Transcript Chapter 15 The Digestive System

Welcome to Unit 5
Chapters 15 & 16
Chapter 15
The Digestive System
DIGESTIVE SYSTEM
(FIGURE 15-1)


Irregular tube called alimentary canal or
gastrointestinal (GI) tract
Food must first be digested, then
absorbed, and later metabolized
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 3
2
6
7
8
1
3
4
55
9
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 4
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 5
WALL OF THE DIGESTIVE TRACT
(FIGURE 15-2)


Digestive tract described as tube that extends
from mouth to anus
Wall of the digestive tube is formed by four layers
of tissue:




Mucosa—mucous epithelium
Submucosa—connective tissue
Muscularis—two layers of smooth muscle
Serosa—serous membrane that covers the outside of
abdominal organs; it attaches the digestive tract to the
wall of the abdominopelvic cavity by forming folds called
mesenteries
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 6
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 7
1
2
3
4
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 8
MOUTH



Roof—formed by hard palate (parts of maxillary and palatine
bones) and soft palate, an arch-shaped muscle separating
mouth from pharynx; uvula, a downward projection of soft
palate (Figure 15-4)
Floor—formed by tongue and its muscles; papillae, small
elevations on mucosa of tongue; taste buds, found in many
papillae; lingual frenulum, fold of mucous membrane that
helps anchor tongue to floor of mouth (Figure 15-4)
Typical tooth (Figure 15-5)

Three main parts—crown, neck, and root
 Enamel, which covers the crown, is hardest tissue in body
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 9
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 10
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 11
MOUTH



Types of teeth—incisors, cuspids, bicuspids, and
tricuspids
Twenty teeth in temporary set; average age for
cutting first tooth about 6 months; set complete at
about 2 years of age
Thirty-two teeth in permanent set; 6 years about
average age for starting to cut first permanent
tooth; set complete usually between ages of 17
and 24 years (Figure 15-6)
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 12
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 13

What is the largest salivary gland?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 14
SALIVARY GLANDS
(FIGURE 15-7)



Parotid glands—largest salivary glands
Submandibular glands—open into mouth
on either side of frenulum
Sublingual glands—open into floor of
mouth
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 15
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 16
PHARYNX

Tubelike structure that allows both food
and air to pass.
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 17

What connects the pharynx to the stomach?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 18
ESOPHAGUS


Connects pharynx to stomach
Dynamic passageway for food
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 19
STOMACH (Figure 15-8)





Size—expands after large meal; about size of
large sausage when empty
Food enters stomach through gastroesophageal
(cardiac) sphincter
Pyloric sphincter muscle closes opening between
pylorus (lower part of stomach) and duodenum
Wall—many smooth muscle fibers; contractions
produce churning movements (peristalsis)
Lining—mucous membrane; many microscopic
glands that secrete gastric juice and hydrochloric
acid into stomach; mucous membrane lies in folds
(rugae) when stomach is empty
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 20
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 21
SMALL INTESTINE
(FIGURE 15-9)


Size—about 7 meters (20 feet) long but
only 2 cm or so in diameter
What are the three divisions
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 22
SMALL INTESTINE
(FIGURE 15-9)

Divisions



Duodenum
Jejunum
Ileum
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 23
The surface
is folded
and covered
with villi.
Can you tell
what this
does?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 24
SMALL INTESTINE


Wall—contains smooth muscle fibers that
contract to produce peristalsis
Lining—mucous membrane; many
microscopic glands (intestinal glands)
secrete intestinal juice; villi (microscopic
finger-shaped projections from surface of
mucosa into intestinal cavity) contain blood
and lymph capillaries
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 25
LIVER AND GALLBLADDER



Size and location—liver is largest gland; fills
upper right section of abdominal cavity and
extends over into left side
Liver secretes bile
Ducts (Figure 15-10)




Hepatic—drains bile from liver
Cystic—duct by which bile enters and leaves gallbladder
Common bile—formed by union of hepatic and cystic
ducts; drains bile from hepatic or cystic ducts into
duodenum
Gallbladder


Location—undersurface of the liver
Function—concentrates and stores bile produced in the
liver
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 26
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 27

What does bile do?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 28

Bile acts as a detergent to mechanically
break up, or emulsify fats.
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 29

What is the exocrine gland that lies behind
stomach?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 30
PANCREAS

Functions


Pancreatic cells secrete pancreatic juice (most
important digestive juice) into pancreatic ducts;
main duct empties into duodenum
Pancreatic islets (of Langerhans)—cells not
connected with pancreatic ducts; secrete
hormones glucagon and insulin into the blood
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 31
Large Intestine

What are the three divisions?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 32
LARGE INTESTINE
(FIGURE 15-12)

Divisions






Cecum
Colon—ascending, transverse, descending, and sigmoid
Rectum
Food enters through ileocecal valve; external
opening called anus
Wall—contains smooth muscle fibers that contract
to produce churning, peristalsis, and defecation
Lining—mucous membrane
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 33
?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 34
APPENDIX


Blind tube off cecum
No important digestive functions in
humans
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 35
PERITONEUM (FIGURE 15-14)


Definitions—peritoneum, serous membrane lining
abdominal cavity and covering abdominal organs; parietal
layer of peritoneum lines abdominal cavity; visceral layer of
peritoneum covers abdominal organs; peritoneal space lies
between parietal and visceral layers
Extensions—largest are the mesentery and greater
omentum



