phys exam 4

motility

movement of food through the alimentary tract through the actions of several processes

ingestion

taking food into mouth

mastication

chewing food and mixing it with saliva

deglutition

swallowing food 

peristalis

rhythmic, wavelike contractions 

segmentation

mixing contractions in different segments 

both peristalsis and segmentation

moves through the AC

secretion

includes both exocrine and endocrine secretions

exocrine

water, hydrochloric acid, bicarbonate, and many digestive enzymes are secreted into the lumen of the alimentary tract.

endocrine

the stomach and SI secrete a number of hormones that help to regulate the digestive system 

digestion

breaking food down into smaller units, both physically and chemically

absorption

passing broken down food into blood or lymph

storage and elimination

temporary storage and subsequent elimination of undigested food molecules 

immune barrier

simple columnar epithelium that lines the intestine with its tight junctions between cells, provides a physical barrier to the penetration of pathological organisms and their toxins. Cells of the immune system reside in the connective tissue located just under the epithelium 

accessory digestive enzymes

  Teeth, tongue, salivary glands, liver, gallbladder, and pancreas 

GI tract

30 feet mouth to anus

chemical and mechanical digestion

break down food into smaller parts to aid in digestion

mechanical digestion

  Occurs in oral cavity, physical breakdown of food, done by teeth

chemical digestion

\
  Is the enzymatic reactions that break down of food, done in the mouth by saliva 

peristalsis

  When bolus is moved down the esophagus to the stomach, involuntary contraction and relaxation of circular and longitudinal muscles throughout the digestive 

·      Trace the pathway of ingested substances through the gastrointestinal (GI) tract

Oral cavity

Pharynx (throat

 Esophagus 

Stomach

Small intestine

Large intestine

 Anus

layers of GI tract

mucos, submucosa, mascularis, serosa

mucosa

  Epithelium

 Areolar connective tissue

 Musculairs mucosae

submucosa

Areolar connective tissue

Very vascular

Contained neurons

Contains digestive enzymes 

mascularis

Two layers of smooth muscle (circular and longitudinal)

 Contains neurons 

serosa

Aereolar connective tissue

Simple squamous epithelial tissue 

mastication

\
Chewing breaks down food into smaller pieces for deglutition and mixes it with saliva 

functions of saliva

Dissolves food chemicals for taste

 Moistens food-compacts into bolus 

begins to digest starch

composition of saliva

Over 99% water

Contains electrolytes (Na+, k+, Ca2+, Cl-, HCO3-, HPO4-)

Mucous: makes food slippery

 IgA: helps prevent attachment

 Salivary amylase 

functions of esophagus

 It moves bolus from the mouth to stomach through peristalsis, because of the circular smooth muscle contracts behind the bolus and relax in front of it 

functions of stomach

a.     Stores food

b.     Churns food to mix with gastric secretions

c.     Begins protein digestion

d.     Kills bacteria in food (acid)

e.     Moves food into small intestine in the form of chyme 

parietal cells

secrete HCL, intrinsic factor (required for the absorption of vitamin B12)

mucus cells

secrete mucus, protection

chief cells

secrete pepsinogen to turn into pepsin 

\
 Enterochromaffin-like cells

\
secrete histamine and serotonin 

G-cells

secrete gastrin

D-cells

secrete somatostatin

gherlin

regulates hunger

inferior esophageal (cardiac, lower)

relaxes to allow food to pass into stomach, stays closed to prevent regurgitation

what does the lower esophageal sphincter use

cholinergic neurons

what is the receptor for lower esophageal sphincter

muscarinic

what is the lower esophageal sphincter lined with

smooth muscle

what is the lower esophageal sphincter controlled by

autonomic nervous system

what is the upper esophageal sphincter lined with

skeletal muscles

what is the function of the pyloric sphincter

moves chyme to SI

where is the pyloric spincter located

stomach

what does the SI absoprb

nutrients

what does the SI digest completely

carbs, proteins, and fats

what is absorbed in the duodenum and jejunum of SI

sugars, lipids, amino acids, calcium, and iron

what is absorbed in the ileum of SI

bile salts, vitamin B12, water, and electrolytes

Plicae circulares

folds of mucus membrane

villi

columnar epithelium

what do goblet cells in villi do

secrete mucus

what do capillaries in villi do

absorb monosaccharides and amino acids

what does lacteal do in the capillaries in villi do

absorb fat

where are paneth cells located in villi of SI

Crypts of lieberkuhn

what do paneth cells in villi do

secrete antibacterial molecules of lysosome and defensin

what dos the mitotic stem cells do in the villi of the Crypts of lieberkuhn do

replenish interatrial cells every 4-5 days

what is the microvilli

brush border, foldings of the apical surface of the epithelial cell

what are the segments of SI

duodenum, jejunme, and ileum

where is the brush border located

attached to plasma membrane with active sites towards the chyme

what does the brush border do

Hydrolyze disaccharides, polypeptides and other substrates to \n simplest nutrient molecules

what is the duodenum

first 10 inches of SI, most absorption

what is the jejunme

middle 2/5 of SI

what is the ileum

last 3/5 of SI

what do the specialization of SI tunics do

These structures increase surface area of the SI, which speeds up the absorption of carbohydrates, proteins, fats, and nutrients

intestinal gland (crypts of Lieberkühn):

secrete antibacterial molecules of lysozomes and defesnins, miotic stem cells replenish intestinal cells every 4-5 days

