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biology > week 7- muscular system and movement > Flashcards

week 7- muscular system and movement Flashcards

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1
Q

function of muscular tissues

A
  • producing movement
  • stabilising body position
  • support soft tissue
  • generating heat
  • storing & moving substances within body
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2
Q

what are the 3 types of muscle tissue

A

smooth, cardiac, skeletal

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3
Q

where is the smooth muscle located

A
  • Located in walls of hollow internal structure
  • Blood vessels - changes diameter
  • Stomach, intestine, bladder, uterus, airway to lungs

**. no tendons

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4
Q

what is the smooth muscle involuntary control

A
  • Spontaneous rhythmic cycles (pacesetter cells)
  • Influenced by hormones, stretching, ANS
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5
Q

what is smooth muscle histology (cell type)

A
  • Uni-nucleated
  • Spindle shaped
  • Non-striated
  • Autorhythmic
  • Can divide
  • Can regenerate
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6
Q

location of cardiac muscle

A

Only found in the heart

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7
Q

cardiac control involuntary control

A
  • Pacemaker cells (autorhythmic)
  • Influenced by ANS and hormones
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8
Q

what is cardiac muscle histology (cell type)

A
  • Uni-nucleated
  • Striated
  • Branched
  • Intercalated discs
  • Myoglobin stores O2
  • Cannot divide
  • Cannot regenerate
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9
Q

where is the skeletal muscle located

A

Most abundant muscle type in the body

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10
Q

skeletal tissue voluntary control

A
  • Controlled by nerves of the central nervous system
  • Can be influenced by hormones
  • Contraction = shortens muscle
  • Relaxation = lengthens muscle
  • Skeletal muscle can ONLY pull bone
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11
Q

skeletal muscle histology (cell type)

A
  • Very long
  • Multinucleated
  • Cylindrical
  • Striated
  • Myoglobin stores O2
  • Cannot divide
  • Can repair
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12
Q

what is muscle hypertrophy

A

increase muscle size
* increase in use ->
* increase of tissue size->
* due increase size of cells
eg skeletal muscle

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13
Q

what is muscle hyperplasia

A

increase cell number
- increase of tissue size
- due to increase in cell number
eg smooth muscle

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14
Q

what is muscle atrophy

A

decrease size of muscle
- decrease use
- decrease in tissue size
- due to decrease in size of cells

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15
Q

skeletal muscle organisation

A

muscle -> fascicle -> myofibril -> myofilaments

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16
Q

what is the tissue that wraps around the whole muscle

A

epimysium

17
Q

what is the tissue that wraps around the whole fascile

A

endomysium

18
Q

what is the connective tissue under epimysium

A

perimysium

19
Q

Myofibril structure components

A
  • Bundles of protein filaments (myofilaments)
  • Actin
  • Myosin
  • Titin
  • Myofilaments are responsible for muscle contraction
  • Sarcomere = contractile unit
20
Q

How does muscle contraction occur

A
  • Occurs at the level of myofibrils (contractile elements)
  • During contraction and relaxation actin and myosin slide past each
    other
  • Contraction is stimulated by the presence of CALCIUM
  • Requires ATP as an energy source
21
Q

Sliding filament theory

A
  • ↑ Overlap of actin and myosin
  • Sarcomeres shortening
  • Muscle contraction
22
Q

Summary: steps in muscle contraction/relaxation

A
  1. ACh released in NMJ; binds to receptors
  2. Action potential reaches T tubule
  3. Sarcoplasmic reticulum releases Ca2+
  4. Active site exposure; cross bridge formation
  5. Contraction cycle begins
  6. Ach broken down by AChe
    (acetylcholine esterase)
  7. Sarcoplasmic reticulum recaptures Ca2+
  8. Contraction ends
  9. Relaxation occurs; passive return to resting length
23
Q

Muscle tone

A
  • Certain degree of contraction or undertone of contraction that occurs in muscles while at rest
  • Allows us to maintain posture
  • Stabilises bones and joints
  • Ready response state
24
Q

hypertonia

A

stiff limbs, high muscle tension, difficulty moving, muscle spasms

25
Q

hypotonia

A

floppy limbs, low muscle tone, difficulty standing, instability

26
Q

The stimulation of the motor neurons will lead to the activation of the muscle cel are

A
  • Nerve impulse arrives at axon terminal: Stimulation of Ca2+ voltage- dependent channel on pre-synaptic button: Ca2+ enters axon terminal
  • Exocytosis of Acetylcholine
    Acetylcholine diffuses into synaptic cleft and binds to nicotinic receptor sites on sarcolemma of the muscle
  • Na+ entry creates depolarisation, Action Potential is generated and transferred along the sarcolemma.
    -Depolarisation along sarcolemma reaches T tubule and leads to sarcoplasmic reticulum releasing Ca++into the sarcoplasm
  • Calcium attaches to troponin, exposing the point of attachment for myosin on actin myofilament and ‘sliding’/contraction begins in the presence of ATP
27
Q

Describe the major age-related changes in the muscular system

A

change in muscle size
loss of strength and elasticity
decrease exercise tolerance
slower recovery from injury

28
Q

. Describe how bones grow and develop throughout the lifespan ** at puberty**

A
  • Increasing sex hormone levels with rising GH and thyroid hormone
  • Stimulate osteoblasts to build bone mass → rapid bone growth
  • Sex hormones close epiphyseal plates (stop long bone lengthening)
  • Oestrogen closes plate before testosterone does (males generally taller than females)
29
Q

Skeletal system declining with aging

A
  • Rate of bone formation progressively decreases with age from 30’s or 40’s
  • Partly due to decrease in muscle mass
  • Partly due to decreasing sex hormone levels allowing an osteoclast-osteoblast functional imbalance
  • Decreased collagen to mineral content → brittle bones
30
Q

why are females more susceptible to osteoporosis/ fractures after menopause

A
  • Sudden drop in oestrogen leading to increased osteoclast activity; osteoclast function overtakes osteoblast function
  • Female bones generally have less mass than male bones at peak bone mass during early adulthood
  • Testosterone levels drop more slowly therefore slower bone loss in males
  • Osteoporosis more likely in females → vertebral fractures
31
Q

Osteopenia

A

Early loss of bone mineral density
Osteopenia due to lower than normal peak density but not low enough to be classified as osteoporosis

32
Q

Osteoporosis

A

Decreased total bone mass and bone matrix
Bone resorption by osteoclasts is greater than bone formation by osteoblasts
Higher risk of fractures for example in hip, pelvis, wrists and vertebrae

33
Q

Osteomalacia

A

Softening of bones due to a lack in vitamin D, calcium, phosphate and low hormones that regulate blood calcium levels

34
Q

Rheumatism

A

General term for pain and stiffness in the muscular system, the skeletal system or both

35
Q

Kyphosis

A

Abnormal posterior curve mainly in thoracic vertebrae; more common in elderly
Intervertebral disc damage more likely in elderly
Drop in muscle tone and loss of posture
Drop in Anti-diuretic hormone (ADH) production → dehydration → loss of intervertebral disc mass
Vertebral fractures more likely with bone matrix loss

36
Q

Describe the major age-related changes in joints

A

Articular cartilage thins
Most pronounced in weight-bearing joints (hips and knees)
Decreased production of synovial fluid
Ligaments shorten and lose some flexibility (drop in collagen and elastin)

biology (22 decks)

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