Download Muscular and Skeletal System

Muscular and Skeletal
System
Powerpoint #2
Unit 8 – Chapters 35/36
Working together to create
movement
Skeletal System
Structures:
Bones
Cartilage
Ligaments
Tendons
Skeletal System
Function:
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
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: found in most long bones
(leg and arm bones) cartilage continues
to grow here until completely replaced
by bone during adolescence
Types of Joints
Ball and socket
Types of Joints
Hinge
Types of Joints
Saddle
Types of Joints
Pivot
Structure of Joints
Ligaments: Connect Bone to Bone
Anterior Cruciate Ligament
Structure of Joints
Bursa:
20
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
Cardiac muscle
Smooth muscle
21
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
22
Skeletal Muscles work in PAIRS
Bending or straightening of elbow requires
the coordinated interplay of the biceps
and triceps muscles
23
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
24
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
25
Components of skeletal muscle
myofibril
26
muscle fiber
muscle fiber bundle
Muscle Fibers

Cylinder-shaped cells that make up skeletal muscle

Each myofibril is made up of a number of myofilaments

Diameter of fiber (0.05-0.10 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
27
High microscope magnification of sarcomeres
within a myofibril
28
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
29
Muscle Contraction
 During muscle contraction the myofilaments
myosin and actin slide toward each other and
overlap. This shortens the sacromere and the
entire muscle. Muscle cells are "shocked" by
nerve impulses from motor neurons.
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
Tendons
Connect Muscle to Bone
Tendon Ruptures