Chapter 7 Muscular System Functions and Types of

Chapter 7 Muscular System

Functions and Types of Muscle • Has three types – Smooth – Cardiac – Skeletal

Functions and Types of Muscle • Smooth Muscle: – Wall of hollow internal organs – Involuntary contractions – Moves materials – Single nucleus – Parallel lines, forming sheets – No striations – Sustain prolonged contraction, doesn’t fatigue easy

Functions and Types of Muscle • Smooth Muscle:

Functions and Types of Muscle • Cardiac Muscle: – Wall of heart – Uninucleiated – Striated, tubular, and branched – Intercalated disks = quick contractions – Involuntary and rhythmic

Functions and Types of Muscle • Cardiac Muscle:

Functions and Types of Muscle • Skeletal Muscle: – Multinucleated – Striated – Voluntary

Functions and Types of Muscle • Skeletal Muscle:

Functions and Types of Muscle • Connective Tissue Coverings: – Endomysium: each muscle fiber is surrounded by – Fascicles: groups of muscle fibers – Perimysium: Connective tissue covering of fascicles – Epimysium: Covers the entire muscle

Functions and Types of Muscle • Connective Tissue Coverings:

Functions and Types of Muscle • Skeletal muscle: – Supports the body – Makes bones and other body parts move – Helps maintain a constant body temperature – Contraction assists movement in cardiovascular and lymphatic vessels – Protects internal organs and stabilizes joints

Contraction of Skeletal Muscle

Contraction of Skeletal Muscle • Muscles acquire ATP in 3 ways – Creatine phosphate breakdown – Cellular respiration – Fermentation

Contraction of Skeletal Muscle • Creatine Phosphate Breakdown – Creatine Phosphate builds up when muscle is at rest – Speediest way to make ATP available – 8 seconds of intense energy

Creatine Phosphate Breakdown

Contraction of Skeletal Muscle • Cellular Respiration: – Completed in mitochondria – Only when oxygen is available – From glycogen and fatty acids – End products are carbon dioxide, water, and heat

Cellular Respiration

Contraction of Skeletal Muscle • Fermentation: – Anaerobic – Glucose breaksdown into lactic acid – Build up of lactic acid leads to cramping

Fermentation

Contraction of Skeletal Muscle • All or nothing law • A single fiber either contracts or rest • However, a group of fibers some contract and other will not to appear to have the ability for partial contractions

Contraction of Skeletal Muscle • Muscle twitch- single contraction that last for a fraction of a second – Latent period: time between stimulation and initiation of contraction – Contraction period: muscle shortens – Relaxation period: muscle returns to its former length

Contraction of Skeletal Muscle • Summation – increase in muscle contraction until maximal sustained contraction is achieved • Tetanic contraction- maximum contraction

Contraction of Skeletal Muscle • While some muscles are contracting others are resting, this helps prevent fatigue • Tone: some fibers are always contracting – Helps maintain posture

Contraction of Skeletal Muscle • Atrophy- loss of muscle tone due to inactivity or nerve damage – Muscle will eventually be replaced by adipose and fibrous tissue – Muscles will shorten, leaving parts contracted

Contraction of Skeletal Muscle • Pertrophy- increase in muscle size – Prolonged period of forceful muscular activity increases myofibrils

Contraction of Skeletal Muscle • Slow-twitch muscles – Steadier and more endurance – Highly resistant to fatigue – Substantial reserve of glycogen and fat – Abundant mitochondria, few fibers – Aerobic

Contraction of Skeletal Muscle • Fast-twitch muscles – Anaerobic – Designed for strength – Many fibers, few mitochondria – Little or no myoglobin – Few blood vessels – Vulernable to cramping

Skeletal Muscles • Origin – of a muscle is on the stationary bone • Insertion- of a muscle in on the bone that moves

Skeletal Muscles

Skeletal Muscles • Prime mover- the muscle that does most of the work • Synergists- the assisting muscles

