Anatomy & Physiology-Marieb-Ch 23: Digestive System (Objectives)

Front 1

Describe the function of the digestive system

Objective 1 (a)

Back 1

Digestive System-

FUNCTION:
(1) to take in food
(2) break food down into nutrients molecules
(3) absorb these molecules into the bloodstream
(4) rid the body of the indigestible remains

Front 2

Describe the function of the alimentary canal and list its organs


Objective #1 (a)

Back 2

The alimentary canal (aka gastrointestinal (GI) tract) -

is the continuous muscular digestive tube that winds through the body

FUNCTION:
digesting and ABSORBING foodstuff;

ORGANS:
(1) the mouth, (2) pharynx, (3) esophagus, (4) stomach, (5) small intestine, and (6) large intestine.(pp. 852–853; Fig. 23.1).

Front 3

Describe the function of the accessory digestive organs and list its organs


Objective #1 (b)

Back 3

Accessory digestive organ-

FUNCTION:
aid digestion physically and PRODUCTION SECRETIONS that break down foodstuff in the GI tract;

ORGANS:
(1) the teeth, (2) tongue, (3) gallbladder, (4) salivary glands, (5) liver, and (6) pancreas.(pp. 852–853; Fig. 23.1).

Front 4

Define Ingestion


Objective #2 (a)

Back 4

Ingestion

-is the simple act of putting food into the mouth (p. 853).

Front 5

Define Propulsion


Objective #2 (b)

Back 5

Propulsion-

moves food through the alimentary canal

INCLUDES:
(1) swallowing and (2) peristalsis (p. 853; Fig. 23.3).

Front 6

Define Mechanical Digestion


Objective #2 (c)

Back 6

Mechanical digestion-

is the physical process of preparing the food for chemical digestion and

INVOLVES (1) chewing, (2) mixing, (3) churning, and (4) segmentation (pp. 853–854).

Front 7

Define Chemical Digestion


Objective #2 (d)

Back 7

Chemical digestion-

is a series of catabolic steps in which complex food molecules are broken down to their chemical building blocks by enzymes (p. 854).

Front 8

Define Absorption


Objective #2 (e)

Back 8

Absorption-

is the passage of digested end products from the lumen of the GI tract through the mucosal cells into the blood or lymph (p. 854).

Front 9

Define Defecation


Objective #2 (f)

Back 9

Defecation-

eliminates indigestible substances from the body via the anus as feces (p. 854).

Front 10

List the major processes occurring during digestive system activity.


Objective #2 (g)

Back 10

major processes (digestive system activity)

(1) Ingestion
(2) Propulsion
(3) Mechanical Digestion
(4) Chemical Digestion
(5) Absorption
(6) Defecation

Front 11

Describe stimuli of digestive activity.


Objective #3 (a)

Back 11

Digestive activities within the GI tract are triggered by:

(1) mechanical stimuli
(2) chemical stimuli.(p. 854; Fig. 23.4).

Front 12

Describe controls of digestive activity.


Objective #3 (b)

Back 12

Controls of the digestive activity-

are both:
(1) extrinsic
(2) intrinsic (nervous and hormonal). (p. 854; Fig. 23.4).

Front 13

Describe the functions of the visceral and parietal peritoneum.


Objective #4 (a)

Back 13

(1) visceral peritoneum-

covers the external surfaces of most of the digestive organs

(2) parietal peritoneum-

lines the body wall of the abdominopelvic cavity.

Front 14

Describe the location of the peritonial cavity.


Objective #4 (b)

Back 14

The peritoneal cavity-

LOCATION: between the visceral and parietal peritoneums and is filled with serous fluid.

Front 15

Describe the location and function of the mesentery.


Objective #4 (c)

Back 15

Mesentery-

LOCATION:
is a double layer of peritoneum that extends to the digestive organs from the body wall.

FUNCTION:
(1) It allows blood vessels, lymphatics, and nerves to reach the digestive organs,
(2) holds the organs in place
(3) as well as stores fat.

Front 16

Define retroperitoneal and name the retroperitoneal organs.


