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26 Cards in this Set

  • Front
  • Back

Overview of the Role of the Renal System

Overview of Kidney Functions

Renin

-regulation of BP

Erythropoietin

-Regulation of red blood cell production

Internal Anatomy of Kidneys

-Renal cortex


-Renal medulla


-Papilla

Nephrons

- structural and functional units that from urine


- > 1 million per kidney


- tubular structure responsible for filtration


- 2 main parts:


--- renal corpuscle


--- & renal tubule


Renal Corpuscle

2 parts


---Glomerulus


------tuft capillaries; fenestrated endothelium 》highly porous 》allows filtrate formation


---Glomerular Capsule (Bowman's capsule)


------cup shaped, hollow structure surrounding glomerulus

Renal Tubule

Three Parts


1. Proximal convulated tubule


--proximal: closest to renal corpuscle


2. Nephron loop


3. Distal convulated tubule


--distal: farthest from renal corpuscle

Glomerulus

-specialised for filtration


-different from other capillary beds: fed and drained by arteriole


》》Afferent arteriole 》 glomerulus 》efferent arteriole


-BP in glomerulus high because


》》Afferent arterioles larger in diameter than efferent arterioles


》》arterioles are high-resistant vessels

Peritubular capillaries

-low pressure, porous capillaries adapted for absorption of water abd solutes


-arise from efferent arterioles


-cling to adjacent renal tubules in cortex


-empty into venules

Juxtaglomerular Apparatus

-anatomical component of the nephron vitally important in the control of BP and therefore the glomerular filtration rate


-comprised of Juxtaglomerular cells (JGC) and Macula Densa cells

Juxtaglomerular cells

1. Lie within the arteriole wall


2. Detect BP within vessels


3. Secrete renin when activated.

Renin

-an enzyme which aims to control BP via Renin-Angiotensin-Aldosterone System (RAAS system)


------activated when the BP is to low and in turn increases BP which increases filtration in the kidneys

Macula Densa cells

-located in distal tubule


-chemoreceptors; sense NaCl content of filtrate (levels of NaCl)


-------If NaCl levels are to low in the tubes they increase Renin production and blood flow via the afferent arteriole (vasodilation) which increase volume of blood which increase BP which increases level of filtration which increases NaCl

Glomerular filtration

-produced cell and protein free filtrate

Tubular reabsorption

-selectively returns 99% of substances from filtrate to blood in renal tubules and collecting ducts

Tubular secretion

-selectively moves substances from blood to filtrate in renal tubules and collecting ducts


Glomerular Filtration Rate

-GFR directory proportional to hydrostatic pressure in glomerulus


-constant GFR allows kidneys to make filtrate and maintain extracellular homeostasis


-GFR affects systemic BP


---- increase in GFR 》increase in urine output 》decrease in BP, and vice versa

Intrinsic Controls

-maintain GFR in kidney


----vasodilation (macula densa)


----vasoconstriction

Extrinsic controls

-maintain systemic BP


-RAAS system

RAAS System

Renin-Angiotensin-Aldosterone System


Tubular Reabsorption of Filtrate

Urine

-95% water and 5% solutes


-nitrogenous wastes


-----Urea: from amino acid breakdown, largest solute component


-----Uric acid: from nucleic acid metabolism


-----Creatinine: metabolite of creatine phosphate


Other normal solutes


----- Na+, K+, PO4^3-, SO4^2-, Ca2+, Mg2+, HCO3-

Diuretics

-any agent which enhances the flow of urine


-commonly used in treatment of high BP and oedema caused by heart failure, liver cirrhosis and renal failure

Micturation

-or urination/voiding


-three simultaneous events must occur


------contraction of detrusor by ANS


------opening of internal urethral sphincter by ANS (involuntarily)


------opening of external urethral sphincter by somatic nervous system (voluntarily control)

Incontinence

-usually from weakened pelvic muscles



-stress incontinence: increased intra-abdominal pressure forces urine through external sphincter



-overflow incontinence: urine dribbles when bladder overflows



-urinary retention: bladder unable to expel urine, common after general anesthesia, hypertrophy of prostate, treatment: catheterization