Final Exam

Biomedical Science 308 with Timson at Missouri State University

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By: Michael Harris
Created: 2012-05-11
Size: 102 flashcards
Views: 32

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What is mastication?
Deglutition?
Digestion?
Ingestion?

Mastication - chewing movements to pulverize food
Deglutition - swallowing food
digestion - mechanical and chemical breakdown of food
Ingestion - taking in food to the GI through mouth

What is the GI tract?

The tube extending from the mouth to the anus

List the parts of the GI tract.

mouth, pharynx, esophagus, stomach, SI, LI, rectum, anal canal

List the accessory glands of the GI

Teeth, tongue, salivary glands, liver, gallbladder pancreas

What are the layers of the GI tract?

Mucosa, Submucosa, Muscularis, Serosa

Physiologically speaking, what are the innermost and outermost structures of the GI tract?

innermost is the serosa and the outermost is the mucosa; this would be reversed if talking anatomically

What does the mucosa do and consist of?

surrounds lumen and is the major absorption/secretion layer; has musculature called the muscularis mucosa

What is the submucosa?

highly vascularized connective tissue that supports the mucosa; nutrients go from mucosa to the vessels of the submucosa

What neural structure is important of the submucosa?

It has a submucosal nerve plexus called Meissner's Plexus which innervates the muscularis mucosa

What does the muscularis do? What type of smooth muscle is it made of?

It regulates peristaltic movement and segmental contractions of the GI; both circular and longitudinal smooth muscle

What does the serosa do?

It provides protection and supports the GI tract

By what 2 means is external control carried out?

The peripheral nervous system, and also the endocrine system

Digestive regulation occurs through what functions?

autonomous smooth muscle, intrinsic nerve plexus, extrinsic nerves, and gastrointestinal hormones

What is special about the smooth muscle of the GI tract?

It can self-initiate its contractions without any nerve stimulation because of pacemaker cells

Pacemaker cells in the GI have what type of potentials?

Slow wave potentials

What regulates the pacemakers in the GI?

The mechanical sensors

since smooth muscles of the GI are connected together by gap junctions, they can also be called?

functional syncytium

What are the nerve plexuses of the GI?

Myentric plexus and the submucosal plexus

Where are the two nerve plexuses located?

Myenteric = between longitudinal and circular smooth muscle layers
Submucosal = within the submucosa

The intrisic nerve plexus promote what functions ?

digestive tract motility, secretion of digestive juices, and secretion of GI hormones

Which portions of the GI tract have intrinsic innervation?

Everything from the esophagus to anus

What do both types of autonomic control do to the GI system?

parasympathetic = increases peristalsis and secretion
Sympathetic = decrease peristalsis and secretion

GI hormones are secreted by what cells?

by enteroendocrine cells

Enetroendocrine cells secrete hormones due to what factors?

local changes in luminal content, such as presence of fats, proteins, or acids

What digestive process occurs at the mouth?

It is the first line of digestion, where mastication occurs;

What are the three functions of the mouth in digestion?

1. Mechanical breakdown of food into globs
2. Mix food with saliva
3. stimulate the taste buds

What do the taste buds do ?

when activated, they send signals that stimulate secretion of salivary, gastric, pancreatic, and bile secretions

How does mechanical digestion differ from chemical?

mechanical doesn't involve the breaking of chemical bonds while chemical does

What are the percentages of protein and water in saliva?

99.5% water, 0.5% protein

What are the salivary proteins and their functions?

Mucus - provides lubrication for deglutition
Salivary Amylase - begins to digest carbs in the mouth
Lingual Lipase - begins digestion of triacylglycerols in the mouth
Lysozyme - enzyme that destroys bacteria

What type of receptors are the taste buds?

chemoreceptors

What are the two types of ways that salivary secretion can be stimulated and give examples of each.

1. Simple Reflex - chemoreceptors and pressurereceptors
2. Conditioned Reflex - sight of food, smells, thought of food

Explain the pathway of simple reflex.

