1. Muscular and Skeletal System
Powerpoint #2
Unit 8 – Chapters 35/36
Working together to create movement

2. Skeletal System
Structures:
Bones
Cartilage
Ligaments
Tendons

3. Skeletal System Function: Supports body Protects internal organs
Allows for movement
Stores mineral reserves
Provides a site for blood cell formation

4. Bones: 206 bones in the human body

5. Bones: 3 Parts Spongy bone Not soft or spongy Very strong
Structure resembles the supporting structure of bridges.
Strong but lightweight

6. Compact bone:
Very dense (no spaces like spongy bone)
Outer portion of bone
Contains Haversian canal for veins and arteries to run though

7. Bone Marrow:
Soft tissue
Found in bone cavities
Yellow Marrow: fat cells
Red marrow: makes red blood cells

8. Muscle Structure and Function

9. Types of Muscle The human body is comprised of 324 muscles
Muscle makes up 30-35% (in women) and 42-47% (in men) of body mass.
Three types of muscle:
Skeletal muscle
Smooth muscle
Cardiac muscle

10. A. Skeletal (Striated) Muscle
Connects the various parts of the skeleton through one or more connective tissue tendons
During muscle contraction, skeletal muscle shortens and moves various parts of the skeleton
Activated through signals carried to the muscles via nerves voluntary control
Repeated activation of a skeletal muscle can lead to fatigue
Can have many nuclei

11. Skeletal Muscles work in PAIRS Bending or straightening of elbow requires the coordinated movement of biceps and triceps muscles

12. B. Smooth Muscle
Located in the blood vessels, the respiratory tract, the iris of the eye, the gastro-intestinal tract
The contractions are slow and uniform
Is fatigue resistant
Activation is involuntary
Has one nucleus

13. C. Cardiac Muscle
Has characteristics of both skeletal and smooth muscle
Functions to provide the contractile activity of the heart
Is very fatigue resistant
Activation of cardiac muscle is involuntary (like smooth muscle)
Can have 2 nuclei, usually has 1

14. Components of skeletal muscle
myofibril muscle fiber muscle fiber bundle

15. Muscle Fibers Cylinder-shaped cells that make up skeletal muscle
Each fiber is made up of a number of myofilaments
Diameter of fiber ( mm) Length of fiber (appr. 15 cm)
Each fiber contains contractile machinery and cell organelles
Group of fiber activated via same nerve: motor unit
Each fiber has capillaries that supply nutrients and eliminate waste
Divided into functional units called sarcomeres

16. High microscope magnification of sarcomeres within a myofibril

17. - Myosin: thick filament
Muscle Contraction
Organized in series ( attached end to end)
Two types of protein myofilaments:
- Actin: thin filament
- Myosin: thick filament
Projecting from each myosin are tiny contractile myosin bridges

18. Muscle Contraction
During muscle contraction the myofilaments myosin and actin slide toward each other and overlap. This shortens the sarcomere and the entire muscle. Muscle cells are "shocked" by nerve impulses from motor neurons.

19. Muscle Contraction
The filaments slide together because myosin attaches to actin and pulls on it. Myosin head (H) attaches to actin filament (A), forming a cross bridge.
After the cross bridge is formed the myosin head bends, pulling on the actin filaments and causing them to slide:
Muscle contraction is a little like climbing a rope. The cross bridge cycle is: grab -> pull -> release, repeated over and over
(a) At rest
b) Contraction

21. Cartilage Tough, elastic, connective tissue
Found in: ears, between bones, larynx, and other various places.

22. Tendons
Connect Muscle to Bone

23. Ligaments
Connect Bone to Bone