Seeley's Anatomy And Physiology Chapter 24 Digestive System

Front 1

Digestive System

Back 1

Consists of the digestive tract/alimentary tract (mouth to anus) and its accessory organs

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Gastrointestinal Tract

Back 2

Refers to the stomach and intestines

Front 3

Regions of the digestive tract

Back 3

Oral Cavity, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine, Anus

Front 4

Functions of the Digestive System

Back 4

Ingestion, Mastication, Propulsion, Deglutition, Secretion, Digestion, Absorption, Excrement

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Ingestion

Back 5

The intake of solid or liquid food into the stomach.

Front 6

Mastication

Back 6

The process by which teeth chew food.

Digestive enzymes work effectively on particle surfaces, so foods must be broken down into smaller particles.

Front 7

Propulsion

Back 7

The movement of food from one end of the digestive tract to the other.

Swallowing/deglutition - moves a bolus from the oral cavity into the esophagus

Peristalsis - Propels material through the digestive tract.

Mass Movements - Contractions that move material in some parts of the large intestine.

Front 8

Paristaltic Waves

Back 8

Muscular contractions of the circular muscles in front of the bolus followed by a strong contraction of circular muscles behind the bolus force it along the digestive tube.

Front 9

Mixing

Back 9

Some contractions move food back and forth within the digestive tract to help break it into smaller pieces.

Process - A secretion in the digestive tract, segments of the digestive tract alternate between relaxation and contraction, material in the digestive tract is spread out in both directions and becomes more diffuse through time (segmental contractions)

Front 10

Secretion

Back 10

Added to lubricate, liquify, buffer, and digest food.

Mucus is secreted along the entire digestive tract and protects the epithelial cells from mechanical abrasion, stomach acid, and digestive enzymes.

Contain large amounts of water, which liquify the food and make it easier to digest and absorb.

Front 11

Enzymes

Back 11

Secreted by the oral cavity, stomach, small intestine, and pancreas - break down large food molecules into smaller molecules that can be absorbed by the intestinal wall.

Front 12

Digestion

Back 12

The break down of large organic molecules into their component parts
Carbohydrates into monosaccharides
Proteins into amino acids
Triglycerides into fatty acids and glycerol

Front 13

Mechanical Digestion

Back 13

Mastication and mixing of food.

Front 14

Chemical Digestion

Back 14

Digestive enzymes secreted along the digestive tract.

Front 15

Absorption

Back 15

The movement of molecules out of the digestive tract and into the circulation or lymphatic system.

Molecules pass out of the digestive tract by diffusion, facilitated diffusion, active transport, symport, or endocytosis.

Front 16

Elimination

Back 16

The process by which the waste products of digestion are removed from the body.

Front 17

Mucosa

Back 17

The innermost tunic

Consists of the inner mucous epithelium, the lamina propria, and the muscularis mucosae.

Front 18

Mucous epithelium

Back 18

Moist stratified squamous epithelium in the mouth, oropharynx, esophagus, and anal canal and simple columnar epithelium in the remainder of the digestive tract.

Extends deep into the lamina propria to form intestinal glands and crypts.

Front 19

Lamina propria

Back 19

A loose connective tissue in the mucosa.

Front 20

Muscularis Mucosae

Back 20

A thin outer layer of smooth muscle.

Front 21

Submucosa

Back 21

Beneath the mucosa. Thick connective tissue layer with nerves, blood vessels, and small glands.

Front 22

Parasympathetic submucosal plexus

Back 22

A network of nerve cells in the submucosa. Consists of axons, scattered nerve bodies, and neuroglial cells.

Axons from the submucosal plexus extend to cells in the epithelial intestinal glands to stimulate secretion.

The esophagus and the stomach lack a submucosal plexus.

Front 23

Muscularis

Back 23

2 Layers of smooth muscle, which are circular and longitudinal (except the stomach and esophagus where muscles are striated)

Contains myenteric plexus between two muscle layers

Important in control of movement and secretion

Front 24

Myenteric Plexus

Back 24

Consists of axons, scattered neuron cell bodies, and neuroglial cells.

Controls the motility of the intestinal tract.

Front 25

Enteric Nervous System

Back 25

Made up by the submucosal and myenteric pexuses and contains more neurons than the spinal cord.

Controls secretion and movement/ nervous control of the digestive tract.

Functions through local reflexes

Capable of controlling peristaltic and mixing movements, along with blood flow to DT without any outside influence.

Front 26

Three major types of enteric nerurons

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Enteric sensory neurons - detect changes in the chemical composition digestive tract contents and mechanical changes like the stretch of intestinal walls.

Enteric Motor Neurons - simulate or inhibit smooth muscle contraction and glandular secretion.

Enteric interneurons - connect the sensory and motor neurons.

Front 27

CNS control of digestive system

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CNS works with the ENS.

Control of the DS by the CNS occurs when reflexes are activated by stimuli originating in the digestive tract or CNS.

ex. sight or smell of food can stimulate hunger

Front 28

Major neurotransmitters of the ENS

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Acetylcholine - Stimulates

norepinephrine - Inhibits motility and secretions

Serotonin - Stimulates digestive motility (cancer treatments cause nausea because of increased serotonin release from endocrine cells)

Front 29

Interstitial Cells

Back 29

In the Myenteric Plexus. Form a network of pacemakers that promote rythmic contractions of smooth muscle along the digestive tract.

Help transmit signals from neurons to muscles to regulate movement.