Mesentery is extension of parietal peritoneum, which attaches
most of small intestine to posterior abdominal wall
Greater omentum, or “lace apron,” hangs down from lower
edge of stomach and transverse colon over intestines
X-ray studies of the GI tract—radiopaque contrast medium
used to help visualize structures in study images
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 36
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 37
DIGESTION (TABLE 15-2)

Definition—transforms foods into substances that
can be absorbed and used by cells



Mechanical digestion—chewing (mastication),
swallowing (deglutition), and peristalsis break food into
tiny particles, mix them well with digestive juices, and
move them along the digestive tract
Chemical digestion—breaks up large food molecules
into compounds that have smaller molecules; brought
about by digestive enzymes (Figure 15-15)
Enzymes and chemical digestion


Enzymes are specialized protein molecules that act as
catalysts
Breakdown process called hydrolysis
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 38
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 39
DIGESTION

Carbohydrate digestion—mainly in small
intestine

Pancreatic amylase—breaks polysaccharides
down to disaccharides
 Intestinal juice enzymes
• Maltase—changes maltose to glucose
• Sucrase—changes sucrose to glucose
• Lactase—changes lactose to glucose
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 40
DIGESTION

Protein digestion—starts in stomach; completed in
small intestine




Gastric juice enzyme pepsin partially digests proteins
Pancreatic enzyme, trypsin, continues digestion of
proteins
Intestinal enzymes, peptidases, complete digestion of
partially digested proteins and convert them to amino
acids
Fat digestion


Bile contains no enzymes but emulsifies fats (breaks fat
droplets into very small droplets)
Pancreatic lipase changes emulsified fats to fatty acids
and glycerol in small intestine
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 41
ABSORPTION



Definition—process by which digested food
moves from intestine into blood or lymph
Foods and most water minerals and vitamins are
absorbed from small intestine; some water and
vitamin K also absorbed from large intestine
Surface area absorption


Structural adaptations increase absorptive surface area
Fractal geometry—study of fragmented geometric
irregular shapes such as those in lining of intestine
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 42
Chapter 16
Nutrition and Metabolism
DEFINITIONS




Nutrition—food, vitamins, and minerals that are
ingested and assimilated into the body
Metabolism—process of using food molecules as
energy sources and as building blocks for our own
molecules
Catabolism—breaks food molecules down,
releasing their stored energy; oxygen used in
catabolism
Anabolism—builds food molecules into complex
substances
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 44
ROLE OF THE LIVER




Secretes bile, which breaks down large fat
globules
Helps maintain normal blood glucose level
Helps metabolize carbohydrates, fats, and
proteins; synthesizes several kinds of
protein compounds
Removes toxins from the blood
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 45
NUTRIENT METABOLISM

Carbohydrates—preferred energy food of the body

What are the three series of chemical reactions in glucose
metabolism?
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 46
NUTRIENT METABOLISM

Carbohydrates—preferred energy food of the body

Three series of chemical reactions in glucose metabolism
• Glycolysis




Changes glucose to pyruvic acid
Anaerobic (uses no oxygen)
Yields small amount of energy (transferred to ATP)
Occurs in cytoplasm
• Citric acid (Krebs) cycle




Changes pyruvic acid to carbon dioxide
Aerobic (requires oxygen)
Yields large amount of energy (mostly as high energy electrons)
Occurs in mitochondria
• Electron transfer system


Transfers energy from high energy electrons (from citric acid cycle) to
ATP molecules
Located in mitochondria
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 47
NUTRIENT METABOLISM

Carbohydrates (cont.)

Carbohydrates are primarily catabolized for energy (Figure 16-1), but
small amounts are anabolized by glycogenesis (a series of chemical
reactions that changes glucose to glycogen—occurs mainly in liver
cells where glycogen is stored)
 Adenosine triphosphate (ATP)—molecule in which energy obtained
from breakdown of foods is stored; serves as a direct source of energy
for cellular work (Figure 16-2)
 Blood glucose (imprecisely, blood sugar)—normally stays between
about 80 and 110 mg per 100 mL of blood during fasting; insulin
accelerates the movement of glucose out of the blood into cells,
therefore decreases blood glucose and increases glucose catabolism


Fats—catabolized to yield energy and anabolized to form adipose
tissue (Figure 16-3)
Proteins—primarily anabolized and secondarily catabolized
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 48
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 49
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 50
Catabolism
of nutrients
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 51
VITAMINS AND MINERALS


Vitamins—organic molecules that are
needed in small amounts for normal
metabolism (Table 16-2)
Minerals—inorganic molecules found
naturally in the earth, required by the body
for normal function (Table 16-3)
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 52
METABOLIC RATES


Basal metabolic rate (BMR)—rate of
metabolism when a person is lying down
but awake and not digesting food and
when the environment is comfortably warm
Total metabolic rate (TMR)—the total
amount of energy, expressed in calories,
used by the body per day (Figure 16-4)
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 53
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 54
BODY TEMPERATURE


Hypothalamus—regulates the
homeostasis of body temperature
(thermoregulation) through a variety of
processes
Skin—can cool the body by losing heat
from the blood through four processes:
radiation, conduction, convection,
evaporation (Figure 16-5)
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 55
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 56

Questions??
Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Slide 57