An elderly female patient has a history of osteoporosis, chronic type II diabetes mellitus, and high blood pressure.What could be going on that explains all of this? How are blood pressure, kidney function, and bone mass related?
background
anatomy of the urinary system
kidneys
ureters
bladder
urethra
anatomy
renal cortex
renal medulla, cone shaped tissue mass
renal pelvis
renal columns
renal pyramids
a funnel-shaped tubes continuous with the ureter leaving the hilum. branching extension of the pelvis form two or three
major calyx subdivision to form several
function
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structure of a nephron
Balance the body's fluids
Release hormones to regulate blood pressure
Control production of red blood cells
Remove waste products and drugs from the body
kidneys remove urea from the blood through tiny filtering units called nephrons.
narrow tubes carry urine from the kidneys to the bladder.
function: small amounts of urine are emptied into the bladder from the ureters.
hollow organ is located in the lower abdomen.
expand to store urine
function; tube allows urine to pass outside the body.
nephron
they are structural and functional units of the kidneys
sponsible for removing waste products, stray ions, and excess water from the blood.
is light coloured and has a granular appearance, the most superficial
appear stripped because they are formed almost entirely of parallel bundles of microscopic urinecollecting tulles and capillaries
inward extensions of cortical tissue,seperate the pyramids.
minor caylx
the calyces collect urine, which drains continuously from the papillae, empty into renal pelvis and into the ureter, which moves to bladder to be stored.
the muscle = smooth muscle that contracts rhythmically to propel urine by peristalsis
blood and nerve supply
renal arteries
deliver one fourth of the total cardiac output to the kidney- about 1200 ml each min
divides into five segmental arteries
branches further form several interloper arteries
cortical radiate arteries(interlobular arteries) radiate outward from the acruate arteries to soppy to corticel tissue
arcuate arteries
arch over the bases of the medialary pyramids
renal viens
afferent arterioles branching from the cortical radiate arteries begin a complex arrangment of microscopic blood vessels
blood leaving the renal cortex drains sequentially into the cortical radiate , arcuate, intrerlobar, and finally Renal veins.
exit the kidneys and empty into the inferior vena cava
the inferior vena cava lies to the right of the vertebral column,
renal corpuscle
consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
capillaries is fenestrated(penetrated by many pores, which makes capillaries exceptionally pores.
this plasma-derided fluid or filtrate is the raw material that the renal tubules process to form urine.
glomerular capsule
parietal
visceral
simple squamous epithelium, this layer contributes to the capsule structure but plays no part in filtering
this layer clings onto capillaries, consists of highly modified, branching epithelium cells called podocytes
have openings between the foot processes are called filtration slits
renal tubes and collecting duct
proximal convoluted tubule-formed by cubical epithelial cells with large mitochondria,they have apical or luminal surfaces bear dense microvilli-for reabsorbing water and solutes from the filtrate and secreting substances; drops down into a hairpin loop
nephron loop- then twist again as the
distal convoluted tubule;cubiodial and confined to the cortex before entering entering collecting duct
descending limb
ascending limb
consists of simple squamous epithelium
cubiodial epithelium bc its thicker on that side
classes of nephrons
cortical nephrons
juxtamedullary nephrons
85% of the nephrons in the kidneys. except for small parts of their nephron loops that dip into the outer medulla, located entirely on cortex
near the cortex-medulla junction, ability to produce urine that is concentrated(conserves water)
capillary beds
peritubular capillaries
glomerulus
afferent arterioles
efferent arterioles
from the cortical radiate arteries that run through the renal cortex
feed into either the peritubular capillaries or vasa recta
arise from efferent arterioles, high resistant and low pressure
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urine formation
1)filtration- takes place in bowmans capsule and produces a cell- and protein- free filtrate
2)tubular reabsorption- is the process of selectively moving substances from the filtrate back into blood.
takes place in the renal tubs and collecting ducts
reabsorption reclaims almost everything filtered- all of the glucose and amino acids, and some 99% of the water, salts. anything not reabsorbed is urine
3)tubular secretion- is the process of selectively moving substances from the blood into filtrate.
filtration membrane
3 layers
fenestrated endothelium of the glomerular capillaries
allow all blood components except blood cells to pass through
basement membrane
lies between the other two layers and is composed of their fused basal laminae. it Forsyths a physical barrier that blocks all but smallest proteins while still permitting most other solutes to pass
foot process of podyocytes
have filtration slits between
pressures that affect filtration
outward pressures
promote filtrate formation
hydrostatic pressure in glomerular capillaries
it is the chief force pushing water and solutes out of the blood and across the filtration membrane.
