Renal system- Kidneys Flashcards
What are some diseases that could be associated with oral health issues?
cardiovascular
rheumatoid arthritis
respiratory diseases
metabolic disease
kidney disease
Kidneys are excretory organs that do what?
process blood and rid the body of the waste products of metabolism via urine
what is the kidneys main function?
maintain internal homeostasis of fluid- fluid, electrolytes (blood pressure)
acid/base- blood ph, calcium/ vitamin D, erythropoietin
Describe the broad urinary system
two kidneys- produce urines
ureters- convey urine
bladder-stored
urethra- void urine
Do the kidneys lie behind or infront of the peritoneal cavity?
behind
What are the three distinct parts of the kindey?
cortex, medulla, pelvis
Describe the cortex part of the kidney
contains 85% of all kidney tubules (nephrons)
Describe the medulla part of the kidney
the site where urine is concentrates
prevents excess water loss
describe the pelvis part of the kidney
collection area for urine which is funnelled into the ureter
Are kidneys vascular?
highly vascular
describe basic blood supply to kidneys
renal artery delivers blood from abdominal aorta
How many litres of blood is processed per minute?
1.2 litres blood per minute (1/5 cardiac output)
Describe the blood vessels of the kidney
afferent arteriols deliver blood to glomerural capillaries and then to the efferent arteriols and to the peritubular capillaries
What is the site of blood filtration?
glomerular capillaries
What is the part of the kidney which is responsible for oxygen and nutrient delivery?
Peritubular capillaries
What is the nephron?
is the basic functional unit of kidney, optimally evolved to filter blood plasma and excrete waste products of metabolism in urine.
What are the two types of nephrons
cortical- located in cortex and juxtamedullary- located in medulla nephrons
What allows juxtamedullary nephrons to be good at filtration?
large loops of henry
describe the basic structure of nephrons
glomerulus— Bowmans capsule ( both these are involved in filtration)—– Proximal convoluted tubule— loop of Henle– distal convoluted tubule— collecting duct ( reabsorption and secretion)
Describe the Glomerulus
a network of fine capillaries, a single layre of endothelial cell resting on a basement membrane
fenestrated.
What is a function of the glomerous?
enables rapid filtration of blood plasma, surrounded by bowmans capsule
Describe the bowmans capsule
A cuplike structure surrounding the glomerulus, the outer/ parietial layer.
Has visceral layer comprised of special epithelium- podcytes
What are the glomerulus and Bowmans capsule known as together?
renal corpuscle
What forms the filtration barrier?
The glomerular, endothelium, basement membrane and pedicles
this is freely permeable to water and smaller molecules
What is the first step in blood processing?
Glomerular filtration
Describe glomerular filtration
- unfiltered blood arives at the glomerulus via the affarent arteriol
- blood components filtered through filtration barrier
- filtered blood exits the glomerulus via the efferent arteriol
What is filtration facilitated by?
pressure gradient
What is filtered in the glomerulus?
water, glucose, amino acids, urea creatinine, sodium, chlorine, calcium, phosphate, potassium, bicarbonate
What is not filtered by the glomerulous?
Cells, large proteins, negatibely charged proteins
What is the Glomerular filtration rate (GFR)
The rate at which blood is filtered through the glomerulus into the Bowman’s capsule
Primarily driven by glomerular hydrostatic pressure
Counteracted by hydrostatic pressure in the Bowman’s capsule
Counteracted by glomerular osmotic pressure
What is a healthy/ or normal GFR?
125ml/min
180l/day
What is GFR influenced by?
Hydrostatic pressure
osmotic pressure
systemic blood pressure
systemic blood pressure
renin-angiotensin system
disease
What happens to GFR with kidney damage?
reduces GFR- ineffiecent blood clearance and waste removal
waste can accumulate in blood
How much filtration is reabsorbed?
