CMQ

An organ is a structure made up of two or more kinds of tissues organized in such a way that they can together perform a more complex function than can any tissue alone.

An organ system is a group of organs arranged in such a way that they can together, perform a more complex function than can any organ alone.

Knowledge of individual organs and how they are organized into groups makes the understanding of how a particular organ system functions as a whole more meaningful.

Now we’ll review the basic structures and functions of the body’s organ systems.

The integumentary system has only one organ, the skin, but it has many appendages (or attached structures).

Skin appendages include the hair, nails, microscopic sense receptors, sweat glands, and oil glands.

The primary function of the integumentary system is protection. Additional functions include regulation of body temperature, synthesis of chemicals, and its use as a sense organ.

The skeletal system is comprised of bones, cartilage, ligaments, and joints.

Bones are the organs of the skeletal system. There are 206 named bones in the skeleton, but additional variable bones occur in each individual.

Cartilage connects and cushions joined bones.

Ligaments are bands of fibrous tissue that hold bones together.

Joints are the connections between bones that make movement possible.

The skeletal system functions as the supporting framework for the entire body. It protects the brain and internal organs, and provides movement with joints and muscles. It also stores minerals and forms blood cells.

The next system to review is the muscular system.

Muscles are the primary organs of the muscular system and are divided into three types: voluntary or striated skeletal muscle; involuntary or smooth muscle tissue in the walls of some organs; and cardiac muscle in the wall of the heart.

The muscular system functions in movement, maintenance of body posture, and production of heat.

If you hear the term “skeletomuscular system,” this simply means a combination of the skeletal and muscular systems.

The nervous system can be considered a communications system of the body.

It also integrates body functions, controls body functions, and is involved in the recognition of sensory stimuli.

The nervous system is divided structurally into the central nervous system (or CNS), which includes the brain and spinal cord, and the peripheral nervous system (or PNS), which includes the cranial nerves and their branches, the spinal nerves and their branches, and the sense organs.

The endocrine system consists of ductless glands that secrete signaling hormones directly into the blood.

Its functions are the same as the nervous system—communication, integration, and control. However, in the endocrine system, control is slow and of long duration.

The term neuroendocrine system is a combination of nervous and endocrine systems.

Examples of functions regulated by hormones: include growth, metabolism, reproduction, and fluid and electrolyte balance.

The cardiovascular system is also called the circulatory system.

It includes the heart and blood vessels.

Functions of the cardiovascular system are transportation of substances throughout the body, regulation of body temperature, and immunity (or body defense).

The next systems to review are the lymphatic and immune systems.

Structures of the lymphatic system include the lymphatic vessels, lymph nodes and tonsils, thymus, spleen, and red bone marrow.

The lymphatic system functions in transportation of lymph, and in immunity.

Structures of the immune system include unique cells and defensive protein compounds.

Phagocytes and secretory cells are the unique cells.

Antibodies and complements are the defensive protein compounds.

Functions of the immune system include phagocytosis of bacteria, as well as chemical reactions that provide protection from harmful agents.

You may be familiar with some of the functions of the next system, the respiratory system.

It is involved in the exchange of waste gas (carbon dioxide) for oxygen in the alveoli of the lungs; infiltration of irritants from inspired air, and in regulation of acid-base balance.

Structures of the respiratory system include the nose, pharynx, larynx, trachea, bronchi, and lungs.

Functions of the next system, the digestive system, are also likely familiar to you.

They include mechanical and chemical breakdown of food (called digestion), absorption of nutrients, and elimination of undigested waste product—referred to as feces.

In addition, the appendix holds bacteria that assist digestion.

Structures of the digestive system are considered either primary organs or accessory organs.

Primary organs form the alimentary canal, called the gastrointestinal (or GI) tract. They are the mouth, pharynx, esophagus, stomach, small and large intestines, rectum, and anal canal.

Accessory organs assist the digestive process. Accessory organs include the teeth, salivary glands, tongue, liver, gallbladder, pancreas, and appendix.

The next system to review, the urinary system, includes these structures: the kidneys, ureters, urinary bladder, and urethra.

In males, the urethra is part of both the urinary and the reproductive systems.

Functions of the urinary system are “clearing,” or cleaning the blood of waste products, which are excreted from the body as urine; electrolyte balance; water balance; and acid-base balance.

The reproductive systems ensure survival of genes and produce sex cells: sperm in the male: ova in the female.

These systems also transfer and fertilize sex cells; develop, birth, and nourish offspring, and produce sex hormones.

Structures of the reproductive system of the male include the testes, which are the gonads of the male, as well as other structures including the vas deferens, urethra, prostate, and external genitalia, the penis and scrotum.

Structures of the reproductive system of the female include the ovaries, which are the gonads of the female, as well as other structures: the uterus, uterine (or fallopian) tubes, vagina, external genitalia (also called the vulva), and the mammary glands, the medical term for breasts.

As you review the individual body systems, keep in mind the concept of the body as a whole. No one body system functions entirely independently of other systems. All body systems are structurally and functionally interrelated and interdependent.

This concludes the audio review of Chapter 5.