Body Organization

Cell – Tissue – Organ – Organ System - Body

Tissues: Many similar cells that perform a specific function

Tissue Types

1. Connective – Blood, Bone, Cartilage, Ligaments, & Tendons2. Nervous – Tissue that transmits and receives messages or impulses (brain, spinal cord)

3. Epithelial – Skin

4. Muscle

Skeletal System

The skeletal system consists of 206 bones. At birth humans have 270 bones but many bones fuse

together during growth.

Ligaments – join bones to other bones

Cartilage - soft portion on the tips of all bones and in the nose and ears (doesn’t contain calcium)

 Skeletal System Functions

1. support

2. protection

3. produces blood cells

Bones have two parts:

Spongy bone – the soft inner portion of the bone

- yellow marrow that stores fat

- red marrow where red & white blood cells are manufactured

Compact Bone – the hard outer portion of the bone

- contains Haversian canals which contain blood vessels

Why would there need to be blood vessels in bones?

Osteocytes (bone cells) – need oxygen and food for energy

Development of Bones

In the second month of development bone starts to form where before the embryo had only a cartilage skeleton

Ossification – is the process of cartilage turning into bone

Epiphyseal plate is a layer of cartilage found at the end of each bone where growth takes place. Cells in this area

undergo mitosis

Divisions of these cells cause the cartilage to grow and the bones to lengthen as the bone cells ossify 

Growth stops when these cells stop dividing

Bones continue to grow in width throughout life growth in length stops at 25 if not sooner.

Joints

The place where bones meet is a joint

Joints can be movable and immovable

Where are immovable joints?Four major types of joints:

1. Hinge – elbow, knee, and ankle2. Pivot – neck

3. Ball-and-socket – hip and shoulder

4. Gliding – carpal and tarsal bones

Cartilage and synovial fluid (the WD-40 of your body)

keep joints moving smoothly

Skeletal System problems

Sprain – A stretch or tear of a ligament

Arthritis – when joints become swollen or painful

Rheumatoid arthritis – cartilage becomes

swollen. Eventually it is replaced by bone,

which fuses and prevents movement

Osteoarthritis – when cartilage wears away

and bones rub together

Osteoporosis – a person loses bone density (usually

begins around 40)

More common in women because they

lose their ability to absorb Calcium

efficiently when they have children

THANK YOU MOM!!

The Muscle System

The body has more than 600 muscles (35-45% of body weight)

 

Functions of Muscle System

1. Movement – main function

2. Digestion, Breathing, Heart Beating etc

3. Protection of internal organs

4. Sitting & Standing

 

Muscles only pull a bone

Muscles CANNOT push a bone

This is why muscles act in pairs

One muscle to extend

One muscle to bend

 

2. Smooth Muscle – found in internal organs (digestive tract, arteries, respiratory system)

 

Muscle Types

1. Skeletal Muscles – move bones attached directly to bones or by a tendon

3. Cardiac Muscle – heart muscle

Smooth and Cardiac are both involuntary

What does involuntary mean?

How Muscles Contract:

1. A nerve impulse transmitted to the muscle cell by a nerve.

2. The nerve releases Calcium into the cytoplasm of the muscle cell

3. Calcium attaches to molecules located in the cytoplasm called actin (protein)

4. ATP connects to myosin (protein)

What does ATP do?5. Using the energy from the ATP the myosin (protein) pulls the actin & the muscle contracts

6. When the message from the brain ends the Calcium leaves and the muscle relaxes

Exercise

With aerobic exercise, chest muscles can be strengthened so that more air enters the

body. This type of exercise helps your cardiovascular endurance.

Why would this help?

 Anabolic steroids increase the size and strength of your muscles, synthetic chemicals (that resemble

testosterone) trick your muscles into growing larger. They also cause many irreversible side

effects including cancer, heart disease, and altered sexual development.

Resistance (anaerobic) exercise like weight lifting increases muscle size and

strength but it does not increase the amount of oxygen that enters the body.

Muscle Problems 

Shin Splints – inflammation of the tendons on the inside front of the lower leg, muscle strain , overuse injury 

Muscle Cramps – occurs when a muscle cannot relax

 

Muscular Dystrophy – muscle tissue degenerates and is replaced by fatty tissue

 

Integumentary System

Covers the body

Made up of the skin, hair, nails, & a variety of glands

The Skin is the human body's largest organ

The most important function is protection.

Example

The hormone melatonin, which

secreted by a gland in the brain called the

pineal gland, is secreted at night

when light is absent or dim. Melatonin is what makes us feel

tired

Endocrine System

Controls the body through hormones