1. Muscular System
Chapter 8

5. Intro to Muscles Nearly half our weight comes from muscle tissue
There are 650 different muscles in the human body

6. Three Main Functions Responsible for body movement
Responsible for body form and shape (posture)
Responsible for body heat and maintaining body temperature

7. 4 Characteristics
CONTRACTILITY – the capability or quality of shrinking or contracting
EXCITEABILITY– the ability to respond to certain stimuli by producing impulses
EXTENSIBILITY – the ability to be stretched.
ELASTICITY – ability of muscle to return to its original length when relaxing.

8. 3 Types of Muscles Skeletal Muscle VOLUNTARY Attached to bone
Striated (striped) appearance
Contract quickly, fatigue easily, can’t maintain contraction for long period of time

9. 3 Types of Muscles Smooth Muscle INVOLUNTARY Visceral (organ) muscle
Found in walls of digestive system, uterus and blood vessels
Act slowly, do not tire easily, can remain contracted for long time

10. 3 Types of Muscles Cardiac Muscle Found only in the heart! INVOLUNTARY
Striated and branched
Cells are fused – when one contracts, they all contract

11. Connective Tissues Fascia – encloses the muscle
Ligaments –bone to bone
Tendons – muscle to bone

12. Connective Tissues EPIMYSIUM = surrounds whole muscle
This model of the muscles uses straws to represent fibers.
Green = endomysium Yellow = perimysium Blue = epimysium
Connective Tissues
EPIMYSIUM = surrounds whole muscle
PERIMYSIUM = surrounds each fascicle (bundle of muscle fibers)
ENDOMYSIUM = surrounds each muscle fiber

13. It is important to remember the hierarchy
Wrapped in EPIMYSIUM
MUSCLE
Wrapped in PERIMYSIUM
Wrapped in FASCIA
FASCICLES
Wrapped in ENDOMYSIUM
MUSCLE FIBERS
MYOFIBRILS
FILAMENTS
ACTIN (light)
MYOSIN (dark)

14. Muscle Layers

15. Epimysium
Perimysium
Endomysium

16. Contractions
Links form between actin (THIN) and myosin (THICK) to produce a contraction
ATP supplies energy for contraction to occur
Fibers have an ALL or NONE contraction

17. Neurons/Muscles Motor neurons stimulate muscle fibers to contract
Motor neuron secretes neurotransmitter known as ACETYLCHOLINASE
One motor neuron connected to muscle fibers make up a motor unit

18. SMOOTH Muscle Fibers Also contain actin and myosin
Triggered by two neurotransmitters:
Acetylcholine and Norepinephrine
Contract using PERISTALSIS
a wave-like motion found in tubed organs

19. Cardiac Muscle Intercalated discs connect cardiac cells together
Rhythmic contractions