muscle and skin

Question 1

skeletal functions:

Answer 1

• movement
• support/posture
• sheild organs
• controls digestice and urinary tracts
• body temperature

Question 2

skeletal muscle fibre connective tissue layers:

Answer 2

endomyosin - wrap around each individual myosin /fibre
perimysium - wraps them into fascicles. allows the nervous system to trigger a specific movement of a muscle by activating a subset of muscle fibers within a bundle
Epimysium - allows a muscle to contract and move powerfully while maintaining its structural integrity and separates muscle from other tissues and organs in the area, allowing the muscle to move independently.

Question 3

Myosin -

Answer 3

thick filament, each filament with 300 globular heads, each cycle 5 times per second.

Question 4

Neuro muscular junction activity AND cause of contraction:

Answer 4

nerve impulse reaches nmj, ca2+ releasd causes ACh release into cleft, binds to receptors. Entry of Na+ into sarcoplasm produce action potential.
Ca2+ release, binds to troponin and conformational change occurs. unmasks myosin binding sites so can slide along actin
Requires ATP
terminates when the nerve impulse stops
ACh broken down by AChesterase and Ca2+ reabsorbed by sarcoplasmic reticulum

Question 5

what is Botulinum toxin :

Answer 5

cleaves proteins needed for exocytosis (SNAREs) od ACh in ANS. leads to paralysis. can be in cardiovascular cause death

Question 6

clinical uses of botulinum toxin:

Answer 6

• treat cross eyednedd

- uncontrolled eye movement

Question 7

What is tetnus:

Answer 7

• bacterial toxin
• a sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate.
• lock jaw - interfere with ability to breath
• stops release of ACh

Question 8

difference between slow and fast fibres-

Answer 8

slow - 1/2 diameter of fast, longer to contract, aerobic metabolism, 38 ATP, fatigue resistant

fast - anaerobic, 2 ATP, lactic acid, fatigue but can use creatine to produce ATP which reduces fatigue

Question 9

use of creatine by muscles:

Answer 9

to produce ATP as creatine phosphate acts as a phosphate donor. Enzyme creatine kinase synthesises P-creatine to provide P for energy in first fe min of intense exercise. creatine recycled at rest in mitochondria where P is added

Question 10

Hypertophy?

Answer 10

increase diameter of muscle fibres as her myofiliments are added in anaerobic exercise

Question 11

Skin uses?

Answer 11

• protection from impact
• barrier to chemicals and infections
• maintain temperature
• vitamin D3 synthesis
• excretes salt and water and milk(mammary)

Question 12

Thick vs thin skin

Answer 12

thick - palms, no hair, 5 layers

thin - 4 layers

Question 13

EPIDERMIS layers/ stratum

Answer 13

basale - 3 cell types = keratinocytes(miotic), melanocytes(colour) and merkel (sensory touch and connect to nerves)

Spinosum - thickest, keratinocytes wit higher keratin, cells detach from basement membrane and migrate upwards

granulosum - glycolipid covers keratinocytes to make water resistant barrier

lucidum - only in thick skin, no nuclei or organelles

corneum - top layer, dead skin, high lipid content as a barrier

Question 14

Dermis layers/stratum

Answer 14

dermis is thicker than epidermis

papillary layer - connective tissue
reticular layer- irregular dense rich in collagen
hypodermis - connective tissue and adipocytes

Question 15

Sweat glads of body

Answer 15

apocrine - in hair follicles

Mercocrine- secrete perspiration

Question 16

how is skin a barrier:

Answer 16

sebum contains bactericidal substances with a pH 4-6

keratin is tough

Question 17

Vitamin D3 production

Answer 17

produced in skin, synthesised in basal and spinosum and further processed in liver and kidneys to produce cofactor VDR that is a transcription factor