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GASTROINTESTINAL (RIGHT SIDE) AND THE RENAL SYSTEM (LEFT SIDE) - Coggle…
GASTROINTESTINAL (RIGHT SIDE) AND THE RENAL SYSTEM (LEFT SIDE)
Digestive Organs & Functions
Mouth: Chewing, saliva begins starch digestion.
Pharynx: Passage for food; swallowing.
Esophagus: Moves bolus to stomach via peristalsis.
Stomach: Stores/mixes food; begins protein digestion (pepsin); forms chyme.
Small intestine: Major digestion & absorption; receives bile & enzymes.
Large intestine: Absorbs water/electrolytes; forms feces; gut flora.
Rectum & anus: Store & expel feces.
Accessory Organs
Salivary glands: Produce saliva (amylase, mucus, IgA).
Liver: Produces bile; detoxifies; processes nutrients.
Gallbladder: Stores/concentrates bile.
Pancreas: Enzymes (lipase, amylase, proteases) + bicarbonate.
Digestive Glands
Gastric glands: HCl (parietal), pepsinogen (chief), mucus.
Intestinal glands: Enzymes, mucus, stem cells.
Pancreatic glands: Enzymes + bicarbonate.
Brunner’s glands: Alkaline mucus (duodenum).
Liver & gallbladder: Bile production & storage.
GI Vasculature
Venous: All drain to portal vein (except lower rectum → systemic).
Lymph: Follow arteries → celiac/SMA/IMA nodes → cisterna chyli → thoracic duct.
Arteries:
Celiac trunk → foregut
SMA → midgut
IMA → hindgut
Innervation
Enteric Nervous System
Myenteric plexus: Motility.
Submucosal plexus: Secretion, blood flow.
Autonomic
Parasympathetic: Vagus + pelvic splanchnic → ↑ motility, ↑ secretion.
Sympathetic: T5–L2 → ↓ motility, ↓ secretion, ↑ sphincter tone.
Four Processes of Digestion
Motility: Peristalsis & mixing.
Secretion: Enzymes, mucus, hormones.
Digestion: Mechanical + chemical breakdown.
Absorption: Mainly in small intestine.
Phases of Digestion
Cephalic: Sight/smell → vagus → saliva + gastric juice.
Gastric: Food in stomach → gastrin, mixing, acid secretion.
Intestinal:
CCK: ↑ enzyme release, ↑ bile, satiety, slows gastric emptying.
Secretin: ↑ bicarbonate, ↓ gastric acid.
Digestion of Macromolecules
Carbs: Polysaccharides → monosaccharides.
Proteins: Proteins → amino acids.
Fats: Triglycerides → monoglycerides + fatty acids.
Defecation Reflex
Rectal stretch → relax internal sphincter.
External sphincter voluntary control.
Valsalva increases pressure to defecate.
Energy Balance
Energy intake vs. expenditure (BMR, activity, TEF).
Types: Positive / Negative / Neutral balance.
Short-term regulation: ghrelin, CCK, GLP-1, PYY, insulin, vagus.
Long-term: leptin, insulin, liver signals, hypothalamus (ARC, PVN, LHA).
Thermoregulation & Energy
Heat production = major energy expenditure.
Cold: ↑ sympathetic → shivering, brown fat → ↑ energy use.
Heat: ↓ metabolism → sweating → ↓ energy use.
Urinary Organs & Functions
Kidneys: Filter blood, regulate fluids/electrolytes/pH.
Ureters: Transport urine.
Bladder: Stores urine.
Urethra: Excretion.
Urine Formation (Nephron)
Glomerular filtration: Plasma → filtrate (no proteins/cells).
Tubular reabsorption: Reclaims water, glucose, amino acids, ions.
Tubular secretion: Removes H⁺, K⁺, drugs, toxins.
Body Fluid Compartments
ICF: High K⁺, phosphate, proteins.
ECF (plasma + interstitial): High Na⁺, Cl⁻, HCO₃⁻.
Water Balance & Control
ADH: Water reabsorption ↑ (less urine).
Aldosterone: Na⁺ + water reabsorption ↑.
ANP: Promotes water & sodium loss.
Hypothalamus: Thirst mechanism.
Electrolyte Balance
Regulated mainly by kidneys.
Key hormones:
Aldosterone: ↑ Na⁺, ↓ K⁺.
ADH: Controls osmolarity.
PTH: ↑ Ca²⁺.
Calcitonin: ↓ Ca²⁺.
Vitamin D: ↑ Ca²⁺ & phosphate absorption.
Regulation of Blood pH
Buffers (immediate): Bicarbonate, phosphate, proteins.
Respiratory (minutes): CO₂ regulation via breathing.
Renal (hours–days): H⁺ excretion, HCO₃⁻ reabsorption/generation.