the blood pressure in the glomerulus is extraordinary high (55mm hg compared to and average of 22 mm hg)
as a result filtration occurs along the entire length of each glomerular capillary and reabsorption doesn't occur.
inward pressures
inhibit filtrate formation by opposing HPgc
hydrostatic pressure in the capsular space
pressure exerted by filtrate in the glomerular capsule,HPcs it is much higher than hydrostatic pressure surrounding most capillaries because filtrate is confined in a small space with a narrow outlet
colloid osmotic pressure in glomerular capillaries
exerted by the proteins in the blood that sucks water into the capillaries
Glomerulus filtration rate (GFR)
volume of filtrate formed each min by the combined activity of all million glomeruli pf kidneys
factors;
net filtration pressure - is the main controllable factor.of the pressures determining nfp, the most important is hydrostatic pressure in glomerulus. this is pressure can be controlled by changing the diameter of the afferent arterioles
total surface area available for filtration. glomerular capillaries have a huge surface area. glomerular mesangial cells surrounding these capillaries can fin tune grr by contracting to adjust the total surface area available for filtration.
regulation of glomerular filtration
intrinsic control
extrinsic control
purpose: maintain grr in spit of the change sin the blood pressure
mechanisms: myogenic, tubuloglomerular feedback
operating conditions: mean arterial pressure between 80 and 180mm hg
purpose: maintain systemic blood pressure
mechanisms
hormonal
renin-angiotensin-aldosterone
neural
operating conditions
mean atrial pressure far outside of the normal range
informationa about diseases
Osteoporosis
is a bone disease that occurs when the body loses too much bone, makes too little bone, or both.
As a result, bones become weak and may break from a fall or, in serious cases, from sneezing or minor bumps.
cause of osteoporosis is a lack of certain hormones, particularly estrogen in women and androgen in men.
symptoms
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Back pain, caused by a fractured or collapsed vertebra
Loss of height over time
A stooped posture
A bone that breaks much more easily than expected
Osteoporosis is more common in people who have too much or too little of certain hormones in their bodies.
examples
Sex hormones.
Lowered sex hormone levels tend to weaken bone. The reduction of estrogen levels in women at menopause is one of the strongest risk factors for developing osteoporosis.
veractive parathyroid and adrenal glands.
Thyroid problems.
Too much thyroid hormone can cause bone loss. This can occur if your thyroid is overactive or if you take too much thyroid hormone medication to treat an underactive thyroid.
DM II
causes
develops when the body becomes resistant to insulin or when the pancreas is unable to produce enough insulin.
How insulin works
Insulin is a hormone that comes from the gland situated behind and below the stomach (pancreas).
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The pancreas secretes insulin into the bloodstream.
The insulin circulates, enabling sugar to enter your cells.
Insulin lowers the amount of sugar in your bloodstream.
As your blood sugar level drops, so does the secretion of insulin from your pancreas.
Glucose — a sugar — is a main source of energy for the cells that make up muscles and other tissues.
Glucose comes from two major sources:
liver
food
Sugar is absorbed into the bloodstream, where it enters cells with the help of insulin.
When your glucose levels are low, such as when you haven't eaten in a while, the liver breaks down stored glycogen into glucose to keep your glucose level within a normal range.
Complications
Heart and blood vessel disease.
Kidney damage.
Diabetes dramatically increases the risk of heart disease, stroke, high blood pressure and narrowing of blood vessels (atherosclerosis).
Diabetes can sometimes lead to kidney failure or irreversible end-stage kidney disease, which may require dialysis or a kidney transplant.
Symptoms
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Increased thirst
Frequent urination
Increased hunger
Unintended weight loss
Fatigue
Blurred vision
Slow-healing sores
Frequent infections
Areas of darkened skin, usually in the armpits and neck
starts with low blood pressure causing the juxtaglomerular complex to release renin
activated macula dense cells
sympathetic nervous system
the adrenergic receptors caused the granular cells to be released
low blood pressure or vasoconstriction of the afferent arterioles by the sympathetic nervous system reduces gfr. slowing down filtrate through renal tubules. when the macula cells sense a low NaCl concentration of this sluggishly flowing filtrate.they signal less atp.
steps
transcellular route inovolves:
1) transport across the apical membrane
2) diffusion through cytosol
3)transport across the basolateral membrane
4)movement through the interstitial fluid and into the capillaries
paracellular route involves:
movement through leaky tight junctions, particular in the proximal convoluted tubule
movement through the interstitial fluid and into the capillary.
depending on the substance it can be two ways
active tubular reabsorption
passive reabsorption
requires ATP either directly indirectly
encompasses diffusion, facilitated diffusion and osmosis- processes in which substances move down the electrochemical gradients
reabsorption of sodium
Na + is transported out of the tube cell by primary active transport
1) bulk flow of water sweeps Na into adjacent peritubular capillaries
this bulk flow of water and solutes into the peritubular capillaries is rapid bc the blood there has low hydrostatic pressure and high osmotic pressure
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high blood pressure
DM II
osteoporosis
High Blood Pressure can cause more blood to rush into the kidneys; kidneys usually regulate this function via feedback loop: needs to rid the body of waste = increase blood pressure/flow to kidneys OR lower blood pressure/flow to the kidney’s to reduce water loss.
