Renal System Flashcards
(30 cards)
Excretory system
Removes excess and unnecessary materials from the body fluid pod an organism. Helps maintain internal chemical homeostasis and prevent damage to the body.
Renal system
Organs, tubes, muscles and nerves that work together to create, store and carry urine.
Gets rid of waste products from metabolism (nitrogen-containing compounds like urea) and potentially toxic metabolites.
Waste management — nitrogen containing
- Protein and nucleic acids contain nitrogen - excess nitrogen needs to be excreted.
- Detoxify ammonia by converting it into urea or uric acid. Ammonia is toxic and rises the pH of bodily fluids.
Renal (Urinary) System
- 2 kidneys
- 2 ureters
- 1 urinary bladder
- 1 urethra
The only different between male and female systems is the length of the urethra.
Kidneys
- Bean-shaped and reddish in colour
- Located between the posteriors abdominal wall abdominal wall and parietal peritoneum.
Receive some protection from the lower part of the ribcage.
Renal functions
Regulates
- Blood osmolarity - affected by solute concentration in blood. All animals need to maintain the concentration of water and solutes within a certain range.
- Blood ionic composition. Regulate the blood levels of several ions.
- Blood pH (acid-base balance). Controlling the secretion of hydrogen ions.
Renal functions 2
- Blood volume and blood pressure. Adjust blood volume by conserving or eliminating water in the urine., An increase in blood volume increases blood pressure; a decrease in blood volume decrease blood pressure. (Releasing erythropoietin and renin)
- Blood glucose levels (gluconeogenesis). During prolonged fasting, the kidneys synthesise glucose form non-carbohydrates pre-cursors (amino acids) and release into the blood.
Renal functions
Produces hormones and enzymes
Erythropoietin (hormone)
- Controls red blood cell (erythrocytes) production
-Synthesised in peritubular capillaries which run alongside the nephron and are associated with reabsorption/secretion.
Renin (enzyme)
- Controls formation of angiotensin and influences blood pressure and sodium balance.
Secreted from granular cells in the juxtaglomerular apparatus.
Kidney Internal Anatomy
Renal Cortex
- Outer region, just inside renal capsule. Light red and granular.
Renal Medulla
- Found deep in the cortex; darker, reddish brown cone shaped regions called renal pyramids.
Renal Pelvis
- The area at the centre of the kidney. Urine collects here and is funnelled into the ureter, the tube that connects the kidneys to the bladder.
Kidney Internal Anatomy 2
The Journey:
- Filtrate formed by the nephrons drains into large papillary ducts.
- The ducts drain into cup-like structures called minor and major calyces.
- Minor calyx receives urine from the papillary duct and delivers it to a major calyx.
- Once the filtrate enters the Clyde’s it becomes urine because no further re absorption can occur.
From the major calyces, urine drains into a singe of large cavity called the renal pelvis and then out through the ureter to the urinary bladder.
Blood supply of the Kidney
Receives roughly 20%-25% of the resting cardiac output via renal arteries.
renal artery divides into several segmental arteries. Each one giving off several branches; interlobar arteries, divisions of which are the accurate arteries producing a series of cortical arteries and branches called afferent arterioles.
- Each nephron => 1 afferent arterioles, which divides into a tangles, ball like capillary network called the Glomerulus.
Globular capillaries then reunite to form an efferent arterioles that carries blood out of the glomerulus.
- Glomerular capillaries are unique among capillaries because they are positioned between tow arterioles, rather than between an arterioles and venule.
Basic Renal Functions
- Filtration - Glomerular filtration (ultrafiltrate)
- Secretion - Tubular secretion and remover from the body
- Reabsorption - Tubular reabsorption and retained by the body
Amount of any substance excreted in urine:
- =(amount filtered + amount secreted) - amount reabsorbed.
Where the processes occur
- Glomerular Filtration - the movement of fluid and solutes from the glomerular capillaries into Bowman’s space - filtrate.
