BIO 2302 Exam #3

Chapter 23, 24, 25

Digestive System: GI tract organs

• mouth

• pharynx

• esophagus

• stomach

• small intestine

• large intestine

Digestive System: Accessory organs

• teeth

• tongue

• salivary glands

• liver

• gallbladder

• pancreas

6 major functions of Digestive System

1. Ingestion and mastication: mouth

2. Propulsion: swallowing( pharynx), peristalsis( esophagus→intestines)

3. Mixing: stomach churning, segmentation in small intestine

4. Secretion: enzymes, mucus, bile, acid, hormones

5. Digestion: mechanical(chewing, churning)+chemical(enzymes)

6. Absorption: mostly small intestine

   1. water/electrolytes in large intestine

7. Elimination: rectum/anus

Histology of GI tract

• Mucosa( innermost)

  • Epithelium( stratified squamous or simple columnar)

  • Lamina Propria( capillaries, lymphatic vessels, immune cells)

  • Muscularis Mucosae( smooth muscle, creates local movements)

• Submucosa

  • provides elasticity, houses nerve network that regulate secretion

• Muscularis( muscular layer)

  • Inner circular layer( forms sphincters)

  • Outer longitudinal layer( shortens the tube)

• Serosa or Adventitia( outermost)

  • Serosa( found in intraperitoneal, reduce friction)

  • Adventitia( found in retroperitoneal, anchors organs in place)

MY STUDENTS MAKE SUCCESS

Peritoneum

serous membrane lining abdominal cavity

Mesentery

double layered peritoneum anchoring intestines

Peristalsis

wave-like contractions moving food

Mechanical digestion

physical breakdown

Chemical digestion

enzymatic breakdown

Oral Cavity

• Teeth: mechanical digestion

• Tongue: manipulation+taste+lingual lipase

• Salivary glands: parotid, submandibular, sublingual

• Saliva: moistens food, begins starch digestion( amylase) contain lysozyme

Pharynx Anatomy

• Nasopharynx( uppermost, posterior to nasal cavity)

  • air passage only, contain pharyngeal tonsil(adenoid)

• Oropharynx( posterior to oral cavity)

  • extend from soft palate→epiglottis

  • passageway for both food and air

• Laryngopharynx( lowest part, posterior to larynx)

  • extend from epiglottis→esophagus

  • passageway for food and air

Phases of Swallowing/Deglutition

1. voluntary: tongue pushes bolus

2. pharyngeal: soft palate/uvula block nasopharynx; epiglottis blocks trachea

3. esophageal: peristalsis moves bolus to stomach

Esophagus

• muscular tube with mucosa, submucosa, muscularis, adventitia

• lower esophageal sphincter(cardiac sphincter): prevents reflux

Stomach anatomy

• Stomach Regions

  • Cardia( where esophagus enters stomach)

  • Fundus( dome shaped region superior to esophageal opening)

  • Body( major site of mixing and gastric secretion

  • Pylorus( contains pyloric canal and pyloric antrum)

• Pyloric Sphincter

  • regulates release of chyme into duodenum

• Rugae

  • large folds of mucosa and submucosa

Tunics of Stomach

1. Mucosa( contain gastric pits→gastric glands)

2. Submucosa( contain blood vessels, lymphatics, nerves)

3. Muscularis( only one with 3 layers)

   1. inner oblique→enhance churning

   2. middle circular

   3. outer longitudinal

4. Serosa( visceral peritoneum)

Histology of Stomach

• Parietal cells

  • HCL( activates pepsinogen→pepsin)

  • Intrinsic factor( required for vitamin B12 absoprtion)

    • ESSENTIAL FOR LIFE

• Chief cells

  • Pepsinogen(inactive enzyme)

  • Gastric lipase( begins lipid digestion)

• Endocrine cells( entroendocrine)

  • G cells=gastrin secreting cells

  • Entrochromaffin like cells( histamine)

Sections of Small Intestine

1. Duodenum= site of most chemical digestion

2. Jejunum= primary site of nutrient absorption

3. Ileum= absorbs B12, bile salts, and remaining nutrients

Ileocecal

• Valve= prevents backflow of fecal material into small intestine

• Sphincter= regulates passage of chyme from ileum→ large intestine

Histology of Small Intestine

• Circular folds( plicae circulares)

  • slow down chyme→increases absorption time

• Villi

  • Contains: capillary bed(absorb carbs and proteins) and lacteal( absorb lipids)

• Microvilli( brush border)

  • microscopic projections on the apical surface of absorptive cells

Major cell types of Duodenal Mucosa

• Absorptive cells( enterocytes)

