The respiratory system is necessary to the body because the cells need a way to obtain oxygen and eliminate carbon dioxide. 

The functions include:

1. providing an extensive area for gas exchange between air & circulating blood
2. moving blood to & from the exchange surface of the lungs
3. protecting respiratory surfaces from dehydration, temp changes, and other environmental variations
4. defending itself and other tissue from invasion by pathogenic microorganisms
5. producing sounds involved in speaking, singing, or nonverbal communication
6. assisting in the regulation of blood volume & pressure, and the control of body fluid pH

• Inspiration - The diaphragm contracts downward, increasing the volume in the thoracic cavity. The external intercostals assist in this increase by elevating the ribs, aided by the serratus anterior,  sternocleidomastiod, pec minor, and scalenes
• Expiration - When the diaphragm relaxes, it aches upward, reducing the volume of the thoracic cavity. The internal intercostals depress the ribs, assisting in the reduction of volume.  The transversus thoracis, oblique and rectus abdominis muscles aid the internal intercostals by compressing the abdominal contents

1. Elastic tissue throughout the body deteriorates and is replaced with collagen.  This decreases the lungs' ability to inflate & deflate
2. Movements of the rib cage are restricted by arthritic changes
3. Some degree of emphysema is common

1. Ingestion (food & liquid enter digestive tract via mouth)
2. Mechanical processing (including squashing with tongue, tearing/crushing with teeth, and mixing, churning & propulsion in the rest of the tract
3. Digestion (chemical & enzymatic breakdown of complex sugars, lipids & proteins into small organic molecules that can be absorbed by the digestive epithelium
4. Secretion (acids, enzymes, and buffers produced by the lining of tract or accessory organs such as pancreas)
5. Absorption (movement of small molecules across the digestive epithelium & into interstitial fluid)
6. Excretion (waste products are secreted into the tract primarily by accessory glands like the liver)
7. Compaction (dehydration of indigestible material & organic wastes prior to defecation, into compacted form known as feces)

1. The mucosa, which is in contact with the food, is a mucous membrane
2. The submucosa
3. The muscularis externa, which is filled with smooth muscle used both to propel food through the tract and mechanically process it
4. The serosa, a serous membrane covering the muscularis externa.

Remember that food is considered to be outside the body.

• Peristalsis contracts the muscularis externa behind the bolus, creating pressure behind it.  There is lower pressure in front and so the bolus moves forward
• Segmentation also contracts the muscularis externa, but produces no net movement. The muscle in front and behind contract at the same time, chopping up the boluses.

1. Analysis of material before swallowing
2. Mechanical processing using the teeth, tongue, and palatal surfaces
3. Lubrication by mixing with mucous & salivary secretions
4. Limited digestion of carbohydrates by a salivary enzymes

Saliva helps to kill bacteria even when no foo is present. The 3 salivary glands are:

1. Parotid salivary glands - largest, toward the back of the oral cavity
2. Sublingual salivary glands - covered by a mucous membrane, found at the floor of the mouth below the tongue
3. Submandibular salivary glands - also found in the floor of the mouth, further posterior

At the ultimate center, blood vessels and nerves travel through the "root canal."  The next layer is dentine, the hardest substance in the body. The outer layer is enamel.  The top of the tooth above the gums (givgina) is known as the crown, the part touching the gingiva is the neck, and the long portions into the bone are the roots.

The 4 types of teeth are:

1. Incisors - blade-shaped at the front of mouth
2. Cuspids - canines which have pointed tips for tearing & slashing (fangs)
3. Bicuspids - aka premolars, have flattened crowns with ridges used for crushing, mashing, & grinding
4. Molars - large flattened crownswith prominent ridges for crushing & grinding

The many types signify that we are omniverous

1. Buccal Phase - compression of bolus against hard palate, retraction of tongue forces bolus into the pharynx. This phase is the only one that is voluntary
2. Pharyngeal phase - once the bolus reaches the oropharynx, involuntary reflexes take control. Elevation of the larynx & folding of the epiglottis direct the bolus past the closed glottis into the esophagus
3. Esophageal phase - after passing through the now-open upper esophageal sphincter, peristalsis pushes the bolus along the esophagus. The lower esophageal sphincter allows the bolus into the stomach

1. Bulk storage of ingested food
2. mechanical breakdown of ingested food
3. Chemical digestion of ingested foor through the disruption of chemical bonds by acids and enzymes

1. Cardia  - where the esophagus contacts the stomach
2. Fundus - the superior portion, above the gastroesophageal junction
3. Body - the area from the fundus to the posterior edge of the stomach
4. Pylorus - the "curve of the J", the portion which is to the right side of the body (in anatomical position) connecting to the small intestine

• Duodenum - shortest & widest segment, connecting stomach to small intestine, the "mixing bowl" which receives chyme from the stomach and digestive secretions from the liver & pancreas
• Jejunum - superior portion of the winding intestine, where the majority of chemical digestion & nutrient absorption occurs.
• Ileum - inferior portion of the winding intestine, which ends at the ileocecal valve, a sphincter that controls the flow of materials from the ileum into the cecum of the large intestine, and is important in keeping certain bacteria out of the small intestine

1. The reabsorption of water and electrolytes & compaction of intestinal contents into feces
2. The absorption of important vitamins produced by bacterial action
3. The storing of fecal material before defecation

