Lecture Exam 4 Practice Flashcards

Flashcards covering renal function, fluid/electrolyte balance, acid-base regulation, digestive processes, metabolism, and reproductive development.

Nephron

The functional unit of the kidney that filters blood, reabsorbs necessary substances, secretes waste, and produces urine.

Renal corpuscle

The component of the nephron made of the glomerulus and Bowman’s capsule where filtration begins.

Proximal convoluted tubule (PCT)

The major site of reabsorption that reabsorbs most filtered water, sodium, glucose, and other solutes, while beginning secretion of hydrogen ions and creatinine.

Loop of Henle

A tubule structure with a descending limb permeable to water and an ascending limb impermeable to water; it creates a concentration gradient in the medulla.

Distal convoluted tubule (DCT)

A segment that fine-tunes electrolyte balance by reabsorbing sodium, chloride, and calcium (if parathyroid hormone is present) and helping secrete hydrogen and potassium.

Collecting duct

The final site of water reabsorption where the presence of antidiuretic hormone (ADH) determines if urine will be concentrated or dilute.

Cortical nephrons

Nephrons mostly located in the renal cortex with shorter loops of Henle that produce more dilute urine.

Juxtamedullary nephrons

Nephrons with long loops of Henle extending deep into the renal medulla; they are essential for producing concentrated urine.

Afferent arteriole

The blood vessel that brings blood into the glomerulus; its dilation or constriction controls the glomerular filtration rate.

Vasa recta

Blood vessels associated mainly with juxtamedullary nephrons that help maintain the medullary concentration gradient.

Juxtaglomerular apparatus (JGA)

A regulatory structure near the glomerulus consisting of macula densa and juxtaglomerular cells that helps regulate GFR and blood pressure.

Macula densa cells

Cells in the distal convoluted tubule that sense sodium chloride concentration in the filtrate to detect filtration speed.

Juxtaglomerular (JG) cells

Cells in the wall of the afferent arteriole that release renin when blood pressure or blood flow is low.

Glomerular filtration rate (GFR)

The amount of filtrate formed by the glomeruli each minute, averaging about $115$ to $125\,mL/min$.

Glomerular hydrostatic pressure

The blood pressure inside the glomerular capillaries that serves as the main force promoting filtration.

Net filtration pressure (NFP) formula

$$NFP = \text{glomerular hydrostatic pressure} - \text{blood colloid osmotic pressure} - \text{capsular hydrostatic pressure}$$

Transcellular route

A reabsorption route where substances move through the tubule cells by crossing the apical and basolateral membranes.

Paracellular route

A reabsorption route where substances move between tubule cells through tight junction spaces.

Aquaporins

Water channels inserted into the collecting ducts by ADH to increase water reabsorption.

Proteinuria

The presence of protein in urine, which can indicate damage to the glomerular filtration membrane.

Specific gravity

A measurement in urinalysis that evaluates urine concentration; high values indicate dehydration or increased solutes.

Intracellular fluid (ICF)

Fluid inside cells, comprising approximately two-thirds of total body water, characterized by high potassium and magnesium levels.

Extracellular fluid (ECF)

Fluid outside cells, including interstitial fluid and plasma, characterized by high sodium and chloride levels.

Bicarbonate buffer system

The main chemical buffer system in the body that can quickly bind hydrogen ions to reduce acidity.

Respiratory acidosis

An acid-base imbalance characterized by low pH and high $CO_2$ caused by hypoventilation.

Metabolic acidosis

An acid-base imbalance characterized by low pH and low bicarbonate levels, often caused by diarrhea or kidney failure.

Enteric nervous system

The "gut brain" consisting of the myenteric and submucosal plexuses that control GI motility and secretions.

Myenteric plexus

A part of the enteric nervous system that controls smooth muscle movement and regulates motility and peristalsis.

Segmentation

A motility pattern in the small intestine that mixes chyme back and forth to contact enzymes and absorptive surfaces.

Chyme

A mixture of partially digested food and gastric juice formed in the stomach.

Intrinsic factor

A stomach secretion produced by the lining that is essential for the later absorption of vitamin $B_{12}$ in the small intestine.

Gastrin

A hormone released by the stomach that stimulates gastric acid secretion, stomach motility, and gastric emptying.

Ghrelin

A hormone released by the stomach that stimulates hunger through the hypothalamus.

Emulsification

The process by which bile breaks large lipid droplets into smaller droplets to facilitate enzyme digestion.

Cholecystokinin (CCK)

A hormone triggered by fat and protein that stimulates gallbladder contraction and the secretion of pancreatic enzymes.

Secretin

A hormone triggered by acidic chyme in the duodenum that stimulates the release of bicarbonate from the pancreas.

Absorptive state

The "fed state" where insulin is the main hormone and the goal is to use glucose for energy and store extra nutrients.

Postabsorptive state

The "fasting state" where glucagon is the main hormone and the goal is to maintain blood glucose via glycogenolysis and gluconeogenesis.

Leptin

A hormone released by adipose tissue that signals to the hypothalamus that energy stores are sufficient (satiety).

Somatic cells

Diploid body cells containing $23$ pairs of chromosomes (total of $46$).

Gametes

Haploid sex cells (sperm or oocytes) containing $23$ total chromosomes.

Sertoli cells

Cells in the seminiferous tubules that support developing sperm and produce the hormone inhibin.

Leydig cells

Cells in the testes that produce testosterone in response to luteinizing hormone (LH).

Corpus luteum

The structure formed in the ovary after ovulation that secretes progesterone and estrogen to support the uterine lining.

SRY gene

A gene on the Y chromosome that codes for testis-determining factor (TDF), initiating male reproductive development.

Gastrulation

An embryonic process where three germ layers (ectoderm, mesoderm, and endoderm) are formed.

Müllerian ducts

Early embryonic structures that develop into the female internal reproductive tract if TDF is absent.