Integumentary System

Integumentary System

• A system composed of multiple types of tissue: – Epithelial tissue– Connective tissue– Muscle tissue– Nervous tissue

• Also includes, hair and nails.

Integumentary System

• The function of the system is:– to protect the body– maintain homeostasis – regulate temperature– respond to stimuli

Skin makes up the largest portion of the system.

Structure of Skin

Your skin is composed of two main layers:

Epidermis

Dermis

The epidermis is the outermost layer made of two parts:

1. Exterior Layer: 25-30 layers of dead skin cells that are continually shedding

2. Interior Layer: living cells that divide in order to replace dead cells, contains melanin

Structure of Skin Epidermis

Melanin is a pigment that accounts for the differences in skin color among people.

Melanin also helps protect underlying cells from UV light, which can lead to the development of skin cancer.

Structure of Skin Epidermis

Outer Layer of Epidermis

Fun Fact!

Every 4 weeks, all cells of the epidermis are

replaced by new cells!

That’s a whole lot of skin…

A man standing

behind 21 square feet of skin substitute

– the amount covering an

average human body!

The epidermis on your fingers, palms, toes and soles of your feet formed ridges and grooves before your were born.

The ridges are important for gripping because they increase friction.

Structure of Skin Epidermis

These fingerprints and footprints are often used to identify individuals since each person has a unique set.

The shapes of the fingerprints form

in the womb and can depend on

nutrition, position in the womb and

growth rate.

Structure of Skin Epidermis

Fun Fact!

Identical twins DO NOT

have the same fingerprints!

Structure of Skin

Your skin is composed of two main layers:

Epidermis

Dermis

The dermis is the inner, thicker portion of the skin.

The thickness varies between parts of the body.

Structure of Skin Dermis

Structure of Skin Dermis

The dermis contains:

Oil glands

Sweat glands

Blood Vessels

Nerves

Hair Follicles

Structure of Skin Dermis

• Blood Vessels- deliver materials to cell, pick up wastes

• Nerves/receptors- send messages to your brain to explain touch, heat, etc

• Hair- protect skin, provide insulation

• Sweat glands- cool and clean body surface

• Oil glands- usually connected to hair follicle, keeps skin and hair from drying out, protect from pathogens

Below the dermis is a layer of fat which helps the body absorb impact, retain heat, and store energy.

Structure of Skin Dermis

Fat Layer

Or Hypodermis

• Protection- your skin is the first line of defense from pathogens and UV rays.

• Protect your skin by wearing sunscreen EVERY day!

Function of Skin

• Homeostasis- your skin regulates your body temperature by increasing or decreasing the blood flow

• Also, when your body heats up your sweat glands release liquid to cool your skin

Function of Skin

• Your skin has nerve endings and receptors for touch, pain, and heat.

• Your receptors send messages to your brain/spinal cord so that you can move or make adjustments.

Function of Skin

• Other animals use skin for gas exchange

Other Animals Skin

Section Check

Question 1What part of the skin responds to external stimuli such as heat and pressure?

D. muscle tissue

C. connective tissue

B. nervous tissue

A. epithelial tissue

The answer is B, nervous tissue.

Nerve endings

Question 2Why is your skin considered an organ?

AnswerSkin is composed of cells and tissues. A group of tissues that work together to perform a specialized function are called an organ.

Question 3The thicker portion of skin that is composed of blood vessels, nerves, nerve endings, hair follicles, sweat glands, and oil glands is called the _______.

D. fat tissue

C. epidermis

B. subcutaneous layer

A. dermis

The answer is A, dermis.

Question 4What gives skin color?

D. fat tissue

C. cellulose

B. melanin

A. tanning

The answer is B, Melanin.

Question 5Which is not a function of your skin?

D. Allowing water to escape through pores.

C. Preventing pathogens from entering the body

B. Protecting your organs from harm.

A. Maintaining homeostasis.

The answer is D.

Your skin protects your body from harm, regulates temperature, maintains homeostasis and responds to stimuli.