  • produce brush border enzymes

• Goblet cells

  • secrete mucus, protect mucosa from acidic chyme and enzymes

• Paneth cells

  • secrete lysozyme and antimicrobial peptides, innate immunity

• Endocrine cells( enteroendocrine)

  • release hormones into bloodstream

Key Small Intestien Structures

• Duodenal glands( brunner)

  • secrete alkaline mucus, neutralize acidic chyme, optimal pH

• Intestinal glands( crypts of Lieberkuhn)

  • produce intestinal juice

• Peye patches( lymphatic nodules)

  • protect against pathogens entering from large intestine

Anatomy of Large Intestine

1. Cecum( contains appendix)

2. Ascending( upward on right side)

   1. ends at right colic(hepatic) flexure

3. Transverse( cross abdomen)

   1. ends at left colic( splenic) flexure

4. Descending( down left side)

5. Sigmoid( S shaped, lead to rectum)

6. Rectum( store feces)

7. Anal canal( internal and external anal sphincters)

Histology of Large Intestine

• Mucosa( no villi, many goblet cells)

• Submucosa( standard)

• Muscularis

  • outer longitudinal→Teniae coli(3 bands of smooth muscle)→Haustra(pouches)

• Serosa( epiploic appendages=fat tages)

Secretions of Large Intestine

• Mucus= lubricate, protect mucosa

• Vitamin K= essential for blood clotting

Major functions of Large Intestine

• Absorption of water and electrolytes

• Absorption of vitamins

• Microbial fermentation

• Formation and storage of feces

• Propulsion of feces

Gross anatomy of Liver

• Right( largest), Left, Caudate, Quadrate lobes

• Falciform ligament= anchors liver to anterior abdominal wall, separate right and left lobes

• Coronary ligaments= anchor liver to diaphragm, form “bare area”

Porta Hepatis( hilum of liver)

• Hepatic artery proper→ brings oxygenated blood

• Hepatic portel vein→ brings nutrient-rich blood from GI tract

• Common hepatic duct→ drains bile

Histology of Liver

• Functional unit: hepatocytes

• Portal triad: each corner of lobule

  • interlobular vein= branch of hepatic portal vein

  • interlobular artery= branch of hepatic artery

  • interlobular duct

Flow through the lobule(liver)

1. Blood from portal vein+hepatic artery

2. Flows through sinusoids

3. Passes by hepatocytes(processing occurs)

4. Drains into central vein

5. hepatic veins→inferior vena cava

BILE( opposite direction of blood)

• hepatocytes→bile canaliculi→bile ducts→hepatic ducts

Bile Functions

1. emulsifies fats

2. aids in absorption of lipids

3. excretion of waste products

Major functions of liver

• Metabolic functions( carbohydrate, lipid, protein)

• Detoxification( remove drugs, alcohol, toxins)

• Storage( glycogen, ADEK, B12, iron, copper)

Gross anatomy of Gallbladder

1. Fundus( rounded end that projects slightly below liver)

2. Body( main central portion where bile is stored)

3. Neck( narrow region that connects to cystic duct)

Duct System Connections:

• cystic duct↔connects gallbladder to common hepatic duct

  • together form common bile duct, which empties into duodenum

Functions of Gallbladder

1. store bile

2. concentrates bile( remove water and electrolytes)

Release bile when fatty chyme enters the duodenum( CCK hormone)

Duct system of Pancreas

• Main Pancreatic duct( duct of Wirsung)

  • joins common bile duct

  • empties into major duodenal papilla

• Accessory Pancreatic duct( duct of Santorini)

  • may empty into minor duodenal papilla

Histology of Pancreas

• Pancreatic Acini= exocrine portion

  • clusters of acinar cells, produce pancreatic juice

• Pancreatic Islets( islets of langerhans)= endocrine portion

  • regulate blood glucose

Pancreatic Secretions

• Bicarbonate( neutralize acidic chyme, protect duodenal mucosa)

• Pancreatic amylase( digest starches→maltos and small carbohydrates)

• Pancreatic lipase(main enzyme for fat digestion)

Proteolytic Enzymes of Pancreas

• Trypsinogen→Trypsin

  • break proteins→peptides

• Chymotrypsinogen→Chymotrypsin

  • breaks proteins→ peptides

• Procarboxypeptidase→Carboxypeptidase

  • removes amino acids from carboxyl end of peptides

Carbohydrate absorption and transport

• Absorption

  • Final digestion occur at brush border( maltase, sucrase, lactase)