Taste buds sense food, send signals to the salivary center in the medulla, which stimulates autonomic nervous system, and this stimulates the salivary glands to secrete saliva

What functions does the stomach provide?

food storage, initiation of digestion of proteins and short chain triacylglycerols, and move food into the small intestine as a pasty material known as chyme

What mechanical process occurs in the stomach that aids digestion? Why is this important?

Several minutes after eating food, peristaltic movements are initiated every 15-20 seconds; it helps mix gastric juices with the food to form chyme

Chemical digestion in the stomach... explain.

As food enters the stomach, it is broke down by lingual lipase and salivary amylase; soon after, gastric secretion of pepsinogen, HCl, and Mucus occurs which will inhibit salivary amylase and lingual lipase; pepsinogen will be activated and begin digesting proteins

Gastric secretions come from anatomical areas of the mucosa called?

gastric pits

What are the secretory cells in gastric pits called and what does each secrete?

Parietal - HCl
Chief - Pepsinogen
Goblet - Mucus
Eneteroendocrine - Gastrin

Which stomach enzymes/chemicals are secreted into the lumen and which is secreted into the blood?

HCl, Pepsinogen, and mucus; Gastrin

Precursors to enzymes which are inactive compounds are collectively known as?

zymogens

How is pepsinogen activated?

When it enters the stomach, it interacts with HCl in a low pH environment which will convert it to pepsin

How does pepsin breakdown proteins?

It has enzymatic functions which hydrolyze the peptide bonds of a protein, forming short peptide chains

How is gastrin involved with polypeptide hydrolysis?

It travels through the blood to the parietal cells and stimulates the secretion of HCl, which aids in conversion of pepsinogen to pepsin

What are the phases of gastric regulation and are they activating or deactivating.

Cephalic Phase - activation
Gastric Phase - activation
Intestinal Phase - deactivation

Explain the cephalic phase of GI regulation.

1. receptors for sight, smell, and taste activate the cerebral cortex and hypothalamus
2. Cerebral Cortex and hypothalamus stimulate medulla
3. Medulla activates parasympathetic nerves (vagus nerves) that activate the submucosal plexus
4. submucosal plexus increases secretion of gastric juices, gastrin, and promotes gastric peristalsis

Explain the gastric phase of regulation of digestion.

1. Food enters stomach, raises pH, and distends the stomach wall
2. stretch receptors and chemoreceptors activate submucosal plexus
3. submucosal plexus stimulates increase in gastric secretions, gastrin, and also promotes gastric peristalsis

Describe the intestinal phase of digestive regulation.

1. increased gastric motility from cephalic and gastric phases move chyme into the SI
2. Stretch receptors respond to distension in walls and chemoreceptors detect fatty acids and glucose
3. enteroendocrine cells secrete CCK, GIP, and secretin that inhibit gastric secretions and peristalsis
4. enterogastric reflex via the medulla inhibits the gastric secretions and peristalsis

Chemical digestion in the SI depend on primarily what accessory structures?

Liver, gallbladder, and the pancreas

List the 8 major functions of the liver.

- production/secretion of bile
- carbohydrate metabolism
- lipid metabolism
- protein metabolism
- detoxification of drugs and hormones
- Chemical storage
- phagocytosis
- Vitamin D activation

What is bile made of? Whats its pH?

water, bile salts and acids, cholesterol, lecithin, bile pigments, and ions ; 8.0

What gives poop its brown color?

RBC's are broken down into iron, globin, and bilirubin, and bilirubin is broken down into constituents that have a brown color

What does the term glycogenolysis mean?

glycogen hydrolysis

Carbohydrate metabolism in the liver is important because...

It regulates blood-glucose levels;

Low blood glucose will result in?

glycogenolysis, gluconeogenesis, and isomerization of fructose and galactose into glucose

Describe how lipid metabolism is aided by the liver.

lipoproteins that transport fatty acids, triacylglycerols, and cholesterol in the blood are synthesized, and cholesterol is also synthesized to be used in bile

Explain protein metabolism in the liver.

