Physiology Lecture: Digestive, Renal, Blood & Cardiovascular Systems

Vocabulary flashcards cover key terms from digestive motility and secretion, liver and gallbladder physiology, renal filtration and hormonal control, hematology, and cardiovascular regulation.

Tissue

A group of similar cells that perform a specific physiological function.

Esophageal Motility

Coordinated muscular contractions that propel a swallowed bolus from pharynx to stomach.

Upper Esophageal Sphincter (UES)

Striated-muscle valve that prevents air entry into the esophagus during breathing.

Lower Esophageal Sphincter (LES)

Smooth-muscle valve that prevents gastric reflux into the esophagus.

Oral Phase of Swallowing

Voluntary stage where tongue pushes bolus to oropharynx to initiate deglutition.

Pharyngeal Phase

Involuntary stage coordinating soft-palate rise, glottis closure, UES relaxation.

Primary Peristalsis

Continuation of pharyngeal contraction that propels bolus through entire esophagus.

Secondary Peristalsis

Reflex contraction triggered by residual food or esophageal distension.

LES Relaxation

Transient nitric-oxide/VIP-mediated relaxation allowing bolus to enter stomach.

Esophageal Manometry

Diagnostic pressure study assessing UES/LES tone and peristaltic coordination.

Receptive Relaxation

Vagus-mediated fundic relaxation accommodating incoming food without large pressure rise.

Gastric Mixing Peristalsis

3-per-minute waves in body/antrum that blend food with gastric juice.

Antral Pumping

Strong antral contractions that grind chyme and retropulse large particles.

Gastric Emptying

Regulated release of chyme through pylorus, slowed by fat, low pH, CCK.

Migrating Motor Complex (MMC)

Motilin-driven fasting pattern that sweeps residual debris every 90–120 min.

Haustral Contractions

Slow segmental colon movements that mix and absorb water/electrolytes.

Mass Movements

Powerful colonic contractions propelling feces toward rectum, often post-meal.

Enteric Nervous System (ENS)

Intrinsic gut neural network governing motility and secretion independently.

Autonomic Nervous System (ANS)

Extrinsic sympathetic (inhibitory) and parasympathetic (vagal excitatory) control of gut.

Cholecystokinin (CCK)

Duodenal hormone that contracts gallbladder, slows gastric emptying, stimulates pancreatic enzymes.

Gastrin

Stomach G-cell hormone that increases gastric acid and motility.

Secretin

Duodenal S-cell hormone that stimulates pancreatic bicarbonate and inhibits gastric motility.

Gastric Inhibitory Peptide (GIP)

Duodenal hormone that slows gastric activity and enhances insulin release.

Motilin

Small-intestine hormone that initiates MMC during fasting.

Acetylcholine (ACh)

Excitatory neurotransmitter that increases gut smooth-muscle contraction and secretion.

Serotonin (5-HT)

Excitatory mediator regulating peristaltic reflex and smooth-muscle tone.

Substance P

Neuropeptide that augments gut muscle contraction and pain sensation.

Nitric Oxide (NO)

Inhibitory transmitter causing smooth-muscle relaxation and LES opening.

Vasoactive Intestinal Peptide (VIP)

Inhibitory peptide that relaxes gut muscles and increases fluid secretion.

GABA in ENS

Inhibitory neurotransmitter dampening excessive enteric neuronal activity.

Salivary Amylase

Enzyme from parotid/submandibular glands initiating starch digestion in mouth.

Lysozyme

Salivary enzyme with weak antibacterial action in oral cavity.

Hydrochloric Acid (HCl)

Parietal-cell secretion that denatures proteins and converts pepsinogen to pepsin.

Pepsin

Protease from chief cells that begins protein digestion in stomach.

Intrinsic Factor

Parietal-cell glycoprotein necessary for vitamin B₁₂ absorption.

Bile Salts

Liver-derived amphipathic molecules that emulsify dietary fats for absorption.

Pancreatic Bicarbonate

Ductal secretion that neutralizes acidic chyme entering duodenum.

Trypsin

Pancreatic protease activated from trypsinogen; cleaves peptide bonds in small intestine.

Chymotrypsin

Pancreatic protease that works with trypsin to digest proteins.

