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Flashcards in Structure And Function Deck (65)
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1

What is a myocyte?

A muscle fibre which which is a cell and makes up muscle.

2

What's is the function of the muscular system?

Movement -muscular contraction and moving the bones, joints and muscles.
Posture - stabilising joints and balance
Heat production via thermogenesis. Shivering by muscular contractions
Glycogen store
Movement of substances such as sphincters, blood vessels, skeletal system, movement of food.

3

What does contractility mean?

The ability of muscles to contract or shorten

4

What does excitability mean?

The ability to generate an electrical current through action potentials.

5

What does extensibility mean?

Ability to stretch muscles without being damaged

6

What is elasticity?

The ability for something to return to its original length and shape after extension.

7

What are the three types of muscles?

Cardiac, smooth and skeletal

8

What does striated mean?

Cell aligned in parallel bundles so stripes are visible with a microscope

9

What does non striated mean?

Randomly arranged cell with no stripes visible.

10

What is skeletal muscle?

Voluntary movement which are striated and multi nucleated. Can not do mitosis but develop by hypertrophy.

11

What is cardiac muscle?

Involuntary heart muscle which is striated and single nucleus in the cells. It is intercalated discs - fibres that mean contraction can spread like a wave. More and larger mitochondria which mainly use aerobic respiration.

12

What does auto-rhythmic mean?

Contractions without nervous stimulation

13

What is smooth muscle?

Involuntary, form the walls of hollow organs and blood vessel. Single nucleus and non striated. Filaments attach to structures called dense bodies which are pulled closer when muscle shortens.

14

How are myocytes formed?

Embryonic fusion of myoblasts so each muscle skeletal fibre has many nuclei.

15

Hypertrophy

Enlargement of existing fibres

16

Atrophy

Wasting of muscles

17

Fascia

Connective tissue that organises muscle, secures it to skin and provides stability.

18

What is the skeletal muscle hierarchy?

Muscle is made of muscle fibre bundles which is made of muscle fibre which is made up of myofibrils. Myofibrils are made of myofilaments.

19

Sarcolemma

Plasma membrane of muscle cell

20

Transverse tubules

Tubes extending from sarcolemma into muscle cell

21

Sarcoplasm

Muscle cell cytoplasm

22

Sarcoplasmic reticulum

Tubular network that circulates cytoplasm and store terminal cisterns

23

Terminal cisterns

Store calcium and attach on the SR.

24

Myoglobin

Red coloured oxygen binding proteins in sarcoplasm

25

What are myofilaments?

Made up of actin (thin) and myosin (thick) which overlap to form sarcomeres.
A bands - dark area where myofilaments over lap
I bands - light area with only actin filaments.

26

What is epismyosium?

Wrapped around entire muscle.

27

What is perimyosium?

Surround groups or bundles of 10-100 muscle fibres forming fascicles

28

What is endomyosium?

Thing sheath around individual muscles.

29

Explain how a neuromuscular junctions works.

Action potential travels down the moron neuron. This causes Ca to be to enter the axon terminal. Ca causes ACh to be release by exocytosis. ACh diffuses across the synapse and binds to receptors on sarcolemma. ACh binds to sodium potassium pump receptors cause them to open. Na enter the muscle cell and k leave muscles cell cause end plate potential.

When ACh is broken down by acetylcholinesterase this ends the end plate potential.

30

Explain sliding filament theory

Action potential arrives as neuromuscular junctions.
Action potential spreads along sarcolemma and t tubules. Muscle cell releases Ca from storage (SR reticulum).
Ca and adenosine triphosohate (ATP) trigger myosin to bind to actin so filament slide over each other and this shortens the fibre.