ANAPHY: U13.1 Digestive System (Gastrointestinal Tract)

Gastrointestinal Tract

Another name for the Digestive System

1. Ingestion & Mastication

2. Propulsion & Mixing

3. Digestion & Secretion

4. Absorption

5. Elimination

5 Functions of the Digestive System

Ingestion & Mastication

One of the 5 functions of the Digestive System

(1) Taking in food

(2) Chewing

Propulsion & Mixing

One of the 5 functions of the Digestive System

(1) Moving food from one end to the other

(2) Churning of food with digestive secretions

Food mixed with saliva

Digestion & Secretion

One of the 5 functions of the Digestive System

(1) Breakdown of large organic molecules into smaller molecules by mechanical and chemical means

(2) Adding of liquids, enzymes and mucus to the ingested food

Absorption

One of the 5 functions of the Digestive System

Movement of molecules from GIT and into blood and lymphatic system. (amino acids, fatty acids, monosaccharides, vitamins and minerals and water)

Amino acids, fatty acids, monosaccharides, vitamins, minerals, water

What molecules are moved from the GIT and into blood and lymphatic system?

Elimination

One of the 5 functions of the Digestive System

Removal of undigested materials like fibers and waste products as feces

Bolus

(From Google)

Small, rounded mass of chewed food mixed with saliva that forms in the mouth during chewing, ready to be swallowed and transported down the esophagus to the stomach for further digestion

Esophagus

Where does bolus of food go to?

Stomach

Where is chyme located?

Bolus & Gastric Secretion

What is chyme consisted of?

1. Cheeks & Teeth

2. Oral Cavity Proper

2 Divisions of Oral Cavity

Lips, Cheeks, Teeth, Tongue, Salivary Amylase

5 Components of the Oral Cavity Proper

Lips

One of the components of the Oral Cavity Proper

Formed by orbicularis oris muscle with outer surface by skin as transparent epithelium

Orbicularis Oris

What muscle forms the lips?

Cheeks

One of the components of the Oral Cavity Proper

Served as lateral walls of the mouth with buccinator muscles for mastication

Buccinator

What muscles form the cheeks?

Teeth

One of the components of the Oral Cavity Proper

Breaks down food into smaller pieces

Tongue

One of the components of the Oral Cavity Proper

Propels bolus to pharynx for swallowing

Salivary Amylase

One of the components of the Oral Cavity Proper

Starts carbohydrate digestion

Tongue

Part of the Oral Cavity

Muscular organ attached to floor of the mouth by frenulum. Anterior 2/3 covered by papillae with taste buds. Posterior 1/3 has lymphatic tissue, forms lingual tonsil.

Major organ for: swallowing, taste and speech.

Frenulum

What attaches the tongue to the floor of the mouth?

Papillae with Taste Buds

What is the Anterior 2/3 of the tongue covered by?

Lymphatic Tissue, forming Lingual Tonsil

What does the Posterior 1/3 of the tongue have?

Teeth

Part of the Oral Cavity

Divided into R & L upper, R & L lower located in mandible and maxillae. Deciduous - 20, Adult - 32

R & L upper, R & L lower

What are the teeth divided into?

Mandible & Maxillae

What bones are the teeth attached to?

20

How many deciduous/baby teeth are there on average?

32

How many adult teeth are there on average?

1. One Central

2. One Lateral Incisor

3. One Canine

4. 1st & 2nd Premolars

5. 1st, 2nd, 3rd Molars

5 Types of Teeth Present in Each Quadrant of the Oral Cavity

Crown, Neck, Root

What does each tooth have?

Enamel

What is the crown of teeth covered in?

Dentin and Pulp Cavity (BV, Nerves, Connective Tissue)

What is present in the neck of teeth?

Palate

Roof of the oral cavity

Hard & Soft Palate

2 Parts of the Palate

Hard Palate

Part of the palate

Anterior with bone

Soft Palate

Part of the palate

Posterior with skeletal muscle and connective tissue and uvula as extension

Uvula

Extension of the soft palate

Protection

What is the purpose of tonsils?

Pharyngeal/Adenoid Tonsil, Palatine Tonsil, Lingual Tonsil

3 Types of Tonsils

Parotid Glands, Sublingual Glands, Submandibular Glands

3 Types of Salivary Glands

Parotid Glands

Type of salivary gland

Largest

Submandibular Glands

Type of salivary gland

Produce saliva

Saliva

Mixture of serous and mucous fluids

Protection, moisture, digestive process

3 Roles of the Salivary Glands

Oropharynx & Laryngopharynx

What specifically connects the mouth with esophagus?

Pharyngeal Constrictor Muscles

Muscles that line the posterior wall of the pharynx

Swallowing

What moves the bolus from the mouth to esophagus?

Mucus Secretion

What provides lubrication in the pharynx?

Esophagus

Muscular tube that extends from pharynx to stomach

Upper 1/3 - Skeletal Muscle

Middle 1/3 - Skeletal & Smooth Muscles

Lower 1/3 - Smooth Muscles

What type of muscles are present in each 1/3 of the esophagus?

Peristaltic Contractions

Move the bolus from the pharynx to the stomach

Upper & Lower Esophageal Sphincters

What limits reflux of stomach contents?