99%
What is the early form of urine called?
filtrate
What does the renal tubule do?
reabsorption and secretion
What is the primary site or reabsorption?
proximal convolute tubule
what is found on the proximal convoluted tubule to help aid absorption?
miicrovilli
What are all portions of the nephrons closely associated with?
the peritubular capillaries( vasa Recta)
Describe passive diffusion and where is it used?
movement of molecules from high to low concentration until equilibrium is reached- needs pours and passenger proteins
tubule lumen—– peritubular capillary
What does water move from tubule lumen move to peritubular capillaries by?
aquaporins
How do glucose and amino acids move across the apical surface?
via sodium co-transporters
how much filtrate remains in tubule?
50%
50% filtrate reabsorbed into blood
describe sodium potassium pumps
Uses 1 x ATP to move 3 x Na+ out of cell in exchange for 2 x K+ into cell
Na+ moves against its concentration gradient
Everything (almost) follows Na+
Water follows Na+ wherever it goes - osmosis
Glucose and amino acids co-transported with Na+
Chloride and negative ions follows Na+
How much Na+ reabsorption is facilitated by the basolateral membrane?
65%
How are negative ions such as chlorine moved across the basolateral surface?
electrical gradient created by reabsorption of sodium
Describe sections of the loop of Henle
Thin descending limb, thin ascending limb, thick ascending limb
Describe the loop rules in the thin decending limbs
contains aquaporins
freely permeable to water
does not contain active sodium pumps
Describe the loop rules that occurs to thick and thin ascending limbs
does not contain aquaporins
impermeable to water
what is the main site for diuretic drugs such as furosemide?
NKCC2 pump on apical membrane
What conditions are created in the medulla as sodium is actively reabsorbed from the filtrate?
salty
thick ascending limb site of active sodium reabsoption, thick and thin limbs impermeable to water
What happens to the water in the filtrate as it enters the Loop of Henle?
salty
again impermeable to water
how does water flow out of tubule?
osmosis
What happens to the concentration of the filtrate as it descends the thin ascending limb?
becomes much more concentrated.
What happens to the concentration of the filtrate as it ascends the thick ascending limb?
concentration of filtrate will decrease as no more of water can leave, sodium is pumped out so filtrate conc decreases
counter current multiplication
Where does the reabsorbed water (and salt) go?
retains water through the salt
go back into blood stream via vesa recta
What helps to maintain the osmotic gradient of the medulla?
Vesa Recta counter current exchange
at the bottom it’s salty
Where is some salt and water reabsorbed and put back into the blood
Vesa recta
What is the part of the nephron that the filtrate will flow through after the loop of henle?
distal convoluted tubule
In the distal convoluted tubule sodium and water reabsorption is regulated by what?
hormones
What is the fine turning distal convoluted tubule a site of?
site of fluid volume and electrolyte regulation
tubule fluid entering the distal tubule is hypotonic compared with the……..
interstitium
In the absence of external hormonal regulation what happens?
large volume of dilute urine is produced
What does ADH act on?
distal and collecting tubules causing insersion of aquaporins allowing water to be reabsorbed from filtrate
What happens when aldosterone hormone is released?
Aldosterone acts on distal and collecting tubulesUpregulates activity and insertion of Na+K+ pumps and channels
sodium leaves and water follows
aldosetrone hormone can directly diffuse across the membrane and into the nucleus allowing transcription of sodium channels how is this?
its a steroid hormone
ANP acts on decreased blood pressure how does it return it to normal?
produces ANP conteracts effects of ADH and aldosterone, lowers fluid levels, salt and water is retained in tubule and secreted from body.
what hormones act distally to ‘fine tune’ the filtrate?
ADH and Aldosterone
out of 180 litres filtered per day how much is excreted as urine?
only 1-2%
Which of the following is the primary force that drives glomerular filtration?
Glomerular hydrostatic pressure
What substance is typically measured to give an indication of the glomerular filtration rate?
Creatinine
The kidney uses sodium handling in various different ways to support reabsorption of a large volume of filtrate. In which section of the kidney is the majority of sodium reabsorbed?
