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biology > The muscular system > Flashcards

The muscular system Flashcards

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1
Q

Muscle structure

A

A muscle is a group of specialised elastic tissues Muscles comprise 23% of a woman’s and 40% of a
man’s body

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2
Q

Each skeletal muscle is an organ that consists of ——-

A

various integrated tissues these Tissues include the skeletal muscle fibres, blood vessels,
nerve fibres, and connective tissue

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3
Q

Each skeletal muscle has three layers of connective tissue These compartmentalize the muscle fibres within the muscle

A

1-Epimysium
2-Perimysium
3-Endomysium

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4
Q

what is Epimysium

A

Each muscle is wrapped in a sheath of dense connective tissue called the epimysium
* Separates muscle from other tissues and organs in
the area, allowing the muscle to move independently

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5
Q

what is Perimysium

A

Inside each skeletal muscle, muscle fibres are organized into individual bundles Each called a fascicle,
surrounded by a middle layer of connective tissue
called the perimysium

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6
Q

what is Endomysium

A
  • Inside each fascicle, each muscle fibre is encased in a thin connective tissue layer of collagen and reticular fibres called the endomysium.
  • The endomysium contains the extracellular fluid and nutrients to support the muscle fibre.
  • These nutrients are supplied via blood to the muscle tissue.
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7
Q

Muscle function

A
  • The best-known feature of skeletal muscle is its ability to contract and cause movement
  • They can also stop movement E.g. resisting gravity to maintain posture
  • Small, constant adjustments of the skeletal muscles are needed to hold a body upright or balanced in any position
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8
Q

what is Skeletal muscle

A
  • Striated and voluntary
  • Muscles under conscious control
  • Has cylindrical cells which make up fibres
  • Each muscle fibre (cell) is multinucleated
  • Muscle fibres form bundles
  • Bundles all run in the same direction
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9
Q

1-The plasma membrane of muscle fibers is called the-
2-The cytoplasm is referred to as ——
3-The endoplasmic reticulum is called the——-

A

1-sarcolemma
2-sarcoplasm
3-sarcoplasmic reticulum

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10
Q

The sarcomere

A
  • The functional unit of a skeletal muscle fibre
  • Contains thin filaments of actin and thick filaments of myosin
  • These slide over each other during contraction
  • Approximately 2μm in length
  • Bordered by z-discs/z-lines
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11
Q

how does the The sarcomere work

A
  • ATP and Ca+ are required for the muscle to contract
  • Myosin heads on the thick filaments form cross bridges with the thin filaments
  • Thin filaments slide over the thick filaments
  • Sarcomere shortens
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12
Q

what is Smooth muscle

A
  • Non striated and involuntary
  • Found in the walls of hollow organs e.g. urinary bladder, uterus, stomach, intestines etc.
  • Muscle fibres are spindle shaped
  • Have a single nucleus
  • Have no distinct membrane
  • Also have actin and myosin
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13
Q

what is Cardiac muscle

A

-Only found in the heart
-Involuntary but similar to skeletal muscle
-Also organised into sarcomeres
-Fibres are shorter than skeletal muscle fibres
-Fibres contain only 1 nucleus
-Possess many mitochondria and myoglobin
-ATP produced mainly from aerobic respiration
-Cells connected by intercalated discs

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14
Q

Types of contractions

A

1-Isometric contraction
* As the muscle contracts its length remains the same whilst the tension increases
2-Isotonic contraction
* As the muscle contracts its length changes whilst the tension remains constant

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15
Q

Making movement

A
  • Muscle contraction pulls one bone towards another moving the limb
  • Muscles never work alone
  • Any movement results from the actions of several muscles
  • Muscles generally work in pairs
  • Agonist & antagonist
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16
Q

The agonist is the—–
The antagonist is the——

A

1-contracting muscle
2-opposing relaxing muscle
The agonist and antagonist must contract and relax equally for smooth movement

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17
Q

what cuses muscles contract

A
  • Impulses from a motor neuron causes muscle contraction
  • Each motor neuron synapses with numerous muscle fibres
  • All the muscle fibres innervated by a single motor neuron contract together
  • Motor unit
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18
Q

Requirements for muscle contraction

A

An adequate blood supply is required to:
* Provide oxygen and nutrients
* Remove carbon dioxide and waste products
* Muscles receive nutrients and oxygen from the arterial capillaries
* They are used by the muscle to generate energy
* Waste products e.g. lactic acid is excreted into the venous blood stream

19
Q

What affects muscle contraction

A

1-Energy available
2-Strength of the stimulus from the nerve
3-Time muscle has been contracting
4-Adequate blood supply bringing enough oxygen and nutrients
5-Strength of inhibitory nerve supply
6-Temperature of muscle (warmth increases response)
7-Presence of waste products e.g. lactic acid

20
Q

Different stages of contraction

A

1-Tone
Slight degree of contraction by some fibres as others are relaxing This happens even during sleep Also to maintain posture
2-Relaxation
A lessening of tension A reduction in the number of fibres contracting at any one time Muscle tension can be affected by conscious effort

