Digestive System

What are the 6 general functions of the digestive system?

Ingestion, motility, secretion, digestion, absorption, elimination

What is the first step in process of digesting and absorbing nutrients

Ingestion

What is the voluntary and involuntary muscular contractions that moves food through the digestive system

Motility

What is the process of producing and releasing fluid products facilitating digestion

Secretion

What is the breakdown of ingested food into smaller structures, both chemical and mechanical

digestion

What is the transport of digested materials into the blood or lymph

Absorption

What is the expulsion of indigestible components that are not absorbed

Defecation/ Elimination

What are the four concentric layers of the GI tract

Mucosa, submucosa, muscularis, and serosa/ adventitia.

What layer of the mucosa is luminal, made of simple columnar epithelium, lines with nonkeratinized epithelium, and withstands abrasion.

The epithelium

What layer of the mucosa has areolar tissue with small blood vessels and nerves and absorb subtances.

The lamina propria

Where do lipophilic substances get absorbed

Lymphatic capillaries

Where do hydrophilic substances get absorbed

Blood capillaries

What layer of the mucosa has thin layers of smooth muscle contractions that facilitate secretion into the lumen

Muscularis mucosae

What gentry shakes materials into villi

Muscularis Mucosa

What layer of the gi tract is made of areolar and dense irregular connective tissue

Submucosa

What layer of the gi tract contains the majority of blood vessels, lyymph vessels, and nerves

Submucosa

Nerves and ganglia innervating smooth muscle and glands

Submucosal nerve plecus

What prevents ingested microbes from crossing the Gi tract wall

MALT

What layer is MALT tissue found in

Submucosa

What two layers make up the muscularis externa

Circular and longitudinal layer

What layer of muscle is organized into a belt and constricts the lumen

Circular layer

What layer of muscle has cells oriented lengthwise and contractions shorten tube

Longitudinal layer

Which axons and ganglia are between layers and control contractions

Myenteric plexus

The muscularis thickens at several points to form a

sphincter

Alternating contractions sequence of inner and outer layer of muscle, moves material through tract

Peristalsis

What type of movement blends materials with secretions

Mixing

What are the two names of the outer layer of the gi tract

serosa and adventitia

Where is the adventitia found

outside the peritoneal cavity

Where is serosa found

within the peritoneal cavity

What outer layer is completely covered by visceral peritoneum

serosa

Serous membrane that lines the surface of the abdominal wall

parietal peritoneum

Serous membrane that covers the surface of the internal organs

visceral peritoneum

Space between the parietal and visceral peritoneum

peritoneal cavity

What is secreted that allows abdominal organs to move fluid

serous fluid

What type of organs are completely surrounded by visceral peritoneum

intraperitoneal organs

The stomach, jejunu, ileum, transverse, and sigmoid colon are ____peritoneal

intra

What type of organs lie directly against posterior to the abdominal wall

retroperitoneal organs

What portion of retroperitoneal organs are covered with peritoneum

Anterolateral portions

What type of organs are most of the duodenum, pancreas, ascending and desending colon, and the rectum

retroperitoneal

What is is a double layer of peritoneum that supports, suspends, and stabilizes intraperitoneal GI organs

Mesentery

What is sandwiched between the folds of the mesentery

blood and lymph vessels, and nerves

What two receptors regulate the gi tract

baroreceptors and chemoreceptors

Where are the receptors in the gi tract

embedded throughout the mucosa and submucosa

What type of receptors detect stretch or pressure in the Gi tract

Baroreceptors

What type of receptors detect specific substances within the lumen

Chemoreceptors

What type of reflex involves sensory input relayed to CNS

long reflexes

What causes coordinated secretion and smooth muscle contractions

impulses from the CNS

What does the parasympathetic division do to the digestive system

stimulates digestion, Increases motility, relaxes sphincters, increases water & gland

secretions, causes vasodilation to blood vessels in GI tract

What does the sympathetic division do in the gi tract

opposes digestion, Decreases motility, contracts sphincters, causes vasoconstriction

to blood vessels in GI tract

Short reflexes go through the ____ nervous system

enteric

What controls short reflexes

submucosal plexus and myenteric plexus

The ens bypasses the

CNS

What changes does the ens detect

changes in the tract wall and chemical makeup of lumen content

What does the ENS coordinate

mixing, propulsion, & secretions from the glands in the submucosa of GI tract

The ENS is ____, meaning it controls short segments

localized

What are the four hormones that participate in regulation of digestion

gastrin, secretin, cholecystokinin, and motilin

What is the entrance of the GI tract that initiates chemical and mechanical digestion

The mouth

What separates the mouth from the nasal cavity

The hard and soft palates

What is the opening between the oral cavity and oropharynx

The fauces

What two folds bind the fauces

The palatoglossal arch (anterior) and palatopharyngeal arch (posterior)

What is housed between the palatoglossal and palatopharyngeal arch

Palatine tonsils

What tonsil on the tongue helps defend against foreign materials

Lingual tonsil

What attaches the mouth to the tongue

the lungual frenulum

The tongue is important for ______ and ______

swallowing, speech

What type of epithelium lines the oral cavity

stratified squamous epithelium

Most of the epithelium in the mouth is

nonkeritinized

Where do you find keratinized connective tissue in the mouth

Lips, portions of the dorsum on the tongue, and small region of the hard palate

Where are intrensic salivary glands located

inside the oral cavity

What type of salivary gland continuously releases secretions independent of food, have unicellular glands, and contain lingual lipase

Intrinsic salivary glands

What are the three extrinsic salivary glands

Parotid, submandibular, and sublingual glands

What salivary gland produces 25-30% of saliva

Parotid gland

What salivary gland produces 60-70% of saliva

Submandibular gland

What salivary gland only contributes to 3-5% of saliva

Sublingual gland

What are the two types of cells within salivary glands

Serous cells and mucous cells

What salivary cells secrete mucin and form mucus upon hydration

Mucous cells

What salivary cells secrete watery fluid containing electrolytes and salivary amylase

Serous cells

How much saliva is secreted daily

1-1.5L

Saliva helps moisten ingested food to help become ____

bolus

What enzyme in the mouth begins the breakdown of carbs

salivary amylase

Food molecules dissolved in the mouth stimulate ____ receptors

taste

What fluid cleanses the oral cavity and inhibits bacterial growth

Saliva

What mechanical digestion happens in the mouth

mastication

Chewing increases ____ ____ to facilitate exposure to digestive enzymes

surface area

Where is the mastication center in the brain

Nuclei in medulla oblongata and pons

Teeth are collectively known as the

dentition

Teeth fit tightly into

dental alveoli

How many deciduous teeth are there

20

Teeth are bound to processes by

periodontal ligaments

When do deciduous teeth errupt

between 6-30 months

How many permanent teeth are there

32

The more ____ placed permanent teeth erupt first

anteriorly

Passageway for air and food, lined with nonkeratinized stratified squamous epithelium

pharynx

The esophagus is normally

collapsed

What is the opening in the diaphragm that the esophagus passes through

esophageal hiatus

What is the area where the esophagus and pharynx meet, closed during the inhalation of air

upper esophageal sphincter

What is the the superior esophageal sphincter composed of

circular skeletal muscle

What sphincter allows entrance of food into stomach

lower esophageal sphincter

What is the inferior esophageal sphincter composed of

circular smooth muscle

What are the three phases of swallowing

the voluntary phase, pharyngeal phase, and esophageal phase

What controls the voluntary phase of the swallowing process

cerebral cortex