Objective #5

Back 16

Retroperitoneal organs-

are found posterior to the mesentery, lying against the dorsal abdominal wall.

ORGANS:
(1) pancreas
(2) most of the large intestines

Front 17

Define splanchic circulation.


Objective #6

Back 17

The splanchnic circulation-

serves the digestive system and includes those arteries that branch off the abdominal aorta to serve the digestive organs and the hepatic portal circulation (p. 856).

Front 18

Indicate the importance of the hepatic portal system.


Objective #7

Back 18

hepatic portal system-

(1) collects nutrient rich-venous blood draining from the digestive viscera and delivers it to the LIVER

(2) the liver collects the absorbed nutrients before releasing them back to the bloodstream for general cellular use

Front 19

Describe the tissue composition and the general function of mucosa of the alimentary canal.


Objective #8 (a)

Back 19

Mucosa-

is the innermost, moist, epithelial membrane that lines the entire digestive tract.

FUNCTION:
It secretes mucus, digestive enzymes, and hormones; absorbs digestive end products into the blood; and protects against infectious disease.

Front 20

Describe the tissue composition and the general function of submucosa of the alimentary canal.


Objective #8 (b)

Back 20

Submucosa

- is a moderately dense connective tissue layer containing blood and lymphatic vessels, lymphoid
follicles, and nerve fibers.

FUNCTION:
(1) abundant ELASTIC FIBERS enable the stomach to regain its normal shape after temporarily storing a large meal
(2) extensive vascular network SUPPLIES surrounding tissues of the GI tract wall

Front 21

Describe the tissue composition and the general function of muscularis externa of the alimentary canal.


Objective #8 (c)

Back 21

Muscularis externa-

typically consists of smooth muscle

FUNCTION:
(1) responsible for-peristalsis
(2) responsible for -segmentation.

Front 22

Describe the tissue composition and the general function of the serosa the alimentary canal.


Objective #8 (d)

Back 22

Serosa

-the protective outer layer of the intraperitoneal organs, (aka visceral peritoneum). Made up of areolar connective tissue covered with mesothelium (single layer squamous epithelial cells).

Front 23

List the four layers of the alimentary canal.


Objective #8 (e)

Back 23

4 layers of the alimentary canal

(1) mucosa
(2) submucosa
(3) muscularis externa
(4) serosa

Front 24

What is the function of the enteric neurons of the alimentary canal?


Objective #8 (?)

Back 24

The alimentary canal has its own nerve supply made up of enteric neurons that

communicate widely with each other to regulate digestive activity (pp. 857–858).

Front 25

Describe the gross and microscopic anatomy of the MOUTH.


Objective #9 (a)

Back 25

The mouth is a stratified squamous epithelial mucosa-lined cavity with boundaries of the lips, cheeks, palate, and tongue (pp. 858–864; Figs. 23.7–23.11).

Front 26

Describe the gross anatomy and the basic functions of the LIPS and CHEEKS.


Objective #9 (b)

Back 26

The lips and cheek-

ANATOMY: have a core of skeletal muscle covered externally by skin.

FUNCTION:
(1) helps to keep food between the teeth when we chew
(2) plays a small role in speech.

Front 27

Describe the gross anatomy and the basic functions of the PALATE.


Objective #9 (c)

Back 27

The palate-

ANATOMY: forms the roof of the mouth and has two parts: the hard palate anteriorly and the soft palate posteriorly.

Front 28

Describe the gross anatomy and the basic functions of the TONGUE.


Objective #9 (d)

Back 28

The tongue-

ANATOMY: is made of interlacing bundles of skeletal muscle

FUNCTION:
(1) is used to reposition food when chewing,
(2) mixes food with saliva
(3) compacts food into a bolus
(4) initiates swallowing (VOLUNTARY PHASE)
(4) helps form consonants for speech.

Front 29

Describe the gross anatomy and the basic functions of the SALIVARY GLANDS.


