Anatomy Flashcards
What are the functions of the kidney?
- Excreting waste products & toxins
- Maintaining fluid homeostasis: regulating BP, V & osmolarity
- Balancing electrolytes: Ca, K & Na
- Acid-base balance: blood pH
- Control production of red blood cells through the release of erythropoietin (hormone)
What are the components of the urinary system?
- kidneys
- ureter
- urinary bladder
- urethra
What do the kidneys do?
produce urine
What do the ureters do?
Connect the kidneys to the urinary bladder
What does the urinary bladder do?
Temporarily stores urine prior to elimination
What does the urethra do?
A tube that connects the urinary bladder to the exterior of the body.
- transports semen in males as well
Where are the kidneys located in the body?
On either side of the vertebral column (T12-L3) against the dorsal abdominal wall
Which kidney is lower in position, the right or the left?
The right kidney is lower in position than the left kidney
What is located on the upper surface of the kidneys?
The adrenals glands are located on the upper surface of the kidneys
What surrounds the kidneys and provides cushioning and protection?
The kidneys are embedded in fat (peri-renal fat) which surrounds and provides cushioning & protection
What are the regions of the kidney?
- renal cortex
- renal medulla
- renal pelvis
(slide 6)
What is the lobed structure present in the kidney’s medulla?
the medullary pyramids
Where does urine empty into after passing through the kidney?
Urine empties into the renal pelvis, which is formed by the joining of renal calyces.
What is the central fissure of the kidney called, and what structures enter and leave through it?
The hilum - it is the point of entry & exit for the renal artery and vein, lymphatics, nerves, and the ureter.
What is waste excretion?
Waste excretion is the process of removing waste from the blood while conserving valuable nutrients.
What are the 3 processes of waste excretion?
- filtration
- reabsorption
- secretion
What is filtration in waste excretion?
Filtering out large volumes of serum, including waste products, toxins, nutrients, ions, and water.
What is reabsorption in waste excretion?
Selectively reabsorbing what is needed - e.g. nutrients, water, and ions.
What is secretion in waste excretion?
Specifically secreting unwanted substances - e.g. drugs, toxins, ions, and water
What composition of urine is made up of water?
95% water
What are the nitrogenous by-products from protein metabolism found in urine?
- urea (2%)
- uric acid
- creatinine
What is urobilin and what is its role in urine?
Urobilin is a broken down haemoglobin that gives urine its yellow color
What kind of waste products can be found in urine?
- toxins and drugs
- waste metabolites (e.g., steroids)
- miscellaneous waste (e.g., betalain, which causes beeturia)
What percentage of cardiac output goes through the kidney for filtration?
Approximately 25% of cardiac output goes through the kidney for filtration
How many times is blood filtered in the kidney in a day?
Blood is filtered around 60 times a day in the kidney
What is the pathway of blood supply to the kidney?
renal artery
↓
segmented artery
↓
interlobar arteries (between renal pyramids)
↓
arcuate arteries run across cortico-medullary junction
↓
cortical radiate artery
↓
afferent arterioles
↓
glomerulus (where the filtration occurs)
(slide 10)
What is the pathway of blood drainage from the kidney?
efferent arterioles
↓
cortical radiate vein
↓
arcuate vein
↓
interlobar vein
↓
segmented vein
↓
renal veins
What is a nephron?
A nephron is the basic functional unit of the kidney responsible for filtering blood and producing urine.
What is the nephron composed of?
- capillary portion
- tubular portion
What is the capillary portion of the nephron composed?
- the glomerulus
- peri-tubular capillaries
What is the function of the glomerulus?
The glomerulus is the filter unit of the nephron that is responsible for filtering blood from the afferent arteriole and producing glomerular filtrate.
What is the pressure like in the glomerulus capillaries?
High pressure circuit
How is the glomerulus fed and drained?
- fed by the afferent arteriole
- drained by the efferent arteriole, which has a smaller diameter
What is the function of the peri-tubular capillaries?
The peri-tubular capillaries wrap around the nephron tubule and are adapted for absorption of substances that were not filtered by the glomerulus.
How are the peri-tubular capillaries fed and drained?
- fed from the efferent arterioles
- drain into the renal venous system
How are the peri-tubular capillaries adapted for absorption?
- low pressure
- porous
What does the renal corpuscle consist of?
glomerular (Bowman’s) capsule and glomerulus
What are the tubules of the Nephron structure?
- Proximal Convoluted Tubule (PCT)
- Loop of Henle
- Distal Convoluted Tubule (DCT)
- Collecting duct
What do the tubular functions depend on?
cell type - e.g. how modified epithelial cells
What are the components of the nephron in the cortex?
- glomerulus
- convoluted tubules
What are the components of the nephron in the medulla?
- loop of Henle
- collecting duct
- tubular capillaries
What are the 2 types of nephrons?
- juxtamedullary nephrons (15%)
- cortical nephrons (85%)
What are the characteristics of the juxtamedullary nephrons?
- adapted for water reabsorption
- because of thier long loop of Henle that extends into the medulla
What are the characteristics of the cortical nephrons?
- a shorter loop of Henle
- adapted for the regulation of urine composition rather than volume
- good lymphatic supply
What is the appearance of the kidney cortex?
reddish brown and granular in appearance
What is the appearance of the kidney medulla?
appears striated due to the presence of loops of Henle
How many nephrons are present in the kidney?
1 million nephrons
How many collecting ducts are present in the kidney?
1000s of collecting ducts
What do collecting ducts fuse to form?
Collecting ducts fuse to form ducts of Bellini, which end at the pyramid tip and drain into the calyx.