Lacteals/lymphatic capillaries:

capillaries absorb monoscarchides and amino acids

lacteals absorb fat

mucosa of LI

columnar epithelial cells with goblet cells, crypts, lymphatic nodules, but no villi

haustra of LI

pouches that promote contractions to squeeze H2o out

Large intestine functions absorption of

Water electrolytes

Vitamin K

Some vitamin B

Production of vitamin K and B vitamins via microbial organisms

Storage of feces

the liver detoxifies what from the blood

hormones, drugs, and other substances

how does the liver detoxify blood

Excreted into bile

Phagotized by Kupffer cells lining sinusoids

Chemically altered by hepatocytes

the liver secretes bile, how

Synthesis of bile salts

Conjugation and excretion of bile pigment

how are carbohyrdates metabolized in liver

Conversion of blood glucose to glycogen and fat p

Production of glucose from liver glycogen and other molecules (amino acids, lactic acid) by gluconeogenesis

  Secretion of glucose into blood

how does the liver metabolize lipids

Synthesis of triglycerides and cholesterol

Excretion of cholesterol in bile

  Production of ketone bodies from fatty acids

how does the liver synthesize proteins

Production of albumin

Production of plasma transport proteins

Production of clotting factor

Trace the flow of blood through the liver, including the two major sources of blood flow to the liver.

Capillaries of small and large intestines

Superior mesenteric vein and inferior mesenteric vein (joined by splenic vein)

Hepatic portal vein

Sinusoid capillaries of the liver

Lobular central veins

Hepatic veins

inferior vena cava

structure of gallbladder

Sac-like organ attached to inferior surface of the liver

what is the function of the gallbladder

  Stores and concentrates bile form liver

islet cells in pancreas

makes insulin and glucagon (endocrine)

acina cells in pancreas

makes pancreatic juice, which is delivered to the duodenum via pancreatic duct

Left and right hepatic duct

between the lobules, converge on the inferior side to form the common hepatic duct

common hepatic duct

joined by the cystic duct, which descend through the lesser momentum towards the duodenum

cystic duct

a tube that carrier bile from the gall bladder, joins the common hepatic duct to form the common bile duct

common bile duct

carrier bile from liver and gallbladder through the pancreas into the small intestine

main pancreatic duct

drains most of the pancreas

Hepatopancreatic ampulla

bile duct is joined by the pancreatic duct and forms this expanded chamber, entry point for bile, where ampulla terminates

Hepatopancreatic sphincter

regulates the passage of bile and pancreatic juice

Trace the path of bile and pancreatic juice through the biliary apparatus

a.     Liver

b.     Bile ducts

c.     Hepatic duct

d.     Cystic duct

e.     Gallbladder

f.      Cystic duct

g.     Common bile duct

h.     Sphincter of ampulla or Oddi in the duodenum

Oral (voluntary)

Forms food into bolus

Tongue moves up and back

Pharyngeal (involuntary)

Closer of respiratory passageways

   Relaxation of esophageal

1\.     Parasymtehtic

Esophageal (involuntary)

Controlled by the swallowing center of the brain (medulla)

Bolus is moved down esophagus to stomach via peristalsis

 

Explain how volume, chemical composition, and osmolarity of chyme affect motility in the stomach and in the duodenum.

Duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes \n Duodenum enhances gastric secretion, but soon inhibits it \n Stretching of duodenum accentuates vagovagal reflex that stimulates stomach \n Peptides and amino acids in chyme stimulate G cells of duodenum to secrete more gastrin, stimulating stomach \n Soon acids and fats trigger enterogastric reflex—duodenum sends inhibitory signals to stomach by way of enteric nervous system \n Duodenum also signals medulla to: inhibit vagal nuclei (reducing vagal stimulation of stomach) & stimulate sympathetic neurons (sending inhibitory signals to the stomach) \n \n Secretin: released from duodenum in response to acidic chyme arriving from the stomach \n \n Intestinal crypts secrete 1 to 2 L of intestinal juice per day \n hypertonic chyme, and distension of intestines pH of 7.4 to 7.8

Describe the defecation reflex and how it is affected by somatic and autonomic innervation.

a.     Controlled by hypothalamus

b.     As pressure increases in rectum, the internal anal sphincter relaxes and the need for defecate arises

c.     During defecation, longitudinal rectal muscles contract to increase pressure as the anal sphincters relax

d.     Aided by contraction of abdominal and pelvic skeletal muscles-Valsalva’s maneuver

\

\

pepsin susbtrate

proteins

pepsin products

shorter polypeptides

pancreatic amylase source

pancreatic juice

pancreatic amylase substrate

starch