Ch 3- Integumentary System & Ch 4 -The Skeletal System

Integumentary System & The Skeletal System

by Mrs. Davis

​The integumentary system is made up of our skin and all of the items which can be found within the skin including hair, nails, and glands.

The outermost layer of our skin we see every day (which is known as the epidermis) is made up of 30-50 layers of stratified squamous epithelium.

These tissue layers are external (towards the surface of the body) to a second layer of the skin known as the dermis/hypodermis.

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The outer epidermis is avascular meaning it is not supplied with any nutrients from the blood. Without a regular supply of oxygen, the cells within these layers of our skin are dead.

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Yes... All of the skin you see on the human body is actually made up of dead cells!

Open Ended

What is the outermost layer of our skincalled and what is it made of?

​Definition of vascular system - aka the circulatory system is made up of vessels that carry blood and lymph throughout the body.

​As you move deeper into the epidermis you pass through several sub-layers of tissue until you finally reach one known as the stratum basale.

This sub-layer is attached to the dermis/hypodermis layer of the skin with the help of a connective tissue known as basement membrane.

The dermis/hypodermis as well as the stratum basale is vascular as they are regularly supplied with nutrients from the blood. As the stratum basale receives plenty of nutrients from the dermis/hypodermis blood supply through the basement membrane, it regularly grows and divides into new cells.

The deeper cells within the stratum basale remain close to the dermis/hypodermis layer as they remain in contact with the rich nutrient supply.

The cells that are not close to the dermis/hypodermis are pushed outward, towards the surface of the skin.

And, within seven weeks these cells become the outermost layers of the epidermis where they perish due to a lack of nutrients from the blood.

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Why is it important that the basement membrane is vascular?

​The stratum basale has another very important function.

​It produces 3 very important chemicals:

​This vascular layer of the skin creates a specific chemical known as vitamin D.

What is unique about this compound is the energy source required for its production - the sun!

Specific wavelengths of light from the sun allow the stratum basale to generate this very important vitamin.

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Once secreted throughout the body, vitamin D (also known as the "sunshine vitamin") is responsible for the absorption of the elements calcium and phosphorus from the foods we eat.

​Special cells within the epidermis regularly produce a protein known as keratin.

As the dead cells are pushed externally, keratin spreads throughout the tissue layers, toughening the tissue layers and creating a semi-waterproof barrier on the surface of the skin.

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Within the stratum basale you will find cells which are responsible for the production of a pigment called melanin.

Melanin is a brown-black pigment which varies in concentration among different ethnic groups and is very good at absorbing harmful ultraviolet light. The formation of a tan several hours/days after being exposed to the sun is due to an increased production of melanin within the epidermis

Open Ended

Name 3 chemicals produced by the stratum basale and the epidermis.

​The skin helps to maintain our constant body temperature!

​Let's say you're outside on a hot summer day.

Your skin has detected that its surface temperature is well above 98.6 degrees so it sends a message to the hypothalamus which then begins to set things in motion to cool you down.

By allowing the inner walls of the blood vessels to become thinner through a process known as vasodilation, blood is allowed to flow more freely through the warmed area.

In addition, heat is allowed to escape through the vessels more readily and into the epidermis where it can be released into the environment thereby cooling the individual body!!

​If you have ever exercised to the point that your face becomes flushed, you have seen vasodilation in action! At the same time, our sudoriferous glands secrete sweat onto the surface of the skin, taking with it much of this newly released heat from the blood. Once at the surface, the sweat (and heat) is carried away from the skin through evaporation. Cool, huh?

Open Ended

Describe the process of vasodilation and explain why it is needed?

​The Skeletal System...

Open Ended

Write EVERYTHING you know about the skeletal system...

​Now watch this video...

Open Ended

Using your notes and knowledge answer the following questions:  Name 5 functions of the skeletal system

Open Ended

Where are the short bones located and what function do they support?

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How is the thickness of new skeletal tissues maintained within our bones?