21
Q

Problems with over-contraction

A

Muscle tension and Muscle fatigue

22
Q

what is Muscle tension

A

*Over stimulation of muscle fibres
*More fibres contract than are necessary to maintain postural tone

23
Q

what is Muscle fatigue

A

*Muscles need oxygen and fuel for its energy
*Glucose is the main source of energy
*Glucose is stored as glycogen and fats in muscle
*Glucose and fats are burned to release energy using oxygen from the blood
*Continuous contraction leads to oxygen deficiency
*Results in lactic acid build up causing a burning sensation
*Muscle soon stops contracting.
*Causes stiffness and pain

24
Q

Important terms in muscles

A

1-Origin
* The fixed end of a muscle
* This end barely moves during muscle action
2-Insertion
* The moving end of a muscle
* The point to which the force of a muscle is directed
* A muscle always works from its insertion towards its origin
3-Attachment
* At their origin and insertion muscles are attached to bone via tendons
* This produces movement of joints
* They sometimes take attachment from other connective tissue e.g. cartilage or fascia of other muscle
4-Belly
* Thickest part or main body of a muscle
* Usually the middle part of the muscle

25
Q

what is Shivering and what it is caused by

A

Shivering raises the metabolic rate and is a form of adaptive thermogenesis Thermogenesis = the production of heat using energy and Shivering is caused by muscle contraction Muscles contract and relax to produce heat

26
Q

Muscle attachment to the body

A
  • Ligaments, tendons and fascia are soft tissues composed primarily of collagen fibres
  • In ligaments and tendons these fibres are organised into parallel bundles
  • Transmit tensile forces between two bones in ligaments
  • Transmit tensile forces between muscle and bone in tendons
  • Fascia are a sheet of fibrous tissue which encloses muscle
27
Q

what is Deep fascia

A

Deep fascia are dense and inelastic. Covers muscles and are broad surfaces for attachment. Assists muscle action through tension and pressure

28
Q

what is Superficial fascia

A

Superficial fascia are found beneath the skin. Found over almost the whole surface of the body. Layer that primarily determines the shape of the body

29
Q

Anatomical terms of movement

A

1-Flexion decreases the angle between two body parts.
2-Extension increases the angle between two body parts
3-E.g. abduction of the shoulder raises the arms out to the sides of thebody
4-E.g. Adduction of the hip squeezes the legs together
5-Eversion of the foot moves the bottom (sole) of the foot away from the midline of the body, while foot 6-6-6-inversion faces the sole toward the midline.
7-Dorsiflexion of the foot at the ankle joint moves the top of the foot toward the leg, while plantar flexion lifts the heel and points the toes

30
Q

Muscles of the face

A

Humans have well developedmuscles in the face.
* Permit a large variety of facial expressions.
* Four pairs of muscles responsible for chewing. They
all connect to the mandible.
* These are the masseter, temporalis, medial pterygoid,
and lateral pterygoid muscles.

31
Q

The major muscle that laterally flexes and rotates the head is the ——

A

sternocleidomastoid.

32
Q

the important Muscles of the
head and neck

A

masseter
sternocleidomastoid.
trapezius

33
Q

Muscles of the trunk – neck, chest and abdomen

A

trapezius
deltoid
biceps
external oblique
internal oblique
rectus abdominis
transverse abdominis

34
Q

The deltoid muscles are——-
The abdomen, unlike the thorax and pelvis, has no ————–
The wall consists entirely of four muscle
pairs, arranged in ———

A

the triangular muscles over each shoulder.
bony reinforcements or protection.
layers, and the fascia that envelops them

35
Q

Muscles of the trunk – neck, chest and abdomen

A

latissimus dorsi
external oblique
gluteus medius
gluteus minimus
gluteus maximus

36
Q

Muscles of the shoulder and arm

A

biceps
triceps
teres minor

37
Q

Muscles of the leg

A

quadriceps
hamstring
gastrocnemius
tendon of achilles

38
Q

what is Fibromyalgia

A
  • Also called fibromyalgia syndrome (FMS)
  • A long term condition
  • Chronic
  • Pain, stiffness and tenderness of the muscles, tendons and joints.
39
Q

what is Cramp

A
  • Unpleasant and painful sensation
  • Caused by contraction or over-shortening of muscles
  • Caused by cold, overexertion or low levels of calcium in the blood
40
Q

what is Muscle atrophy

A
  • Caused by undernourishment or lack of use
  • Or by neurological problems
  • Body will break down the muscle to conserve energy
41
Q

what is Sprain

A
  • Caused by a sudden twist or wrench of the joint’s ligaments
  • Results in an injury or damage to a joint
  • Painful damage to a joint
42
Q

what is Tendonitis

A

An inflammation in or around tendons

43
Q

what is Tetanus

A

An acute and serious infection of the central nervous system caused by bacterial infection of open wounds Symptoms include High fever, sweating, rapid heartbeat and high blood pressure

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