Body Organization Levels of Organization Section 7 4

Body Organization

Levels of Organization Section 7 - 4 Muscle cells Go to Section: muscle tissues Organ systems

These Organ Systems function together to maintain homeostasis – a stable internal environment

Figure 35 -2 Human Organ Systems Part I Section 35 -1 Nervous System Integumentary System Skeletal System Muscular System Circulatory System

Figure 35 -2 Human Organ Systems Part 2 Section 35 -1 Respiratory System Endocrine System Digestive System Excretory System Reproductive System Lymphatic System

4 Main Types of Tissues 1. Epithelial Tissue – cells pack tightly together and cover and protect underlying tissue; Lines our organs; Ex: stomach lining & skin

4 Main Types of Tissues 2. Connective Tissue joins, supports, protects, and nourishes organs; Ex: ligaments, tendons, cartilage, bone, blood

4 Main Types of Tissues 3. Muscle Tissue – contracts and relaxes for movement – – – Skeletal muscle- moves bone; voluntary (works when you want it to) Cardiac Muscle-Only found in the heart. Involuntary (works all the time) Smooth Muscleinvoluntary (works all the time)

4 Main Types of Tissues 4. Nervous Tissue – sends electrical signals throughout the body. Ex: Brain, Spinal Cord, Nerves

Integumentary System

Functions of the Skin 1. Covers and protects the body What does the skin protect us from? – Pathogens – Injury – Ultra-violet radiation Body’s Museum in Atlanta

Functions 2. Regulate body temperature/reduces water loss How does it regulate temperature? – Sweating – Dilate/constrict of blood vessels – Goose bumps

Functions 3. Excretes Waste like Urea How are wastes excreted? In sweat subcutaneous

Functions 4. Sensory receptors input information to the brain about the outside environment Chemo Mechano Chemo Photo Mechano

There are 2 main layers of skin outer layer deeper layers

Epidermis Outer (surface) layers of skin Stratum corneum Stratum lucidum Stratum granulosum 10 -30 cells thick Two Parts: Inner part Dead keratinocytes Lamellar granules Keratinocyte Langerhans cell Stratum spinosum composed of living cells Outer part is of dead cells Melanocyte Stratum basale Dermis Merkel cell Tactile disc Sensory neuron

Dermis Deeper layers of skin 10 -20 times thicker than epidermis. Top layer arranged In ridges. Dermis

Specialized Cells of the Epidermis Melanocytes are cells that produce melanin. Melanin is a pigment that helps to protect the skin from harmful ultraviolet solar radiation from the sun. Makes your skin darker or lighter

Interesting Tidbit Melanocytes Do some people have more melanocytes than other people?

Interesting Tidbit Skin pigmentation is due to the type and amount of melanin produced Eumelanin produces darker pigments Phaeomelanin produces lighter pigments and freckles These often occur together in varying amounts Melanocyte

Interesting Tidbit Ridges help the epidermis bind to the dermis. The uneven ridges create fingerprints Dermis

Accessory Organs of the Dermis 1. Hair follicles – tube-like depression where the hair develops

Accessory Organs of the Dermis 2. Sebaceous glands – secret oily sebum to soften and waterproof skin

Accessory Organs of the Dermis 3. Nails – protective covers of ends of fingers and toes.

Accessory Organs of the Dermis 4. Sweat glands: – secrete waste – regulate heat

Accessory Organs of the Dermis 5. Blood vessels – to nourish skin cells

Accessory Organs of the Dermis 6. Nerves – to send and receive messages Subcutaneous

Accessory Organs of the Dermis 7. Erector pilli muscle -smooth muscle -causes “goosebumps” -causes hair to stand erect subcutaneous

Subcutaneous layer Anchors dermis to the body Contains fat cells to protect and cushion Subcutaneous layer

Self Quiz What are three layers of skin?

Self Quiz

Interesting Tidbits • A fingernail or toenail takes about 6 months to grow from base to tip • Fingernails grow faster than toenails • An average human scalp has 100, 000 hairs • We lose between 40 and 100 hairs per day • Blondes have more hair than brunettes

Interesting Tidbits • Friction of the epidermis causes cell division to increase. • This outward thickening is called a callous. • Sometimes growth is inward, creating a corn. • Humans shed about 600, 000 particles of skin per hour – about 1. 5 pounds per year. • At age 70, you will have lost about 105 lbs of skin.

Interesting Tidbits • Fingerprints provide traction for grasping objects • Even identical twins have different fingerprints • Every square inch of dermis contains twenty feet of blood vessels • Skin on our hands and feet is thicker. When we bathe, skin takes on water and swells slightly. • In the thicker areas, increased surface area creates crowding. The skin must wrinkle to accommodate the changes

Interesting Tidbits • Your body is composed of approximately 100 Trillion cells • About 16% of your body weight is skin • The skin is completely renewed every 27 days • You will make almost 1000 new skins in a lifetime • If all the layers of your skin were laid out on the ground, it would cover about 20 m 2 or 2 parking spaces

Disorders of the Skin 1. Acne – infection of sebaceous gland

Disorders of the Skin 2. Vascular Birthmarks – Blood vessel abnormality affecting. 5% of population – darkens skin

Disorders of the Skin 3. Dermatitis – dry, sensitive skin

Disorders of the Skin 4. Fungal infections Athlete’s Foot Ring Worm

Disorders of the Skin 5. Impetigo – bacterial infection

Disorders of the Skin 6. Psoriasis – chronic inflammation

Disorders of the Skin 7. Cancer Carcinoma Melanoma

Disorders of the Skin 8. Warts- viral infection

Disorders of the Skin 9. Burns First degree Second degree Third degree

Concept Map Section 36 -3 Skin functions as a Barrier to infection Regulator of body temperature is made up of the Remover of waste products Protector against UV radiation Epidermis which is the Outer layer Dermis which is the Inner layer

Albanism: a defect of melanin production that results in little or no color (pigment) in the skin, hair, and eyes.

Albanism is a genetic disorder that is carried on the recessive allele.