Organ Systems

Organ Systems Digestive System Consists of three divisions including the mouth, the pharynx, and the alimentary canal, comprising the esophagus, the stomach, the small intestine, and the large intestine. Performs specific functions: essential food-processing activities. In the mouth, the food is moistened by saliva; is masticated and mixed by the mandible, teeth, and tongue; and is propelled by the pharynx and esophagus into the stomach, where it is mixed with the gastric juice and converted into chyme. Performs specific functions: in the small intestine, the food or chyme is digested by secretions from glands in the intestinal wall and from the liver, gallbladder, and pancreas; digested end products are absorbed into the blood and lymph capillaries in the intestinal wall. Performs specific functions: in the large intestine, water and electrolytes are absorbed and the waste products are transported to the rectum and anal canal, where they are eliminated as feces. Respiratory System Consists of a conducting portion and a respiratory portion. Air is transported to the lungs through the conducting portion, which comprises the nose, nasal cavity and paranasal sinuses, pharynx, larynx, trachea, and bronchi. As the air passes through these organs, it is filtered, humidified, and warmed by their mucous membranes. Consists of a respiratory portion: the lungs , which contain the terminal air sacs, or alveoli , where exchange occurs between oxygen in the air and carbon dioxide in the blood with the aid of the diaphragm and thoracic cage. Is concerned with speech, which involves the intermittent release of exhaled air and the opening and closing of the glottis. Urinary System Comprises the kidneys, which remove wastes from the blood and produce the urine; the ureters , which carry urine from the kidney to the urinary bladder; the urinary bladder, which stores urine; and the urethra, which drains urine from the bladder and conveys it out of the body. Contains the kidneys, which are important in maintaining the body water and electrolyte balance and the acid-base balance, in regulating the urine volume and composition and the blood volume and blood pressure, and in eliminating waste products from the blood. Reproductive System Male Reproductive System Consists of (a) the testes , which produce spermatozoa and sex hormones; (b) a system of ducts, through which spermatozoa travel from the testis to reach the exterior; (c) various glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which contribute secretions to the seminal fluid; and (d) the urethrae, which pass the ejaculate to an opening at the tip of the external genital organ, the penis. Has ducts : leading from each testis are the duct of the epididymis, the ductus deferens, and the ejaculatory duct, which opens into the urethra. Has glands : the prostate, the seminal vesicles, and the bulbourethral glands, all of which secrete into the urethra. Female Reproductive System Consists of ovaries, uterine tubes, uterus, vagina, and external genital organs. The ovaries produce oocytes (ova or eggs) that are conveyed from the ovaries through the uterine tubes to the cavity of the uterus and also produce the steroid hormones. Each ovulated oocyte is released into the peritoneal cavity of the pelvis; one of the uterine tubes captures the oocyte by the fimbriae, where it begins its journey toward the uterus. The uterine tubes transmit spermatozoa in the opposite direction, and fertilisation of an oocyte usually occurs within the expanded ampulla of a uterine tube. A fertilized oocyte becomes embedded in the wall of the uterus, where it develops and grows into a fetus, which passes through the uterus and vagina (together called the birth canal). The vagina provide a passage for delivery of an infant; it also receives the penis and semen during sexual intercourse. Includes female external genitalia: the mons pubis, which is a fatty eminence anterior to the symphysis pubis; the labia majora, which are two large folds of skin; the labia minora , which are two smaller skin folds, commence at the glans clitoris, lack hair, and contain no fat; the vestibule , which is an entrance of the vagina between the two labia minora and has the hymen at the vaginal orifice; and the clitoris , which is composed largely of erectile tissue, has crura, body, and glans (head), and is hooded by the prepuce of the clitoris. Endocrine System Is a series of ductless or endocrine glands that secrete messenger molecules called hormones directly into the blood circulation and are carried to body cells. Controls and integrates the functions of other organ systems and plays a very important role in reproduction, growth, and metabolism, which are slow processes compared to the rapid processes of the nervous system. Comprises pure endocrine organs such as the pituitary, pineal, thyroid, parathyroid,and suprarenal glands; other endocrine cells are contained in the pancreas, thymus,gonads, hypothalamus, kidneys, liver, and stomach. Includes tropic hormones , which affect other organs and regulate the functional states of other endocrine glands and control a variety of physiologic responses. Integumentary Consists of the skin (integument), and its appendages including sweat glands, sebaceous glands, hair, and nails. Contains sense organs called sensory receptors associated with nerve endings for pain, temperature, touch, and pressure. Skin Is the largest organ of the body and consists of the epidermis , a superficial layer of stratified epithelium that develops from ectoderm, and the dermis , a deeper layer of connective tissue that develops largely from mesoderm. The dermis contains downgrowths from the epidermis, such as hairs and glands, and the epidermis is an avascular keratinized layer of stratified squamous epithelium that is thickest on the palms and the soles. Just deep to the skin lies a fatty layer called the hypodermis. Is not only a protective layer and an extensive sensory organ but also is significant in body temperature regulation, production of vitamin D, and absorption. Appendages of the skin Have the sweat glands that develop as epidermal downgrowths, have the excretory functions of the body, and regulate body temperature; have the sebaceous glands that develop from the epidermis (as downgrowths from hair follicles into the dermis) and empty into hair follicles, and their oily sebum provides a lubricant to the hair and skin and protects the skin from drying; have hairs that develop as epidermal downgrowths, and their functions include protection, regulation of body temperature, and facilitation of evaporation of perspiration; and have nails that develop as epidermal thickenings and that protect the sensitive tips of the digits. ◄.....Go back to the Gross Anatomy homepage