A&P II Digestive Chapter 24

what is the difference between the actual gastrointestinal tract and the accessory digestive organs?

Actual GI tract= food passes through

Accessory digestive organs= food doesn't pass through

name the structures of the alimentary canal (actual GI tract) from the mouth to the anus

1. mouth, 2. pharynx 3. esophagus 4. stomach 5. small intestine 6. large intestine 7. anus

give examples of accessory digestive organs

salivary glands, pancreas, liver, gall bladder

what is mastication

chewing and breaking down food through the mouth

name a skeletal muscle that closes the mouth

massseter

which cranial nerve are involved in mastication

trigeminal

what is deglutition

swallowing

which cranial nerves are involved in deglutition

glossopharyngeal, vagus, and hypoglossal

does deglutition involve smooth, skeletal muscle or both? explain

both **

what is digestion

breaking down food; mechanical and chemical

what is mechanical digestion

physical grinding of food by churning and chewing

what is chemical digestion

enzymes by hydrolysis

name 5 key characteristics of enzymes

1. they are proteins= made up of amino acids

2. work by "lock and key" mechanism. only catalyze one type of reaction

3. can be used over and over. they aren't used up cause they aren't changed during reaction.

4. speed up reaction so they can occur at a rate fast enough to maintain life processes.

5. they have a specific pH and temperature at which they work best

chemical digestion occurs by a process called

hydrolysis

what is hydrolysis

breaking of a bond in a molecule using water

is water a reactant or a product in a hydrolysis reaction

reactant

where does most absorption occur in the GI tract

jejunum

where does food go once it is absorbed

moves from the lumen into the bloodstream (to nourish body)

what is peritoneum

serous membrane that lines the abdominal cavity

what is a serous membrane

lining of cavities, lubrication

name 2 types of tissues that make up a serous membrane

1. mesothelium

2. areolar tissue

2 layers of peritoneum

1. parietal peritoneum

2. visceral peritoneum

where is parietal peritoneum located

attached to wall of abdominal cavity

where is visceral peritoneum located

located directly on organs in the abdominal cavity

the space between the visceral and parietal peritoneum layers is called

peritoneal cavity

what does the peritoneal cavity contain

fluid to reduce friction between organs

what is meant by intraperitoneal organs

completely surrounded by peritoneum

examples of intraperitoneal organs

stomach, spleen, liver, transverse colon, small intestine, gall bladder

what is meant by retroperitoneal organs

don't have visceral peritoneal on all sides

examples of retroperitoneal organs

duodenum and pancreas

parietal and visceral peritoneum are connected by

folds of tissues

5 types of peritoneal folds of tissues

1. greater omentum

2. lesser omentum

3. falciform ligament

4. mesocolon

5. mesentery proper

where is greater omentum located

between the body wall and the anterior surface of the small intestine

where is the lesser omentum located

between the stomach and the liver

which important blood vessels are found in the lesser omentum

hepatic portal vein, common hepatic artery, common bile duct, and some lymph nodes

where is the falciform ligament located

between the liver and the anterior abdominal wall

where is the mesocolon located

where is the mesentery proper located

the walls of hollow organs contain 4 histological layers

1. mucosa

2. submucosa

3. muscularis externa

4. serosa or adventitia

the mucosa is the layer that comes in contact with

food (luminal side)

the mucosa has 3 tissue layers

1. epithelium

2. lamina propria

3. muscularis mucosa

what type of tissue is found in the epithelium

stratified squamous and simple columnar????