High blood pressure may be due to the Type II Diabetes; since your body can’t create properly use insulin, your kidneys are trying to get rid of excess sugar via high blood pressure.
What are the effects of high blood pressure on kidneys?
What are the effects of DM II on kidneys?
Over time, uncontrolled high blood pressure can cause arteries around the kidneys to narrow, weaken or harden.
this will cause the damaged arteries to not be able to deliver enough blood to the kidney tissue.
this will also effect the nephrons that filter your blood don’t receive the oxygen and nutrients they need to function well.
Damaged kidney arteries do not filter blood well.
Kidneys have small, finger-like nephrons that filter your blood
Each nephron receives its blood supply through tiny hair-like capillaries, the smallest of all blood vessels.
When the arteries become damaged, the nephrons do not receive the essential oxygen and nutrients — and the kidneys lose their ability to filter blood and regulate the fluid, hormones, acids and salts in the body.
Damaged kidneys fail to regulate blood pressure
Healthy kidneys produce a hormone called aldosterone to help the body regulate blood pressure.
Kidney damage and uncontrolled high blood pressure each contribute to a negative spiral.
As more arteries become blocked and stop functioning, the kidneys eventually fail.
diabetes, the small blood vessels in the body are injured.
your kidneys cannot clean your blood properly.
Your body will retain more water and salt than it should, which can result in weight gain and ankle swelling. You may have protein in your urine.
osteoprosis
hypertension and osteoporosis are a common occurrence. This association may reflect greater calcium losses associated with high blood pressure, which may contribute to the risk of hip fractures.
chronic kidney disease (CKD) could be due to osteoporosis, some form of renal osteodystrophy defined byr chronic kidney disease-mineral and bone disorder
CKD occurs when damaged kidneys and abnormal hormone levels cause calcium and phosphorus levels in a person's blood to be out of balance. Mineral and bone disorder commonly occurs in people with CKD and affects most people with kidney failure receiving dialysis.
.
means your kidneys are damaged and can't filter blood the way they should. The disease is called “chronic” because the damage to your kidneys happens slowly over a long period of time
some kidney diseases that might cause high blood pressure/hypertension
Glomerulonephritis refers to a range of inflammatory kidney conditions of the tiny blood vessels in the kidneys, known as glomeruli.
If the glomeruli become damaged, the kidney can no longer remove waste and excess fluids efficiently. Blood and protein cannot be filtered and are excreted in the urine.
secondary glomerulonephritis is caused by another disease, such as diabetes, lupus, infection, or drug use.
secondary glomerulonephritis
symptoms
blood or protein in the urine
high blood pressure
swollen ankles or face, because of water retention
urinating frequently during the night
bubbles or foam in the urine, caused by excess protein
Treatment
whether the condition is acute or chronic
antibiotics to kill the pathogens causing the infection.
reduce fluid intake and avoid drinks or food containing alcohol or high levels of protein, salt, or potassium.
Diuretics can help reduce hypertension and the slow decline of kidney function, and blood pressure medication relaxes the blood vessels. Corticosteroids and immune-suppressing drugs control inflammation.
Temporary dialysis may be necessary in cases of acute glomerulonephritis. In dialysis, a machine does the kidney’s job of filtering out waste products from the body. Dialysis also helps to control hypertension and to remove surplus fluid.
kidney transplant may be possible if the individual is otherwise health
Glomerulonephritis can lead to hypertension,
heart failure,
Without treatment, the kidneys might fail completely
pulmonary edema
What happens in the nephron when blood pressure rises
arterial pressure increases
nephron reduces sodium and water reabsorption thus increasing sodium and water excretion
to return ECFV and blood pressure to normal; the so called “pressure natriuresis” phenomenon.
kidneys do not function properly extra parathyroid hormone is released in the blood to move calcium from inside the bones into the blood
Chronic kidney disease causes mineral and bone disorder because the kidneys do not properly balance the mineral levels in the body.