Objective #9 (e)

Back 29

Salivary glands-

produce saliva,

FUNCTION:
(1) cleanses the mouth
(2) dissolves food chemicals for taste
(3) moistens food
(4) contains chemicals that begin the breakdown of starches.

Front 30

Describe the gross anatomy and the basic functions of the TEETH.


Objective #9 (f)

Back 30

The teeth-

FUNCTION:
(1) tear and grind food
(2) breaks food into smaller pieces.

Front 31

What anatomical parts make up the oral cavity (aka mouth) ?


Objective #9 (g)

Back 31

Oral cavity-

(1) lips
(2) cheeks
(3) soft and hard palate
(4) tongue
(5) salivary glands
(6) teeth

Front 32

Describe the gross and microscopic anatomy and the basic functions of the PHARYNX.


Objective #9 (h)

Back 32

The pharynx (oropharynx and laryngopharynx)

ANATOMY:
(1) stratified squamous epithelium
(2) skeletal muscles in wall (CONSTRICTOR MUSCLES which help move food to ESOPHAGUS

FUNCTION:
(1) Primarily a FOOD CONDUITS for food, fluids, air (p. 864).
(2) conducts food from the MOUTH-->OROPHARYNX-->LARYNGOPHARYNX --->STOMACH by PERISTALSIS

Front 33

Describe the gross and microscopic anatomy and the basic functions of the ESOPHAGUS.


Objective #9 (i)

Back 33

The ESOPHAGUS (laryngopharynx / joins the stomach)

ANATOMY:
(1) esophageal mucosa = stratified squamous epithelium
(2) muscularis = skeletal muscle (superiorly)
(3) muscularis =smooth muschle (inferiorly)
(4) adventitia instead of serosa

FUNCTION:
(1) Primarily a FOOD CONDUIT for food and fluids
(2) conducts it to the STOMACH by PERISTALSIS from the LARYNGOPHARYNX -->STOMACH where it joins at the cardiac orifice (pp. 864–866; Fig. 23.12).

Front 34

Describe the composition of saliva


Objective #10 (a)

Back 34

Saliva

COMPOSITION:
(1) water
(2) ions
(3) proteins
(4) metabolic wastes
(5) lysozome
(6) defensins
(7) IgA
(8) salivary amylase
(9) cyanide compound
(10) mucin

Front 35

Describe the functions of saliva


Objective #10 (b)

Back 35

Saliva-

FUNCTIONS:
(1) moistens mouth
(2) cleanses mouth
(3) moistens foods-aiding in its compaction
(4) dissolves food chemicals to allow for taste
(5) begins chemical digestion of starch (salivary amylase)

Front 36

Explain how salivation is regulated.


Objective #10 (c)

Back 36

Saliva output

REGULATION:
(1) increase by parasympathetic reflexes initiated by activation of CHEMICAL & PRESSURE receptors in mouth & conditioned reflexes

(2) sympathetic nervous system DEPRESSES salivation

Front 37

Name the glands that produce saliva.


Objective #10 (d)

Back 37

Saliva-

PRODUCED BY:
(1) small buccal glands
(2) 3 pairs of major salivary glands:

(a) parotid
(b) submandibular
(c) sublingual

Front 38

Explain the dental formula


Objective #11 (a)

Back 38

Dental formula-

FOR 1/2 of the mouth: (Upper + Lower) , then x 2

PERMANENT DENTITION:
(2) incisors + (1) canine + (2) premolars + (3) molars (Upper Jaw)
____________________________________________

(2) incisors + (1) canine + (2) premolars + (3) molars (Lower Jaw)

8 + 8 = 16 x 2 = 32 permanent teeth

PRIMARY DENTITION: ****no PREMOLARS--only 2 molars!!!
(2) incisors + (1) canine + (2) molars (Upper Jaw)
____________________________________________

(2) incisors + (1) canine + (2) molars (Lower Jaw)

5 + 5 = 10 x 2 = 20 primary teeth

Front 39

Differentiate clearly between deciduous and permanent teeth


Objective #11 (b)

Back 39

Deciduous teeth (aka milk or baby teeth)

(1) first appear at age 6 months
(2) at 2 years old all 20 primary teeth have erupted

Permanent teeth
(1) resorb the roots of the primary teeth causing them to fall out
(2) begin to erupt at age 6 and continue till age 12.
(3) wisdom teeth erupt at ages 17-25
(4) consist of 32 teeth (some fully erupt some don't)

Front 40

Describe the mechanism of chewing (mastication)


Objective #12 (a)

Back 40

Mastication (or chewing)

-begins the mechanical breakdown of food and mixes the food with saliva (p. 866).

