Human Anatomy and Physiology Chapter 24

Human Anatomy and Physiology Chapter 24

flow of urinary fluid

kidneys to ureter to urinary bladder to urethra

layers of the kidney

outer layer renal cortex, middle layer renal medulla, and inner layer renal sinus

glomerulus

filters blood to form initial filtrate in the nephron

tubules

carry out resorption (reclaiming useful substances) and secretion (removing waste into filtrate)

tubules + collecting duct

conserve water by adjusting urine concentration

cortical nephrons

glomerulus and convoluted tubules. located mostly in the renal cortex and have a short or absent loop of Henle

juxtamedullary nephrons

glomerulus, convoluted tubules and loop of Henle. located near the cortex-medulla junction and important for producing concentrated urine.

fenestrated endothelium

capillary blood vessel lining with pores that allow fluid and small solutes to pass.

fenestrated epithelium

specialized epithelial layer (podocytes) that helps filter blood while retaining proteins and cells

renal autoregulation of GFR

High BP or high NaCl at macula densa → afferent arteriole constricts → GFR decreases/stabilizes

decreased blood pressure

vasodilation of afferent arteriole and increase in glomerular filtration surface area

increased blood pressure

vasoconstriction of afferent arteriole and decrease in glomerular filtration surface area

glomerulus

filtration of blood

proximal convoluted tubules

resorption of material into blood or secretion of material into tubules

loop of Henle, distal convoluted tubule and collecting duct

promoting the osmotic gradient for retention of water

Proximal convoluted tubule (PCT) reabsorption

Na+, K+, Ca2+ and bicarbonate ions, glucose, and amino acids

Proximal convoluted tubule (PCT) secretion

nitrogenous wastes, antibiotics, toxic drugs and hemoglobin metabolites

Medullary osmotic gradient components

Na⁺ (sodium ions) and urea

Water reabsorption in the kidney

Aquaporins - membrane proteins that allow water to move by osmosis

Antidiuretic hormone (ADH) - increases the number of aquaporins, reducing water loss (preventing diuresis)