  • Absorb as monosaccharides( glucose, galactose, fructose)

• Transport across enterocytes

  • glucose and galactose: secondary active transport

  • fructose: facilitated diffusion

• Transport in blood

  • all monosaccharides enter capillaries in villi→hepatic portal vein→liver

Protein absorption and transport

• Absorption

  • digested into amino acids, dipeptides, tripeptides

• Transport across enterocytes

  • amino acids: secondary active transport

  • Di- and tripeptides: H+ dependent cotransport→broken into amino acids in cell

• Transport in blood

  • amino acids enter capillaries→hepatic portal vein→liver

Lipid absorption and transport

• Digestion

  • bile salts emulsify fats→pancreatic lipase break triglycerides into monoglycerides and free fatty acids

• Absorption

  • lipid products form micelles→diffuse into enterocytes

  • inside cell: reassembled into triglycerides, packaged into chylomicrons

• Transport

  • chylomicrons enter lacteals

  • travel throug lymph→enter blood stream at left subclavian vein

Lipoproteins

transport lipids through bloodstream

• Chylomicrons= carry dietary triglcerides to tissues

• VLDL= transport endogenous triglycerides to tissues

• LDL= deliver cholesterol to tissues( bad cholesterol)

• HDL= picks up excess cholesterol from tissues( good cholesterol)

Peptic Ulcer Disease

• erosion of stomach or duodenal mucosa

• burning epigastric pain, bleeding

GERD

• chronic reflux of stomach acid into esophagus

• heartburn, regurgitation, chest discomfort

Gallstones( cholelithiasis)

• crystallized cholesterol or bilirubin in gallbladder

• can block cystic or bile ducts→ severe pain

Appendicitis

• inflammation of appendix

• caused by obstruction

Peritonitis

• inflammation of peritoneum

• caused by ruptured appendix, perforated ulcer, infection

Catabolism vs. Anabolism

• Catabolism( large→ small)

  • breakdown, release ATP

• Anabolism( small→ large)

  • building, requires ATP

5 Major Nutrient Categories

• Macronutrients

  • Carbohydrates(4 kcal), lipids(9 kcal), proteins(4 kcal)

• Micronutrients

  • Vitamins, minerals

Vitamins

• Water soluble

  • B complex, C, excreted in urine

• Fat soluble

  • ADEK, store in adipose tissue and liver

Building blocks

• carbohydrates→monosaccharides(glucose)

• lipids→fatty acids+glycerol

• Proteins→amino acids

Carbohydrates

• Monosaccharides(glucose, lactose, galactose)

• Disaccharides( sucrose, lactose, maltose

• Polysccharides( starch, glycogen, cellulose)

Glycolysis

• occur in cytosol, anaerobic

• glucose→2 pyruvate

• 2 ATp

• 2 NADH

if oxygen present→ pyruvate enters mitochondria

If no oxygen→ lactic acid

Citric Acid cycle( Krebs cycle)

• occur in mitochondria, requires oxygen indirectly

• from 1 glucose(2 acetyl CoA):

  • 2 ATP

  • 6 NADH

  • 2 FADH

Electron Transport Chain

• occur in inner mitochondrial membrane

• uses NADH and FADH2 to generate 28 ATP

Glycogenesis

• glucose→glycogen

• storage in liver and skeletal muscle

Glycogenolysis

• glycogen→glucose

• occur during fasting/exercise

Gluconeogenesis

• formation of glucose from NON-carbohydrate sources

• amino acids, glycerol, lactate

• occur in liver

Lipid metabolism pathways

• Keogenesis

  • form ketone bodies from fatty acids, occur during fasting/low carb/ diabetes

• Lipogenesis

  • form of lipids( triglycerides) from glucose or amino acids, occur when caloric intake>needs

• Lipolysis

  • breakdown of stroed fats→fatty acids+glycerol

Protein metabolism

• proteins→amino acids

• amino acids used for:

  • new proteins, enzymes, hormones, energy

• excess amino acids→ converted to glucose or fat

Cholesterol metabolism and transport

• used for:

  • cell membranes, steroid hormones, bile salts, vitamin D

• Transported in blood via lipoproteins

Basal Metabolic Rate(BMR)

• energy required at rest to maintain essential body functions

• influenced by age, sex, hormones, body size

Obesity

• BMI≥30

• increases risk of diabetes, hypertension, heart disea

Hypercholesterolemia

• high blood cholesterol

• often high LDL

• risk factor for atherosclerosis and cardiovascular disease

Organs of Urinary system

• Kidneys( filter blood, regulate fluid, electrolytes, pH)

