Renal (Urinary) System Flashcards
Where are the kidneys and ureters?
They lie retroperitoneal in the abdominal cavity; partly covered by ribs. Kidneys lie on the posterior wall
Where is the urinary bladder?
In the pelvic cavity
Where is the urethra?
Below the pelvis
What are the renal arteries?
Branch from the aorta
What are the renal veins?
Join the inferior vena cava
What are the 3 layers of the ureter?
- Transitional epithelium & goblet cells
- Smooth muscle
- Areolar connective tissue
What does peristalsis do?
Moves urine from the renal pelvis to the urinary bladder
Explain the urethra in women?
It travels a slightly curved course as it passes interiorly through the pelvic floor into the perineum, where it passes through the deep perineal pouch and perineal membrane before opening in the vestibule that lies between the labia minora
Explain the urethra in men?
Beginning at the base of the bladder and passing inferiorly through the prostate, it passes through the deep perineal pouch and perineal membrane and immediately enters the root of the penis.
What is the urethra?
The exit tube for urine from the bladder to the outside world
What 2 muscular sphincters control the flow of urine?
- Internal urethral sphincter
- External urethral sphincter
What is the indentation on the kidneys medial border called?
Renal hilum
What surrounds the kidneys?
Perinephric fat surrounds and cushions the kidney. This also anchors the kidney to the posterior abdominal wall
What are the 2 regions of the kidney?
The outer light red renal cortex and the inner darker red/brown renal medulla
How many pyramids in the kidneys medulla?
8 - 18 pyramids separated by columns or cortical tissue
What 2 zones are the kidneys divided into functionally?
The functional area and the drainage area
What does the functional area of the kidney consist of?
Renal cortex and renal medulla
What happens in the drainage area of the kidney?
Apex of a pyramid is known as the renal papilla where thousands of papillary ducts drain urine into cup like minor calyces
What are minor calyces?
Drain into 2 - 3 major calyces
What are major calyces?
Drain into the renal pelvis which connects to the ureter
What are nephrons in kidneys?
They are the functional unit of the kidney. They consist of a renal tubule and associated blood vessels
What are cortical nephrons?
They have short loops of Henle that mostly stay in the cortex
What are juxtamedullary nephrons?
They have long lops of Henle
What is the structure of a nephron?
Renal corpuscle - Glomerulus - Glomerular (Bowmans) capsule Renal Tubule - Proximal convoluted tubule - Loop of Henle - Distal convoluted tubule
What 3 stages does urine production occur?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
What is glomerular filtration?
Takes place in the glomerulus. Blood pressure in afferent arterioles forces water and most solutes in the plasma through wall of glomerulus capillaries and into the glomerular capsule which empties into the renal tubule
What is glomerular filtration rate (GFR)?
GFR is the amount of filtrate formed by both kidneys each minute
- males 125ml/min
- females 105ml/min
GFR is directly related to blood pressure
Which hormones can affect GFR?
- Atrial Natriuretic Peptide (ANP)
- Angiotensin
- Hypovolaemia
What is ANP?
This hormone produced by the atria of the heart when the pressure inside them exceeds normal. This means that there is more fluid circulating than healthy.
What is the response of ANP?
To squeeze more blood filtrate through the glomerulus (by making the glomerular exit vessel small) so excess fluid will go to the bladder and out the body thus reducing bp
What is angiotensin?
This hormone is released during haemorrhage states, will result in too little fluid circulation
What is hypovolaemia?
First angiotensin lowers the GFR initially, it reduces kidney circulation to conserve circulation to other organs (like the brain). This reduces GFR temporarily. Angiotensin’s action later restores GFR because it influences another hormone called aldosterone this rescues water as it leaves the kidney, this reabsorption restores circulating blood volume levels
What is tubular reabsorption/vasa recta?
As filtered fluids move along renal tubule to collecting ducts most water and useful solutes are reabsorbed by tubular cells and returned to peritubular capillaries. 99% of glomerular filtrate is reabsorbed by tubules. Occurs mostly in PCT
What is tubular secretion?
This is the process by which substances move into the distal and collecting tubules from blood in the peritubular capillaries mainly by active transport.
What is tubular secretion important for?
- disposing of substances not already in the filtrate
- maximising removal of waste e.g. urea
- excretion of some drugs
- removal of excess ions
- secreting H+ to restore blood pH
What is antidiuretic hormone (ADH)?
Produced by the posterior pituitary in response to plasma concentration. it regulates bodies fluid balance by the concentration or dilution of urine
- Bp low or dehydration = high ADH
- Excess intake of fluid = low ADH
What is micturition?
Reflex action in infants and small children. Older children and adults learn to control micturition by controlling the external urethral sphincter and pelvic floor muscles. Eventually bladder filling will override these voluntary controls
What should be found in normal urine?
- water
- urea
- uric acid
- creatine
- excess inorganic salts
What might be found in abnormal urine?
- albumin
- glucose
- red blood cells
- white blood cells
- kettle bodies
- bilirubin
- urobiligen
- bacteria
