Skeletal and Muscular Systems Powerpoint #2 Unit 8 – Chapters 36 Working together to create...
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Transcript of Skeletal and Muscular Systems Powerpoint #2 Unit 8 – Chapters 36 Working together to create...
Skeletal and Muscular Systems
Powerpoint #2Unit 8 – Chapters 36
Working together to create movement
Skeletal System
Structures:
Bones
Cartilage
Ligaments
Functions
Supports body
Protects internal organs
Allows for movement
Stores mineral reserves
Provides a site for blood cell formation
• How many bones in a human Skeleton?• 206
• How many in babies?• ~ 300
• Axial Skeleton: spine, ribcage, skull
• Appendicular: arms, legs, pelvic girdle, shoulders
• What are bones?• A solid network of living cells and
protein fibers that are surrounded by deposits of calcium salts
Bones: 3 Parts Spongy bone
•Not soft or spongy• Very strong• Structure resembles the supporting structure of bridges. • Strong but lightweight
Compact bone:
• Very dense (no spaces like spongy bone)• Outer portion of bone• Contains Haversian canal for veins and arteries to run through
Haversian Canals
Bone Marrow:•Soft tissue•Found in bone cavities•Yellow Marrow: fat cells•Red marrow: •makes red blood cells, platelets and most white blood cells• ~1/2 red marrow turns into
yellow in adults• If severe blood loss, some
yellow can turn back to red
Development of bone:• Cartilage: Tough, elastic, connective
tissue• Found in: ears, between bones,
larynx, and other various places.
Development of Bone• http://www.youtube.com/watch?v=78RBpWSOl08
• Ossification: cartilage replaced by bone
• Osteoblasts:cells that build bone
• Osteoclasts:cells that break down bone• Growth Plates (epiphyseal plates): found in most
long bones (leg and arm bones) cartilage continues to grow here until completely replaced by bone during adolescence=stop growing
Types of Joints -Ball and socket
Types of Joints- Hinge
Types of Joints- Saddle
Types of Joints
• Pivot
Structure of Joints
Anterior Cruciate Ligament
Fractures
Structure of Joints• Bursa: small fluid-filled sac• provides a cushion between bones
and tendons and/or muscles around a joint.
Bursitis
Arthritis
Arthritis
Rheumatoid arthritis Osteoarthritis
Compare Osteoarthritis and normal knee
Total Knee Replacement
Total Knee Replacements
Total Knee Replacement
Osteoporosis
29
Types of Muscle
32
The human body is comprised of ~640-850 muscles (sources varying regarding what is defined as different parts of a single muscle or as several muscles)
makes up 30-35% (in women) and 42-47% (in men) of body mass.
Three types of muscle:
Skeletal muscle
Smooth muscle
Cardiac muscle
A. Skeletal (Striated) Musclemoves various parts of the skeletonvoluntary controlRepeated activation of a skeletal muscle
can lead to fatigueCan have many nuclei Striated (striped appearance)
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Skeletal Muscles work in PAIRSBending or straightening of elbow
requires the coordinated interplay of the biceps and triceps muscles
34
B. Smooth Muscle
Located in the blood vessels, the
respiratory tract, the iris of the eye,
the gastro-intestinal tract
contractions are slow and uniform
Is fatigue resistant
Activation is involuntary
Has one nucleus
35
C. Cardiac Muscle
Functions to provide the contractile activity of the
heart
Activation is involuntary (like smooth muscle)
Can have 2 nuclei, usually has 1
Is very fatigue resistant
36
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myofibril muscle fiber muscle fiber bundle
Components of skeletal muscle
Muscle Fibers: Cylinder-shaped cells that make up skeletal muscle
38
Made of myofibrils which is made up of a number of
myofilaments Two types of protein myofilaments:
- Actin: thin filament
- Myosin: thick filament
Divided into functional units called sarcomeres,
seperated by region called Z lines.
Group of fibers activated via same nerve: motor unit
High microscope magnification of sarcomeres
within a myofibril
39
Muscle Contraction
Muscle Contraction Steps
1. Myosin head attaches to binding site on actin forming a cross bridge
1. After the cross bridge is formed the myosin head bends, called a power stroke, pulling on the actin filaments and causing them to slide.
1. Myosin attached to actin until another ATP binds causing it to release (explains rigor mortis)
1. Muscle contraction is a little like climbing a rope. The cross bridge cycle is: grab -> pull -> release, repeated over and over
Control of Muscle Contraction (animation)
1. Muscle cells are "shocked” by nerve impulses from motor neurons.
2. Neurotransmitters (acetylcholine) are released by neuron, stimulating muscle fiber to release Ca2+
3. When a muscle is relaxed, tropomyosin blocks cross-bridges.
4. When Ca2+ high enough, it binds to troponin, displacing tropomyosin, exposing myosin binding sites on actin.
5. Myosin can now form crossbridge
Control of Muscle Contraction (Neuromuscular junction)
Tendons
Connect Muscle to Bone
Tendon Ruptures
Terminology
Sprain: when a ligament is stretched too much
Strain: when a muscle or tendon is stretched too much