PowerPoint Presentation to accompany

Hole’s Human Anatomy and Physiology, 9/e

by

Shier, Butler, and Lewis

UNIT FIVE

Chapter 17

Digestive System

Alimentary Canal• Mucosa

– surface epithelium with underlying connective tissue and small amount of smooth muscle

– contains glands, including mucus glands

– carries on secretion and absorption

Alimentary Canal

• Submucosa– loose connective

tissue with glands, blood and lymphatic vessels, and nerves

Figure 17.1

Alimentary Canal• Muscular layer

– two layers of smooth muscle

• circular fibers compose inner coat

• longitudinal fibers compose outer coat

• Serosa or serous layer– visceral peritoneum– epithelium on the outside

and connective tissue beneath, secretes serous fluid

Figure 17.3

Movement of the Tube• Mixing movements

– smooth muscles contract rhythmically

– mix food with digestive juices

• Propelling movements– wavelike movements

called peristalsis– receptive relaxation occurs

ahead of peristalsis

Figure 17.4

Innervation of the Tube

• Parasympathetic impulses increase digestive system activities

• Sympathetic impulses decrease digestive system activities

• Submucosal plexus– controls secretion by the GI tract

• Myenteric plexus– muscular layer, controls motility

Mouth• Cheeks

– muscles of expression and chewing

• Lips– contain skeletal muscles

and sensory receptors

• Tongue– tongue muscles mix food– taste buds provide

sensation– lingual tonsils are

lymphatic tissue at the root of the tongue

Figure 17.5

Figure 17.6

Palate• Roof of the oral

cavity– hard palate is anterior– soft palate is posterior

and ends in the uvula

Figure 17.7

Palate

• Palatine tonsils– located in the back of

the throat

• Pharyngeal tonsils (adenoids)– located above the soft

palate

Figure 17.7

Teeth• Primary or deciduous teeth– 20 teeth, erupt between

6 months and 4 years

• Secondary or permanent teeth– 32 teeth, erupt between

6 and 25 years of age– incisors, cuspids,

bicuspids, molars

• Teeth break food into small pieces

Figure 17.9

Teeth

• Crown – projects out from

the gum– covered with

enamel

Figure 17.10

Teeth• Root

– anchored to the jaw by the periodontal ligament

– covered with cementum

• Dentin– living tissue similar

to bone, but harder– surrounds the pulp

cavity which contains nerves and blood vessels

Saliva• Saliva moistens food

• Saliva contains bicarbonate ions that buffer acids in the mouth

• Two types of secretory cells– serous cells

• secrete a watery fluid contains amylase, an enzyme that splits starch and glycogen into disaccharides

– mucous cells• secrete a thick fluid, mucus, that binds and

lubricates

Salivary Glands• parotid glands

– largest, secrete watery fluid rich in amylase

• submandibular glands– secrete a viscous fluid

• sublingual glands– smallest, secrete thick mucus fluid

• Innervation – sympathetic impulses stimulate a small amount

of viscous secretion– parasympathetic impulses stimulate a large

volume of watery saliva

Figure 17.11

Pharynx

• Nasopharynx– communicates with the nasal cavity, air passage

• Oropharynx– posterior to the mouth, passage for food and air

• Laryngopharynx– inferior to the oropharynx, leads to esophagus