toughness
75
what are the features of the stratum granulosum?
- Keratinocytes that are undergoing apoptosis as they get further away from their nutrition supply.
- Contains keratinohyalin and lamellar granules.
76
what are the features of the stratum spinosum?
- Numerous keratinocytes producing keratin in the keratin intermediate filaments. Active mitosis.
77
what are the features of the stratum basale?
Contains cuboidal/columnar keratinocytes. Stem cells are found here that undergo cell division to produce new keratin from keratin intermediate filaments.
78
what are the functions of keratinocytes?
- produces keratin
- barrier: prevents pathogens and toxins getting in
- prevents loss of moisture, heat
- Stimulates inflammation and activates Langerhans cells in response to injury.
79
what is the function of melanocytes?
- develops from ectoderm
- produces melanin to absorb radiation
- They donate melanin to keratinocytes so the melanin wraps around nucleus to protect DNA from radiation.
80
what is the function of langerhans cells?
- originate from myeloid precursors in bone marrow
| - participate in immune response by presenting antigens onto the cell surface
81
what is the function merkel cells?
- They contain Merkel disc – detect touch sensations.
82
what are the features of the dermis and its two layers?
- dense irregular connective tissue containing collagen and elastic fibres
- Contains fibroblasts and proteoglycans within its extracellular matrix
- papillary region and reticular region
83
what are the features of the superficial papillary layer (of the dermis)?
- 1/5 of the total thickness of the dermis
- contains fine collagen and elastic fibres - lose connective tissue providing both strength and flexibility
- dermal papillae provides increased surface area
- messiners corpuscles and free nerve endings present
- contains ending of end of blood and lymph vessels
- provides nutrients to epidermis through nerve endings
84
what are the functions of the dermal papillae?
- lie as thick ridges which project into the epidermis and is what we see as finger prints
- creates a strong bond between dermis and epidermis to prevent moving under high mechanical stress - because of ridge like structure
- The ridges help to increase grip as well as increases the number of touch sensory neurons increasing tactile sensitivity, very useful in hands and feet.
85
what are the feature of the reticular layer (of the dermis)?
- thick layer, forming dense irregular connective tissue
- It attaches onto subcutaneous layer below
- contains collagen and elastic fibres which allows the skin to stretch and return back to its normal shape
- It supports hair follicles, sweat glands and sebaceous glands
86
what are the 5 skin receptors?
Meissener corpuscle - fine touch and pressure (fast)
Merkels disc- fine discrimatory touch, shapes and textures (slow)
Pacinian corpuscle - pressure and vibration (fast)
Ruffinian corpuscle - propiception and stretching (slow)
Free nerve endings - touch, thermal and noiciception (fast and slow fibres)
87
what are the features of the hypodermis (subcutaneous layer)?
- layer of adipose and areolar tissue
- a large depot for fat
- contains large blood vessels to the skin
- insulator to maintain body temprature
- anchors the skin layers to the muscle beneath and protects bones and muscles through shock absorbing
88
what is the function of sebaceous glands in the skin?
- oil glands
- connected to hair follicles
- secretes sebum - to prevent water loss and growth of some bacteria
- sebum production leads to skin problems such as acne and oily skin
- when sebum accumlates and blocks the gland it causes an inflamatory reaction
89
what are the 2 types of sweat glands (Sudoriferous glands)?
Eccrine- regulate body temp through evaporation
| Apocrine - larger ducts and lumens and activates after puberty
90
describe a ceruminous gland
- modified sweat gland in external ear
- simple, coiled tubular glands
- forms a waxy lubrication secretion
- opens into external auditory canal
- earwax helps protect the ear from damage and microbial invasion
91
what are the two forms of melanin?
- Pheomelanin – yellow/red
| - Eumelanin – brown/black
92
what happens when the body needs to cool down (thermoregulation)?
- blood vessels dilate so a greater amount of blood flows towards the surface of the skin and body releases heat through thermal radiation
- body can cool through conduction, placing a cool object on the skin
- sweating, as it evaporates it takes heat with it
- hair on skin stays flat (arrector pilli muscles relax) , causes heat loss via convection
93
what happens the body need to heat up (thermoregulation)?
- blood vessels constrict so less blood flows near the skin
- limited sweat
- hairs stand up on end (arrector pilli muscles contract), traps heat in an insulating layer
- shivering, muscle spasms generate heat
94
what is the process of epidermal wound healing?
when a wound only affects the epidermal layer:
- the basal cells of the epidermis detach from the basal membrane and migrate across the wound until in reaches the middle. This happens on both ends of the wound.
- Once the basal cells from each side encounter each other in the middle, they stop migrating due to contact inhibition.
- Epidermal growth factor stimulates the basal cells to divide until it builds a new strata and thickens the epidermis.
95
what are the 4 phases of deep wound healing?
INFLAMMATORY
- blood clot forms, and vasodilation occurs
MIGRATORY
- clot forms a scab
- epithelial cells beneath scab migrate to cover wound
- fibroblasts synthesis scar tissue
damaged blood vesels grow and granulation tissue forms
PROLIFERATIVE
-proliferation of the epithelial cells beneath the scab
MATURATION
- scab falls off
96
what are the benefits of the normal flora?
- colonisation leads to resistance from more virulent bacteria
- resists other colonisation attempts ( competition)
97
what bacteria form the natural flora on the skin?
- staph
- aureus
- diphtheroids
- streptococci
- pseudomonas aeruginosa
- candida
98
what agents can penetrate skin?
- Athropods
- Needles
- surgical wounds
- abrasions and wounds
- animal bites
99
what does ganglion mean?
a bump on a nerve, collection of nerve cell bodies
100
what are the different types of A fibres?
alpha, beta, gamma, delta
| -> A fibres are heavily myelinated
101
what are the features of B fibres?
- all associated with the preganglionic autonomic fibres of the autonomic nervous system
- usally myelinated , but as heavily as A fibres
102
what the features of C fibres?
unmyelinated, responsible for slow pain
103
what nerve supplies the extensor muscles in the arm?
radial nerve
104
what muscles does the radial nerve supply?
- brachioradialis
- extensor pollicis longus muscle
- extensor carpi radialis longus
105
what muscle does the musculocutaneous nerve supply?
biceps brachii
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