Flashcards in Session 1 - Anatomy of the Urinary system Deck (55)
Why is the urinary system important?
• It is vital in the maintenance of homeostasis
What is the main function of the Urinary system?
• Controls excretion of a wide range of ions and small inorganic molecules
• Controls the concentration of key substances in ECF
Where is fluid located in the body?
• Intracellular fluid (ICF) or cytosol(~25L)
• Extracellular fluid (ECF)(~15L)
What fluid does ECF include?
• Interstitial fluid (~12L)
How do the kidneys effect ICF?
• By moderating the ECF
What happens if kidneys fail to control ECF volume?
• Changes in BP
• Tissue fluid
• Cell function
What happens if kidneys fail control ECF osmolarity?
• Cells shrink or swell
Describe the structure of the Urinary system
• Kidneys connected to the bladder by the ureters, which then expels urine via the urethra.
Where are the kidneys found?
• In the retropritoneal area (outside of the peritineum), at the level of T12-L3. Enclosed with Renal fascia and surrounded by perineal fat.
What muscle can be used as a reference point to find the right and left kidney?
• Psoas major
Where is the bladder found in males?
• The base of the bladder lies between the rectum and pubic symphysis. It is superior to the prostate and separated from the rectum by rectovesical pouch.
Where is the bladder found in females?
• The bladders sits inferior to the uterus and anterior to the vagina - thus its maximal capacity is lower than in males.
Where is the prostate found?
• situated in the pelvic cavity, below the lower part of the pubic symphyisis, above the superior fascia of the urogenital diaphragm, and in front of the rectum
Outline the course of the Ureters
• The ureters arise from the renal pelvis on the medial aspect of each kidney, before descending towards to bladder on the front of the psoas major muscle. The ureters cross the pelvic brim near bifurcation of the iliac arteries. They then run under the uterine artery/ductus deferens, down the pelvic sidewall and inset in the posterior surface of the bladder
Give three possible points along the course of the ureter where kidney stones can develop
• Where the ureters cross the pelvic brim
• At the ureterovesical valve (bladder entry)
• At the pelvouteric junction (where the renal pelvis meets the ureter in the renal hilum)
How does the path of the ureter differ between males and females
• In males it passes under the vas deferens, and in females in passes under the uterine arteries
How much of the cardiac output do the kidneys supply?
• Roughly 20-25%
Where do the kidney receive blood from?
• The left and right renal arteries which branch directly from the abdominal aorta
Describe the divisions of the renal arteries
• Divide first into interlobar arteries which penetrate renal capsule
• Then supply arcuate arteries that run into the boundary of the medulla and cortex
• These supply interlobular arteries that feed into afferent arterioles
• Afferent go into glomerulus and drain via efferent
• Efferent into afferent
Describe the venous drainage of the kidney
• Efferent -> Peritubular capillaries (cortical nephron)/Vasa recta (juxtamedullary nephron)
• Interlobular veins
• To arcuate veins
• Interlobar veins
• Renal vein
• Inferior vena cava
Why is moderation of salts and waters by the kidneys important?
• In a constant state of flux, due to variable ingestion
Do kidneys have a direct effect on ICF?
• No, only effect ECF
What is osmolality?
• Solute per kilogram of solvent
What is osmolarity?
• Number of osmoles of solute per litre
What ions are concentrated in ECF?
• Cl- and Na+
What ions are concentrated in ICF?
• A- and K+
What does the pH of ECF depend on?
• Depends in part on the concentration of HCO3-
What are the 4 roles of the kidney?
- Control volume
– Control osmolarity
– Help to control pH
– Excrete some waste products
What is ultrafiltrate?
• Filtered fluid produced by kidney, contains water and ions - NO CELLS