Front 30

Serosa or Adventitia

Back 30

Connective tissue/serous membrane

Where serosa is present, called visceral peritoneum.

Where adventitia is present, connective tissue blends with the tissue of surrounding structures - in esophagus and reproductive organs.

Front 31

Serous Membranes

Back 31

Walls and organs of the abdominal cavity are lined with serous membranes.

Smooth and secrete a serous fluid that provides a lubricating film between the layers of membranes, which reduces friction as the organs move in the abdomen.

Front 32

Peritoneum

Back 32

Visceral- Covers the organs

Parietal - Covers the interior surface of the body wall

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Retroperitoneal

Back 33

Certain organs are covered by the peritoneum on one surface and are considered to be behind the the peritoneum

ex. kidneys, duodenum, adrenal glands, urinary bladder

Front 34

Peritonitis

Back 34

A potentially life threatening inflammation of the peritoneal membranes as a result of chemical irritation by bile.

ex. appendix rupture

Front 35

Mesenteries

Back 35

Two layers of peritoneum with a thin layer of loose connective tissue in between.

Hold organs in place.

Routes by which vessels and nerves pass from body wall to organs.

Front 36

Mesoappendix

Back 36

The mesentery of the appendix.

Front 37

Mesentery Proper

Back 37

The mesentery associated with the small intestine

Front 38

Transverse Mesocolon

Back 38

The mesenterys of part of the colon which extend from the transverse colon to the posterior body wall and the sigmoid mesocolon.

Front 39

Lesser Omentum

Back 39

The mesentery connecting the lesser curvature of the stomach and proximal end of the duodenum to the liver and diaphragm.

Front 40

Greater Omentum

Back 40

The mesentery extending as a fold from the greater curvature to the transverse colon.

Front 41

Ascites

Back 41

An accumulation of excess serous fluid in the peritoneal cavity. Can be caused by alcoholism, starvation, or liver cancer.

Front 42

Omental bursa (pocket)

Back 42

The cavity - the greater omentum forms a double fold of mesentery that extends inferiorly from the stomach over the surface of the small intestine.

"fatty apron"

Front 43

Vestibule v. Oral Cavity Proper

Back 43

The vestibule is the space between the teeth, lips and cheeks.

The Oral cavity is lined with moist, stratified, squamous epithelium. Is located medial to the alveolar processes.

Front 44

Two sets of teeth

Back 44

Primary, deciduous, milk

Secondary, permanent, adult - Incisors, canine, molars, and premolars

Front 45

Parts of the teeth

Back 45

Anatomic Crown - Enamel covered part of the tooth

Clinical Crown - Section of tooth above the gum line

Neck - Enameled part of the tooth below the gum line

Enamel - Outer most layer of anatomical crown. Non-living.

Front 46

Dentin

Back 46

Living, calcified tissue. In the root, dentin is covered by cellular, bone-like structures that help hold the tooth in place. Surrounds the pulp.

Front 47

Pulp Cavity

Back 47

Filled with nerves, blood vessels, and connective tissue.

Front 48

Lips

Back 48

Muscular structures formed by the orbicularis oris muscle and connective tissue.

Lips are not highly keratinized, so the epithelium of the skin is more transparent than the rest of the body.

Front 49

Labial frenula

Back 49

Mucosal folds that extend from the alveolar process of the maxilla of the upper lip and from the alveolar process of the mandible to the lower lip.

Front 50

Cheeks

Back 50

Made up of buccinator muscle, which flattens the cheek against the teeth, and the buccal fat pad, which rounds out the profile on the side of the face.

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Palate

Back 51

Separates the oral and nasal cavities.

Consists of the hard palate and soft palate

Front 52

Fauces

Back 52

The throat and posterior boundary of the oral cavity that is the opening to the pharynx.

The palatine tonsils are in the lateral wall of the fauces.

Front 53

Lingual Frenulum

Back 53

Attaches the tongue to the floor of the mouth.

Front 54

Tongue Muscles

Back 54

Intrinsic Muscles - Within the tongue - responsible for changing the shape of the tongue.

Extrinsic Muscles - Attached to the outside of the tongue - protrude and retract the tongue and move it from side to side.

Front 55

Terminal Sulcus

Back 55

A groove that divides the tongue in two.

The part anterior to the terminal sulcus is covered by papillae which contain taste buds.

The posterior third of the tongue has no papillae and only a few taste buds. It has a few small glands that form the lingual tonsil.

Front 56

Apical Foramen

Back 56

The nerves of the tooth enter and exit the pulp through a hole at the point of each root called the apical foramen.

Front 57

Muscles that move the mandible during mastication

Back 57

Temporalis - Retracts the jaw
Masseter, medial pterygoid, lateral pterygoid - Protraction, lateral, and medial excursion of the jaw

Front 58

Mastication Reflex

Back 58

Integrated in the medulla oblongata and is stimulated by the presence of food in the mouth.

Front 59

Salivary glands/Compound acinar glands

Back 59

Parotid - Serous glands - produce watery saliva

Submandibular - Mixed glands with more serous than mucous acini

Sublingual - Mixed glands with some serous acini, but mostly mucous acini

Front 60

Salivary Amylase

Back 60

The serous part of saliva.

Breaks covalent bonds between glucose molecules in starch and other polysaccharides to produce the disaccharides maltose and isomaltose- which give starches a sweet taste.

Front 61

Lysozyme

Back 61

An enzyme in saliva that has weak antibacterial action.