Muscular System

Question 1

What is myalgia?

Answer 1

Muscle pain

Question 2

What is Myocardium?

Answer 2

Muscular component of the heart

Question 3

What is myasthenia?

Answer 3

Weakness of the muscles

Question 4

What is Myopathy?

Answer 4

Any disease of the muscle

Question 5

What is Myoclonus?

Answer 5

A sudden spasm of the muscles

Question 6

What is a sarcolemma?

Answer 6

The outer membrane of the muscle

Question 7

What is the sarcoplasm?

Answer 7

The cytoplasm of the muscle

Question 8

What is the sarcoplasmic reticulum?

Answer 8

The smooth endoplasmic reticulum of a muscle cell

Question 9

What are the three types of muscle?

Answer 9

Skeletal
Cardiac
Smooth

Question 10

What is the difference between red, intermediate and white muscle fibres?

Answer 10

Red have the smallest diameter, many mitochondria, contact slowly, repetivie and weak, fatigue slowly, few ATP-ases, in limbs of animals
Intermediate- in the middle
White- opposite and in Extraocular muscles (eye)

Question 11

What is myoglobin?

Answer 11

Red protein with Haem
not present in smooth muscle
Diving animals have lots of myoglobin so can submerge for longer
Haemoglobin gives up oxygen to myoglobin

Question 12

What causes the mobility of the tongue?

Answer 12

Multidirectional orientation of the tongue and plasticity and strength of connective tissue

Question 13

What is atrophy of muscles?

Answer 13

Muscles fibres are destroyed more than replaced

Question 14

What is hypertrophy of muscles?

Answer 14

Muscle fibres are replaced more than destroyed

Question 15

What causes Atrophy?

Answer 15

Disuse- Not moving limb- loss of protein reduced fibre diameter, loss of power
Age
Denervation- signs of ;power motor neurone lesions

Question 16

What causes Hypertrophy?

Answer 16

More protein, increased diameter- exercise

Question 17

How can more sarcomeres develop?

Answer 17

Increased by frequent stretching

Question 18

What is MHAZI?

Answer 18

M line inside H zone
H zone inside A band
A band is inside the two Z discs
Z disc is inside the the I band

Question 19

What are Troponin assays useful for?

Answer 19

Marker for Cardiac ischaemia (heart attack)
must measure in 20 hours
not proportional to degree of damage

Question 20

What is Creatine Kinase used for?

Answer 20

Diagnose cardiac ischaemia (heart attack)
proportional to degree of damage
Can result from many reasons so Troponin used more
caused by- exercise, fall etc

Question 21

What is the sliding filament model?

Answer 21

Actin filament (thin filaments)
Myosin (thick filaments)
Myosin heads form cross bridges with actin filaments exert force on them to move
Contraction begins when an ATP bound to myosin is hydrolysed to ADP and P
This causes myosin head to extend
Power stroke occurs- shortening sarcomere
ATP binds which caused the Myosin head to become unattached
When muscle is relaxed Tropomyosin blocks the binding sites, if calcium is present it binds to troponin which moves the tropomyosin

Question 22

What are the events lead to contraction of a skeletal muscle?

Answer 22

1. nerve impulse arrives at neuromuscular junction
2. ACh is released into synaptic cleft causing local depolarisation of the sarcolemma
3. Na+ channels open and Na enter cells
4. General depolarisation occurs and spreads over the sarcolemma and into T tubules
5. Voltage sensor proteins in T tubules change their conformation
6. Gated Ca2+ are opened
7. Ca is released from the terminal in to the sarcoplasm
8. Ca2+ binds to the troponin
9. contraction initiated and ca returns

Question 23

Where are nuclei positioned in cardiac muscle?

Answer 23

Central

Question 24

What is present is skeletal muscle that isn’t present in cardiac muscle?

Answer 24

Distinct myofibrils

Question 25

What are gap junctions in cardiac muscle used for?

Answer 25

Electrical coupling

Question 26

What are Adherens-type junctions used for in cardiac muscle?

Answer 26

anchor cells and actin filaments

Question 27

What is cell hypertrophy?

Answer 27

Enlargement of cell

Question 28

What is cell Hyperplasia?

Answer 28

Multiplication of cells

Question 29

What is heart Atrophy?

Answer 29

Heart is smaller than normal size

Question 30

What is heart hypertrophy?

Answer 30

Heart is bigger than normal size

Question 31

What is a natriuretic peptide?

Answer 31

peptide hormones that reduce arterial pressure by decreasing blood volume and systemic vascular resistance

Question 32

Who has high levels of ANP?

Answer 32

Patients with left ventricular hypertrophy and mitral valve disease

Question 33

What is ANP?

Answer 33

Atrial Natriuretic peptide- Released in response so Atrial distension- so found in hypervlemic states

Question 34

What us BNP?

Answer 34

Brain type natriuretic peptide- synthesised by ventricles, marker for heart failure

Question 35

What system of natriuretic peptides serve as a counter regulatory system for?

Answer 35

Renin-angiotensin-aldosterone system

Question 36

What are the purkinje fibres?

Answer 36

specialist myocardial cells which are distal conducting cells carrying impulses to the ventricular muscle

Question 37

What are parking fibres like?

Answer 37

large, abundant glycogen, sparse myofilaments, extensive gap junctions

Question 38

What is different about smooth muscle to other types?

Answer 38

Not striated, contraction is slower and can occur for hours or days

Question 39

Where is smooth muscle found?

Answer 39

often forms contractile walls of passageways e.g. vascular structures an in gut, reparatory tract and genitourinary system

Question 40

What disorders are due to smooth muscle?

Answer 40

``` High blood pressure dysmenorrhea Asthma Atherosclerosis Abnormal gut motility Detrusor muscle instability ```

Question 41

What is a myoepithelial cell?

Answer 41

stellate cells forming basketwork around secretory units of some exocrine glands

Question 42

What are myofibroblasts?

Answer 42

produce collagenous matrix at would healing sites, also contract

Question 43

How does skeletal muscle repair?

Answer 43

Cannot divide but the tissue can regenerate by mitotic activity of satellite cells, these can also fuse with existing muscle to increase mass

Question 44

How does cardiac muscle repair?

Answer 44

Incapable of regeneration | fibroblasts invade and develop scar tissue

Question 45

How does smooth muscle repair?

Answer 45

cells can undergo mitosis e.g. pregnant uterus walls become thicker