1AA3 - WEEK 7

Phases of Digestion

Phases of Digestion

cephalic, gastric, intestinal

Cephalic Phase of Digestion

• before/as food is eaten

• stimulates gastric secretion and motility

sensory receptors: to cerebral cortex, hypothalamus, brain stem

CN VII and IX: salivation

CN X: gastric juice release

Gastric Phase of Digestion

• once bolus reaches stomach

• increases secretion and motility

• neural and hormonal regulation

Intestinal Phase of Digestion

• once chyme enters SI

• inhibits gastric emptying

• neural and hormonal regulation

Secretin

• stimulates release of pancreatic juice

• decreases gastric secretions

Cholecystokinin

• stimulates release of pancreatic juice

• contraction of gallbladder for release

• decreases gastric emptying through pyloric sphincter contraction

Components of Long Intestine

• cecum

• colon

• rectum

• anal canal

• ileocecal sphincter

• right/left colic flexure

• omental appendices

• vermiform appendix

• intestinal glands

Teniae Coli

• thickened region of longitudinal muscle

• forms haustra

Mechanical Digestion in Large Intestine

• gastroileal reflex

• haustral churning

• peristaltic waves

• mass peristalsis

• defacation reflex

Chemical Digestion in Large Intestine

• only mucus secreted

bacteria ferment: produce vitamins B and K / decompose bilirubin

Feces

• 3-10 hours

• 90% of H2O reabsorbed

• dead epithelia, undigested food, bacteria

Kidney Functions

1. excretion

2. regulation of blood pressure and volume

3. regulation of solute concentration in blood

4. pH regulation

5. RBC synthesis regulation

6. vitamin D synthesis

External Anatomy of Kidney

• renal capsule

• adipose capsule

• renal fascia

• peritoneum

• renal hilum

Internal Anatomy of Kidney

• renal lobe

• renal medulla

• nephron

Urine Drainage after Creation

collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureters → urinary bladder

Nephron Components

• renal corpuscle

  • glomerulus

  • bowman’s capsule

• renal tubules

  • PCT

  • loop of Henle

  • DCT

Nephron Types

cortical and juxtamedullary

Histology of Nephron

• glomerulus

• capsule

• PCT

• nephron loop

• DCT

• CD

Juxtaglomerular Apparatus

maculla densa

• dense sensory receptors on tubule site

• detect H2O, Na+, Cl-

juxtaglomerular cells

• afferent artery side

• some in glomerulus

• contraction decreases blood flow to glomerulus

Mesengial Cells

• afferent/efferent arteries

• smooth muscle cells

• contraction decreases blood flow to glomerulus