Post on 16-Jan-2016
ORGANS: THE MOUTH
Breakdown of food begins in the mouth.
Starches are broken down by an enzyme called salivary amylase.
Teeth are NOT bones!Teeth are anchored by jaw bones
mastication, beginning of mechanical digestionSaliva: moistens food (easier to
chew/swallow)Chemical digestion: enzymes
COMPONENTS OF THE DIGESTIVE SYSTEM
CONTINUED…
Stomach: continues the mechanical and chemical digestion of foodChemical digestion: stomach
produces HCl, which activates enzymes that digest proteins
Mechanical digestion: stomach muscles contract to churn and mix stomach fluids and food, gradually producing chyme. Chyme eventually flows into the small intestine.
ORGANS: THE ESOPHAGUS
Bolus = chewed clump of food
Esophagus = tube that connects the mouth to the stomach and also begins the process of peristalsis.
Peristalsis: The movement of food down the digestive tract by waves of muscle contractions
Controlled by smooth muscle!
ORGANS: THE STOMACHStomach = a thick-walled muscular sac that
contains enzymes and gastric juices (HCl).Contains 3 smooth muscle layers that alternate
contracting Solids are broken down into a thin, soupy
liquid called chyme.
The enzyme Pepsin breaks down proteins in the stomach into smaller polypeptide fragments
ORGANS: SMALL INTESTINE Coiled tube about 20 ft. long and 2.5
cm. in diameter. 1st part = duodenum, where digestive
enzymes enter intestine
Most digestion and ALL nutrient absorption is completed here.
Lined with millions of tiny “fingers” called villi which increase surface area and aide in absorption of nutrients.
SMALL INTESTINAL ENZYMES
Amylase, Maltase, Sucrase, LactaseContinued breakdown of starches
Trypsin, PeptidaseContinued breakdown of proteins
LipaseBreakdown of fats
ORGANS: LARGE INTESTINE
Tube about 5 ft. long and 6 cm. in diameter…No digestion occurs here!Contains many bacteria!
Functions:Reabsorption of waterReabsorption of vitamins (K and B)
created by E. coli bacteria!Elimination of feces through the anus
(stored in rectum)
OTHER IMPORTANT ORGANS
Liver: gland that produces bile which breaks down fat in the small intestineLocated above, right of stomachProduces sodium bicarbonate
(neutralizes HCl)
Gall Bladder: Stores bile
Pancreas: Releases enzymes into the small intestine.Produces hormones that regulate blood
sugar!
EXCRETION - DEFINED
Excretion:The process by which the skin, lungs,
and kidneys remove metabolic wastes and other excess substances from the body
Humans excrete: water, urea (toxic), salts, proteins, sugars, carbon dioxide, etc…
THE ROLE OF THE LIVER
The liver not only produces bile, but has 2 other major functions:1) Detoxification
Usually of alcohol and drugs
2) Formation of UreaThe liver converts Amino acids from broken down proteins into other compounds
The liver takes potentially poisonous compounds and turns them into urea, which will be removed from bloodstream by kidneys
THE URINARY SYSTEM
Kidneys: Produce urineUreters: Tubes that carry the urine
down to the…Bladder: Storage chamber for urineUrethra: Tube that urine travels
through to exit the body
KIDNEY FUNCTIONThe kidneys play an important role in maintaining homeostasis…
They can filter all blood in your body in 45 minutes!
They regulate the blood’s:Water ContentVolumepHWaste Products
Kidneys remove urea, wastes from blood, and send them to the ureter
KIDNEY STRUCTURE
Two major parts:The outer region is the CortexThe inner region is the Medulla
The real work of the kidneys (the filtering of blood) is done by structures called nephrons (area with arterioles & venules).
Each kidney has about 1.25 million nephrons!
KIDNEYS CONTINUED… Location
Either side of the spine, lower back
Ureter: tube that leaves the kidneys carrying urine to the urinary bladderUrinary bladder: stores
urine prior to excretion, which occurs through the urethra
Nephrons: processing units that do the “actual” filtering of the blood
THE NEPHRON
The nephron is composed of a group of capillaries called the Glomerulus surrounded by the Bowman’s capsule.
THE NEPHRON, CON’T
Wastes are filtered through the glomerulus into the Bowman’s capsule, down the loop of Henle, and eventually out of the kidney…
THE ROLE OF THE LUNGS
Considered excretory organs because they remove carbon dioxide and water from the body…
THE ROLE OF THE SKIN
The skin has two layers that contain:Sweat and oil glands, hair, blood vessels,
and fatty tissue…
Functions include:ProtectionExcretion of water, urea, salts, and heat