Skeletal Muscles • Antagonist- pair of muscles working against the synergist

Skeletal Muscles • Naming muscles – Size • Example: gluteus maximus, largest butt muscle – Shape • Deltoid, shaped like a delta – Direction of fiber • Rectus abominis, rectus = straight – Location • Frontalis, overlies the frontal bone

Skeletal Muscles • Naming muscles – Attachment • Ex. Brachioradialis, brachium and the radius – Number of attachments • Ex. Bicep = two attachments – Action • Extensor digitorum – extends fingers

Skeletal Muscles • Muscles of the Head – Frontalis: frontal bone • Raising eyebrows, wrinkle brow – Orbicularis oculi: encircles eye • blinking – Orbicularis oris: encircles mouth • Pucker lips

Skeletal Muscles • Muscles of the Head – Buccinator: cheek • Compresses to whistle – Zygomaticus: cheekbone to corner of mouth • Smile

Skeletal Muscles • Muscles of Mastication – Masseter: zygomatic arch to mandible • Ex. chewing – Temporalis: overlies temporal bone • Ex. Elevates mandible

Skeletal Muscles • Muscles of the Neck – Deep neck muscles are responsible for chewing – Superficial muscles are responsible for moving the head

Skeletal Muscles • Muscles of the Neck – Sternocleidomastoid • Turns head from right to left – Trapezius • Triangular • Shrug shoulders

Skeletal Muscles • Muscles of the Trunk – External intercostal: between ribs • Ex. Elevate rib cage during inspiration – Diaphragm • Ex. Assists in inspirations – Internal intercostal • Ex. Normally no muscular contraction, only with forced expiration

Skeletal Muscles • Muscles of the Abdominal Wall – External and internal obliques: Lower ribs and pelvic girdle • Ex. Trunk rotation and lateral flexion – Transversus abdomininis: horizontal across abdomen • Synergist muscles – Rectus abdominis: from pubic bones to the ribs and strernum • Ex. Flex and rotate lumbar region

Skeletal Muscles • Muscles of the Shoulder – Serratus anterior: from armpit to chest • Ex. Helps elevate arm above head

Skeletal Muscles • Muscles of the Arm – Deltoid • Abducts arm to horizontal position – Pectoralis major – Latissimus dorsi: from lower spine to humerus • Ex. Swimming, rowing and climbing rope – Rotator cuff: muscles over proximal humerus

Skeletal Muscles • Muscles of the Arm – Biceps brachii: muscles of the forearm • Turn a doorknob unscrew a jar – Brachilais: humerus to ulna • Ex. Flexing the forearm – Triceps brachii: scapula to humerus • Ex. To punch and in tennis

Skeletal Muscles • Muscles of the Arm – Flexor carpi and extensor carpi • Flexes and extends wrist – Flexor digitorum and extensor digitorum • Flexes or extends fingers

Skeletal Muscles • Muscles of the Hip and Leg – Iliopsoas: ilium to lumbar vertebrae • Ex. walking, bowing, standing erect – Gluteus maximus: large buttocks muscle • Ex. Walking, jumping, climbing stairs – Gluteus medius: small buttocks muscle – Adductor group • Ex. Thighs inward

Skeletal Muscles • Muscles of the Leg – Quadricep femoris: thigh • Ex. Extends leg – Sartorius: thigh to knee • Ex. Sit cross legged – Hamstring: Back of thigh • Ex. Antagonist muscle group

Skeletal Muscles • Muscles of the Ankle and Foot – Gastrocnemius • Ex. Pushing forward while walking, dancing – Tibialis anterior • Ex. Inversion of foot – Peroneus • Ex. Plantar flexion – Flexor and extensor digitorum longus • Ex. Flexes and extends toes

Effects of Aging • Mass and strength decrease • Muscle tissue initially replaced by connective tissue then eventually fat

Homeostasis • Heartbeat and movement of blood • Protect internal organs • Moves bones and allows daily activities