What are the end products of metabolism?
CO2
Nitrogenous waste
Water
What are Nitrogenous wastes
The end products of protein, creatinine, phosphate and nucleic acid metabolism
Nitrogenous waste includes the following
Urea
Creatinine
Uric acid
What is Urea and how is it produced?
Most abundant organic waste
Produced from breakdown of aa. Deamination leads to ammonia production. Ammonia is v. toxic and converted to urea which is less toxic by the liver
How is creatinine generated?
by skeletal muscle through the breakdown of creatinine phosphate for energy
How is Uric acid generated?
It is derived from the nitrogenous bases of RNA molecles
What materials are excreted through the urinary system
End products of metabolism (CO2, Nitrogenous wastes and water) and ANY substance which is in excess of body needs
Why does excretion play a major role in homeostasis?
It maintains the proper concentration for body fluids
What does the urinary system do?
Responsible for bulk of all other excretion except for CO2
What organs make up the urinary system
Kidneys
Ureters
Bladder
Urethra
Where is urine formed
The Kidneys
What do the ureters do?
Muscular tubes that transport urine
What does the bladder do?
Stores urine
Why is the bladder able to stretch?
Transitional epithelium
What does the urethra do?
Muscular tube, transports urine from bladder to outside
What are the functions of the kidney (6)
Regulate composition and volume of blood directly, other body fluids indirectly
Excrete waste from blood
Regulate urethral pyosis by releasing urethra pyotin
Aid in regulating pH
Regulate blood pressure by releasing renin which activates the angeotensin system
Assist liver w/ detoxification, deamination and glyconeogenis
What is the external anatomy of the kidney
Large bean shape w/ hilus (indentation) where ureters exit
Made up of 3 layers of tissue
What are the 3 layers of kidney tissue?
Renal capsule
Adipose capsule
Renal fascia
What is the renal capsule and what does it do?
Innermost layer of the kidney
Protects against infection and kidney
What is the adipose capsule and what does it do?
Middle layer
Consists of fatty tissue
Cushions against shock an anchors kiney
What is the Renal fascia and what does it do?
Outter layer
Consists of thin connective tissue
Anchors kidney to body wall and also surrounds adrenal gland
What 2 layers make up the inside of the kidney?
Medulla
Cortex
What is the medulla?
Innermost layer of kidney, made up of 5-14 pyramids
What is the renal papillae?
Broad base of pyramid that faces out
Where is your loop of Henle found?
Medulla
What is the cortex?
Outter layer of the internal kidney, most nephrons are found here
What areas go from the pyramids to the ureter?
Pyramid -> minor calyx -> major calyx -> renal pelvis -> ureter
What is the functional unit of the kidney and what does it do?
Nephron, site of urine formation
Name the parts of a nephron
Glomerular (Bowman's) capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting ducts
What do the glomerular capsules do?
Filter
Name the 2 layers of the glomerular capsule and their epithelial type
Outter - perietal cup - squamous epithelium
Inner - visceral layer - podocytes
What are podocytes?
Special epithelial cells with filtration slits to filter plasma
What lines the proximal convoluted tubule?
Microvilli
What part of the nephron is heavily surrounded by capillaries?
Distal convoluted tubule
There is one duct for each nephron T of F
F
Several nephrons will empty in to 1 duct
What are the 2 types of nephrons?
Cortical
Juxtamedullary
Describe a cortical nephron
Glomerular lie in the outter region of cortex
No loop of Henle
Don't dip into medullary area
Make up about 85% of nephrons
Describe a juxtamedullary nephron
Glomerular lie in cortex close to pyramid
Have loop of Henle which penetrates deep into pyramid
Major role is water balance (osmotic gradient)
Describe the vascular pathway in the kidney
Renal artery -> segmental arteries -> lobar arteries -> Interlobar arteries -> arcuate arteries -> interlobular arteries -> afferent arterioles -> glomerulus -> efferent arterioles -> peritubular capillary beds
What is a renal plexus?
Nerve supply for kidney, has a capillary network that surrounds loop of Henle calle vasa recta
What are the 3 different processes for urine formation
Filtration
Reabsorption
Secretion
What makes the glomerular best for filtration?
It is very permeable, open pores, no cell, basement membrane, surface area is very large, has a high blood pressure
Why is the blood pressure high in the gloerulus?
The efferent arterial is smaller in diameter than the afferent
And the osmotic pressure in the unfiltered blood pulls fluid back into glomerulus
What is the standard measurement for the glomerular filtration rate?
