Chapter 17 Digestive System

Human Physiology

What is Digestive?

is the mechanical and chemical breakfown of foods into forms that cel membranes can absorb.

2 parts of digestion

mechanical and chemical breakdown(absorption of resulting nutrients by cells)

What are the 2 components of the digestive system?

alimentary canal(GI track) and accessory organs

Alimentary Canal(GI track)

1.Mouth 2.pharynx 3.esophagus 4.stomach 5.small intestine 6.large intestine 7.anal canal

Accessory Organs

1. salivary glands 2.liver 3.gall bladder 4.pancreas; accessory organs add things to food to help it get out

What are the two motor functions of the alimentary canal?

mixing movements and propelling movements

Mixing Movements

smooth muscle (controls rythmically);includes segmentation in SI

Propelling movements(peristalis)

wavelike motion ring contracts, front relaxes, pushes contents ahead

How is a GI camera used?

the patient swallows the camera and it reveals blockages and sites of bleeding which helps diagnose cancer and oter diseases

What is the function of the mouth?

begins digestion by mechanically breaking solid particles into smaller pieces and mixing them with saliva

Oral cavity

Chamber between the palate and tongue

Vestibule

narrow space between the teeth, cheeks and lips

A. Cheeks

lateral walls of the mouth(expression and chewing)

B. Lips

highly mobile structures that surroud the mouth opening(test temperature and texture)(red color due to numerous blood)

C. Tongue

root of BLANK is anchored to hyoid bone

Lingual Frenulum

mucous membrane covers the tongue, and a membranous fold(connects tongue to floor of mouth)

Papillae

The surface of the tongue has rough projections(provides friction to handle food; taste buds)

palate

What forms the roof of the oral cavity(and makes up the palantine bone and palantine process)?

uvula

The muscular arch which extends posteriorly and downward as a cone-shaped projections is called the____?

Tonsils

all are masses of lymphatic tissue

These tonsils are round masses of lymphatic tissue that cover the root of the tongue____?

lingual tonsils

These tonsils lie in the back of the mouth and help protec the body from infection?

palantine tonsils(these are sometimes removed)

These tonsils are often called the adenoids?

pharyngeal tonsils

What is the function of teeth?

break food into smaller pieces, which begins mechanical digestion

Teeth:Primary(deciduous)

usually erupt trough the gums at six months to 4 years(you have 20)

Teeth:secondary(permanent)

erupt at six years of age 17-25 years (you have 32)

Incisors

front 4, bite off large pieces of food(8 total)

Cuspids

next teeth lateral, for grasping/tearing food(4 total)

bicuspids(premolars)

next 2 lateral, flattened teeth for grinding (8 total)

Molars

next 3 out; also for grinding(12 total)

Crown

projects beyond the gum

root

anchored to the jaw

enamel

glossy, white, covers the crown; made of calcium salts; hardest substance in the body

dentin

surrounds pulp cavity like bone

pulp cavity

a central/cavity that is filled with pulp. pulp is a mass of tissue including blood vessels nerves and connective tissue

root canals

connects pulp cavity to root

What is the function of salivary glands?

secrete saliva; moisten, binds, carbohydrate digestion, cleanse mouth

What are the two types of cells in the salivary glands?

serous and mucous cells

What do serous cells produce?

watery fluid that contains amylase

What do mucous cells secrete?

thick liquid(mucous); these bind food particles together and lubricates mouth/esophagus during swallowing

What are the 3 pairs of salivary glands?

parotid glands, submandiular glands, sublingual glands

How big and where are the parotid glands?

they are largest; between cheek and masseter muscle

What do the parotid glands secrete?

a clear water fluid rich in salivary amylase

Where the submandibular glands?

are in the(floor of the mouth)on the inside surface of the mandible

How big and where are the sublingual glands?

they are the smallest; (floor of the mouth)inferior to the tongue

What do the sublingual glands secrete?

mucous type(secrete very thick and stringy fluid)

What does the pharynx connect?

nasal and oral cavities

What are the 3 parts of the Pharynx?

nasopharynx, oropharynx, laryngopharynx

What is the nasopharynx?

passageway for air during breathing

What is the oropharynx?

passageway for food moving downward and air moving to/from nasal cavity

What is the laryngopharynx?

passageway to esophagus

What is the pharynx?

throat

What is the first step to swallowing?

food is chewed and mixed with saliva-tongue rolls food into a mass orbolus and then travels to pharynx

What is the 2nd swallowing step?

swallowing reflex

What are the 6 steps to the swallowing reflex?