• Cecum - pouch at the entrance from the small intextine to the large, where materials first arrive.
• Colon - The entire length of the large intestine. It has a larger diameter but shorter length than the small intestine. The ascending colon travels up from the cecum, and turns to the left side of the body at the right colic (hepatic) flexure. The portion traveling to the left side of the body is the transverse colon, which turns to travel downward at the left colic (splenic) flexure. The portion traveling to the inferior of the abdomen is the descending colon, which curves back toward the center line of the body at the sigmoid flexure. This "curve of the J" is known at the sigmoid colon.
• Rectum - the last portion, which is explandable to hold fecal matter. At the bottom of the rectum is the anal canal, ending in the anus and internal & external anal sphincters (external is voluntary, internal is not)

• Metabolic regulation - storage of energy reserves, iron, vitamins, synthesis of cholesterol
• Hematological regulation - synthesis of plasma proteins & clotting factors, blood storage, phagocytosis of damaged rbc's
• Synthesis & secretion of bile - helps to buffer the acids in chyme that enters the small intestine

1. Rate of epithelial stem cell division declines along the absorption surfaces lining the tract
2. Smooth muscle tone decreases (weaker peristaltic contractions)
3. Effects of cumulative damage become apparent (such as tooth decay)
4. Cancer rates increase
5. Changes in other systems have an effect in the digestive system

1. Regulating plasma concentrations of sodium, potassium, chloride, calcium & other ions by controlling the quantities lost in urine
2. Regulating blood volume & blood pressure by adjusting the volume of water lost in urine, and releasing erythropoietin & renin
3. Contributing to the stabilization of blood pH
4. Conserving valuble nutrients by preventing their excretion in urine
5. Eliminating organic waste products, especially nitrogenous wastes such as urea and uric acid
6. Synthesizing calcitriol, a hormone derivative of vitamin D₃ that stimulates calcium ion absorption in the intestinal epithelium
7. Assisting the liver in detoxifing poisons &, during starvation, deaminating amino acids so other tissues can break them down.

Artery entry: Renal artery > segmental artery > interlobar artery > arcuate artery > cortical radiate artery > afferent arteriole > glomerulus > efferent arteriole

Vein exit: Peritubular capillary > venule > interlobular vein > arcuate vein > interlobar vein > renal vein

NOTE: glomerulus is not the end of the arterial chain; efferent arterioles carry blood from the kidney but still considered arterial chain because in nephron

1. A decline in the number of functional nephrons
2. A reduction in glomerular filtration
3. Reduced sensitivity to ADH, resulting in less reabsorption of water and sodium ions
4. Problems with the micturition reflex (peeing)

Epididymis (sperm storage), ductus (vas) deferens, urethra, penis, and accessory glands.

The main functions are storage, nourishment, maturation & transport of spermatozoa. 

The 3 accessory glands are the seminal ("awaken" flagella of sperm), prostate (antibiotic functions), and bulbo-urethral (helps to neutralize urinary acid in urethra)

Step 1: Activated by FSH, a number of primordial follicles develop into primary follicles

Step 2: Only a few of the primary follicles develop into secondary follicles

Step 3: 8-10 days into cycle, the ovaries usually contain only 1 secondary follicle that will proceed with development. by the 10th-14th days, this single follicle has developed into a tertiary follicle. Until now, the primary oocyte was suspended in prophase of meiosis I, and the (now secondary) oocyte beings meiosis II. (Meiosis II will only be completed in fertilization occurs)

Step 4: A rise in LH levels & estrogen triggers ovulation.

Step 5:  The corpus luteum is formed, where lipids are used to synthesize progestins, causing continuation of the uterine preparation

Step 6: Unless pregnancy occurs, the corpus luteum disintegrates and the leftover scar tissue forms the corpus albicans

• Female menopause is the time when ovulation & menstruation cease, typically occuring at age 45-55.  It is accompanied by a sharp rise in GnRH, FSH & LH, while concentrations of estrogen and progesterone decline.
• Male climacteric occurs more gradually, with testosterone levels beginning to decline and LH & FSH levels increasing between age 50 and 60.  Sperm production continues, but sexual activity declines due to the drop in testosterone

• At ovulation, a secondary oocyte surrounded by a corona radiata is released
• Enzymes from multiple sperm create gaps in the corona radiata & 1 sperm makes contacts with the oocyte membrane. Immediate changes in the plasmalemma prevent additional entry of sperm. Membrane fusion occurs, which triggers oocyte activation & completion of meiosis.
• The sperm is absorbed into the cytoplasm and both sperm and egg form pronucleii. Spindle fibers appear in preparation for the first cleavage division
• Metaphase begins, and over about 30 hours the spindle fibers pull apart the duplicate chromosomes, completing the first mitotic division (cleavage)

• 1st trimester - the period of embryonic & early fetal development, when the rudiments of all major organ systems appear.
• 2nd trimester - the time when the organs & organ systems complete most of their development. By the end, the fetus looks distinctly human
• 3rd trimester - rapid fetal growth, and most of the organ systems become fully functional

1. Dilation stage - cervix dialates and fetus begins to move down the cervical canal
2. Expulsion stage (I&II) - fetus begins to pass through the vagina and out of the body (once it passes the hip bones, ex. stage II)
3. Placental stage - the placenta is ejected from the mother's body