Anatomy & Physiology II

BIOS 2320

Instructor: Mrs. Sarah Jeffers

Introduction

• Syllabus

• Typical schedule with resources

• Student email

• Helpful websites:

• http://faculty.mccneb.edu/sajeffers

• http://www.quia.com/pages/sjeffers53/bios2320

• www.mhhe.com/saladin5

• “Student edition” link

Unit I: MetabolismDigestive System

Part I

Chapter 21

Digestive system

NutrientsTissue cells

Wastes Urinary system

Cardio-vascular

system

O2 and CO2

Cardiopulmonarysystem

Metabolism

• multiple changes in the molecules of the food we eat.

• Digestive System:

• primary purpose – to break food down into forms that can be used by the body and to absorb them so they can be distributed to the tissues.

Digestive Processes

• Motility

• Secretion

• Membrane transport

Digestive Functions

1. Ingestion

2. Digestion

• Mechanical• Chemical

3. Absorption

4. Compaction

5. Defecation

Stages of Digestion

• Mechanical digestion

• Chemical digestion

a. enzymes

– series of hydrolysis reactions that break macromolecules into their monomers (residues)

– Results:

• Monosaccharides, amino acids, glycerol, fatty acids, and nucleotides

Vitamins, minerals, cholesterol, & water are absorbed.

Mouth

Oral cavity,teeth, tongue

Pharynx

Esophagus

Stomach

Small intestine

Large intestine

Anus

Pancreas

Gallbladder

Liver

Salivary glands

Accessory Organs

Anatomical Subdivisions of Digestive System

• Digestive tract – (Alimentary canal)– 30 foot long tube– GI tract

• Accessory organs– salivary glands,

teeth, tongue, liver, gallbladder, pancreas

Muscularis Externa

Serosa

Myenteric plexus

Circular layer

Longitudinal layer

MucosaSubmucosa

Lymphatic vesselArtery and vein

Submucosal plexus

Muscularis mucosae

Lamina propria

Villi

Circular Folds Components of the Mucosa

stratified squamous epithelium or simple columnar epithelium

Tissue Layers

• Mucosa

• Submucosa

• Muscularis Externa

• Serosa/Adventitia

Mouth/Oral Cavity/Buccal Cavity

Upper lip

Tongue

Lower lip

SubmandibularSublingual

Salivary glands:

Palatine tonsil

Hard palate and friction ridges

Soft palate

Uvula

Palatopharyngealarch

Labial frenulumVestibule

Functions:

• Ingestion

• Taste

• Mechanical digestion

• Chemical digestion

• Swallowing

• Speech

• Respiration

Stratified Squamous

Skeletal Muscle

Superior Boundary

Anterior and LateralBoundary

Nasal cavity

Labium, or lip

Cheek

Body of the tongue

Soft palateHard palate

Pharyngeal tonsil

Uvula

Root of the tongue

Lingual tonsil

Palatine tonsil

Inferior BoundaryThe geniohyoid and mylohyoid musclessupporting the floor of the mouth

Posterior Boundary

Boundaries of the Oral Cavity

Dentition

• Deciduous (20) by 3 years; Permenant (32) between 6 and 25 years

• Types of teeth:

• Incisors

• Canines/ Cuspids

• Premolars and molars/ Bicuspids

Salivary gland duct Mucous cells Serous cells

Submandibular salivary gland LM x 600

Salivary Glands

• Small intrinsic glands found dispersed amid oral tissues, lips, cheeks and tongue - secrete at constant rate

• 3 pairs extrinsic glands connected to oral cavity by ducts– Parotid– Submandibular– Sublingual

Sublingual

Submandibular Parotid

Saliva

• Hypotonic solution of 99.5% water + solutes

– Salivary amylase: begin starch digestion

– Lingual lipase: fat digestion in stomach

– Mucus: bind food together into bolus

– Lysozyme: inhibit bacteria

– Immunoglobin A: inhibit bacteria

– Electrolytes (Na, K, Cl, phosphate, bicarbonate)

• pH 6.8 - 7

Pharynx

Oropharynx

Nasopharynx

Laryngopharynx

Pharynx:

Vomer

• Muscular funnel 13 cm long

• Skeletal muscle

– deep layer –

– superficial layer -

• Superior

• middle

• inferior (UES)

• Stratified squamous

Esophagus

• Straight muscular tube 25-30 cm long

• Extends from pharynx to cardiac stomach passing through esophageal hiatus in diaphragm

– Cardiac orifice

– Lower esophageal sphincter (LES)

Why do you think acid causes such problems for people

when acid is actually a natural product found in the

digestive system?

i.e. How does the stomach tolerate such acidity?

Healthy Mucosa and Peptic Ulcer

Helicobacter pylori

Stomach

• Mechanically breaks up food, liquifies food

– chyme

• Does not absorb significant amount of nutrients

– absorbs aspirin and some lipid-soluble drugs

Esophagus

Lessercurvature

The Pylorus

Cardiac

Fundus

Body

Layers of theMuscularis Externa

Greater curvature

Rugae

Circular layerOblique layer

Longitudinal layer

Anteriorsurface

Pyloric sphincter

Lessercurvature

EsophagusLesseromentum

LiverSpleen

Diaphragm

Greateromentum

Greatercurvature

Duodenum

Pylorus

Body

CardiacFundus

Stomach Regions

• Volume: 50ml – 4L

• Four regions

•Muscular sac

Gross Anatomy of Stomach

Unique Features of Stomach Wall

• Mucosa

– simple columnar glandular epithelium

– Rugae / gastric pits

• Muscularis externae: 3 layers

Gastric Secretions

1. HCl• Gastric glands contain carbonic anhydrase (CAH)

• Functions:

• Activates pepsin and lingual lipase

• Breaks up connective tissues and plant cell walls

• Converts iron to a usable form (Fe2+)

• Destroys ingested bacteria and pathogens

2. Pepsin -

– pepsinogen (inactive) + HCl pepsin (active)

– Chief cells

3. Gastric Lipase

− Digests fats

− Chief cells

4. Intrinsic factor

– Essential for vitamin B12 absorption

– RBC production (lack causes pernicious anemia)

– Parietal cells

Gastric Secretions

Chemical Secretions

5. Chemical Messengers

• Many produced by G-cells

– Ex.) gastrin, serotonin, histamine, somatostatin

– hormones

– paracrine secretions

– Gut-brain peptides