Plasma proteins such as albumins, globulins, prothrombin, and fibrinogen are synthesized here, transamination and deamination of amino acids, and conversion of ammonia into urea for urine secretion

What is stored in the liver?

glycogen, Vitamins A, D, B12, E, and K, and also ferritin

What is phagocytized in the liver?

worn out RBC's and WBC's by the Kupffer Cells , and also some bacteria

What is the function of the gallbladder?

its function is to store and concentrate bile until needed in the SI

What causes the gallbladder to release bile?

CCK will stimulate smooth muscle contractions and this forces bile into the ducts

The pancreas secretes pancreatic juices which are composed of?

bicarbonate ions which increase pH of chyme entering the SI, and also digestive enzymes

So again, how do CCK and secretin affect digestive function related to the pancreas?

As acidic chyme moves into the SI, CCK and secretin are going to be secreted, which travel through the blood and stimulate the pancrease to release bicarbonate and digestive enzymes

Identify the ways which CCK is involved in digestion.

Stimulates secretion of pancreatic enzymes, stimulates contraction of the gallbladder, and decreases gastric peristalsis

Describe all digestive functions of secretin.

increases the secretion of bicarbonate ions in pancreatic juices, increases secretion of bicarbonate into the bile, and decreases gastric secretions

What are the enzymes secreted in pancreatic juice and what do they do?

trypsinogen - cleaves internal peptide bonds
chymotrypsinogen - cleaves internal peptide bonds
proelastase - cleaves internal peptide bonds
procarboxypeptidase - cleaves C-terminal amino acids
prophospholipase - cleaves fatty acids on phospholipids
lipase - cleaves fatty acids from glycerol
amylase - digests starch to short glucose polymers
cholesterolesterase - frees cholesterol from other molecules

What are brush-border enzymes?

They are enzymes found in the microvilli of the SI that participate in digestion of carbohydrates, proteins, and nucleic acids

Explain the activation of the protein digesting enzymes in pancreatic juice for use in the SI.

Trypsinogen will be activated into trypsin by enterokinase, and then trypsin will activate chymotrypsinogen, proelastase, and procarboxypeptidase

What are the 4 families of brush-border enzymes?

Disaccharidases, peptidases, phosphatases, and nucleosidases

What are the disaccharidases, whats their substrate, and whats their products?

Sucrase - hydrolyzes sucrose into fructose and glucose
Maltase - hydrolyzes maltose into two glucose molecules
Lactase- breaks down lactose into glucose and galactose

What are the peptidases, whats their substrate, and their products?

Aminopeptidase - cleaves the N-terminal amino acids of a polypeptide
Enterokinase - activates trypsin

What do phosphatases and nucleosidases do?

Phosphatases - cleaves phosphate groups from nucleotides
Nucleosidases - cleaves bases from ribose or deoxyribose sugars

What are the two processes of mechanical digestion in the SI?

Segmentation - localized contractions in areas of SI with food which mixes chyme and juices
Peristalsis - minor form compared to segmentation; propels chyme through the intestinal tract

How are carbohydrates broken down in the SI?

By pancreatic amylase and brush border enzymes

What are the substrates and products of the carbohydrate enzymes of SI?

pancreatic amylase - takes starches and makes disaccharides and dextrin
brush-border enzymes - take disaccharides and dextrin and make monomer sugars

What are the protein enzymes in the SI, and differentiate between them.

Exopeptidases - cleave external bonds and make AA's
Endopeptidases - cleave internal bonds and produce small polypeptides

What enzyme destroys lipids in the SI? What does it do?

Pancreatic Lipase - hydrolyzes triacylglycerols into fatty acids and monoglycerides

What breaks down nucleotides in the SI?

