Introduction to Anatomy & Physiology

• The lymphatic system provides immunity against pathogens with the help of white blood cells.
• White blood cell types include lymphocytes and macrophages. Lymphocytes can be considered B or T cell types.
• Macrophages will alert Helper T cells when a pathogen enters the body. Helper T cells secrete protein signals to gather B cells and Killer T cells.
• B cells do not directly attack pathogens, but have receptor proteins on their surface called antibodies. They can secrete them and tag pathogens for recognition.
• Killer T cells recognize tagged pathogens and release enzymes that promote the pathogen to complete apoptosis, a process of cell self-destruction.
• Macrophages will consume the pathogens and waste remains of infected cells.
• Allergies are an immune response to certain pathogens or an “overreaction” to harmless substances.
• Vaccination is the introduction into the body of a dead or disabled pathogen or of a harmless microbe with the protein of a pathogen on its surface.
• In autoimmune diseases, the ability to distinguish cells of the body from foreign cells breaks down, causing the body to attack its own cells.

The Urinary System

• The urinary system eliminates wastes from the body, regulates blood and water levels, and secretes hormones that directly influence various physiological processes in the body.
• The kidneys filter the blood and form urine as a byproduct, which travels through the ureter before being stored in the bladder and eventually excreted from the body via the urethra.
• Nephrons are the functional units and structures of the kidneys that play a large role in filtration, reabsorption, and secretion.
• After blood enters the kidneys through the renal artery, it is filtered in the glomerulus. Then, it travels through the proximal tubule, the loop of Henle, and the distal convoluted tubule before accumulating as urine in the collecting duct.
• Urinalysis is a method used to evaluate the quality of urine and help diagnose various urinary health problems.

The Endocrine System

• The endocrine system functions with the nervous system to regulate the many activities critical to the maintenance of homeostasis.
• Chemical signals, or ligands, are molecules released from one location that move to another location to produce a response.
• Chemical signals bind to proteins or glycoproteins called receptor molecules to produce a response.
• A hormone is an intercellular chemical signal that is produced in minute amounts by collections of cells to influence the activity of those tissues in a specific way.
• Hormones are distributed in the blood to all parts of the body, but only certain tissues, called target tissues, respond to each type of hormone.
• Negative-feedback mechanisms control the secretion of hormones.
• The endocrine system consists of ductless glands that secrete hormones directly into the blood.
• The aging process affects hormone activity.

The Reproductive System

• The reproductive system enables sexual reproduction in humans.
• Sexual maturity occurs during puberty. Humans are capable of reproduction for several decades.
• The male reproductive system provides the sperm, the carrier of the genetic contribution from the father.
• The female reproductive system provides the ovum, or egg cell, which contains the genetic contribution from the mother.
• The male testicles are analogous to the female ovaries. There are other similarities in the male and female reproductive systems.
• After ovulation, the ovum is transported from the ovary to the uterus though the Fallopian tube of the female reproductive system. If sperm are present in the Fallopian tube, fertilization may occur.
• A fertilized zygote embeds in the endometrium of the uterus for gestation; an unfertilized ovum passes out of the body during subsequent menstruation.
• The female reproductive system supports fertilization; provides the mechanical protection and nurturing environment needed for embryogenesis and gestation; and performs the actions necessary for the birth of the infant.