1.soft palate rises;closing off nasal cavity

2. hyoid/larynx raise;epiglottis closes off trachea

3. tongue pushes against soft palate and uvula;closes off nasal cavity

4. pharynx muscles contract; pulling pharynx toward food

5. inferior muscles relax,opening esophagus

6. superior muscles contract, stimulating peristalsis to move food

What is the 3rd step to swallowing?

peristalsis transports food through the esophagus to stomach

How long is the esophagus?

about 25 cm

What does the esophagus connect?

pharynx to stomach

What is the esophageal hiatus?

where esophagus penetrates diaphragm

What is another name for lower esophageal sphincter?

cardiac sphincter

What is the lower esophageal sphincter?

closes the entrances to stomach to prevent regurgitation

How much does the stomach hold?

1 liter of fluid and chyme

What are rugae?

Thick folds that disappear when stretched

What are the functions of the stomach?

receives food from esophagus, mixes food with gastric juice, initiates protein digestion, undergoes limited absorption, moves food to small intestine

What is the 1st part of the stomach that is near the esophagus?

cardiac

What is the 2nd part of the stomach that is a temporary storage area; goes superior to cardia?

fundic

What is the 3rd part of the stomach that is the main portion?

body

What is the 4th part of the stomach that is near the small intestine?

pyloric

What is the pyloric sphincter?

valve between stomach and SI that controls gastric emptying

What are gastric pits?

small openings in the mucous membrane

What is the 1st type of gastric glands that secretes mucus?

mucous cells

What is the 2nd type of cell within gastric glands that secrete digestive enzymes?

chief cells

What is the 3rd type of cell within gastric glands that release HCL?

parietal cells

What is the 4th type of cell within gastric glands that secrete hormones?

enteroendocrine cells

What are the digestive enzymes in gastic juice?

pepsin, mucous cells, intrinsic factor, gastrin, cholecystokinin

Pepsin

secreted by chief cells as pepsinogen

Mucous cells

alkaline solution that coats stomach wall(prevents stomach from digesting itself)

Intrinsic factor

secreted by parietal cells(helps SI absorb Vitamin B12)

Gastrin

peptide hormone(increases secretory activity of gastric glands)

Cholecystokinin

peptide hormone released by intestinal wall (decreases gastric mobility as SI fills with food)

Is it true that the stomach absorbs only small quantities of water and salts?

true

What is chyme?

semifulid paste of food particles and gastric juice

What does peristalsis do for chyme?

peristalsis pushes chyme, and releases it little by little into the SI

What determines the rate of chyme?

fluidity(fluid goes quickly)(fatty food take the longest(3-6 hours))(carbs are the quickest)

What do the pancreas, gall bladder, and liver do as chyme enters duodenum?

add their secretions

What is the function of the pancreas?

secretes pancreatic juice

What does the pancreatic duct connect with?

duodenum

What is pancreatic juice made up of?

pancreatic amylase, pancreatic lipase, nucleases, trypsin(a proteinase), chymotrypsin, carboxypeptidase

What does pancreatic amylase do?

digests carbohydrates

What does pancreatic lipase do?

digests fats

What do nucleases do?

break down nucleic acids

What does trypsin(a proteinase), chymotryosin, and carboxypeptidase do?

protein-splitting enzyme

Secretin

peptide hormone(stimulates secretion of pancreatic juice)

Cholecystokinin

stimulates gall bladder to contract and release bile(and secretes small amount of pancreatic juice)

Acute Pancreatitis

when pancreatic enzymes become active before being secreted; digests part of pancreas (can be caused by gallstones blocking, alcoholism, infections, injuries, meds)

Where is the liver and gallblader?

upper right quadrant

How heavy are the liver and gallbladder?

they are the heaviest organ-around 3 lbs

What does hepatic generally refer to?

liver

Do liver and gallbladder have a lot of blood vessels?

yes

What are the hepatic lobules?

the functional units