Pancreatic enzymes ribonuclease and deoxyribonuclease, which breakdown the nucleic acids into nucleotides, but also brush-border enzymes nucleosidases and phosphatases which breakdown nucleotides into pentoses, phosphates, and nitrogenous bases

How do sugars, lipids, and proteins enter the luminal epithelial cells int eh SI?

Carbohydrates - glucose and galactose enter through secondary active transport with Na, and fructose through facilitated diffusion
Proteins - enter as amino acids through active transport or secondary active transport with Na, and enter as tripeptides and dipeptides through secondary transport with H+
Lipids - all through simple diffusion

Describe how carbs, proteins, and lipids travel from the epithelial cells to blood stream in the SI

Carbohydrates - facilitated diffusion of monosaccharides
Proteins - diffusion of amino acids
Lipids - diffusion of short-chain FA's

How do fats enter the lymph system?

They become triacylglycerols in the epithelial cells and then are exported as chylomicrons into the lacteal of the lymph system

Describe the functions of the renal system.

- Regulate plasma ionic composition
- Regulate plasma volume
- Regulate plasma osmolarity
- Regulate plasma pH
- Remove metabolic waste products and foreign
substances from body

What are the two types of nephrons and which are a majority?

Cortical and juxtamedullary; cortical

What is filtered out of plasma during glomerular filtration?

proteins and blood cells

How much of the original filtrate goes through the glomerulus into the bowman's capsule?

about 20%

If MAP goes up, what happens to GFR?

It also goes up

how does one calculate for glomerular filtration rate?

Glomerular Filtration Rate =

(P(gc)+π(bc))-(P(bc)+π(gc))

How is the GFR intrinsically and extrinsically regulated?

Intrinsic - myogenic regulation, tubuloglomerular feedback, mesangial cell contraction
Extrinsic - sympathetic nervous system via the Low-Pressure baroreceptors

When do extrinsic and intrinsic regulations of GFR occur?

intrinsic occurs when MAP is between 80 - 180 mmHg, and extrinsic with anything outside of that range

What is reabsorption?

selective transport of solute and water from lumen of renal tubule to the interstitial fluid

How does reabsorption occur?

solute is either actively or passively reabsorbed, and water is wicked up from osmolarity differences created by solute reabsorption

What is the transport maximum?

it occurs whenever all carriers and pumps are saturated, and the excess solutes are simply excreted in the urine; the plasma concentration that this occurs at is called the renal threshold

Differentiate between reabsorption in the proximal and distal convoluted tubules.

The proximal can reabsorb many more molecules than the distal, because the distal has tighter junctions, and the distal is more highly regulated, and also has fewer mitochondria and ATP for use in transport

How does secretion occur?

through carrier proteins, but also primary and secondary active transporters in the basolateral and apical membranes

What waste products and ions are secreted from the ISF to the renal tubule?

K, H, choline, creatine, and penicillin

How does one calculate excretion?

Excretion = Filtered + Secreted - Reabsorbed

(F+R-S)

What is Filtered Load?

The quantity of a solute filtered per minute;

FL = GFR x Plasma Concentration

(mmol/min)

How does one figure out excretion rate?

Excretion Rate =
Urine Conc. x Urine Flow Rate

(E = U*V)

What is renal clearance and what is it used for?

It is the volume of plasma from which that substance is completely removed (cleared) per unit of time; measure of kidney function

Clearance = Excretion Rate / Plasma Conc.
= U*V/P

What are the units of filtered load, excretion, and clearance?

FL = g/min
E = g/day
C = L/day

When doing calculations, what should one always remember to do?

convert the GFR to L/min values!!

What is inulin?

It is a polysaccharide that is NOT secreted or reabsorbed, and so all inulin filtered is secreted, so the clearance of inulin is = GFR

What is PAH?

Para-aminohippuric Acid; plasma containing PAH is completely cleared of PAH in the kindeys, so

C = Renal Plasma Flow
Renal Blood Flow = RPF /( 1-Hct)

About this deck

By: Michael Harris
Created: 2012-05-11
Size: 102 flashcards
Views: 32

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy