Physiology

Question 1

1. Name the four types of neurons
2. How are they defined?
3. Define each
4. What are the four functional regions of neurons

Answer 1

1. Unipolar, pseudounipolar, bipolar, multipolar
2. Number of neurites
3. Unipolar-one neurite
   Pseudounipolar- one neurite that bifurcates
   Bipolar-two neurites
   Multipolar-three or more neurites
4. Input, integrative, conductive and output

Question 2

1. The upstroke of an action potential is caused by an _______ of _________ ions through voltage gated _______ ion channels.
2. The downstroke of an action potential is caused by an ______ of _________ ions through voltage gated ______ ion channels.
3. Myelinated axons exhibit __________ conduction between the nodes of __________.

Answer 2

1. Influx, sodium, sodium
2. Efflux, potassium, potassium
3. Saltatory, Ranvier

Question 3

1. What are the three different morphological types of synapses?
2. What are the two different functional types of synapse?
3. What are the two possible potentials called?
4. What is the difference between spatial summation and Temporal summation
5. Name the two types of neurotransmitter receptors

Answer 3

1. Axodendritic, Axosomatic, Axoaxonic
2. Inhibitory and excitatory synapses
3. Excitatory and Inhibitory Post-synaptic Potential
4. Spatial- many inputs converge on a neuron to determine its output.
   Temporal- one input modulates the output of one neuron
5. Ionotropic- act on ion channels directly
   Metabotropic- act on ion channels indirectly

Question 4

1. Somatosensory neurones are mostly composed of ______ neurones in series.
2. What is meant by modality?
3. What is meant by threshold?

Answer 4

1. Three
2. The type of stimuli that excites a sensory nerve e.g. nociception/mechanoreception
3. The intensity of stimuli necessary to elicit a response- some neurones low threshold, others high
   4.

Question 5

1. Define adaptation
2. What is meant by Slowly Adapting (SA)
3. What is meant by Fast Adapting (FA)

Answer 5

1. is a feature of sensory units that determines whether they change their firing rate only in response to a stimulus of changing intensity, or fire continuously throughout a constant stimulus
2. The units discharge action potentials at a constant, or very gradually reducing, frequency throughout the period of a suprathreshold stimulus.
3. action potentials are discharged initially, but then the unit becomes become ‘silent’ despite the stimulus persisting

Question 6

1. What does RF stand for?
2. What does it mean?
3. ______ _____ is the ability to discriminate between stimuli that are separated in space

Answer 6

1. Receptive field
2. Target territory from which a sensory unit can be excited.
3. Spatial Acuity,

Question 7

1. Identify some sensory receptors found in the skin

Answer 7

1. free nerve endings, Pacinian corpuscles, Meissners Corpuscules, Merkel’s discs, Krause end bulbs, Ruffini endings

Question 8

1. Spinal cord consists of _______ (cell bodies and sensory afferent terminals) and ______(fibre tracts) matter the relative proportions of which vary along its length. _____ matter subdivided into ______(posterior) and ______ (anterior) horns and ten distinct _______ of ______.
2. Name the two somatic sensory pathways.
3. What information is carries by each?

Answer 8

1. Grey, white, Grey, dorsal, ventral, laminae of Rexed
2. DCML (Dorsal Column Medial Lemniscal pathway) and STT (Spinothalamic tract)
3. DCML– Discriminatory touch (stereognosis), pressure, vibration, conscious proprioception
   STT– Pain, thermosensation, crude touch, itch, tickle

Question 9

1. Name the two ascending tracts of the dorsal column
2. The decussation of the DCML occurs at the _________, whereas the decussation of the STT occurs at all levels on the spinal cord.
3. What happens to the somatosensory cortex if a finger (say D3) is lost in an accident, or amputated?

Answer 9

1. Gracile and Cuneate tracts
2. Brainstem
3. The area formerly representing D3, after several months, now responds to stimulation of the adjacent digits (D2 and D4 – their cortical representation expands into the territory formerly representing D3).

Question 10

1. Name the cortex which deciphers information received from the post-central gyrus?
2. What is the name given to the different areas of the somatosensory cortex?

Answer 10

1. Posterior parietal cortex

2. Brodmann areas

Question 11

1. Name the two lateral pathways of the spinal cord

2. Name the four ventromedial pathways

Answer 11

1. Lateral corticospinal tract and rubrospinal tract

2. Pontine and medullary reticulospinal tract, tectospinal tract, vestibulospinal tract.

Question 12

1. What does the somatic motor system consist of?
2. Upper motor neurones (UMNs) are within the _____ and lower motor neurones (LMNs) are with soma within the brain stem and _____ horn of the spinal cord. UMNs supply input to LMNs to ________ their activity
3. LMNs comprise _______ ______ ________ (α-MNs) that innervate the bulk of fibres within a muscle that generate force. _________ motor neurones (γ-MNs) innervate a sensory organ within the muscle known as a _______ ________.

Answer 12

1. Skeletal muscle and Upper/Lower motor neurones
2. Brain, ventral, modulate.
3. alpha motor neurones, Gamma, muscle spindle

Question 13

1. Muscles that work together to perform an action are called ________. Meanwhile muscles that work against these are called _________.
2. Define a motor unit.
3. Define a motor neuron pool

Answer 13

1. Synergists, antagonists
2. A single alpha motor neuron and all the skeletal muscle it innervates
3. A collection of motor neurons that innervate a single muscle
   4.

