Excretory System Flashcards
What are the five functions of the excretory system?
- Urine production
- Acid-base balancing
- Water balancing
- Salt balancing
- Hormone production
What are the two components of a renal corpuscle?
- Bowman’s capsule
- Glomerulus (capillaries)
What is the most basic, functional unit of a kidney?
Nephron
What are the six components of a nephron? (list in order of filtrate flow)
- Renal corpuscle (glomerulus and Bowman’s capsule)
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting tubule
- Collecting duct
What is the region of the kidney where nerves enter, the ureter exits, blood and lymph vessels enter and exit called?
The hilum
Within the hilum of the kidney, the upper end of the ureter expands as the ____ and divides into 2/3 major ____, which branch into minor ____. The area surrounding is rich in adipose tissue.
Within the hilum of the kidney, the upper end of the ureter expands as the renal pelvis and divides into 2/3 major calyces, which branch into minor calyces. The area surrounding is rich in adipose tissue.
What are the conical structures in the renal medulla called? What separates them?
Renal pyramids separated by renal columns
What are the two parts of a distal tubule?
A thick straight part ascending from loop of Henle and a convoluted part completely in the cortex
What are the two limbs of the loop of Henle?
A thin descending and a thin ascending limb
What are the two parts of a proximal tubule?
A convoluted part entirely in the cortex and a long straight part that enters the medulla
Collecting ducts converge in ____ where they deliver urine to a minor calyx.
renal papilla
Blood enters glomeruli via ____ arterioles and leaves via ____ arterioles
Blood enters glomeruli via afferent arterioles and leaves via efferent arterioles
What are the three main renal functions and where do they happen?
- Filtration (water and solutes enter lumen of the nephron)
- Tubular secretion (substances move from epithelia of tubules into lumens)
- Tubular reabsorption (substances move from lumen, across epithelia into the interstitium and surrounding capillaries)
What are the two layers of Bowman’s capsule?
- Visceral layer (closely envelopes glomerular capillaries)
- Parietal layer (forms surface of the capsule)
Where is the urinary space? What does it receive?
Between the two layers of Bowman’s capsule
Receives filtrate from the capillary wall and visceral layer
What are the two poles of renal corpuscles?
- Vascular pole (afferent and efferent arterioles)
- Tubular pole (proximal convoluted tubule begins)
How does epithelium change from the parietal layer of Bowman’s capsule to the tubular pole and proximal convoluted tubule?
simple squamous epithelium to simple cuboidal epithelium (which forms rest of PCT)
What type of cells form the visceral layer of Bowman’s capsule? What type of processes do these have?
Podocytes
With primary processes that give rise to pedicels (which come in direct contact with the basal lamina)
What are slit pores? What bridges these?
The filtration pores between interdigitating pedicels of podocytes on glomerular capillaries. These are bridges by slit diaphragms, which are modifie tight junctions.
Are the glomerular capillaries fenestrated?
Yes
What most separates blood from the urinary space and lies between podocytes and the highly fenestrated endothelial cells of glomerular capillaries?
The glomerular basement membrane (GBM)
What are the three layers of filtration in renal corpuscles?
- Capillary fenestrations (restrict blood cells and platelets)
- Glomerular basement membrane (restricts large proteins)
- The filtration slit diaphragms between pedicels (restricts some small proteins)
What type of epithelium constitutes the thin limbs of the loop of Henle?
Simple squamous epithelium
What type of epithelium constitutes the thick ascending limb of the loop of Henle?
Simple cuboidal epithelium
Does the proximal convoluted tubule have microvilli?
Yes (brush border)
What type of epithelium constitutes the distal convoluted tubule?
Simple cuboidal, smaller cells than in PCT and no brush border
Where does most reabsorption of water, organic nutrients and proteins take place in the nephron?
Proximal convoluted tubule
What type of epithelium constitute the collecting system of a nephron?
Cuboidal to low columnar with distinct cell membranes
Antidiuretic hormone from the pituitary influences the body to retain more water, what renal structure does it affect?
Affects water permeability at the collecting ducts
What are the three transitional epithelium layers that compose the bladder walls?
- Small basal cells resting on very thin basement membrane
- Intermediate region containing one to several layers of cuboidal/columnar cells
- Umbrella cells at the luminal surface, differentiated to protect against hypertonic urine, sometimes bi or multinucleated
Which kidney sits lower in the body? Why?
The right kidney, because of the liver
What is the main driver of migration of materials out of glomerular capillaries and into the urinary space?
The pressure in the capillaries is slightly higher than in the urinary space
What creates an osmolarity gradient across the renal medulla and cortex? What is this gradient?
The loop of Henle
Osmolarity increases from cortex to medulla
How are ions pumped against their concentration gradient in the ascending segment of the loop of Henle?
Ion pumps
What two hormones affects the distal convoluted tubule? How?
Aldosterone causes Na pumps to pump more Na (reclaims more sodium to blood)
Antidiuretic hormone changes water permeability of DCT
What is the wall structure of the ureter?
- Mucosa (transitional)
- Muscularis
- Adventitia (loose connective tissue)
Why is mucosa of the ureter constantly dividing? What layer supports this?
Because urine is harmful to cells
Loose connective tissue of lamina propria supports the dividing mucosa
How many layers of smooth muscle in the bladder? What is the constitution of these layers?
3 layers
Mostly smooth muscle with some skeletal mixed in
