Transcript Anatomy and physiology

Muscular System
ANATOMY AND PHYSIOLOGY
Lori Baker, RN, BSN
1
OBJECTIVES








Identify three types of muscle tissue
Describe the events that occur at the neuromuscular
junction
Explain the role of calcium and adenosine triphosphate
in muscle contraction
Identify the sources of energy for muscle contraction
Trace the sequence of events from nerve stimulation to
muscle contraction
State the basis for naming muscles
List the actions of the major muscles
Identify major muscles of the body
2
MUSCLE FUNCTIONS

Movement – moves the skeleton

Heat – muscle contractions

Form – shape and posture
3
GENERAL POINTS
Muscle cells contract; they pull on bone when
this is done
 Muscles are anchored to bones
 Each muscle has two tendons

 One
is attached to movable point (insertion)
 One is attached to a non-movable point (origin)
 Tendon
merges with fascia on one end
 Tendon merges with periostium on other end
4
MUSCLE TYPES

Smooth – not attached to bones, not under
conscious control, walls of organs and blood
vessels, sphincters

Cardiac – specialized, heart only

Skeletal - attached to bones
5
POINTS OF ATTACHMENT

Ligaments – bone to bone

Tendons - muscle to bone
 How?
 Fascia
of muscle on one end
 Periosteum of bone on other end
6
RELATION TO OTHER SYSTEMS

Nervous –
Transmission of impulses (action potential)
 Excitability
 Contractility
 Extensibility
 Elasticity


Respiratory – exchange (O2 and CO2)

Circulatory - transport
7
TYPES OF MUSCLE

Antagonists – opposites
 Flex
and extend
 Need ROM exercises

Synergists
 Muscles
working together
8
NERVE IMPULSES

Cerebrum – conscious control
 Frontal
lobe
 Impulse, motor nerve, muscle fiber, contraction

Cerebellum – unconscious control
 Coordination
9
MUSCLE TONE

Contraction – continuous slight

Posture - upright

Exercise – isotonic and isometric

Atrophy - wasting

Hypertrophy - enlargement
10
ENERGY
ATP - primary
 Creatine Phosphate – creatine, phosphate, and
energy
 Glycogen – from glucose
 Oxygen – cell respiration (stored as myoglobin)
 Cell respiration
 Lactic Acid – by-product, muscle fatigue, liver
converts it back to glucose

11
MUSCLE FIBERS (CELLS)
Neuromuscular junction – nerve cell and
muscle cell meet
 Synapse - space
 Sarcomeres - individual contracting units

 Actin
and myosin(contractile)
 Troponin and tropomyosin (inhibitory)

Sarcoplasmic reticulum – holds calcium ions
12
SODIUM-POTASSIUM PUMP

Polarization –
 Outside
positive (Na)
 Inside negative (potassium)

Depolarization – started with nerve impulse
 Release
of acetylcholine
 Cell permeable to Na
 Na out and K in
 Cell contraction

Repolarization – depolarization reversed
13
MUSCLE CONTRACTION

Impulse – from the cerebrum

Neurotransmitter released – acetylcholine (Ach)

Electrical change – makes it permeable to
sodium ions

Depolarization – for contraction
14
MUSCLE CONTRACTION (CONTINUED)

What happens with depolarization?
 Calcium
ions attach to myosin and actin
 Myosin signals ATP to release energy
 Myosin attaches to actin – contracts cell

Repolarization
 Troponin
and tropomyosin inhibit myosin and actin
 Cholinesterase released to inhibit Ach
15
MUSCLE ACTIONS
Flexion
 Extension
 Adduction
 Abduction
 Pronation
 Supination
 Dorsiflexion
 Plantar flexion
 Rotation

16
Questions?
17