Functions of the Nephron

Kidney functions

*Filters blood plasma (1200-1500 ml/min) -eliminates waste and excess water, returns useful chemicals to blood *Regulates acid-based balance and osmotic pressure • Secretes renin to regulate the blood pressure • Produces urine (1200-1500 ml/day) • Activates angiotensin, aldosterone from adrenals gland -controls BP & electrolyte balance • Secretes erythropoietin = controls RBC count • Maintains homeostasis-state of balance in the body

Glomerular

*Reabsorption (PCT/loop of Henle) *Secretion (tissues of DCT tubules *Concentration (water conservation in DCT/CD *Urine and renal function test *Urine storage and elimination

Anatomy of Kidney

- Renal cortex is the out 1 cm - Renal medulla: renal columns, pyramids-papilla - Lobe of Kidney: pyramid overlays of the cortex - Frontal section of kidney

Filtrate crosses

1. Glomerulus into 2. Bowman's capsule 3. PCT (proximal convoluted tubule) 4. Loop of Henle 5. DCT (distal convoluted tubule) 6. Collecting duct 7. Renal pelvis of kidney 8. Ureters 9. Bladders 10. Urethra excretes 1-2L or avg 1200-1500 ml/day

Nephron Anatomy

1.3 million nephrons After age 40 functioning nephrons decreased 10% every 10 years at age 80, 40% fewer functioning nephrons that at age 40.

Differences between active and passive transport are:

Active transport: requires cell energy and ADH Passive transport: does not requires cell energy and ADH

Path of Urine Formation

Blood enters: filters 1200/ml/min Afferent arterioles (larger diameter) into Glomerulus (cluster of capillaries) and axis Efferent arterioles (smaller dia.->vasa recta)

Controlling water concentration

Blood is an important part of internal environment Constantly changing water concentration e.g. exercising, sweating, drinking lots of water The body uses negative feedback to control to regulate water content of the blood

Urine composition

Daily volume 1-2L, avg. 1200-1500 ml/day 1% of filtered plasma Largest component of urine =water (96%) next largest components urea, CL, NA, K Followed by : Phosphates, sulfates, crea and uric acid

Which feature of the glomerulus helps the process of filtration?

Glomerulus brings a large surface area of blood capillaries in close contact with Bowman's capsule

What is filtration?

Liquid filtered from the blood

Osmosis vs diffusion

Osmosis diffusion of water between 2 regions separately by selectively permeable membrane in response to the water concentration gradient; lower to greater concentration Diffusion movement of like molecules or ions of greater to lower concentration

Urine formation has 3 process

Plasma formation at the glomerulus filtration Reabsorption Secretion of selected compounds

Renal artery

Renal vein carries blood away from kidney

EXCRETION BY THE KIDNEY

Urea: nitrogenous waste, made by the liver, and has excess amino acids in the blood

The _____ _______ mechanism is responsible for water reabsorption thru out the nephron

countercurrent exchange

Bowman's capsule

cup-shaped part of the nephron that holds a glomerulus and collect the products of filtration from it

Glomerulus

dense mass of very fine blood capillaries and arterioles at the nephron that act as a filter

Protein molecules and red blood cells

don't pass into tubule as they are too big—sign of kidneys not working

What in healthy patient these chemicals are completely reabsorbed (none in urine)?

glucose, bicarbonate, and albumin

Afferent arteriole

goes to the (reference kidney)

Hypertonic solutions

greater concentration of solutes

Angiotensin

is a peptide hormone that causes vasoconstriction and a subsequent increase in blood pressure. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure.

Renal corpuscle

is the initial blood-filtering component of a nephron. It consists of two structures: a glomerulus and a Bowman's capsule. The glomerulus is a small tuft of capillaries containing two cell types.

Glomerulus

large surface area blood capillaries in close contact with the Bowman's capsule

Hypotonic solutions

lesser concentration of solutes

Filtration

liquid is filter from blood under pressure

Glomerular filtrate

liquid removed from the blood by filtration in the kidney

Efferent arteriole

means going out of (reference to kidney)

Nitrogenous waste

must be excreted from the body because it is toxic

Nephron

structure of the kidney that's acts as a microscopic filtration unit the main functional unit of the kidney made up of glomerulus and tubules

Filtration by the kidney

supplied with blood from the renal artery; splits inside into many fine capillaries, each capillary supplies blood to hundreds of thousands of tiny filtration units called nephrons

What 4 components of unfiltered blood appear in the glomerular filtrate?

water glucose salts urea

Glomerular filtrates produces containing

water, glucose, salt, urea