Excretory System Flashcards
Kidney Structure
- Renal cortex
- Renal medulla
- Renal pelvis
Renal Cortex
- Outer layer
- Filtration
Renal Medulla
- Inner layer
- Has nephrons, collecting ducts that carry to the renal pelvis
Renal Pelvis
- Middle
- Urine accumulates, drains into ureter
Nephrons
Small structures where urine made
Peritubular Capillaries
Surrounds nephrons, reabsorbs imp stuff back into blood
Parts of Nephron
- Glomerulus
- Bowman’s capsule
- Proximal tubule
- Loop of Henle
- Distal tubule
Glomerulus
Thin capillaries, where filtration starts
Bowman’s Capsule
Cup shape to catch the filtered stuff from glomerulus
Proximal Tubule
Leads from Bowman’s capsule to Loop of Henle
Loop of Henle
Connects proximal tubule to distal tubule
Distal Tubule
Connects loop of Henle to collecting duct
Formation of Urine
- Filtration
- Reabsorption
- Secretion
Filtration
- Glomerulus gets blood from arteriole
- H2O & other small molecules diffuse into Bowman’s capsule from the high pressure
- Blood cells stay in the blood vessels & leave kidney
Nephric Filtrate
Filtered substances in the bowman’s capsule (urea, water, ions)
Urea
NH3 (from deamination) + HCO3
Reabsorption
- Nephric Filtrate enters proximal tubule
- Molecules are reabsorbed into peritubular capillaries
- H2O osmosis
- Active transport for sugar, amino acids
- Ion pumps for ions
Loop of Henle in Reabsorption
- Descending: More H2O reabsorbed as Na & Cl C are high around
- Ascending: Na actively transported out, which Cl follows & creates high C for descending
Secretion
- Excess H & K ions secreted in nephron which is added into nephric fluid
- If pH is too acidic, more H ions into urine
Nephric Filtrate turns into Urine
Multiple nephrons attach to collecting ducts move fluid from cortex to medulla, to pelvis = urine
Urine Pathway
Urine, Bladder, Urethra
Antidiuretic (ADH)
- Secreted by pituitary, controlled by hypothalamus
- ADH increases permeability, allows more H2O to be reabsorbed
As ADH decreases
- Body releases more H2O
- Urine vol increases
As ADH increases
- Body retains more H2O
- Urine vol decreases
Diuretics
Caffeine, alcohol block ADH, increasing vol of urine
