The document provides an overview of the major organ systems in the human body. It describes the main functions of the nervous system including controlling mental and physical activity. It notes that the integumentary system acts as a protective barrier for the body using skin, hair, and nails. The muscular system is made up of three types of muscles that can contract and help with functions like moving blood vessels. The endocrine system consists of glands that secrete hormones to influence distant cells. The immune, respiratory, circulatory, digestive, reproductive, excretory and skeletal systems are also summarized briefly.

1. Human Body
Organ System Overview

2. Nervous System
• Mental and physical activity and many aspects of homeostasis are controlled
by the nervous system.
• The central nervous system (CNS) includes the brain and spinal cord.
• Main divisions of the brain include the cerebrum-largest portion- and the
brain stem (cerebellum)

3. Integumentary System
• The integumentary system consists of the skin, hair, and nails, acts as a
barrier to protect the body from the outside world. It also functions to
retain body fluids, protects against disease, eliminates waste products, and
regulate body temperature.

4. Muscular System
• A muscle is a tissue in a coordinated fashion and includes muscle tissue,
which can contract blood vessels, nerves, and connective tissue.
• The human body has three types of muscle tissues: skeletal, smooth, and
cardiac.

5. Endocrine System
• Consists of glands that transmit chemical messengers throughout the body called
hormones
• A gland is an organ that consists of cells that secrete materials into other regions of
the body. There are two types of glands: exocrine and endocrine.
• Hormones are compounds that are secreted in small amounts into the blood stream
and that influence the activity of distant cells.
• Amino acid base hormones – proteins amino acids adrenaline
• Steroid hormones—estrogen and testosterone

6. Immune System
• The immune system is the body system that fights off infection and
pathogens.
• Many other tissues and systems help the immune system.
• Skin is a physical barrier to infection.
• Mucous membranes trap pathogens entering the body.
• The circulatory system transports immune cells.
• Some viral diseases can be prevented with vaccines.

7. Respiratory System
• The respiratory and circulatory systems bring oxygen and nutrients to the
cells.
• The respiratory system is where gas exchange occurs.
– picks up oxygen from inhaled air
– expels carbon dioxide and water

8. Circulatory System
• Two fluids move through the circulatory system: blood and lymph
• Blood, heart, and blood vessels form the cardiovascular system.
• Lymph, lymph nodes, and lymph vessel form the Lymphatic system.
• The cardiovascular system and lymphatic system collectively make up the
circulatory system.

9. Digestive System
• Your digestive system is uniquely designed to turn the food you eat into nutrients, which the body uses for energy, growth and cell repair.
1. Ingest the food
2. Transport the food
3. Digest the food into smaller usable components.
4. Absorb the necessary nutrients into the bloodstream.
5. Expel the waste products from the body.
Composed of two separate categories of organs:
digestive organs
accessory digestive organs.
Collectively make up the gastrointestinal (GI) tract.
Also called the digestive tract or alimentary canal.

10. Female Male
Reproductive System
• The human reproductive system produces, stores, nourishes, and transports
functional male and female gametes.
– Sperm
– Ovum
– Fertilization produces a zygote.
• The reproductive system also produces sex hormones that affect the structure and
function of other systems.

11. Excretory System
• The excretory system is the system of an organism's body that performs the
function of excretion, the bodily process of discharging wastes.
• The Excretory system is responsible for the elimination of wastes produced
by homeostasis

12. Skeletal System
The adult human body consists of approximately 206 bones, which are
organized into an internal framework called the skeleton.
The human skeleton is composed of two parts:
1. Axial Skeleton—which is composed of bones from the skull, ribs, spine,
and sternum
2. Appendicular Skeleton—which is composed of the bones from the arms
and legs, along with the scapula, clavicle, and pelvis