Excretion humans

metabolism?

sum of chemical reactions within the body of an organism (anabolic+catabolic)

Anabolic

Chemical reaction in which complex substances are built from simple substances

Catabolic

Chemical reaction in which complex substances are broken down into simple substances

Excretion

removal of metabolic waste products, toxic substances and substances in excess of body’s requirements.

Egestion vs excretion

Egestion is the removal or undigested materials from alimentary canal. Egested materials are not products of metabolic waste (produced by body)

osmoregulation

control of water and solute concentration in blood to maintain a constant water potential in the body

Medulla

structure group tgt to form renal pyramids which project into renal pelvis

Nephron

Bowman’s capsule, glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct

Wall of nephron

layer of epithelial cells

transportation of blood from aorta to kidney

Renal artery —> numerous arteriole —> dense network of blood capillaries (glomerulus)

basement membrane n (endothelium)

partially permeable, thus allowing water, urea, glucose to pass through, prevents larger substances such as red blood cells, plasma protein from leaving glomerulus

Proximal convoluted tubule

epithelial cells bear a brush border of microvilli to increase surface area for reabsorption of substances. Cells have numerous mitochondria to provide ADP(adenosine triphosphate) for active transport of solutes

after collecting duct?

converge at renal pelvis and empty contents into ureter which conveys them to urinary bladder as urine. muscles under bladder relaxes and release

function of kidney

1. remove metabolic waste

2. Osmoregulator in maintenance of salt concentration and water potential of blood plasma, pH balance of blood and volume of blood(blood pressure)

Source of pressure in glomerulus

Contraction of left ventricle in heart

Maintenance of high blood pressure in glomerulus

Afferent arteriole bringing blood into glomerulus is greater in diameter than efferent arteriole bring blood away from glomerulus. The difference in diameter generates higher hydrostatic blood pressure

Filtered out? (ultrafiltration)

Small, soluble substances including water, amino acids, mineral salts, nitrogenous waste products(urea) glucose) are forced out into Bowman’s capsule as blood passes through basement membrane

—> glomerular filtrate passes into pct of nephron

Cannot pass thru glomerulus

Large, insoluble substances like blood cells, plasma proteins, fats, platelets retained in blood

Selective reabsorption

All essential substances useful to body (water, glucose, amino acids)and required to maintain salt concentration and water potential of body fluid at steady state/constant are selectively reabsorbed from glomerulus filtrate across intercellular fluid and back in bloodstream in peritubular capillaries

movement by what process

glucose, amino acids, ions are reabsorbed from filtrate to PCT epithelial cell, then into intercellular fluid by diffusion/ active transport, enter peritubular capillary by diffusion. active transport requires ATP from respiration of tubule epithelial cells

ADH

antidiuretic hormone produced in hypothalamus, stored and released by pituitary gland, can increase permeability of walls of DCT n collecting duct, increasing volume of water absorbed from glomerular filtrate into peritubular capillaries