what type of tissue is found the lamina propria

areolar tissue with blood vessels

what type of tissue is found in the muscularis mucosa

thin layer of smooth muscle (stratified squamous)

what 3 parts of the GI tract is epithelium tissue layer found in

mouth, pharynx, esophagus

where are the goblet cells located in the mucosa

in the secretory cells of stomach mucosa

what type of nerve plexus are found in the submucosa

submucosal or Meissner plexus

what type of tissue is found in submucosa

connective tissue

the nerve plexus of the submucosa regulates

glands and muscularis mucosa

2 layers of muscle of the muscularis externa

inner circular layer of muscle

outer longitudinal layer of muscle

what is the function of the inner circular layer of muscle

squeezes

what is the function of the outer longitudinal layer of muscle

shortens

compared to the inner circular layer of muscle, where is the outer longitudinal layer

inner circular = top

outer longitudinal = bottom

sandwiched between the circular and longitudinal layers is the

myenteric (Auerbach) plexus

what is the function of the myenteric (Auerbach) plexus

carries impulses for the smooth muscle of the muscularis externa

together the function of inner circular and outer longitudinal layer of muscle

smooth muscle that allows for peristalsis

the serosa is what type of serous membrane

visceral peritoneum

when do organs have a adventitia

if they are located outside of the peritoneal cavity

what type of tissue does the serous layer contain

simple squamous with areolar tissue under the adventitia

2 major body systems that control the digestion in any organ of the GI tract

1. endocrine system

2. nervous system

what happens in the endocrine system

hormones secreted into the blood to act on a specific target organ

what happens in the nervous system

nervous control of the digestive system involves intrinsic nerves (enteric nervous system) and extrinsic nerves (parasympathetic and sympathetic nervous system)

the autonomic nervous system includes 3 types nervous systems

1. parasympathetic

2. sympathetic

3. enteric nervous system

what can the autonomic nervous system influence

the enteric nervous system

the parasympathetic nervous system ____ motility and secretion in the GI tract

increase

the major parasympathetic nerve innervating GI organs is the

vagus nerve

the sympathetic nervous system _____ motility and secretion in the GI tract

decreases

what is the function of the enteric nervous system

helps control motility and secretion.

what type of plexus' does the enteric nervous system include

Myenteric (Auerbach) plexus and submucosal plexus

what does the enteric nervous system also include

sensory neurons that can detect the presence of certain foods (chemoreceptors) or stretch of an organ

the enteric nervous system is influenced by

the parasympathetic and sympathetic nervous systems

what type of tissue does the mouth contain

stratified squamous for protection

what is labia

lips

what is labial frenulum

attaches to the center of the upper lip and between upper 2 front teeth

what is gingiva

gums

what is the tissue found in gingiva

stratified squamous

what is the hard palate

which 2 bones make up the hard palate

maxilla and palatine

why would the epithelium of the gums and the epithelium overlying the hard palate be partially keratinized stratified squamous epithelium

they are regions exposed to severe abrasions

what is the significance of the soft palate

supports the uvula

what is the purpose of the uvula

swings back to cover opening of nasopharynx to prevent food from going into it

what is the purpose of the tongue

assist in chewing and help prepare bolus for swallowing; also touch, temp. and taste receptors

which cranial nerve innervates tongue muscles

XII hypoglossal

what is the purpose of the lingual frenulum

connect the body of the tongue to mucosa covering the floor of oral cavity

what is a bolus

compact mass of food to be digested

name 2 functions of papillae located on the tongue

help move objects around the mouth

taste

what is the function of the tonsils

have immune tissue to fight off infection

3 types of salivary glands in the accessory digestive organs

1. parotid glands

2. submandibular glands

3. sublingual glands

what type of gland is the parotid

serous

where is the parotid gland located

in the cheek

what type of gland is the submandibular gland

serous and mucus

where is the submandibular gland located

in the jaw

what type of gland is the sublingual gland

mucus

where is the sublingual gland located

under the tongue

which of the salivary glands has the longest duct and why is that significant

parotid, because it makes very watery saliva

where are the cells in the salivary glands arranged at

in an acinar or alveolar (spherical) structure

what are some functions of saliva

moistening food and helping to create a food bolus so it can swallow easily

4 key components of saliva

1. mucus and h20

2. lysozyme

3. ions

4. amylase - chemical digestion of carbs

what is the function of the enzyme, amylase**

hydrolysis of carbs to monosaccharides

where is amylase made

salivary glands