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Levels of Organization and Body Systems

What are Levels of Organization?

• Levels of organizations refers to a

multicellular organism that is made up of

cells, tissues, organs, and organ systems.

Sapling Video

Levels of Organization and the

Body System

• In our body there are 11 organ systems that work together to maintain homeostasis.

• In case you forgot, homeostasis is the process organisms use to keep internal conditions constant.

Cells

• Smallest level of organization.

• Cells work by themselves but they are also

part of something bigger (TISSUES).

Cheek Cell Neuron Cell Red Blood Cells

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Tissues

• Collection of cells that work together to

carry out a specific function

• The shape of the tissues and cells will relate to its function

Brain Cells Muscle Cells

Organs

• Made up of tissues• Structurally more complex than tissue• Like tissues, an organ has a specific job to

accomplish

• Ex: the heart is in charge of pumping blood throughout the body

Heart

Organ Systems• Group of organs that work

together to accomplish a large and complex job

• Each organ found in the body is part of an organ system

• Ex: red blood cells (part of the circulatory system) carry oxygen and other materials through your body

• Check for understanding: Which organ is responsible for pumping the blood?

The Circulatory System

Digestive SystemFunction:

Converts food into simpler molecules

that can be used by the cells of the body; absorbs food; eliminates waste

Structures:

Mouth, pharynx, esophagus, stomach,

small and large intestine, rectum.

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Mouth

Esophagus

Pharynx

Stomach

Small

Intestine

Large

Intestine

Rectum

Digestive

Excretory System

Function:

Filters blood, eliminate wastes, regulates the

fluid and chemical composition of blood.

Helps maintain acid-base balance

Maintains mineral homeostasis and produce

urine

Structures:

kidneys, ureters, urinary bladder, urethra,

Kidney

Ureters

Urinary Bladder

Urethra

Circulatory System

Function:

Brings oxygen, nutrients, and hormones

to cells; fights infection; removes cell wastes; helps regulate body

temperature.

Structures:

Heart, blood vessels, blood

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HeartBlood Vessels

Respiratory System

Function:

Provides oxygen needed for cellular

respiration and removes excess carbon dioxide from the body.

Structures:

Nose, pharynx, larynx, trachea, bronchi,

bronchioles, lungs.

Nose (Nasal Cavity)

Larynx

Pharynx

Trachea

Lung

Bronchi

Nervous SystemFunction:

Monitors internal and external environments

with receptors, interprets stimuli, responds to stimuli by sending an electrical message to

another nerve, a muscle, or a gland; thus,

regulates bodily activities. Special senses are

taste, smell, sight, hearing and equilibrium.

Structures:

Brain, spinal cord, peripheral nerves, neurons

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Peripheral Nerves

Brain

Spinal Cord

The Neuron

Skeletal System

Function:

Supports the body; protects internal

organs; allows movement; stores mineral reserves; provides a site for blood cells

formation.

Structures:

Bones, bone marrow, cartilage, ligaments,

tendons

Cartilage

Bone

Tendon

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Bone Marrow Muscular System

Function:

Works with skeletal system to produce

voluntary movement; helps to circulate blood and move food through the

digestive system.

Structures:

Skeletal muscle, smooth muscle, and

cardiac muscle.

Skeletal Muscle Cardiac Muscle Smooth Muscle

Integumentary System

Function:

Serves as a barrier against infection and

injury; helps to regulate body temperature; provides protection against

ultraviolet radiation from the sun

Organs:

Skin, hair, nails, sweat, and oil glands

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Hair

Epidermis

(Skin)

Eccrine

Sweat Gland

Sebaceous

(Oil) Glands

Nail

Endocrine System

Function:

Makes hormones

Controls growth, development, and metabolism; maintains homeostasis.

Structures:

Hypothalamus, pituitary, thyroid,

parathyroids, adrenals, pancreas, ovaries

(in females), testes (in males).

Hypothalamus

Pituitary Gland

Thyroid

Parathyroid Gland

Adrenal Glands

Pancreas

Ovary (female)

Testes (Male)

Lymphatic/Immune System

Function:

Helps protect the body from disease;

collects fluid lost from blood vessels and returns the fluid to the circulatory system.

Structures:

White blood cells, thymus, spleen, lymph

nodes, lymph vessels

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Lymph Nodes

Thymus

Spleen

Reproductive System

Function:

Produce reproductive cells (eggs in females and sperm in males); in females, nurtures and protects developing embryo.

Structures:

In males: testes, epididymis, vas deferens, urethra, and penis.

In females: ovaries, Fallopian tubes, uterus, and vagina

Testes

Epididymis

Vas deferens

Urethra

Penis

Uterus

Vagina

Ovary

Fallopian Tubes