- Tubular Secretion - the secretion of solutes from the peritubular capillaries into the tubules
- Tubular Reabsorption - The movement of material from the filtrate in the tubules into the peritubular capillaries.
The nephron
- Smallest functional I=unit of the kidney - one million coiled tubes of epithelial tissue (not constant… number decrease with age)
- Can’t be repaired if damaged, remaining lines must compensate.
- site of blood filtration, reabsorption of substances from this filtrate, addition of substances to this filtrate to make urine.
- Plasma is filtered at the glomerulus into Bowman’s space.
The nephron 2
Functional unit of the kidneys;
- Renal corpuscle, where blood and plasma is filtered. Consists of two components: Glomerulus (capillary network) and glomerular capsule (Bowman’s capsule).
- Renal tubule into which the filtered fluid passes. Consists of three sections: Proximal convoluted tubule (PCT), Nephron loop (loop of Henle), and Distal convoluted tubule (DCT).
Types of nephron
Cortical (80-85%)
- Renal corpuscle (glomerulus + bowman’s capsule) is located in the outer cortex.
Juxtamedullary (15-20%)
- Renal corpuscle loses close to cortical medullary junction.
- Loop of Henle plunges deep into the medulla
- Responsible for generating osmotic gradient responsible for H2O reabsorption.
Renal Corpuscle
Combination of Glomerulus and Bowman’s capsule.
- Endothelia cells lining capillaries are fenestrated.
- Pores - 50-100nm in diameter - “leaky”
- Molecules move into the Bowman’s space
- two factors control movement - molecular size and molecular electrical charge.
Glomerular Filtration
Under normal circumstances, glomerular filtrate has a composition as plasma
Same constituents as plasma in same concentrations
- Except no cells or proteins
Body has no control over what’s is filtered
- **Non-selective
Glomerular Filtration Rate (GFR)
‘Volume of filtrate produced by both kidneys per minute’.
Regulated by:
- Sympathetic nerves - decreases BP stimulates kidney to release Renin (stimulates vasoconstriction) causing an increase BP.
- Renal auto-regulation - the renal system requires a constant BP and therefore flow rate; it is able to mitigate (to some degree) changes in systemic BP.
125ml per minute (men)/ 115 ml per minute (women)
-Roughly equals 180L/day
-Total blood volume 5.5L, filtered every 40 minutes
Tubular Reabsorption
Concerned with conservation of solutes and water.
Can be passive diffusion (concentration gradient - high to low) or active transport (requires the use of energy)
Surface area of tubules increased by microvilli (brush border)
Proximal Convoluted Tubule
- Both urea and water are passivly reabsorbed
- Bicarbonate, chloride, phosphate and sulphate - exchanged for H+ ions. (The pH of ht filtrate.
/blood is maintained.) - Glucose. Amino acids, Na+, K+ etc are actively reabsorbed. Requires energy.
- 65% filtrate reabsorbed by the PCT.
- Independent of the body’s needs
Loop of Henle
’Loop dips down front eh cortex into he deeper tissues of the medulla before loop ping back up into the cortex’s -sets up ‘osmolar gradient between medulla and cortex’
Loop of Henle
Defending limb:
- Highly permeable to water (passivly reabsorbed, aquaporin channels)
- Low ion permeability.
Ascending limb:
- Impermeable to water
- Permeable to ions (medulla is more “salty” due to this)
- Bicarbonate reabsorbed
85% of water and 90% of Na+ and Cl- been reabsorbed. Majority of reabsorption - not influences be bodies needs
Counter Current Multiplier System
Thick ascending limb impermeable to water but Na+ and Cl- ions are actively pumped out into the medulla
Medulla become more concentrated with ion ads you move further down, increasing its osmolarity.
This drives water reabsorption from the descending limb,m as water moves from areas of low osmolarity to areas of high osmolarity.
Allows kidneys to reabsorb 99% of filtered water.
