Human Physiology Lecture Exam 4 Flashcards

Vocabulary-style flashcards covering the major concepts of Chapter 19 (Kidney), Chapter 20 (Fluid/Electrolytes), Chapter 21 (Digestive System), and Chapter 26 (Reproduction) for the fourth Human Physiology exam.

Filtration

The movement of fluid from the blood into the lumen of the nephron, occurring at the renal corpuscle.

Reabsorption

The process of moving substances from the filtrate in the tubule lumen back into the peritubular capillaries.

Secretion

The selective removal of molecules from the blood and adding them to the filtrate in the tubule lumen.

Excretion

The removal of substances from the body in the form of urine.

Glomerular Filtration Rate ($GFR$)

The volume of fluid that filters into the Bowman's capsule per unit time.

Juxtaglomerular apparatus

The region where the distal tubule passes between the afferent and efferent arterioles, playing a role in blood pressure and automated $GFR$ regulation.

Macula densa

Modified cells in the distal tubule that sense flow and send paracrine signals to the afferent arteriole to regulate $GFR$.

Renin

An enzyme secreted by the juxtaglomerular cells that initiates the pathway producing angiotensin II to raise blood pressure.

Transepithelial transport

A process where substances cross both the apical and basolateral membranes of the tubule epithelial cell to reach the interstitial fluid.

Paracellular transport

The movement of solutes through the junctions between adjacent cells.

SGLT

Sodium-glucose co-transporter; a protein on the apical surface of the proximal tubule that uses secondary active transport to reabsorb glucose.

Transport maximum ($T_m$)

The transport rate at saturation, where all available carrier proteins are occupied.

Renal threshold

The plasma concentration of a substance at which it first appears in the urine.

Glycosuria

The excretion of glucose in the urine, usually indicating that blood glucose levels have exceeded the renal threshold.

Micturition

The physiological term for the process of urination.

Vasopressin

Also known as Antidiuretic Hormone ($ADH$); it acts on the collecting duct to increase water reabsorption, making urine more concentrated.

Renal countercurrent multiplier

A mechanism in the loop of Henle that uses energy to create an osmotic gradient in the renal medulla, allowing for urine concentration.

Aldosterone

A steroid hormone that increases sodium ($Na^+$) reabsorption and potassium ($K^+$) secretion.

Hyperkalemia

A condition characterized by elevated levels of potassium ($K^+$) in the blood.

Hypokalemia

A condition characterized by abnormally low levels of potassium ($K^+$) in the blood.

Acidosis

A condition where the body's blood $pH$ falls below $7.35$.

Alkalosis

A condition where the body's blood $pH$ rises above $7.45$.

Myenteric plexus

A network of nerves in the muscularis externa of the $GI$ tract that primarily controls motility.

Migrating motor complex

Housekeeping contractions that move food remnants and bacteria from the stomach and small intestine into the large intestine between meals.

Peristalsis

Progressive waves of contraction that move a bolus forward through the GI tract.

Segmentation

Short segments of intestine contract and relax to mix contents and keep them in contact with the absorptive epithelium.

Gastrin

A hormone produced by G cells in the stomach that stimulates the secretion of gastric acid ($HCl$).

Secretin

A digestive hormone that stimulates the release of bicarbonate from the pancreas to neutralize stomach acid.

Cholecystokinin ($CCK$)

A hormone that stimulates gallbladder contraction and pancreatic enzyme secretion.

Deglutition

The physiological term for the act of swallowing.

Parietal cells

Cells in the gastric glands that secrete hydrochloric acid ($HCl$) and intrinsic factor.

Chief cells

Cells in the gastric glands that secrete pepsinogen, the inactive precursor to pepsin.

Alkaline tide

The temporary increase in blood $pH$ due to bicarbonate ($HCO_3^-$) being pumped into the blood during $HCl$ secretion in the stomach.

Hepatic portal system

A specialized circulatory route that carries blood from the digestive tract directly to the liver.

Bipotential gonads

Embryonic structures that can develop into either male (testes) or female (ovaries) sex organs.

SRY gene

The Sex-determining Region of the Y chromosome; its presence triggers the development of testes.

Wolffian ducts

Embryonic ducts that develop into the male internal reproductive structures in the presence of testosterone.

Mullerian ducts

Embryonic ducts that develop into female internal reproductive structures in the absence of Anti-Müllerian Hormone ($AMH$).

Spermatogenesis

The process of producing haploid ($n$) sperm cells from diploid ($2n$) spermatogonia.

Corpus luteum

A temporary endocrine structure formed from the ruptured follicle after ovulation that secretes progesterone.