Muscular System Flashcards
What is myalgia?
Muscle pain
What is Myocardium?
Muscular component of the heart
What is myasthenia?
Weakness of the muscles
What is Myopathy?
Any disease of the muscle
What is Myoclonus?
A sudden spasm of the muscles
What is a sarcolemma?
The outer membrane of the muscle
What is the sarcoplasm?
The cytoplasm of the muscle
What is the sarcoplasmic reticulum?
The smooth endoplasmic reticulum of a muscle cell
What are the three types of muscle?
Skeletal
Cardiac
Smooth
What is the difference between red, intermediate and white muscle fibres?
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)
What is myoglobin?
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
What causes the mobility of the tongue?
Multidirectional orientation of the tongue and plasticity and strength of connective tissue
What is atrophy of muscles?
Muscles fibres are destroyed more than replaced
What is hypertrophy of muscles?
Muscle fibres are replaced more than destroyed
What causes Atrophy?
Disuse- Not moving limb- loss of protein reduced fibre diameter, loss of power
Age
Denervation- signs of ;power motor neurone lesions
What causes Hypertrophy?
More protein, increased diameter- exercise
How can more sarcomeres develop?
Increased by frequent stretching
What is MHAZI?
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
What are Troponin assays useful for?
Marker for Cardiac ischaemia (heart attack)
must measure in 20 hours
not proportional to degree of damage
What is Creatine Kinase used for?
Diagnose cardiac ischaemia (heart attack)
proportional to degree of damage
Can result from many reasons so Troponin used more
caused by- exercise, fall etc
What is the sliding filament model?
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
What are the events lead to contraction of a skeletal muscle?
- nerve impulse arrives at neuromuscular junction
- ACh is released into synaptic cleft causing local depolarisation of the sarcolemma
- Na+ channels open and Na enter cells
- General depolarisation occurs and spreads over the sarcolemma and into T tubules
- Voltage sensor proteins in T tubules change their conformation
- Gated Ca2+ are opened
- Ca is released from the terminal in to the sarcoplasm
- Ca2+ binds to the troponin
- contraction initiated and ca returns
Where are nuclei positioned in cardiac muscle?
Central
What is present is skeletal muscle that isn’t present in cardiac muscle?
Distinct myofibrils
What are gap junctions in cardiac muscle used for?
Electrical coupling
What are Adherens-type junctions used for in cardiac muscle?
anchor cells and actin filaments
What is cell hypertrophy?
Enlargement of cell
What is cell Hyperplasia?
Multiplication of cells
What is heart Atrophy?
Heart is smaller than normal size
What is heart hypertrophy?
Heart is bigger than normal size
What is a natriuretic peptide?
peptide hormones that reduce arterial pressure by decreasing blood volume and systemic vascular resistance
Who has high levels of ANP?
Patients with left ventricular hypertrophy and mitral valve disease
What is ANP?
Atrial Natriuretic peptide- Released in response so Atrial distension- so found in hypervlemic states
What us BNP?
Brain type natriuretic peptide- synthesised by ventricles, marker for heart failure
What system of natriuretic peptides serve as a counter regulatory system for?
Renin-angiotensin-aldosterone system
What are the purkinje fibres?
specialist myocardial cells which are distal conducting cells carrying impulses to the ventricular muscle
What are parking fibres like?
large, abundant glycogen, sparse myofilaments, extensive gap junctions
What is different about smooth muscle to other types?
Not striated, contraction is slower and can occur for hours or days
Where is smooth muscle found?
often forms contractile walls of passageways e.g. vascular structures an in gut, reparatory tract and genitourinary system
What disorders are due to smooth muscle?
High blood pressure dysmenorrhea Asthma Atherosclerosis Abnormal gut motility Detrusor muscle instability
What is a myoepithelial cell?
stellate cells forming basketwork around secretory units of some exocrine glands
What are myofibroblasts?
produce collagenous matrix at would healing sites, also contract
How does skeletal muscle repair?
Cannot divide but the tissue can regenerate by mitotic activity of satellite cells, these can also fuse with existing muscle to increase mass
How does cardiac muscle repair?
Incapable of regeneration
fibroblasts invade and develop scar tissue
How does smooth muscle repair?
cells can undergo mitosis e.g. pregnant uterus walls become thicker