• Ureters( transport urine from kidneys→bladder, use peristalsis)

• Urinary bladder( store urine)

• Urethra( conducts urine from bladder→outside body)

Urinary system Functions

• excretion of waste

• regulate blood volume and pressure

• regulate electrolytes, pH

• hormone production

Associated structures of Kidney

• fibrous capsule( prevents infection and maintains shape)

• perinephric fat( cushions and protects kidney)

• renal fascia( anchors kidney to abdominal wall)

Anatomy of Kidney

• External

  • renal hilum(entry/exit for vessels, nerves, ureter)

• Internal

  • renal cortex(outer)

  • renal medulla(inner)

    • contain renal pyramids

    • renal papilla→minor calyx

  • minor calyces→major calyces→renal pelvis→ureter

Blood supply of Kidney

Arterial

• Really Sweet Individuals Are Cool

Venous

• Cool Art Is Retro

Nephron components

• Renal corpuscle

  • glomerulus(capillary tuft)

  • function: filtration

• Proximal Convuloted Tubule( PCT)

  • major site of reabsorption(glucose, amino acids, ions, water)

• Loop of Henle(LOH)

  • descending limb: water reabsorption

  • ascending limnb: Na+/Cl- reabsorption

• Distal Convoluted Tubule( DCT)

  • hormone regulated reabsorption(Aldosterone, PTH)

  • secretion of ions, drugs, toxins

• Collecting System

  • collecting ducts→ papillary ducts

  • regulated by ADH(water reabsorption)

Juxtaglomerular Complex( JGC)

• components

  • macula densa( in DCT), juxtaglomerular cells( in afferent arteriole)

• Function

  • regulates GFR

  • releases renin→activates RAAS→increases BP

Types of Nephrons

• Cortical(85%)

  • located mostly in cortex

• Juxtamedullary

  • create concentration gradient for urine concentration

Metabolic waste products

• Urea= from amino acid breakdown

• Creatinine= from muscle creatine phosphate breakdown

• Urea acid= from nucleic acid metabolism

Basic processes of urine formation

• Filtration(occur in renal corpuscle)

• Reabsorption( movement of useful substances back into blood)

• Secretion( active transport of wastes from blood→tubule)

Glomerular Filtration Rate( GFR)

• volume of filtrate produced per minute

• normal: ~125 mL/min

GFR control levels

• autoregulation

  • local control( myogenic and tubuloglomerular feedback)

• hormonal regulation

  • RAAS( increases GFR)

  • ANP( increases GFR by dilating afferent arteriole)

• autonomic regulation

  • sympathetic nervouse system

  • decreases GFR during stress

Renin-Angiotensin-Aldosterone system( RAAS)

• low BP→JG cells release renin

• Renin converts angiotensinogen→angiotensin 1

• ACE converts ang 1→angiotensin 2

• ang 2:

  • vasoconstriction

  • stimulated aldosterone→Na+ and water retention

  • stimulates ADG→water retention

  • increases thirst

result: ↑ blood pressure and ↑ blood volume

Reabsorption and Secretion of PCT

• reabsorb= glucose, amino acids, Na+, Cl-, water

• secrete= drugs, toxins, H+

Reabsorption and Secretion of Loop of Henle

• Descending= water reabsorption

• Ascending= Na+/Cl- reabsorption

Reabsorption and Secretion of DCT

• Aldosterone= Na+ reabsorption

• PTH= Ca2+ reabsorption

• Secretes= K+, H+

Reabsorption and Secretion of Collecting System

• ADH= water reabsorption

• Aldosterone= Na+ reabsorption

Urine Composition

• 95% water

• urea, creatinine, uric acid

• electrolytes

• pH~6

Structure and Function of Ureters

• muscular tubes

• peristalsis moves urine to bladder

Structure and Function of Urinary Bladder

• stores urine

• muscle contract during urination

• funnel urine to urethra

Structure and Function of Urethra

• conducts urine out of body

Male vs. Female Urethra

• Female

  • short

  • higher UTI risk

• Male

  • long

  • 3 regions: prostatic, membranous, spongy

  • carries urine and semen

Urinary reflexes

• storage reflex

  • sympathetic

  • relax detrusor

  • contract internal sphincter

• voiding reflex

  • parasympathetic

  • contract detrusor

  • relax internal sphincter

  • external sphincter inder voluntary control

Age related changes that affect kidney

• decline in nephron number

• reduced GFR

• reduced sensitivity to ADH→ dehydration risk

• increased incidence of incontinence

• enlarged prostate in males→urinary retention