The Excretory System Flashcards
Define excretion
the process of removal of harmful and unwanted nitrogenous wastes, from the body
substances eliminated from body
- CO2 and water vapour (respiratory)
- nitrogenous metabolic wastes (kidneys)
- excess salts (kidneys)
- water
- bile pigments
pigment in urine
urochrome
function of liver
detoxifies ammonia by converting it to urea
breaks down bad cholesterol, alcohol, nicotine, and drugs
location of kidney
located on either side of the backbone and protected by the last two ribs. right one is lower than left one
location of hilum
a notch present in the median surface of each kidney
location of urinary bladder
lower part of the abdomen
urination also known as
micturition
internal structure of kidney
- outer dark cortex and inner light medulla
- medulla consists of finely striped materials arranged in conical pyramids
- apex of each pyramid is papilla and projects into the pelvis of kidney
- cortical tissues extend between adjacent renal pyramids to form renal columns
structural and functional unit of kidneys
uriniferous tubules/ nephrons/ kidney tubules/ renal tubules
Bowman’s capsule
thin-walled cup. Its hollow internal space continues into tubule.
glomerulus
on the outer concavity of bowman’s capsule, there is a knot-like mass of capillaries
malpighian capsule/ renal capsule
bowman’s capsule and glomerulus together
why is there a dotted appearance in cortex of kidney in sectional view
both bowman’s capsule and PCT lie in the cortex
loop of Henle
Middle U-shaped part, that is not convoluted. it runs in medulla to turn back and re-enter cortex to continue into the next convoluted region of tubule
afferent arteriole
renal artery has rebranched into afferent arterioles, which breaks into capillaries and forms glomerulus
efferent arteriole
reuniting capillaries of the glomerulus. after running a short distance, breaks up into a secondary capillary network (VASA RECTA), which surrounds renal tubule, rejoins to form a vein
major steps of urine formation
- glomerular ultrafiltration
- reabsorption
- tubular secretion
glomerular ultrafiltration
blood flows through glomerulus in great pressure, because efferent arteriole is narrower. liquid part of the blood filters out from glomerulus and into renal tubule
parts of blood that come out during ultrafiltration
plasma, its organic and inorganic substances, urea, glucose, amino acids
define glomerular filtrate
fluid entering the renal tubule after ultrafiltration
what does glomerular filtrate consist of
water, urea, salts, glucose, and other plasma
reabsorption
glomerular filtrate passes down the renal tubule, water and useful substances are reabsorbed
define selective absorption
during reabsorption, useful substances are absorbed only to the extent that the normal concentration of blood is not disturbed
tubular secretion
potassium ions in normal course, and foreign chemicals like drugs and penicillin are passed into the forming urine in DCT. the passage involves the activity of cell in tubular wall
define urine
the filtrate left after reabsorption and tubular secretion
function of bowman’s capsule
receives glomerular filtrate\
function of PCT
reabsorbs most water, glucose, sodium and chlorine ions
function of loop of Henle
absorption of water and sodium ions
function of DCT
- reabsorption of remaining chlorides and some water
- walls secrete potassium and foreign drugs into forming urine
define micturition
urine is expelled from the urinary bladder on relaxation of sphincter muscles located at the opening of urinary bladder into the urethra, on impulse sent from nervous system
pH of urine
5-8
specific gravity of urine
1.003- 1.035
organic constituents of urine
- urea
- creatinine
- uric acid
- others
inorganic constituents of urine
- sodium chloride
- potassium chloride
- ammonia
define haematuria
blood passes with urine due to some infection in urinary tract, kidney stones, or some tumour
define glycosuria
excess glucose passes out with urine due to diabetes mellitus
define albuminuria
due to high BP, or increased permeability of bowman’s capsule membrane due to infection, albumin passes out in urine
why does urine contain bile pigments
anaemia, hepatitis, jaundice, liver cirrhosis
define diuresis
increased production of urine
concentration of urine by water reabsorption is controlled by what hormone
antidiuretic hormone (ADH)
where is ADH secreted
posterior lobe of pituitary gland of brain
if ADH secretion reduces…
more urine is produced (diuresis)
examples of diuretics
liquid diets, tea, coffee, alcohole
define osmoregulation
regulation of osmotic pressure of the blood
define uremia
overaccumulation of poisonous urea in body