Question 14

1. What are the four graded stages of muscle activation

2. What are the two major types of skeletal muscle and what colour is each? What other three divisions are there?

Answer 14

1. Twitch (one action potential), wave summation (collection), unfused tetanus, fused tetanus.
2. Slow-oxidative (red meat) and Fast-glycolytic (white meat). Fast fatiguing, fatigue resistant and slow fatiguing

Question 15

Activation of an upper motor neurone (UMN) causes the \_\_\_\_\_\_\_motor neurones that it supplies to be excited.
Motor units (LMNs and the muscle fibres that they innervate) are recruited in the order of their \_\_\_\_ (i.e. progressively increasing – small LMNs are more easily excited than large LMNs)
Activation in such an order allows for a \_\_\_\_\_ \_\_\_\_\_\_ of muscle force across a wide range of \_\_\_\_\_\_\_ developed.

Answer 15

Lower, size, fine control, tensions

Question 16

1. Muscle spindles consist of _______ fibres within a _________ capsule. The _______ fibres are innervated by ________ afferents and _______ ________ _________ efferents.
2. The knee jerk reflex is an example of a ________ reflex. The myotatic reflex (e.g. ‘knee jerk’) can be reinforced by the _________ manoeuvre

Answer 16

1. Intrafusal, fibrous, intrafusal, sensory, gamma motor neurones.
2. Myotatic, Jendrassik

Question 17

1. Name the cells that transduce auditory information
2. Name the nerve which carries sensory information from the otic capsule
3. The ________ membrane separates the Scala vestibuli from the Scala media. The _________ membrane separates the Scala media from the Scala Tympani. The Scala vestibuli and Scala Tympani meet at the _________. The stapes attatches to the _____ window, passing vibrations into the Scala _________.

Answer 17

1. Hair cells on the organ of Corti
2. Vestibulocochlear CNVIII
3. Reissner’s, Basilar, Helicotrema, oval window, Vestibuli

Question 18

1. Name the membrane that vibrates and bends the hair cells of the organ of Corti
2. Name the four main nuclei through which auditory information passes before reaching the Primary auditory cortex

Answer 18

1. Tectorial membrane
2. Cochlear nuclei (medulla), Superior olivary nuclei (pons), Inferior colliculus (midbrain) and medial geniculate nuclei (midbrain).

Question 19

1. Name the three vestibular apparatus
2. Name the two otolith organs and the name of the calcium carbonate crystals that rest on the otolithic membrane
3. Name the structural landmark which divides the otoconia into trenches on each monolith.
4. Name the three vestibular reflexes

Answer 19

1. Anterior, posterior and horizontal semicircular canals
2. Utricle and saccule, otoconia
3. Striola
4. Vestibulo-ocular reflex – keep the eyes still in space when the head moves.
   Vestibulo-colic reflex – keeps the head still in space – or on a level plane when you walk.
   Vestibular-spinal reflex – adjusts posture for rapid changes in position

Question 20

1. Name the two cells through which light passes before reaching the photoreceptors
2. Name the two components of rhodopsin
3. What is meant by convergence?
4. The high convergence of rod cells results in relatively high _________ and low ___________

Answer 20

1. Ganglion cells, bipolar cells
2. Retinal and opsin
3. Where rod/cone cells send collective information to a single ganglion cell.
4. sensitivity, acuity

Question 21

1. Name the two cells which facilitate central-surround/organisation/lateral inhibition
2. What is meant by retinotopy?
3. What is meant by visuotopic organisation?
4. What is the first part of the visual cortex to receive information from the Lateral Geniculate Nucleus?

Answer 21

1. Amacrine and horizontal cells
2. Visual field representation on the retina
3. The way in which the visual field is mapped on the primary visual cortex.
4. Striate cortex

Question 22

1. What are the three forms of pain? Which are physiological?
2. Name the two types of nociceptors and their function
3. Where are the soma of nociceptors found?
4. Define hyperalgesia and allodynia

Answer 22

1. Physiological- nociceptive, inflammatory
   non-physiological- pathological
2. A delta-fibres (first/fast pain) and C-fibres (slow pain)
3. Posterior root ganglia
4. Hyperalgesia- amplified pain sensation,
   allodynia- pain that is caused by something that isn’t normally painful- stroking skin.

Question 23

1. Inflammatory pain is transmitted by _________ nociceptors. They release _______ which promote the production of prostaglandins and bradykinin amongst other effects. They ultimately cause hyperalgesia and __________.
2. Name the two main nociceptive tracts

Answer 23

1. Peptidergic, peptides, allodynia

2. Spinothalamic tract, Spinoreticular tract.

Question 24

1. Identify 7 excitatory neurotransmitters

2. Identify 3 inhibitory neurotransmitters

Answer 24

1. Acetylcholine, noradrenaline, adrenaline, serotonin, dopamine, aspartate, glutamate
2. GABA (gamma-aminobutyric acid), histamine and glycine