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Systems of the Human Body

Author: Sophia

what's covered

In this lesson, you will learn about the eleven organ systems of the human body and their primary functions. Specifically, this lesson will cover:

1. Organ Systems

1. Organ Systems

Anatomy & physiology covers eleven distinct organ systems in the human body. Assigning organs to organ systems can be imprecise since organs that “belong” to one system can also have functions integral to another system. In fact, most organs contribute to more than one system.

key concept

In this course and throughout your studies of biological sciences, you will often read descriptions related to similarities and differences among biological structures, processes, and health-related to a person's biological sex. People often use the words "female" and "male" to describe two different concepts: our sense of gender identity and our biological sex as determined by our chromosomes, hormones, organs, and other physical characteristics. For some people, gender identity is different from biological sex or their sex assigned at birth. Throughout this course, "female" and "male" refer to sex only, and the typical anatomy and physiology of XX and XY individuals is discussed.

There are eleven organ systems that will be covered in A&P I and II and are as follows (in the table below), in order of their appearance in these courses.

Even though there are eleven organ systems, this course will only cover the first four. Why? It is still important to know about all eleven systems as some function together. The rest of the organ systems will be covered in A&P II.

Organ System	Primary Function(s)	Primary Organ(s)	Course That Details Are Taught
Integumentary System	Physical protective barrier Thermoregulation (temperature regulation)	Skin	A&P I
Skeletal System	Physical protection of internal organs Support the body Enable movement	Bones	A&P I
Muscular System	Enable movement Support the body	Muscles	A&P I
Nervous System	Detect, process, and respond to sensory stimuli using electrochemical signals One of two systems that regulate homeostasis	Brain, spinal cord, nerves	A&P I
Endocrine System	Communicate between two body parts using chemical signals called hormones One of two systems that regulate homeostasis	Pituitary Adrenal Glands Thyroid	A&P II
Cardiovascular System	Transport nutrients and waste throughout the body	Blood Heart Blood vessels	A&P II
Lymphatic System	Identify and remove foreign particle in the body Regulate blood volume	Lymph nodes Lymphatic vessels Spleen	A&P II
Respiratory System	Provide the body with oxygen Remove carbon dioxide from the body	Lungs	A&P II
Digestive System	Consume nutrients Digest and absorb nutrients Eliminate waste materials	Esophagus Stomach Small & large intestine	A&P II
Urinary	Regulate blood nutrient concentration	Kidneys Urinary bladder	A&P II
Reproductive	Produce sex hormones and gametes Deliver gametes to female (male only) Support embryo/fetus (female only) Produce milk (female only)	Testes, penis Ovaries, uterus, vagina	A&P II

The first six systems of the human body. The integumentary system is identified by the hair, skin, and nails whose primary functions are enclosing internal body structures, and the site of sensory receptors. The skeletal system is identified by cartilage, bones, and joints, whose primary functions are to support the body and enable movement (with the muscular system). The muscular system is identified by skeletal muscles and tendons, whose primary functions are to enable movement (with the skeletal system) and help maintain body temperature. The nervous system is identified by the brain, spinal cord, and peripheral nerves, whose functions are to detect and process sensory information and activate bodily responses. The endocrine system is identified by pituitary glands, thyroid glands, pancreas, adrenal glands, testes (male), and ovaries (female), whose functions are to secrete hormones and regulate bodily processes. The cardiovascular system is identified by the heart and blood vessels, whose functions are to deliver oxygen and nutrients to tissues and equalize the temperature in the body. — Organ Systems of the Human Body - Organs that work together are grouped into organ systems.

The last five systems of the human body (there are two images for the reproductive system, both male and female). The lymphatic system is identified by the thymus, lymph nodes, spleen, and lymphatic vessels whose primary functions are returning fluid to blood and defending against pathogens. The respiratory system is identified by the nasal passage, trachea, and lungs, whose primary functions are to remove carbon dioxide from the body and deliver oxygen to the blood. The digestive system is identified by the stomach, liver, gallbladder, large intestine, and small intestine, whose primary functions are to process food for use by the body and remove waste from undigested food. The urinary system is identified by the kidneys and urinary bladder, whose functions are to control the water balance in the body, remove wastes from the blood, and excrete them. The male reproductive system is identified by the epididymis and testes, whose functions are to produce sex hormones and gametes and deliver gametes to the female. And finally, the female reproductive system is identified by the mammary glands, ovaries, and the uterus, whose functions are to produce sex hormones and gametes, support the embryo/fetus until birth, and produce milk for the infant. — Organ Systems of the Human Body (continued) - Organs that work together are grouped into organ systems.

hint

The names of each organ system are different. Some are named after their primary anatomical feature. Some are named after their primary physiological function. Some resemble a common term used in everyday English. Others are a little trickier to remember. Here is a brief background on how each system gets its name.