Front 41

List the mechanisms of swallowing (deglutition)


Objective #12 (b)

Back 41

Deglutition, (or swallowing)

(1) Swallowing center in the MEDULLA & PONS controls this phase reflexively.
(2) when the PERISTALTIC WAVE approaches the gastroesophageal sphincter, the sphincter relaxes to ALLOW FOOD ENTRY to stomach

swallowing is a complicated process that involves two major phases (p. 866; Fig. 23.13).

(1) buccal phase (VOLUNTARY)
(2) pharyngeal-esophageal (INVOLUNTARY)

Front 42

Explain what the buccal phase is in the mechanism of swallowing


Objective #12 (c)

Back 42

The buccal phase-

(1) is VOLUNTARY
(2) occurs in the mouth where the bolus is forced into the oropharynx.

Front 43

Explain what the pharyngeal-esophageal phase is in the mechanism of swallowing


Objective #12 (d)

Back 43

The pharyngeal-esophageal phase-

(1) is INVOLUNTARY
(2) occurs when food is squeezed through the pharynx and into the esophagus.

Front 44

Describe capacity and the function of the STOMACH


Objective #13 (a)

Back 44

The STOMACH

CAPACITY:
(1) varies from 15–25 cm long (adult)
(2) its diameter and volume vary depending on the amount of food it contains. (50mL --> 4 L)

FUNCTION:
(1) is a temporary storage tank
(2) where the chemical breakdown of proteins is initiated
(3) food is converted to chyme (pp. 866–869; Fig. 23.14).

Front 45

Identify the MAJOR REGIONS of the STOMACH.


Objective #13 (b)

Back 45

The major regions of the stomach include:

(1) cardiac region (cardia= "near the heart) ---> where food enters stomach
(2) fundus ---> dome shaped
(3) body ---> midsection of stomach
(4) pyloric region. (pyloris = "gatekeeper")

Front 46

Describe the gross anatomy of the STOMACH.


Objective #13 (c)

Back 46

STOMACH:

GROSS ANATOMY:
(1) GREATER CURVTURE =The convex lateral surface of the stomach
(2) LESSER CURVATURE = its concave medial surface

Front 47

Describe the location and function of the two omenta (mesenteries)


Objective #13 (d)

Back 47

Extending from the curvatures are 2 (omenta = "fatty skin")

LOCATION:
(1) LESSER OMENTUM (runs from liver--> LESSER CURVATURE)
(2) GREATER OMENTUM (inferiorly from GREATER CURVATURE --> covers small intestine).

FUNCTION: which help to tie the stomach to other digestive organs and the body wall.

Front 48

Identify structural modifications of the wall of the stomach that enhance the digestive process.


Objective #13 (e)

Back 48

WALL OF THE STOMACH

-although the stomach wall contains the four typical tunics, two are modified for special roles

STRUCTURAL MODIFICATION:
(1) stomach muscularis-
(2) stomach mucosa-

Front 49

Describe the microscopic anatomy and function of STOMACH MUSCULARIS

(explain how its modification enhances the digestive process)


Objective #13 (f)

Back 49

STOMACH MUSCULARIS:

ANATOMY:
(1) made of smooth muscle
(2) inner most layer--runs OBLIQUELY

FUNCTION:
(1) its arrangement allows, mixing churning, and moving of food
(2) but also PUMMELING of food (3) physically breaking it down by JACKKNIFING stomach into a V shape
(4) ramming the food into the small intestine--through propulsive action

***

Front 50

Describe the microscopic anatomy and function of STOMACH MUCOSA and explain how its modification enhances the digestive process


Objective #13 (g)

Back 50

STOMACH MUCOSA (surface epithelium):

ANATOMY:
(1) simple columnar epithelium
(2) composed of entirely of mucous cells

FUNCTION:
(1) produces a protective two-layer coat of alkaline mucus.
(2) PROTECTS the stomach from self-digestion and HCl

Front 51

Describe the function of GASTRIC GLANDS and name the cell types responsible for secreting the various components of gastric juice.


