How do we get rid of toxic waste? Flashcards
Where do the kidneys lie and why does the right kidney lie lower than the left?
- The kidneys lie behind the parietal peritoneum on the posterior abdominal wall on either side of vertebral column.
- Right kidney slightly lower than left (due to liver).
- Lumbar vertebrae and rib cage partially protect the kidneys.
- Bean shaped and about the size of a fist (~130g).
What is the renal capsule, adipose tissue and renal fascia?
- Renal capsule: fibrous connective tissue surrounding each kidney.
- Adipose tissue: engulfs renal capsule and acts as cushioning.
- Renal fascia: thin layer loose connective tissue, which anchors kidneys to posterior abdominal wall.
What is the Hilum, Ureter, Cortex & Renal columns?
- Hilum: Renal artery and nerves enter and renal vein and ureter exit.
- Hilum opens into renal sinus: cavity filled with fat and loose connective tissue.
- Ureter: exits at the hilum; connects to urinary bladder.
- Cortex: outer area.
- Renal columns: part of cortical tissue that extends into medulla.
What is the Medulla, Renal Pyramids, Minor Calyces, Major Calyces & Pelvis?
- Medulla: inner area, surrounds renal sinus.
- Renal pyramids: cone shaped. Base is boundary between cortex and medulla.
- Apex of pyramid is renal papilla, points toward sinus.
- Minor Calyces: funnel shaped chambers into which papillae extend.
- Major Calyces: converge to form the renal pelvis.
- Pelvis: enlarged chamber formed by major calyces.
What is the Nephron, what are the parts and why does the blood enter the nephron?
- Functional unit of the kidney
- Parts of the nephron: renal corpuscle, proximal tubule, loop of Henle, distal tubule.
- Blood enters the nephron for filtration. Filtrate/urine produced.
- Urine continues from the nephron to papillary ducts, minor calyces, major calyces, renal pelvis and ureter.
What are the types of neurons?
-1.3 million nephrons in each kidney and range from 50-55mm in length.
o Juxtamedullary nephrons: The renal corpuscle located near the medulla. Long Loops of Henle which extend deep into the medulla (15%).
o Cortical nephrons: Renal corpuscle located nearer to the periphery of the cortex. Loops of Henle do not extend deep into the medulla (85%).
What is the Bowmans capsule, What is the glomerulus & what does blood/fluid enter
- Bowman’s capsule: enlarged end of the nephron, double walled chamber. Filters the blood/fluid which then enters the proximal convoluted tubule.
- Glomerulus: network/ball of capillaries.
- Blood/fluid enters the glomerulus through afferent arteriole, exits through efferent arteriole.
- Note the size difference Afferent is bigger than efferent = PRESSURE
What is a parietal & visceral layer in bowmans capsule?
- Parietal layer: Outer layer. Simple squamous epithelium – becomes cuboidal in PCT.
- Visceral layer: Inner layer. Specialised podocytes that wrap around the glomerular capillaries.
What is fenestrae, filtration slips, basement membrane & what occurs here?
- Fenestrae: window-like openings in the endothelial cells of the glomerular capillaries.
- Filtrations slits: gaps between podocytes.
- Basement membrane: sandwiched between the endothelial cells of the glomerular capillaries and the podocytes.
- Filtration occurs here.
What is proximal convoluted tubule, loop of henle, distal convoluted tubule & collecting duct?
- Proximal convoluted tubule: filtrate drains from the Bowman’s capsule into the PCT.
- Loop of Henle (nephron loop): each loop has a descending and ascending limb.
- Distal convoluted tubule: shorter than PCT
- Collecting ducts: large diameter. Extend through medulla towards renal papilla → ureter.
In terms of the histology what is the proximal tubule, loop of henle, distal tubule & collecting ducts?
- Proximal tubule: Simple cuboidal epithelium with many microvilli. Active reabsorption of Na+2, K+ & Cl
- Loop of Henle: Thick parts - simple cuboidal. Thin parts - simple squamous epithelium – for osmosis/diffusion.
- Distal tubule: Simple cuboidal, and very few microvilli. Numerous mitochondria.
- Collecting ducts: Larger in diameter, simple cuboidal epithelium.
In urine movement what forces urine through the nephron?
-Pressure forces urine through nephron
What moves urine from renal pelvis to kidneys, through what and what do the ureters enter the bladder through?
- Smooth muscle in ureters: Peristalsis moves urine from the renal pelvis in the kidneys through the ureters to the urinary bladder.
- Ureters enter bladder obliquely through trigone. Pressure in bladder compresses ureter and prevents backflow
What do the ureters do and what are they lined with?
-Bring urine from renal pelvis to urinary bladder. Lined by transitional epithelium
What is the urinary bladder & trigone?
- Urinary bladder: hollow muscular container. Located in pelvic cavity posterior to symphysis pubis.
- Trigone: interior of urinary bladder. Triangular area between the entry of the two ureters and the exit of the urethra.
What is the urethra and what is it lined with?
- Urethra: transports urine from the bladder to the outside of the body. Internal urinary sphincter - Elastic connective tissue and smooth muscle prevent urine continuously flowing out of the bladder.
- Lined with transitional epithelium (top) stratified columnar epithelium (external opening).
What is the external urinary sphincter, what does it act as? Describe the male & female urethras
- External urinary sphincter: skeletal muscle surrounds urethra as it extends through pelvic floor. Acts as a valve that controls the flow of urine
- Male urethra: extends from the inferior part of the urinary bladder through to the tip of the penis.
- Female urethra: shorter; opens into vestibule anterior to vaginal opening
What are the functions of the renal system?
1) Excretion: get rid of waste products. Urine production occurs in the kidneys via filtration of the blood and reabsorption of nutrients. Metabolic wastes and toxic molecules are excreted in urine.
2) Regulate blood volume and blood pressure – control extracellular volume by producing large amounts of dilute urine or small amounts of concentrated urine.
3) Solute (Cl- , Na+ , urea) concentration in the blood, extracellular pH, red blood cell synthesis, vitamin D synthesis
Function of the kidneys, nephrons & what are the stages of urine production?
- Kidneys: regulate body fluid composition. Sorts chemicals in the blood for removal or for return into the blood.
- Nephrons: the structural component of the kidneys that ‘sorts’ the blood.
- Urine production: 3 stages – filtration, tubular reabsorption, tubular secretion.
What is filtration?
-Movement of fluid, derived from blood flowing through the glomerulus, across filtration membrane.
Define filtrate, renal fraction and glomerular filtration rate
- Filtrate: water, small molecules & ions that can pass through membrane. Doesn’t include red blood cells, proteins or large molecules.
- Renal fraction: part of total cardiac output that passes through the kidneys. Varies from 12-30% in a healthy resting adult.
- Glomerular filtration rate (GFR): amount of filtrate produced each minute – 125ml/minute. 180 L/day.
What is the average urine production per day?
-Average urine production/day: 1-2 L.
What does filtration do?
- Most of filtrate (99%) must be reabsorbed
- Removes toxins quickly from blood
What are fenestrae, filtration slits & basement membrane in the renal system?
- Fenestrae: window-like openings in the endothelial cells of the glomerular capillaries.
- Filtrations slits: gaps between podocytes.
- Basement membrane: sandwiched between the endothelial cells of the glomerular capillaries and the podocytes.
