Anatomy and Physiology
• Tests back
• All graded work back
• Please turn in any missing or late work ASAP
they will go in as missing today.
Chapter 14- Digestive System
• Ingestion—taking in food
• Digestion—breaking food down both
physically and chemically
• Absorption—movement of nutrients into the
bloodstream
• Defecation—rids the body of indigestible
waste
• Two main groups
– Alimentary canal (gastrointestinal or GI tract)—
continuous coiled hollow tube
– Accessory digestive organs
Organs of digestive system
•
•
•
•
•
•
•
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Black organs
each have four
layers
4 Layers of the alimentary canal
– Mucosa
• Innermost, epithelium, connective tissue, Small smooth
muscle layer
– Submucosa
• beneath the mucosa, connective tissue with blood vessels,
nerve endings, and lymphatics
– Muscularis externa
• Smooth muscle layer
– Serosa—outermost layer of the wall
• Visceral peritoneum—outermost layer that is continuous
with the innermost layer
• Parietal peritoneum—innermost layer that lines the
abdominopelvic cavity
1. Mouth
• Houses cheeks, palate, uvula, tongue, and
teeth
Mouth Physiology:
• Mastication (chewing) of food
• Mixing masticated food with saliva
• Initiation of swallowing by the tongue
• Allows for the sense of taste
2. Pharynx
• Serves as a passageway for air and food
• No digestive function
Pharynx Physiology:
• Food movement is by alternating contractions
of the muscle layers (peristalsis)
3. Esophagus
• Runs from pharynx to stomach through
diaphragm
• No digestive function
Esophagus Physiology:
– Conducts food by peristalsis (slow rhythmic
squeezing)
– Passageway for food only (respiratory system
branches off after the pharynx)
4. Stomach
• Located on the left side of the abdominal cavity
• Food empties into the small intestine at the
pyloric sphincter (valve)
Stomach Physiology:
• Temporary storage tank for food
• Site of food breakdown
• Chemical breakdown of protein begins
• Delivers chyme (processed food) to the small
intestine
5. Small intestine
• The body’s major digestive organ
• Site of nutrient absorption into the blood
• Structural modifications that increase surface
area
– Microvilli—tiny projections of the plasma
membrane (create a brush border appearance)
– Villi—fingerlike structures formed by the mucosa
– Circular folds (plicae circulares)—deep folds of
mucosa and submucosa
5. Small intestine
Small intestine Physiology:
Chemical digestion- begins in small intestine
– Enzymes are produced by
• Intestinal cells
• Pancreas
– Pancreatic ducts carry enzymes to the small
intestine
– Bile, formed by the liver, enters via the bile duct
6. Large Intestine
• Larger in diameter, but shorter in length, than
the small intestine
• Cecum—saclike first part of the large intestine
• Appendix
• Colon
• Rectum
7. Anus
• Opening of the large intestine
Accessory Organs
1. Teeth
– Baby teeth (milk teeth)
– Permanent teeth- A full set is 32 teeth, but some
people do not have wisdom teeth (third molars)
Accessory Organs
2. Pancreas
– Extends across the abdomen from spleen to
duodenum
– Produces a wide spectrum of digestive enzymes
that break down all categories of food
– Enzymes are secreted into the duodenum
Accessory Organs
3. Liver
– Liver produces bile
– Function—emulsify fats by physically breaking
large fat globules into smaller ones
– Produced in the liver but stored in the gallbladder
Accessory Organs
4. Gallbladder
– When no digestion is occurring, bile backs up the
cystic duct for storage in the gallbladder
– When digestion of fatty food is occurring, bile is
introduced into the duodenum from the
gallbladder
A&P
• Quiz today
• Continue Digestion (Chapter 14)
• Computer labs
Functions of the digestive system
1. Ingestion—getting food into the mouth
2. Propulsion—moving foods from one region of
the digestive system to another
– Peristalsis—alternating contraction and relaxation
that squeezes food along the GI tract
– Segmentation—moving materials back and forth
to aid with mixing in the small intestine
Functions of the digestive system
3. Food breakdown as mechanical digestion and
chemical digestion
– mechanical- prepares food for further degradation
of enzymes
– chemical- Enzymes break down food molecules
into their building blocks
Functions of the digestive system
4. Absorption
– End products of digestion are absorbed in the
blood or lymph
– Food must enter mucosal cells and then into
blood or lymph capillaries
5. Defecation
– Elimination of indigestible substances from the GI
tract in the form of feces
Nutrition
• Nutrient—substance used by the body for
growth, maintenance, and repair
• Major nutrients
– Carbohydrates
– Lipids
– Proteins
– Water
• Minor nutrients
– Vitamins
– Minerals
• Carbohydrates
– Most are derived from plants
– Exceptions: lactose from milk and small amounts of
glycogens from meats
• Lipids
– Saturated fats from animal products
– Unsaturated fats from nuts, seeds, and vegetable oils
– Cholesterol from egg yolk, meats, and milk products
• Proteins
– Complete proteins—contain all essential amino
acids
• Most are from animal products
