Chapter 26 - Urinary System Flashcards
What are the 8 major functions of the kidneys?
- Regulation of blood ionic composition
- Regulation of blood pH
- Regulation of blood volume
- Regulation of blood pressure
- Maintenance of blood osmolarity
- Production of hormones
- Regulation of blood glucose level
- Excretion of wastes and foreign substances
Where are the kidneys located?
Between the levels of the last thoracic and third lumbar vertebrae
- partially protected by 11th and 12th ribs
What is the renal hilum?
Indentation near the center of the concave border
- ureter emerges from the kidney along with blood vessels, lymphatic vessels and nerves
What are the three layers of the kidney?
- Renal capsule
- Adipose capsule
- Renal fascia
What is the renal capsule?
What is it’s function?
Deepest layer of the kidney
- serves as a barrier against trauma and helps maintain the shape of the kidney
What is the adipose capsule?
What is it’s function?
Middle layer of the kidney
- protects the kidney from trauma and holds it firmly in place
What is the renal fascia?
What is it’s function?
Superficial layer of the kidney
- Anchors the kidney to the surrounding structures and to the abdominal wall
What are the two distinct regions of the kidneys?
- Renal cortex
2. Renal Medulla
What is the renal cortex?
Superficial region of the kidney
- light red area
What is the renal medulla?
Inner region of the kidney
- deep, darker, reddish-brown
What does the renal medulla consist of?
Several cone-shaped renal pyramids
What is the renal papilla?
The apex (pointy end) of the renal pyramids - points towards the renal hilum
What are renal columns?
Portions of the renal cortex that extend between renal pyramids
What constitutes the parenchyma?
The renal cortex and renal pyramids (of the renal medulla)
- it is the functional portion of the kidney
What is a nephron?
What does it form?
Functional units of the kidneys
- forms filtrate (filtered fluid)
What do nephrons drain into?
Papillary ducts
- extend through the renal papillae of the pyramids
What do the papillary ducts drain into?
Minor and major calyces
- cuplike structures
- each kidney has 8-18 minor and 2-3 major
Which calyx (major and minor) drains into the other?
Minor calyces drain into major calyces
From the maor calyces, where does urine drain into?
A single large cavity
- renal pelvis
How do the kidneys receive blood?
Through the renal arteries
What is the function of afferent arterioles?
Supply the nephrons with blood
- 1 nephron receives 1 afferent arteriole
- carries blood TOWARDS the glomerulus
What is the glomerulus?
Tangles, ball-shaped capillary network of the kidneys
- afferent arteriole branch into glomerulus
What is the function of the efferent arterioles?
Form from a convergence of the capillaries of the glomerulus
-carry blood AWAY from the glomerulus
What do efferent arterioles divide to form?
Peritubular capillaries
- surround tubular parts of the nephron in the renal cortex
What are vasa recta?
Long, looped-shaped capillaries extending from some efferent arterioles
- supply tubular portions of the nephron in the renal medulla
- around loop of Henle
What is the function of the renal vein?
Carries blood away from the kidneys
- carries blood to inferior vena cava
What is the path of urine drainage?
- Collecting duct
- Minor calyx
- Major calyx
- Renal pelvis
- Ureter
- Urinary bladder
What are the two parts of the nephron?
- Renal corpuscle
2. Renal tubule
What is the purpose of the renal corpuscle?
Filters blood plasma
- part of a nephron in the kidney
What is the purpose of the renal tubule?
Passes filtered fluid
- part of a nephron in the kidney
What are the two components of the renal corpuscle?
- Glomerulus (the capillary network)
2. Glomerular (Bowman’s capsule)
What is the glomerular (Bowman’s capsule)?
A capsule-shaped membranous structure surrounding the glomerulus of each nephron in the kidneys
- extracts wastes, excess salts, and water from the blood.
What does the renal tubule consist of?
- Proximal convoluted tubule (PCT)
- Loop of Henle (nephron loop)
- Distal convoluted tubule (DCT)
What do the distal convoluted tubules of several nephrons empty into?
A single collecting duct
What do collecting ducts converge and unite into?
Papillary ducts
What do papillary ducts drain into?
Minor calyces
What is the pathway of fluid flow through a nephron?
- Glomerular (Bowman’s) capsule
- Proximal convoluted tubule
- Descending limb of the loop of henle
- Thin ascending limb of the loop of Henle
- Thick ascending limb of the loop of Henle
- Distal convoluted tubule
- -> drains into collecting duct
What are cortical nephrons?
- renal corpuscles lie in the outer portion of the renal cortex
- SHORT loops of Henle in the cortex, barely penetrate the renal medulla
What are juxtamedullary nephrons?
- renal corpuscles lie deep in the cortex
- LONG loops of Henle, extend DEEP into the medulla
What do nephrons with long loops of Henle enable the kidneys to do?
Excrete very dilute or very concentrated urine
In which nephron does the loop of Henele consist of two parts (thick and thin)?
Juxtamedullary nephrons
What are podocytes?
Simple squamous epithelial cells of the glomerular capsule
What is the capsular (Bowman’s) space?
Space between the visceral and parietal layers of the glomerular capsule
- the lumen of the urinary tubule
What is the macula densa?
An area of closely packed specialized cells lining the wall of the cortical thick ascending limb
-at the transition to the distal convoluted tubule.
What is the function of juxtaglomerular cells (JG)?
Where are they located?
Helps regulate blood pressure within the kidneys
- located alongside the macula densa
What do principal cells have receptors for?
Where are principal cells located?
Anti-diuretic hormone (ADH) and aldosterone
- located in the last part of the distal convoluted tube
What is the function of intercalated cells?
Play a role in homeostasis of blood pH
In order to produce urine, nephrons and collecting ducts must perform what three basic processes?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
What is glomerular filtration?
First step in urine production
- water and most solutes in blood plasma are filtered in glomerular capillaries, move into glomerular capsule and then into renal tubule
What happens during tubular reabsorption?
As filtered fluid flows through the renal tubules, 99% is re-absorbed
How does re-absorbed water and solutes re-enter the blood?
Through peritubular capillaries and vasa recta
What happens during tubular secretion?
As filtered fluid flows through the renal tubules and collecting ducts, materials (wastes, drugs, excess ions) are secreted into the fluid
What is the difference between tubular reabsorption and tubular secretion?
Reabsorption = returns substances to the bloodstream Secretion = Removes a substance from the blood
What is glomerular filtrate?
Fluid that enters the capsular space