L16 - urinary system Flashcards
The principal role of the kidneys is to control the levels of body constituents and metabolic waste products. This requires the kidneys ‘to filter’, actually 3 processes:
filtration,
reabsorption and secretion from the plasma
and excrete the excess essential body constituents and metabolic waste products.
Nerki odpowiedzialne są za regulacje (5):
blood ionic composition, blood pH blood volume blood pressure blood glucose level
Kidneys are responsible for production, maintenance and excretion of (3):
- Production of hormones (calcitrol and erythropoietin)
- Maintenance of blood osmolarity
- Excretion of wastes from metabolic reactions and foreign substances (drugs or toxins)
• Although kidneys constitute less than … of total body mass, they receive …. of resting cardiac output
0.5%,20-25%
• Each nephron receives …
one afferent arteriole
Renal nerves are part of …..nervous system
• Most are …. regulating …
the sympathetic autonomicvasomotor nerves blood flow
Nephrons consist of (2):
Renal corpuscle – filters blood plasma
Renal tubule – filtered fluid passes into its components
Renal corpuscle – filters blood plasma (2):
- Glomerulus – capillary network
* Glomerular (Bowman’s) capsule – double-walled cup surrounding glomerulus
Renal tubule – filtered fluid passes into (3):
- Proximal convoluted tubule
- Descending and ascending loop of Henle (nephron loop)
- Distal convoluted tubule
• Cortical nephrons – …. of nephrons
80-85%
Cortical nephrons (opisz renal corpuscle):
• Renal corpuscle in outer portion of cortex and short loops of Henle extend only into outer region of medulla
• Juxtamedullary nephrons – … of nephrons
20-25%
Juxtamedullary nephrons (opisz renal corpuscle):
- Renal corpuscle deep in cortex and long loops of Henle extend deep into medulla
- Receive blood from peritubular capillaries and vasa recta
- Ascending limb has thick and thin regions
- Enable kidney to secrete very dilute or very concentrated urine
Opisz Glomerular (Bowman’s) capsule (3)
- Visceral layer
- Parietal layer
- Fluid filtered from glomerular capillaries
(Glometular (Bowman’s) capsule) Visceral layer has…
has podocytes that wrap projections around single layer of endothelial cells of glomerular capillaries and form inner wall of capsule
(Glometular (Bowman’s) capsule) Parietal layer forms ….
forms outer wall of capsule
(Glometular (Bowman’s) capsule) Fluid filtered from glomerular capillaries enters …
enters capsular (Bowman’s) space
Proximal convoluted tubule cells have …, which …
microvilli with brush border, increases surface area
Juxtaglomerular apparatus składa się z (2):
Macula densa, Juxtaglomerular cells
Juxtaglomerular apparatus helps….. in kidney
regulate blood pressure
Macula densa –
cells in final part of ascending loop of Henle
Juxtaglomerular cells –
cells of afferent and efferentarterioles contain modified smooth muscle fibers
Parts of distal convoluted tubule and collecting duct (3)
- Proximal convoluted tubule cells
- Juxtaglomerular apparatus (Macula densa, Juxtaglomerular cells)
- Last part of distal convoluted tubule andcollecting duct (Principal cells, Intercalated cells)
Last part of distal convoluted tubule andcollecting duct składa się z (2):
- Principal cells – receptors for antidiuretic hormone(ADH) and aldosterone
- Intercalated cells – role in blood pH homeostasis
Opisz Glomerular filtration:
Water and most solutes in blood plasma move across the glomerular capillaries wall into the glomerular capsule and then the tubule
Opisz Tubular reabsorption:
As filtered fluid moves along tubule and through collecting duct, about 99% of water and many useful solutes reabsorbed – returned to blood
Opisz Tubular secretion:
As filtered fluid moves along tubule and through collecting duct, other material secreted into fluid such as wastes, drugs, and excess ions – removessubstances from blood
Renal Blood flow determines….
glomerular filtration rate (GFR).
The most common cause of renal failure is …
Reduction of renal blood flow
total blood flow [i.e. to both kidneys] is…. l/minthat’s …. resting cardiac output
1.25, 25%
renal blood flow remains constant if arterial BP (blood pressure) is altered [between…..mmHg]
80-200
Renal blood flow remains constant even when renal nerves are cut (therefore intrinsic control). What are the mechanisms of auto regulation?
- Myogenic hypothesis
- Tubuloglomerular hypothesis
- Metabolic hypothesis
Renal blood flow is autoregulated by varying RVR, i.e. + rozwinięcie skrótu
renal vascular resistance, i.e. the resistances of the afferent and efferent arterioles.
Myogenic Hypothesis (7):
Response of renal afferent arterioles to stretch
- Increase in perfusion pressure
- Distension of afferent arteriole wall
- Smooth muscle fibres stretch
- Smooth muscle fibres then contract [vasoconstriction]
- Increases vascular resistance
- Decreases blood flow
- Smooth muscle relaxes
Tubuloglomerular Hypothesis (4):
- GFR is originally increased if renal perfusion pressure is raised.
- In consequence filtrate flow rate through the nephron increases.
- The raised flow causes a factor to be released from the juxta-glomerular apparatus (renin?).
- This increases afferent arteriolar resistance. Flow and therefore GFR are normalised
Metabolic hypothesis (4):
Renal tissue metabolites maintain a degree of vasodilation
- Increase in perfusion pressure.
- Increase in blood flow.
- Leaching out of metabolites from renal tissue.
- Decrease in vasodilation (vasoconstriction).Humoral factors derived from vascular endothelium i.e. NO may act as vasodilators.
How else is renal blood flow controlled? (extrinsic factors) (2)
- Renal nerves (sympathetic and parasympathetic)
- Humoral factors in the blood- adrenaline/noradrenaline = vasoconstriction (in cortex)- vasopressin = vasoconstriction (next lecture)
renal blood flow control extrinsic factor: Renal nerves (sympathetic and parasympathetic) (2):
- sympathetic stimulation = vasoconstriction of afferentarterioles- parasympathetic = vasodilation
renal blood flow control extrinsic factor: Humoral factors in the blood (2):
- adrenaline/noradrenaline = vasoconstriction (in cortex)- vasopressin = vasoconstriction
