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NURS 120 Midter 2 Lectures 5-8
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This document includes all lectures for nursing 120 midterm 2. This includes modules 5 through 8.
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Module 5 – Muscular SystemLearning objec8ves
• List, locate in the body, and describe the structure and func5on of
the three major types of muscle 5ssues.
• Describe the microscopic structure and func5on of a skeletal
muscle, including sarcomata and motor unit.
• List and explain the most common types of movement produced
by skeletal muscles.
• Name, iden5fy, and give the func5on of the major muscles of the
body.
Muscle Tissue
• Muscular 5ssue enables the body and its parts to move.
o Three types of muscle 5ssue exist in the body.
§ Skeletal muscle, cardiac muscle, smooth muscle.
o Movement caused by muscle cells or fibres that specialized in
contrac5on (shortening)
§ Specialized to contract/ produce movement. Skeletal muscle
o Muscle movement occurs when chemical energy is converted fibres
into mechanical energy.
§ Converted as a result of the nutrients that are supplied.
Cardiac muscle
• Comprises most of the heart.
o Heart is a pump, and the func5on is to pump the blood. ATachments of a skeletal
o Majority of the heart is made of cardiac muscle to muscle
pump effec5vely.
o Has cylindrical fibers and has mul5ple branches that
connect into interconnected 5ssue.
• Involuntary
o We can’t control its contrac5ons.
o By relaxing you are lowering the heart rate, this is a
minor control but s5ll involuntary.
• Intercalated disks
o
• Interconnected structure allows heart to contract
efficiently in its func5on as a pump.
Smooth muscle
• Non-striated or visceral muscle
• Found in walls of hollow structures, such as the diges5ve
tracts, and the walls of blood vessels.
• Contrac5ons are involuntary and highly regulated.
Structure of skeletal muscle
• Muscle organs
o Composed of striated muscle fibres and connec5ve
5ssue
o Threadlike cylindrical cells arranged in bundles &
characterized by crosswise strait ion and mul5ple nuclei.
1
, o Most skeletal muscles extend from one bone across a
joint to another bone.
Func8ons of skeletal muscle
• Movements
o Muscles produce movement by pulling on bones as a
muscle contracts.
§ The inser5on bone is pulled closer to the origin bone.
§ Movement occurs at the joint between the origin and
the inser5on.
• Posture
o Maintained by con5nuous, low-strength muscle
contrac5ons called tonic contrac6ons.
§ When tes5ng for muscle strength if it is low then
there could be something wrong with their tone
§ Good posture is described in terms of body parts
being in place in the op5mum movement.
• If an individual maintains good
posture, they won’t be stressing any
muscles.
• Heat produc5on
o Most heat produced by the contrac5on of
muscle fibres.
§ Hyperthermia and hypothermia
• Hyperthermia: increased or above
the normal
o High/Hot temperature
• Hypothermia: decreased or below
the normal
o Cold/Lower temperature
o Generally, the ideal would be a constant
temperature.
• Muscle Fa5gue
o Results from repeated muscle s5mula5on
without adequate periods of rest
§ Oxygen debt - result of physiological muscle fa6gue
• Muscle becomes over stressed, and you are going to have reduced strength of muscle
contrac5on.
• Can be referred to as physiological muscle fa5gue.
• You are going to use up the nutrient supply you need to make a muscle contrac5on.
o Body isn’t able to replenish the nutrients through the blood.
• Strenuous movement there is going to build up of lac5c acid. If you are a healthy person the
lac5c acid is going to exit the body. Increased respira5ons is ge]ng rid of the lac5c acid. This is
lowering the carbon dioxide in the body. You would except to see increased respira5on to in a
healthy person.
o Individuals who can’t expel the lac5c acid/carbon dioxide are considered unhealthy.
2
,Types of muscle contrac8on
• Muscles produce movement by
shortening/contrac5ng.
• To contract they first need to be
s5mulated.
• Isotonic contrac5on
o Muscle changes length
o Produces movement.
§ At muscle joint
• Isometric contrac5on
o Doesn’t shorten.
o Pulls forcefully against a load.
o Length remains the same.
• Twitch
o Jerky response to isolated muscles to
a s5mulus.
o Not normal in most circumstances.
§ Generally, there is a group of
muscles that are working to
create a smooth movement.
• Tetanic contrac5on Types of muscle contrac1on
o Sustained and steady response produced by a s5mulus or a series of s5mulus.
o ATacks the muscle in a rapid movement so that the movements are con5nuous.
o Seizure is an example.
Movements produced by skeletal muscle contrac8ons.
• Angular movements
o Flexion & extension
o Abduc5on & adduc5on
§ Abduc5on movement away from the body
§ Adduc5on movement towards the body
• Circular movements
o Rota5on
o Circumduc5on
§ Move apart so that the distal movement is away.
o Supina5on and prona5on
§ Supina5on palm towards upwards
• Laying face up
§ Prona5on palm downwards
• Lying face down
• Special movements
o Dorsiflexion and plantar flexion
o Inversion and eversion
3
, flexion and extension of the elbow
• A&B
o The elbow flexes as the
biceps brachii contracts
o Its antagonist -> triceps
brachii relaxes.
• B&c
o Elbow extended the biceps
brachii relax.
o Triceps brachii contracted.
flexion and extension of the knee
examples of body movement
4
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