Histology (4)

• Conducting passages - convey air to the lungs while removing debris, warming, and humidifying the air (nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles)
• Respiratory passages - where the exchange of gases between air and blood occurs (respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli)
• Respiratory System - is responsible for taking in oxygen and expelling carbon dioxide.
• Two types of Respiratory System; Conducting Passages and Respiratory Passages
• Respiratory Epithelium - is a pseudostratified ciliated columnar epithelium with goblet cells that lines much of the conducting passages
• Nasal Cavities - It provide an extensive surface area for removing debris, warming, and humidifying the air. The nasal and oral cavities are separated by the hard and soft palate.
• Base of epiglottis is lined with pseudostratified ciliated columnar epithelium
• Stratified squamous epithelium lines lingual (anterior) and part of laryngeal (posterior) surface
• Epiglottis - The epiglottis is a flap located in the throat that covers the entrance to the larynx during swallowing. Superior part of larynx that projects upward from larynx wall
• Larynx - The larynx is a hollow, tubular structure at the upper end of the trachea. It is involved in breathing and producing sound. The epithelial lining varies depending upon the region of the larynx.
• Trachea - (windpipe) is a fibromuscular tube supported by C-shaped rings of hyaline cartilage. It extends from the larynx toward the lungs.
• Lungs - The adult lungs are sponge-like organs. The main function of the lungs is to provide oxygen and remove carbon dioxidefrom blood.
• Ciliated cells - are most common and extend the thickness of epithelium and sweep the surface
• Goblet cells - are numerous in airways, secrete protective mucus, but decrease in distal parts
• Basal cells -are close to basal lamina, do not reach the surface, and serve as stem cells
• Brush cells - are less numerous, contact afferent axons, and may function as receptors cells
• Small granule cells - contain granules and are analogous to enteroendocrine cells (DNES)
• Type I - Pneumocyte - Squamous and Extremely thin
• Type II - Pneumocyte - Granular and Roughly Cuboidal
• Urinary System - is composed of the kidneys, ureters, urinary bladder, and urethra. Its main function is the production, storage, and expulsion of urine.
• Renin - regulation of blood pressure
• Erythropoietin - stimulates production of red blood cells
• Vitamin D -regulation of calcium levels
• Kidneys - The nephronis the functional unit of the kidney. Each nephron includes a filter (renal corpuscle), and a single, long tubule (renal tubule) through which the filtrate passes before emerging as urine.
• Ureter - are fibromuscular tubes that transport urine by peristalsis from the kidney to the bladder. Like the bladder, it is lined by transitional epithelium (urothelium)
• Urinary Bladder / Bladder - is a muscular sac that stores urine, allowing urination to be infrequent and voluntary. It is lined by transitional epithelium (urothelium), and has a thick layer of smooth muscle.
• Endocrine System - is composed of glands that synthesize and secrete products, called hormones, directly into the blood rather than through a duct. Hormones are transported throughout the body where they influence only those cells that have receptors for that hormone.
• Endocrine - released into blood and act at long distances
• Paracrine - diffuse a short distance through tissue fluids to nearby cells
• Autocrine - act on the same cell that produced the hormone
• Pituitary Gland - often called the "master gland" of the body because it produces hormones that regulate other endocrine glands, as well as, have direct effects on target tissues.
• Thyroid Gland - produces hormones, triiodothyronine (T3) and thyroxine (T4), that primarily influence the basal metabolic rate and protein synthesis.
• Parathyroid Glands - secrete parathyroid hormone (PTH)in response to low blood levels of calcium. PTH secretion causes the release of calcium from bones by stimulating osteoclasts, inhibition of osteoblasts, and increased reabsorption of calcium in the kidney.
• Adrenal glands - produce a variety of hormones that help regulate metabolism, blood pressure, response to stress, and other essential functions.
• Male Reproductive System - consists of the testes, conducting tubules and ducts (epididymis, vas deferens, ejaculatory ducts), accessory sex glands (seminal vesicles, prostate, and bulbourethral glands), and the penis.
• Testes - are responsible for the production of sperm (spermatogenesis) and secretion of male sex hormones (testosterone).
• Epididymis - Sperm leave the testes and enter the epididymis. Each epididymis is a long, tightly coiled duct in which sperm undergo maturation as they move through it.
• Ductus deferens (vas deferens) - is a thick walled, fibromuscular tube that is continuous with the epididymis. Peristaltic movements propel sperm through the duct.
• Seminal Vesicles - are unbranched, highly-coiled tubular glands. Their secretions make up 60 percent of the volume of the semen.
• Prostate - is composed of compound tubuloalveolar glands that contributes a slightly alkaline fluid to semen.