The Major Internal Organs III (Skin, Muscles and Bones)

​The Major Internal Organs

Skin, Muscle, and Bones

Open Ended

Have you ever been cut or scratched on your skin? What did you notice while it was healing?

It is the largest external organ of the body.

It protects the body from microorganisms.

It regulates our temperature by sweating.

It is part of the integumentary system.​

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​The Skin

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Epidermis - outermost layer

• no blood vessels

• gets nutrients from the air

• and the dermis

• has keratinocytes - cells that create hair and nails

• has melanocytes - cells ​that produce skin pigment

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​Layers of the Skin

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Multiple Choice

Which cell in the epidermis forms hair and nails?

• keratinocytes

• leukocytes

• melanocytes

Dermis - the middle part of the skin.

• has blood and lymph vessels, sweat glands, sebaceous glands, and sensory receptors

• has collagen that holds the muscle and skin together.​

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​Layers of the Skin

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Hypodermis - or subcutaneous tissue connects the skin to the bones and muscles.

• insulates and pads the body

• contains large nerves, blood and lymphatic vessels, and fibroblasts

• it stores large amounts of fat​

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​Layers of the Skin

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Multiple Choice

Which layer of the skin contains sweat glands and sebaceous glands?

• epidermis

• dermis

• hypodermis

Open Ended

While you are standing for a long time, you feel like you need to sit down because you are tired. Why do you think this happens?

They give form to the human body.

Muscles come in different shapes and sizes.

Muscles allow you to express emotions too.

There are 650 named skeletal muscles in the body.​

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​Muscles

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Skeletal muscles - voluntary muscles

• have an abundant supply of blood and nerves

• connected to tendons

• they contract bones to move

• maintain posture and position

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​Types of Muscles

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Multiple Choice

Which special tissue attaches the muscle to bones, and helps to move them?

• ligament

• joint

• tendon

Smooth muscles - involuntary muscles

• found in the walls of internal organs: stomach, lungs, intestines, bladder, and blood vessels

• also called visceral muscles

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​Types of Muscles

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Cardiac muscles - involuntary heart muscles

• also known as myocardium

• contracts strongly to create heartbeat to pump blood throughout the body

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​Types of Muscles

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Multiple Choice

What kind of muscle is found in the stomach?

• cardiac

• skeletal

• smooth

Open Ended

Babies have 300 bones, while adults have 206. Where did the other bones go?

Skeletal system - made up of all the bones in the body (plus cartilage and ligaments)

• provides the body with support

• helps in movement and balance

• protects your internal organs​

• stores calcium

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​Bones

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They are made up of compact bone, spongy bone, and bone marrow.​

Yellow bone marrow stores fat.

Red bone marrow produces blood cells.​

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​Bones

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Multiple Choice

The skeletal system is made up of the following, EXCEPT...

• bones

• tendons

• ligaments

Long bones - support weight and help in movement.

Arm bones - humerus, radius, ulna

Leg bones - femur, fibula, tibia

Fingers - metacarpals, phalanges

Toes - metatarsals, phalanges​

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​Types of Bones

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Short bones - provide support and limited motion.

They are mostly spongy bones.​

Wrist bones - carpals

Ankle bones - tarsals​

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​Types of Bones

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Flat bones - provide protection to the vital body parts.

They are made up of spongy bone in between two compact bones.​

Breastbone - sternum

Cranium - skull

Pelvis and ribs​

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​Types of Bones

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Irregular bones - enclose and protect the internal body organs.

They have complex shapes.

Ex. vertebrae, sacrum, jawbone​

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​Types of Bones

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Sesamoid bones - they are small bones shaped like sesame seeds.

They are inside the tendons of the arms, legs, and feet.​

They help decrease pressure on the tendons.

Ex. kneecaps​

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​Types of Bones

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