Introduction to the Kidney Flashcards
List 4 functions of the kidneys.
- Excretion of metabolic waste and toxins
- Regulation of body fluid volume
- Regulation of body fluid composition
- Endocrine functions
What are the key processes of the kidneys?
- Filtration
- Reabsorption
- Secretion
What are the 5 types of tissue in the human body?
- Blood
- Nervous tissue
- Muscle tissue
- Epithelial tissue
- Connective tissue
What are the components of the uriniferous tubules of the kidney?
Nephron + Collecting duct.
What is a nephron?
The functional unit of the kidney.
How many nephrons are there per kidney?
1 million.
In the kidney are there more nephrons or collecting ducts? How do you know this?
More nephrons, because multiple nephrons drain into the same collecting duct.
Which terms are used to describe the locations of nephrons? What is this dependent on? What percentage of nephrons belong to each group?
- Cortical (80%)
- Juxtamedullary (20%)
Dependent on the position of the renal corpuscle.
What are the 4 components of a nephron?
- Renal corpuscle
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
What are the components of the renal corpuscle?
Glomerulus + Bowman’s capsule.
Describe the arterial supply to the kidney starting from the renal artery.
Renal artery - Segmental arteries - Interlobar arteries - Arcuate arteries - Interlobular arteries.
Describe the location of the Arcuate arteries.
Run along the corticomedullary junction.
What do the interlobular arteries give off and to what?
Give off afferent arterioles to the renal corpuscles.
Describe the two capillary beds of the nephrons in terms of their pressure, location, and function.
- High pressure glomerular capillaries - filtration.
- Low pressure peritubular capillaries - reabsorption / secretion.
What is the function of the outer parietal layer of Bowman’s capsule and what is the epithelium?
Containment - simple squamous.
What is the function of the inner visceral layer of Bowman’s capsule and what is the epithelium?
Filtration - modified simple squamous (Podocytes).
Which cells are found between the glomerular capillary loops and what is their function?
Mesangial cells - provide support.
What makes up the filtration barrier of the glomerulus?
- Glomerular capillary endothelium (fenestrated)
- Basement membrane (negative charge)
- Epithelial cells (podocytes)(interdigitating foot processes & filtration slits)
The glomerular filtration barrier limits the passage of substances based on their what?
Size, charge, and shape.
In nephrons, where does the majority of water, sodium, chloride, amino acids, and glucose reabsorption take place?
Proximal convoluted tubule
What is the epithelium of the Proximal convoluted tubule?
Simple cuboidal with microvilli.
What parts can the Loop of Henle be divided into?
- Thin descending limb
- Thin ascending limb
- Thick ascending limb
Describe the thin descending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.
- Permeable to water
- No active reabsorption or secretion of solutes
- Simple squamous
Describe the thin ascending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.
- Impermeable to water
- Essentially no active reabsorption or secretion of solutes
- Simple squamous
Describe the thick ascending limb of the Loop of Henle in terms of permeability to water, active reabsorption or secretion, and epithelium.
- Impermeable to water
- Active reabsorption of sodium and other solutes
- Simple cuboidal
What is the net effect of the Loop of Henle? What is this important in?
To generate a hyperosmolar interstitium in the medulla, which is important in the concentration of urine.
What is the epithelium of the distal convoluted tubule?
Simple cuboidal
What forms the juxtaglomerular apparatus?
The early part of the distal convoluted tubule passing back to the vascular pole of its own renal corpuscle.
Is there active reabsorption and secretion in the distal convoluted tubule?
Yes
What is the water permeability of the distal convoluted tubule dependent on?
The precise part of the distal tubule and the presence of antidiuretic hormone (ADH).
What are the three components of the Juxtaglomerular Apparatus?
- Macula dense cells
- Extraglomerular mesangial cells (Lacis cells)
- Granular or juxtaglomerular cells in the afferent arteriole
Describe the water permeability of the collecting duct.
It is under hormonal control by antidiuretic hormone (ADH).
Which arteries give off afferent arterioles to the renal corpuscles?
Interlobular arteries
What are the main components of extracellular fluid?
- Interstitial fluid
2. Plasma
The plasma and interstitial fluid have similar compositions apart from what?
Apart from proteins - which remain in the plasma.
What is the main cation and anion in ECF?
- Sodium is the main cation.
- Chloride is the main anion.
What is the main cation and anion in ICF?
- Potassium is the main cation
- Phosphate is the main anion
What is the approximate osmolarity of bodily fluids?
280-300 mOsm/L.