Proximal covoluted tubule
What is regulated in the distal convoluted tubule?
composition of filtrate is hormonally regulated
What does ANP (atrialnulirtpeptide) do in the distal convoluted tubule?
inhibits the actions of both aldesterone and ADH and by inhibiting it leads to removal of aquaporins and sodium channels and so salt and fluid remains in filtrate and ultimatley will be excreted in the urine and dilute urine is produced
What signals causes release of ADH and Aldosterone
changes in blood pressure
fall in blood pressure - release of ADH and Aldosterone
How do Kidneys measure and respond to changes in blood pressure?
What is the Glomerular Filtration Rate?
The rate at which blood is filtered through the glomerulus and into the Bowmans Capsule
What can influence GFR
Glomerular Hydrostatic pressure- blood arrives quicker than it can leave generating pressure pushing filtrate through to BC
Caspular hydrostatic pressure
Glomerular Osmotic Pressure
systemic blood pressure
disease
in the convulated tubule how much of the sodium is reabsorbed?
60%
How much sodium is reabsorbed in the loop of Henle?
20% from thickest end
In the distal convulated tubule how much sodium is absorbed?
can be up to 8%
What does the Juxta-glomerular apparatus connect?
connects the distal convoluted tubule with the glomerulus
What is the function of the Juxta-glomerular apparatus?
measure and responds to changes in NA+ conc of the filtrate
What are the specialed cells that detect sodium conc in the juxta-glomerular apparatus called?
macula densa
What are the three main cell types found in the Juxta-glomerular apparatus?
Macula densa
juxtaglomerular cells- when to vasodilate and constrict
mesangial cells- support
When the afferent arteriole constricts what happens to the glomerular hydrostatic pressure?
it decreases
What is tubuloglomerular feedback?
a process by which the diameter of the afferent arteriole is maintained to help keep homeostasis and protect kidneys from fluctuations in blood pressure
With a fall in blood pressure and eventually a decrease in Na+ filtrate conc what does the Macula Densa release?
prostaglandins
When macula densa cells release prostaglandins due to fall in bp what do they signal to juxtaglomerular cells?
to vasodilate- they are already vasodilated so they release renin to activate the renin angiotensin system
How does the angiotensinogen-system restore blood pressure via angiotensin ii
Angiotensinogen released into circulation
Renin converts angiotensinogen into Angiotensin I
Angiotensinogen converting enzyme coverts angiotensin I into angiotensin II
Angiotensin II potent vasoconstrictor – rapidly increases blood pressure
what produces angiotensin
liver
Where can angiotensin 2 bind to target receptors?
Angiotensin II binds target receptors on:
Arterioles - constriction
Hypothalamus- thirst
Pituitary gland – release of ADH
Adrenal medulla- release of aldosterone
Restores blood volume via increased fluid and salt retention
What does ANP conteract?
RAAS
when baroreceptors detect rise in blood pressure what is released?
atrial natriuretic peptide
What are consequences of chronic kidney disease (and GFR)?
inadequate removal of fluid and waste products of metabolism
inappropriate activation of RAAS, high BP
What are some causes of CKD?
Hypertension
Diabetes
High Cholesterol
Kidney Infections
Glomerulonephritis
Polycystic kidney disease
Kidney stones
Long-term use of NSAIDS
What are symptoms of CKD?
Hypertension
Nausea
Oedema
ankles, hands or feet
lungs
Blood/protein in urine
Anaemia
Weak/painful bones
How can CKD be regulated?
diet- reduced salt intake/ weight loss
combination of anti-hypertensive treatments
Diuretics(furosemide)
ACE inhibitors/ angiotensin receptor blockers
Aldosterone agonists
How does furosemide have on reabsorption?
Describe Stage five kidney disease
less than 25% kidney function
dialysis- needs kidney transplant
end stage
What are the 2 types of dialysis?
heamodyalisis- diverting blood from the body into dialysis machine that cleans blood
peritoneal dialysis involves using the peritoneal membrane in abdomen as filter, dialysis fluid pumped into belly excess solutes are filtered there before being removed