– Legumes and beans also have proteins, but are
incomplete
• Vitamins
– Most vitamins are used as coenzymes
– Found in all major food groups
• Minerals
– Play many roles in the body
– Most mineral-rich foods are vegetables, legumes,
milk, and some meats
Where digestion begins for each
macromolecule
• Carbohydrates- amylase initiates starch
digestion in the mouth
• Protein- Pepsin from stomach begins digestion
in the stomach
• Lipids- Bile salts from the liver emulsify fat in
the small intestine
Metabolism
• Chemical reactions necessary to maintain life
– Catabolism—substances are broken down to
simpler substances; energy is released
– Anabolism—larger molecules are built from
smaller ones
Chemical energy (high-energy electrons)
CO2
CO2
Glycolysis
Glucose
Cytosol
of cell
Pyruvic
acid
Mitochondrion
Chemical energy
Krebs
cycle
Electron transport
chain and oxidative
phosphorylation
H2O
Mitochondrial
cristae
Via oxidative
phosphorylation
ATP
ATP
ATP
Cellular Respiration
• Oxygen-using events take place within the cell
to create ATP from ADP
• Carbon leaves cells as carbon dioxide (CO2)
• Hydrogen atoms are combined with oxygen to
form water
• Energy produced by these reactions adds a
phosphorus to ADP to produce ATP
• ATP can be broken down to release energy for
cellular use
• Glycolysis—energizes a glucose molecule so it
can be split into two pyruvic acid molecules
and yield ATP
• Krebs cycle
– Produces virtually all the carbon dioxide and
water resulting from cell respiration
– Yields a small amount of ATP
• Electron transport chain
– Hydrogen atoms removed during glycolysis and
the Krebs cycle are delivered to protein carriers
– Hydrogen is split into hydrogen ions and electrons
in the mitochondria
– Electrons give off energy in a series of steps to
enable the production of ATP
• Kilocalorie (kcal) is the unit of measure for the
energy value of foods and the amount of
energy used by the body
A&P
• Quiz today
• Food lab – did you remember to bring
something to eat?
• Computer labs – urinary system
• Test Friday 
Chapter 15
• Urinary System
– Elimination of waste products
• Nitrogenous wastes
• Toxins
• Drugs
Functions of the Urinary System
• Regulate aspects of homeostasis
– Water balance
– Electrolytes
– Acid-base balance in the blood
– Blood pressure
– Red blood cell production
– Activation of vitamin D
Organs of the Urinary System
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Kidneys
Ureters
Urinary bladder
Urethra
Regions of the Kidneys
Kidney Structures
• Renal or medullary pyramids—triangular
regions of tissue in the medulla
• Renal columns—extensions of cortex-like
material inward that separate the pyramids
• Calyces—cup-shaped structures that funnel
urine towards the renal pelvis
Nephrons
• The structural and functional units of the
kidneys
• Responsible for forming urine
• Main structures of the nephrons
– Glomerulus
– Renal tubule
• Glomerulus
– Knot of capillaries
• Renal tubule extends from glomerular capsule
and ends at the collecting duct
– Glomerular (Bowman’s) capsule
– Proximal convoluted tubule (PCT)
– Loop of Henle
– Distal convoluted tubule (DCT)
Where does the filtrate travel?
1.
2.
3.
4.
5.
Bowman’s (Glomerular) capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting duct
A&P
• Test on Friday
• Finish up Urinary system today
• Kidney Dissections/sections
• Finish study guides in class today also
• Begin work on the FINAL REVIEW!
• Filtrate- the fluid that results from filtration
occurs in the kidneys. Water is filtered out
from other wastes
– Includes:
•
•
•
•
Water
Glucose
Ions
Amino acids
Tubular reabsorption
• Materials not reabsorbed
– Nitrogenous waste products
• Urea—protein breakdown
• Uric acid—nucleic acid breakdown
• Creatine—associated with creatine metabolism in
muscles
Characteristics of Urine
• Solutes normally found in urine
– Sodium and potassium ions
– Urea, uric acid, creatine
– Ammonia
– Bicarbonate ions
Characteristics of Urine
• Solutes NOT normally found in urine
– Glucose
– Blood proteins
– Red blood cells
– Hemoglobin
– White blood cells (pus)
– Bile
Ureters
• Slender tubes attaching the kidney to the
bladder
– Continuous with the renal pelvis
– Enter the posterior aspect of the bladder
• Runs behind the peritoneum
• Peristalsis aids gravity in urine transport
Urinary Bladder
• Smooth, collapsible, muscular sac
• Temporarily stores urine
• Trigone—triangular region of the bladder base
– Three openings
• Two from the ureters
• One to the urethra
– In males, the prostate gland surrounds the neck of
the bladder
Gender differences in urethra
• Function
– Females—only carries urine
– Males—carries urine and is a passageway for
sperm cells
• Kidneys have four roles in maintaining blood
composition
– Excretion of nitrogen-containing wastes
(previously discussed)
– Maintaining water balance of the blood
– Maintaining electrolyte balance of the blood
– Ensuring proper blood pH
Water regulation
– Antidiuretic hormone (ADH)
• Prevents excessive water loss in urine
– Aldosterone
• Regulates sodium ion content of ECF
• Promotes reabsorption of sodium ions