In: Anatomy and Physiology
PART 1 : Draw the nephron and label all its parts, be sure to include associated vasculature.
PART 2: Also indicate the following:
Indicate in your drawing, above, the major substances resorbed or secreted along each part of the nephron (YOU MUST INCLUDE, AT MINIMUM: SODIUM, WATER, CALCIUM, GLUCOSE, POTASSIUM, CHLORIDE, BICARBONATE, PROTONS)
Indicate (either in your drawing or as text, below) the hormones that regulate tubular reabsorption, also indicate their action and the site of action (target)
PART 3:
Define Glomerular Filtration Rate (GFR)
If a patient has renal artery stenosis (narrowing of the renal artery) due to atherosclerosis, what is the impact of this on GFR? Specifically, be sure to discuss the impact on the afferent and/or efferent arterioles as well as effects on hydrostatic and/or oncotic pressure.
ADH (Antidiuretic Hormone)
The brain and kidneys regulate the amount of water excreted by the
body. When the blood volume is low, the concentration of solutes in
the blood is high. When the hypothalamus senses this low blood
volume and increased serum osmolality it synthesizes ADH, a small
peptide molecule. The pituitary gland then releases ADH into the
bloodstream and causes the kidneys to retain water by concentrating
the urine and reducing urine volume. Water retention boosts blood
volume and decreases serum osmolality.
Renin-Angiotensin-Aldosterone System
It is important for the body to keep sodium and water balances in
check, and also to maintain healthy blood volume and blood
pressure. The renin-angiotensin-aldosterone system assists with
this in the following manner:
The glomulerus, a bundle of capillary blood vessels found in the
kidney, senses a drop in blood flow or sodium and secretes an
enzyme called renin into the bloodstream.
Renin moves to the liver where it converts the inactive peptide
angiotensinogen to angiotensin I.
Angiotensin I travels to the lungs where another enzyme converts it
to angiotensin II.
Angiotensin II makes its way to the adrenal glands at the top of
the kidneys where it stimulates the production of
aldosterone.
Aldosterone helps the kidneys conserve sodium and water, leading to
increased fluid volume and sodium levels.
Atrial Natiuretic Peptide
When blood volume and blood pressure increase, the stretched atria
release Atrial Natiuretic Peptide (ANP), a cardiac hormone. ANP
promotes natriurisis by shutting down the
renin-angiotensin-aldosterone system and causing vasodilation. As
the blood vessels expand, urine excretion of sodium and water
increases, stabilizing blood volume and blood pressure
Part 3
GFR-The rate of blood flow through the kidneys is the glomerular
filtration rate,
GFR is equal to the renal clearance ratio when any solute is freely
filtered and is neither reabsorbed nor secreted by the kidneys. The
rate therefore measured is the quantity of the substance in the
urine that originated from a calculable volume of blood.
two main causes of renal artery stenosis include:
Buildup on kidney (renal) arteries. Fats, cholesterol and other
substances (plaque) can build up in and on your kidney artery walls
(atherosclerosis). As these deposits get larger, they can harden,
reduce blood flow, cause kidney scarring and eventually narrow the
artery. Atherosclerosis occurs in many areas of the body and is the
most common cause of renal artery stenosis.
Fibromuscular dysplasia. In fibromuscular dysplasia, the muscle in
the artery wall grows abnormally, often from childhood. The renal
artery can have narrow sections alternating with wider sections,
giving a bead-like appearance in images of the artery.
Hence athroscleoris increase kidney disease and reduce GFR
Hydrostatic and oncotic pressure both contribute GFR-Increases in the glomerular capillary hydrostatic pressure cause increases in net filtration pressure and GFR.. Increases in protein concentration raise glomerular capillary oncotic pressure and draw in fluids through osmosis, thus decreasing GFR.