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26 Cards in this Set
- Front
- Back
Describe the FIVE layers of the epidermis
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stratum corneum - keratinised
stratum lucidum - clear layer not usually seen stratum granulosum - keratin-producing corneum precursor cells stratum spinosum - desmosome-rich mechanical layer stratum basale - mitotically active |
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What epidermal structures are associated with hairs?
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Outer root sheath (entire length), inner root sheath (deeper part), arrector pili muscles
Hair cuticles point toward surface and are apposed by root cuticles |
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How do sinus hairs differ from others?
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Sinus hairs are tactile and contain a blood space in the sheath
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What are the THREE phases of hair growth?
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Anagen - normal growth, capilla provides sustenance
Catagen - no capillar, hair regresses and moults Telogen - new hair growth and capilla formation |
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What is the difference between physiological and competitive antagonists?
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Physiological antagonists oppose the effect of agonists (not receptor-specific)
Competitive antagonists shift the agonist concentration-effect curve right |
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What is tachyphylaxis?
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Self-antagonism: desensitisation to a drug with repeated administrations
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Describe hepatic drug metabolism
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Phase I: lipophilic molecules are converted to more polar molecules
Phase II: a conjugate group is added to further increase polarity and aid excretion |
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Which diet types cause acid or alkali urine?
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Carnivores and concentrate-fed herbivores: acidic urine
Forage-fed herbivores: basic urine |
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What is normal distribution?
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68% of the population are less than one standard deviation from the mean
95% of the population are less than two standard deviations from the mean |
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What are the THREE components of a reflex arc? Where are they found?
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Afferent neurones (sensory): no dendrites; cell body and long axis in PNS, short axon in CNS
Interneurones: entirely in CNS Efferent neurones (motor): dendrites and cell body in CNS, axon in PNS |
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What are the THREE functions of astrocytes?
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Structural support of axons
Form the blood-brain barrier Nutrient transfer between capillaries and neurones |
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Describe how neurones respond to axonal injury
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Wallerian degeneration of all of the axon distal to the first Node of Ranvier proximal to the injury
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What is the resting potential of neurones? How is it maintained?
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-70mV. Maintained by Na+/K+ ATPase (3Na out for 2K in)
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How is an action potential generated in a nerve? In a muscle cell?
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Neurones: opening of fast Na+ and slow K+ channels to allow depolarisation
Muscles: Opening of Na+, K+ and Ca2+ channels to open voltage-gated Ca2+ channels |
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What THREE factors increase speed of transmission of nerve signals?
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Increasing axon diameter
Increasing membrane resistance Saltatory conduction |
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What are the TWO main types of synapse
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Electrical (bidirectional, through gap junctions)
Chemical (unidirectional. e.g. ACh synapses) |
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List the types of nerve fibre and their function, in order of size
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Largest to smallest:
Ia/Ib (A-alpha): proprioception II (A-beta, A-gamma): cutaneous III (A-delta): temperature + pricking pain IV (C): pain, itch, temperature |
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What muscle fibre type does sarcopenia (loss of strength with age) affect?
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Type I - fast/glycolytic
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In terms of the sarcmere, define:
Actin Myosin Titin T-tubules Troponin |
Actin - thin filament
Myosin - thick filament (sliding filament action of head long actin contracts muscle) Titin - binds myosin to Z-disc (spring-like) Troponin - facilitates sliding filament action when Ca2+ is present |
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What affect does insufficient prenatal nutrition have on muscle fibre type?
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Type II (slow, oxidative) is maintained in preference to type I (fast, glycolytic)
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Describe the arrangement of collagen in articular cartilage
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Collagen is arranged in layers at different orientations: perpendicular resists tension and parallel facilitates smooth movement
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What is the function of parathyroid hormone? Calcitonin?
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PTH activates osteoclasts and increases the surface area of their ruffled borders, liberating calcium
Calcitonin inactivates osteoclasts and decreases the size of their ruffled borders. |
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What is Wolff's law?
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Wolff's law dictates the ability of cancellous/trabecular bone to achieve maximum load-bearing strength from minimum mass
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How are osteoclasts formed?
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Fusion of monocytes; they are multinuclear
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What is the function of osteocytes?
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Perceive strain and recruit osteoblasts and osteoclasts as required
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What changes occur with disuse of bones in juveniles? In adults?
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Diameter of bone is reduced in juveniles, cortex is widened in adults.
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