Carboxypeptidase

Pancreatic enzyme that removes terminal amino acids from peptides.

Pancreatic Amylase

Enzyme that continues starch digestion in duodenum after salivary phase.

Pancreatic Lipase

Major enzyme hydrolyzing triglycerides into monoglycerides and fatty acids.

Nucleases

Pancreatic enzymes that degrade dietary DNA and RNA.

Peptidases (Brush-Border)

Intestinal enzymes that complete protein digestion to free amino acids.

Sucrase

Disaccharidase that splits sucrose into glucose and fructose on enterocyte microvilli.

Lactase

Brush-border enzyme that hydrolyzes lactose into glucose and galactose.

Maltase

Enzyme that converts maltose to two glucose molecules in small intestine.

Liver Lobule

Hexagonal structural unit of the liver centered on a central vein.

Glycogen Storage

Liver process of converting excess blood glucose into glycogen for later use.

Detoxification (Liver)

Hepatic conversion of drugs, alcohol, and toxins into excretable forms.

Albumin

Major plasma protein synthesized by liver; maintains oncotic pressure and transports substances.

Bile Storage (Gallbladder)

Concentration and reservoir function releasing bile upon CCK stimulation.

Glomerular Filtration Rate (GFR)

Volume of plasma filtered per minute by glomeruli; normal 90–120 mL/min.

Nephron

Functional kidney unit composed of glomerulus and tubular system for urine formation.

Proximal Convoluted Tubule

First nephron segment reabsorbing ~65 % of filtrate water, Na⁺, nutrients.

Loop of Henle

Nephron segment establishing medullary osmotic gradient for water reabsorption.

Distal Convoluted Tubule

Segment fine-tuning Na⁺, K⁺, H⁺ handling; aldosterone sensitive.

Collecting Duct

Final nephron channel where ADH modulates water reabsorption and urine concentration.

Renin

Kidney enzyme released from juxtaglomerular cells when BP or Na⁺ is low.

Angiotensinogen

Liver-produced plasma protein substrate for renin in RAAS.

Angiotensin I

Inactive decapeptide formed by renin cleavage of angiotensinogen.

Angiotensin II

Potent vasoconstrictor stimulating aldosterone, ADH, thirst, raising blood pressure.

Aldosterone

Adrenal cortex hormone promoting Na⁺ and water reabsorption, K⁺ excretion in kidney.

Juxtaglomerular Cells

Afferent-arteriole cells that sense pressure and secrete renin.

Erythropoietin

Kidney hormone that stimulates red-blood-cell production in bone marrow.

Calcitriol

Active vitamin D formed in kidney; increases intestinal Ca²⁺ absorption.

Red Blood Cell (RBC)

Anucleate biconcave cell containing hemoglobin for O₂/CO₂ transport; lifespan ~120 days.

White Blood Cell (WBC)

Leukocyte subgroup providing immune defense; includes granulocytes and agranulocytes.

Platelet (Thrombocyte)

Cell fragment from megakaryocytes that forms plugs and initiates coagulation.

Hemoglobin

Iron-containing protein in RBCs; each molecule binds four oxygen atoms.

Anemia

Condition of low RBC count or hemoglobin resulting in reduced O₂-carrying capacity.

Leukopenia

Abnormally low white-cell count leading to increased infection risk.

Thrombocytopenia

Platelet count below 150 000/µL causing bleeding tendency.

Blood Pressure

Force exerted by circulating blood on arterial walls; measured in mmHg.

Systolic Pressure

Peak arterial pressure during ventricular contraction.

Diastolic Pressure

Minimum arterial pressure during ventricular relaxation.

Cardiac Output (CO)

Volume of blood pumped by heart per minute (SV × HR).

Stroke Volume (SV)

Blood volume ejected by one ventricle in a single heartbeat (~70 mL).

Mean Arterial Pressure (MAP)

Average arterial pressure during one cardiac cycle; approximated by diastolic + ⅓ pulse pressure.

Baroreceptor Reflex

Rapid neural mechanism adjusting heart rate and vessel tone to stabilize BP.

Brain Hemorrhage

Bleeding within or around brain tissue due to vessel rupture, often from hypertension or trauma.