Cardiac Sphincter

Another name for the Lower Esophageal Sphincter

Thick Mucus

What lubricates the esophagus?

Deglutition

Another name for swallowing

1. Voluntary Phase

2. Pharyngeal Phase

3. Esophageal Phase

3 Phases of Swallowing

Voluntary Phase

Phase of swallowing

Tongue moves bolus towards oropharynx

Pharyngeal Phase

Phase of swallowing

Controlled by a reflex wherein pharyngeal constrictor muscles contract, propels food to pharynx and epiglottis covers the larynx

Esophageal phase

Phase of swallowing

Food moves from pharynx to stomach in peristaltic waves

Cardiac, Fundus, Body, Pyloric

4 Regions of the Stomach

Cardiac

Region of the stomach

Esophagus opens into this through gastroesophageal opening

Gastroesophageal Opening

What does the esophagus open into the cardiac through?

Fundus

Region of the stomach

Above the cardiac opening

Body

Region of the stomach

Largest part with greater and lesser curvatures

Pyloric

Region of the stomach

Opens to small intestine with pyloric sphincter

Pyloric Sphincter

Through what does the stomach open to the small intestine?

Muscularis (Outer Longitudinal, Middle Circular, Inner Oblique), Submucosa, Mucosa

3 Layers of the Stomach

Rugae

Stomach folds

1. Surface mucous cells

2. Mucous neck cells

3. Parietal cells

4. Endocrine cells

5. Chief cells

5 Groups of Epithelial Cells of the Stomach

Surface Mucous Cells

One of the Epithelial Cells of the Stomach

In the inner surface, lines gastric pits, produce mucus that coats & protects lining.

Mucus that Coats & Protects Lining

What do Surface Mucous Cells of the stomach produce?

Mucous Neck Cells

One of the Epithelial Cells of the Stomach

Produce mucus

Mucus

What do Mucous Neck Cells of the stomach produce?

Parietal Cells

One of the Epithelial Cells of the Stomach

Produce hydrochloric acid (HCI) and intrinsic factor

HCl & Intrinsic Factor

What do Parietal Cells of the stomach produce?

Endocrine Cells

One of the Epithelial Cells of the Stomach

Produce regulatory hormones & paracrine signal molecules

Regulatory Hormones & Paracrine Signal Molecules

What do Endocrine Cells of the stomach produce?

Chief Cells

One of the Epithelial Cells of the Stomach

Produce pepsinogen (precursor of pepsin: a protein-digesting enzyme)

Pepsinogen

What do Chief Cells of the stomach produce?

Chyme

Semifluid mixture of food & stomach secretions

Gastric Glands

Where do stomach secretions originate from?

1. HCl

2. Pepsinogen

3. Mucus

4. Intrinsic Factor

4 Stomach Secretions

HCl

One of the Stomach Secretions

pH 2.0, kills microbes, activates enzyme, pepsin

HCl

What activates the conversion of pepsinogen into pepsin?

Pepsinogen

One of the Stomach Secretions

Becomes pepsin, which breaks protein bonds into smaller peptide chains and has optimum enzymatic activity at Ph 2.0

Mucus

One of the Stomach Secretions

Thick layer of lubricant in stomach wall, protecting from acidic chyme and pepsin

Intrinsic Factor

One of the Stomach Secretions

Binds with vit. B12, important in DNA synthesis and RBC production

Vitamin B12

What does Intrinsic Factor bind with, which is key in DNA synthesis and RBC production?

Cephalic, Gastric, Intestinal Stages

3 Stages of Stomach Secretions

Cephalic Stage

One of the stages of Stomach Secretions

Brain phase of stomach secretion, controlled by CNS.

Taste, smell, thought of food or tactile sensation stimulate MO, sent message to parasympathetic in Vagus nerve to the stomach and activate enteric plexus.

Release of HCl, pepsin, mucus & intrinsic factor

Release of gastrin and histamine from endocrine cells that stimulate more secretory activity & more HCI secretions.

Central Nervous System

What is the Cephalic Stage controlled by?

Medullary Oblongata

In the Cephalic Stage, what is stimulated by taste, smell, thought of food or tactile sensation?

Parasympathetic in Vagus Nerve to the Stomach, activating Enteric Plexus

In the Cephalic Stage, when the Medullary Oblongata is stimulated, where does it send a message to, thus activating what?

HCl, Pepsin, Mucus, Intrinsic Factor, Gastrin & Histamine

In the Cephalic Stage, what is released?

More secretory activity & HCl secretions stimulated

In the Cephalic Stage, what is the effect of the release of Gastrin and Histamine?

Gastric Phase

One of the stages of Stomach Secretions

Produces the greatest volume of gastric secretions that is activated by food presence.

Distention of stomach stimulates mechanoreceptors, activates parasympathetic reflex, carried by Vagus nerve to MO.

Stomach distention activates local reflexes & increase stomach secretions

Peptide (from action of pepsin on protein) stimulate secretion of gastrin that goes to blood & back. Gastrin & histamine stimulate secretions.

Distention

In the Gastric Phase, what occurs to the stomach?

Mechanoreceptors, activates parasympathetic reflex, carried by Vagus nerve to MO

In the Gastric Phase, distention of the stomach stimulates what?