Objective #14 (a)

Back 51

GASTRIC GLANDS OF THE STOMACH:

FUNCTION: produce gastric juice,

SECRETORY CELLS (and COMPONENTS they produce)
(1) Mucous neck cells---> mucus
(2) Parietal cells --->HCl & intrinsic factor
(3) Chief cells---> pepsinogen, lipases
(4) Enteroendocrine cells---->hormones.

Front 52

What cell type is responsible for secreting MUCUS in gastric juice?

(indicate the importance of it in stomach activity)

Objective #14 (b)

Back 52

Mucous neck cells secrete

MUCOUS

FUNCTION:
(1) soluble mucous different from that secreted by mucous cells
(2) not yet understood what special function this "acidic"mucous performs

Front 53

What cell type is responsible for secreting HYDROCHLORIC ACID in gastric juice?

(indicate the importance of it in stomach activity)

Objective #14 (c)

Back 53

Parietal Cells SECRETE

HYDROCHLORIC ACID

FUNCTION:
(1) makes stomach contents extremely acidic (pH 1.3-3.5)
(2) acidic condition necessary for ACTIVATION/OPTIMAL activity of PEPSIN
(3) acidity helps in food digestion (denaturing proteins)
(4) breaks down cell wall of PLANT FOODS
(5) Harsh enough to KILL many BACTERIA

Front 54

What cell type is responsible for secreting INTRINSIC FACTOR in gastric juice?

(indicate the importance of it in stomach activity)

Objective #14 (d)

Back 54

Parietal cells SECRETE

INTRINSIC FACTOR- a glycoprotein

FUNCTION:
(1) required for VITAMIN B12 absorption in the small intestine
(2) needed to produce mature erythrocytes
(3) in its absence PERNICIOUS ANEMIA develops

Front 55

What cell type is responsible for secreting PESINOGEN in gastric juice

(indicate the importance of it in stomach activity).

Objective #14 (e)

Back 55

Chief cells secrete

PEPSINOGEN-the inactive form of pepsin (enzyme)

FUNCTION:
(1) catalyzes the conversion of pepsinogen to pepsin (protein-digesting enzyme)

Front 56

What cell type is responsible for secreting LIPASES in gastric juice?

(indicate the importance of it in stomach activity).

Objective #14 (f)

Back 56

Chief cells secrete

LIPASES (fat digesting enzymes)

FUNCTION:
(1) very little is produced by these cells

Front 57

What cell type is responsible for secreting GASTRIN in gastric juice?

(indicate the importance of it in stomach activity).

Objective #14 (g)

Back 57

Enteroendocrine cells secrete

GASTRIN (a hormone)

FUNCTION:
(1) essential in REGULATING stomach secretion & motility

Front 58

Explain how GASTRIC SECRETION is regulated.


Objective #16 (a)

Back 58

Gastric secretion-

is controlled by both neural and hormonal mechanisms and acts in three distinct phases:
(1) the cephalic phase
(2) the gastric phase
(3) the intestinal phase.

Front 59

Explain how STOMACH MOTILITY is regulated


Objective #16 (b)

Back 59

The reflex-mediated relaxation of the stomach muscle and the plasticity of the visceral smooth muscle

FUNCTION:
(1) allow the stomach to accommodate food
(2) maintain internal pressure.

Front 60

Explain how gastric secretion and stomach motility are regulated.


Objective #16 (?)

Back 60

The interstitial cells of Cajal-

FUNCTION: establish the stomach’s basic electrical rhythm of peristaltic waves.