Organ System	How They are Named
Integumentary System	The word integument, from the Latin root, means to cover. The primary organ of this system is the skin which functions to cover the body. Therefore, the name for this system is a fancy way of saying the ‘covering’ system.
Skeletal System	The primary organs of this system are the bones that form the skeleton. Therefore, this is the system related to the skeleton.
Muscular System	The primary organs of the muscular system are muscles attached to the skeleton. Therefore, this is the system related to the muscles.
Nervous System	The primary structures of the nervous system - brain, spinal cord, and nerves - are all composed of nervous tissue. Therefore, this is the system made of nervous tissue.
Endocrine System	From the Greek and Latin roots, ‘endo’ means inside and ‘crine’ means to secrete. The primary function of this system is to produce and release hormones (chemical signals) inside the body. Therefore, the name for this system is a fancy way of saying ‘internally secreting’ system.
Cardiovascular System	From the Greek and Latin roots, ‘cardio’ means heart and ‘vascular’ means vessel. The primary structures of this system are the heart and blood vessels. Therefore, the name for this system is a fancy way of saying the ‘heart and blood vessel’ system.
Lymphatic System	From the Latin root, ‘lymph’ means a colorless fluid. Where the cardiovascular system contains blood, the lymphatic system contains a similar but colorless fluid called lymph. Therefore, this is the organ system related to lymph.
Respiratory System	From the Latin root, ‘respire’ means to breathe again. The primary function of this system is to exchange gasses between the body and the air which is only accomplished by breathing. Therefore, the name for this system is a fancy way of saying the ‘breathing’ system.
Digestive System	From the Latin root, ‘digest’ means to separate, divide, or carry apart. A primary function of the digestive system is to break apart food that has been consumed. Therefore, the name for this system is a fancy way of saying the ‘breaking down’ system.
Urinary System	The primary function of the urinary system is to produce urine (i.e., pee). Therefore, this is the system that produces urine.
Reproductive System	From the Latin root, ‘reproduce’ means to develop or create a copy again. The primary function of this system is to produce sex-specific cells and, through their union, develop offspring (i.e., babies). Therefore this is the offspring development system.

terms to know

Integumentary System

An organ system of the human body made up of the skin which functions as a physical protective barrier and serves in thermoregulation.

Skeletal System

An organ system of the human body made up of bones which functions as protection to certain internal organs and enables movement through freely movable joints.

Muscular System

An organ system of the human body made up of skeletal muscles which functions to produce movement and support for the body.

Nervous System

An organ system of the human body made up of the brain, spinal cord, and nerves which function to detect, process, and respond to a variety of sensory stimuli using electrochemical signals.

Endocrine System

An organ system of the human body made up of multiple organs including the pituitary gland, adrenal glands, and thyroid which function to regulate body processes through chemical signals.

Cardiovascular System

An organ system of the human body made up of the blood, heart, and blood vessels which function to transport nutrients and wastes throughout the body.

Lymphatic System

An organ system of the human body made up of multiple organs including lymph nodes, lymphatic vessels, and the thyroid which function to identify and remove foreign particles from the body and regulate the total blood volume.

Respiratory System

An organ system of the human body made up of the lungs and associated structures which function to provide the body with oxygen and remove carbon dioxide from the body.

Digestive System

An organ system of the human body made up of multiple organs including esophagus, stomach, small intestine, and large intestine which function to ingest, digest, absorb, and defecate nutrient materials.

Urinary System

An organ system of the human body made up of the kidneys, ureters, urinary bladder, and urethra which function to regulate blood solute concentrations and blood volume.

Reproductive System

An organ system of the human body made up of different organs based on biological sex. Males contain testes, penis, and associated structures. Females contain ovaries, uterus, vagina, and associated structures. This system primarily functions to produce sex-specific hormones and gametes.

summary

In this lesson, you learned the eleven organ systems of the human body, their primary functions, and at least one representative organ. You also were introduced to a brief background on how each system gets its name.

Source: THIS CONTENT HAS BEEN ADAPTED OPENSTAX "ANATOMY AND PHYSIOLOGY 2E" AT openstax.org/details/books/anatomy-and-physiology-2e

Terms to Know

Cardiovascular System: An organ system of the human body made up of the blood, heart, and blood vessels which function to transport nutrients and wastes throughout the body.
Digestive System: An organ system of the human body made up of multiple organs including esophagus, stomach, small intestine, and large intestine which function to ingest, digest, absorb, and defecate nutrient materials.
Endocrine System: An organ system of the human body made up of multiple organs including the pituitary gland, adrenal glands, and thyroid which function to regulate body processes through chemical signals.
Integumentary System: An organ system of the human body made up of the skin which functions as a physical protective barrier and serves in thermoregulation.
Lymphatic System: An organ system of the human body made up of multiple organs including lymph nodes, lymphatic vessels, and the thyroid which function to identify and remove foreign particles from the body and regulate the total blood volume.
Muscular System: An organ system of the human body made up of skeletal muscles which functions to produce movement and support for the body.
Nervous System: An organ system of the human body made up of the brain, spinal cord, and nerves which function to detect, process, and respond to a variety of sensory stimuli using electrochemical signals.
Reproductive System: An organ system of the human body made up of different organs based on biological sex. Males contain testes, penis, and associated structures. Females contain ovaries, uterus, vagina, and associated structures. This system primarily functions to produce sex-specific hormones and gametes.
Respiratory System: An organ system of the human body made up of the lungs and associated structures which function to provide the body with oxygen and remove carbon dioxide from the body.
Skeletal System: An organ system of the human body made up of bones which functions as protection to certain internal organs and enables movement through freely movable joints.
Urinary System: An organ system of the human body made up of the kidneys, ureters, urinary bladder, and urethra which function to regulate blood solute concentrations and blood volume.

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Systems of the Human Body

Table of Contents

1. Organ Systems