Insulin
It can be varied by regulating glomeruler pressure
What is the initial composition of filtrate
Same as plasma, minus plasma proteins
Where does reabsorption primarily occure
Proximal convoluted tubule
What is more selective, filtration or reabsorption?
reabsorption
How much glucose and aa are reclaimed?
How much urea?
Almost always 100%
50%
What is the threshold value?
Concentration in the plasma must be exceeded before it appears in the urine
Where does secretion mostly occur?
Distal conveluted tubuel
What is micturitiion
urination
How is water lost from the body?
Kidneys, skin (sweat), lungs, GI tract
What are the 2 main fluid compartments?
Intracellular (fluid w/i the cells)
Extracellular (fluid outside of the cells)
What are the 2 divisions of extracellular fluid?
Interstitial Fluid
Plasma
What is the relationship between Na and water reabsorption?
water follows Na that is reabsorbed in the proximal convaluted tubule
How does aldosterone affect Na?
Produced by adrenal cortex, causes kidney tubules (especially distal portion) to increase Na transport thus increases Na reabsorption
How does the atrial natriuretic factor affect Na?
Realesed by atrial myocardial cells. inhibits renin, modifies activity of angiotensin system, which reduces aldosterone, reducing sodium, reducing water retention and reducing bloo pressure
How do juxtamedullary cells affect blood pressure?
They are cells close to glomerular
They decrease blood supply to kidneys where renin is produced which increases tensinogen, angiotensin 1 and 2 which constricts arteriols and increases blood pressure
3 hormones release by kidney
Renin
Urethropyotin
calcitrial
What happens to urine if there is execs water?
What if the boy is dehydrated?
Diluted urine
Concentrated urine
Where does most water reabsorption occur?
Proximal tubules
Describe the urine as it travels the Loop of Henle
Entering the descending limb - isotonic to plasma
Moving down the descending limb it becomes more concentrated
Moving up the ascending limb begins to loose concentration because chloride is transported out and Na follows, water stays behind
Where does some urea diffuse out?
lower portion of collecting duct
What is the role of the vasa recta?
Maintains the medullary concentration gradient developed by the loop of Henle
T/F the vasa recta carries salts away
F, the salts dilute into an out of the vasa recta
What does ADH control?
The amount of water reabsorbed from collecting ducts
What releases ADH
nurohypophysis
Does ADH cause urine to be more concentrated or diluted?
Concentrated
80% of the total water reabosorption occurs in the _____. The ______ system is responsible for the remaining amount
proximal convoluted tubules
counter-current-ADH
The transport of ___ and ___ from the ascending loop creates an osmotic gradient in the ___. This gradient is enhanced by the reabsorption of ___ in the collecting ducts.
chloride and sodium
interstitial fluid
Urea
The ___ maintains the concentration gradient established by removing the water reabsorbed from the ___.
Vasa recta
collecting duct
What regulates the permeability of the collecting duct?
ADH
What type of urine is produced when the tubule is permeable?
What if the tubule is not permeable?
hypertonic to plasma
hypotonic to plasma, copious amounts
What do electrolytes affect?
water movement, pH, enzyme activity and osmotic pressure
How does chloride affect osmotic pressure?
Indirectly, it is regulated by aldostorone and attracted to Na
What is the most abundant cation in ICF?
Potassium
What regulates calcium and phosphate?
endochrine glands
What increases magnesium excretion?
Increase levels of aldostorone
what is respiratory alkalosis?
pH leads to hyperventalation
What is metabolic alkalosis?
Increase in pH an bicarbonate levels
What is alkalosis?
pH in arteriole blood is greater than 7.45
What is aciosis
When pH is 7.0-7.35
What does respiratory acidosis lead to?
CO2 retention
What does metabolic acidosis do?
decrease in pH brings bicarbonate levels down
What are the 3 major chemical buffers?
Bicarbonate
phosphate
protein
What is diabetes insipidus?
ADH is absent or low, little to no water is reabsorbe
What is glomerulonephritis?
Inflammation of glomeruli. Inflammatory response leads to blockage of many nephrons
What are kidney stones?
crystals formed in renal pelvis, may pass down ureter to bladder and cause pain and/or block urine
What is cystitis?
Inflammation of bladder
What happens in dialysis?
blood is passed through a tube which allows the movement of urea and other small molecules out but blocks proteins and blood cells. Tube runs through a bath which contains the proper concentration of glucose and vitamins
What happens with age?
decrease in GFR
renal blood flow decreases
decrease in concentration of urine in tubules
increased volumes of urine and frequency of urination
What is edema
accumulation of fluid in interstitial space, leading to swelling
What is thirst promoted by?
decrease in saliva
decrease in plasma osmolaity
increase in plasma volume