Regulation and

Control

Excretion

elimination from the body of waste produced during metabolism of cells,

Including removal of;

carbondioxide

Through lungs

Urea

Through kidneys in urine

Production and excretion of Urea:

to deamination

goes into

excretion passes through

Excess protein

liver

urea

blood

kidneys

The Excretory System

Longitudinal Section of Kidney

Structure of A Nephron

Kidney makes urine in a two stage process:

Ultrafiltration

•Filtering small molecules from blood to renal capsule

SelectiveReabsorp

tion

•Taking back useful molecules from the fluid in nephron

Site of Ultrafiltration:

Pedicels •increase the surface area for efficient ultrafiltration

Filtrationslits

•Blood is filtered through them

Many ER Large Golgi App

•Synthesis of proteins required for pedicels to wrap around the capillaries and function

Structural features of podocytes

The process of Ultrafiltration

Reabsorption in Proximal Convoluted Tubule

Active secretion

Reabsorption in Loop of Henle

•Permeable to ions•Non-permeable to water

•Low permeability to ions•Permeable to water

Counter-current mechanism:

Osmoregulation

Secretion of ADH

Effect of ADH on collecting duct

AVP= Arginine vasopressin(ADH) 

Osmoregulation is necessary!

Some marine animals such as the sea stars are osmoconformers; their body fluids are similar to seawater in osmolarity, so they gain and lose water at equal rates and have no need to expend energy expelling water or salt from the body. However, if they are placed in water more or less concentrated than seawater, their tissues shrink or swell, they die!

Our Kidneys have a higher blood flow than our brain, liver or heart.

produce hormones: erythropoeitin (EPO), that stimulates the

production of red blood cells. Calcitrol, promotes absorption

of calcium

Placed end to end, the nephrons of one kidney would stretch about 8 km!

Interesting facts!

Thank You!