Anatomy of the Urinary System PDF

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Summary

Anatomy of the Urinary SystemFunctions of the Urinary System Regulation of volume and solute concentration of blood plasma – blood volume, pH  Removal of waste products produced by cellular metabolism  Elimination of waste products into the environmentBasic Structure Urine production – kidneys ...

Description

Anatomy of the Urinary System Functions of the Urinary System   

Regulation of volume and solute concentration of blood plasma – blood volume, pH Removal of waste products produced by cellular metabolism Elimination of waste products into the environment

Basic Structure    

Urine production – kidneys Urine transfer to the bladder – ureters transfer the urine to the bladder Urine storage – in bladder Urine release – urethra

Kidneys           

Located either side of the midline on the posterior wall of the abdomen Location (T12-L3) The right kidney is located slightly inferior to the left (liver) Behind the peritoneal peritoneum – retroperitoneal Highly vascular Surrounded by a thick layer of fat – perinephric fat (outside capsule) Surrounded by ribs 11 and 12 Renal capsule – collagen rich membrane which supports the tissue of the kidney Renal fascia – collagenous membrane Suspensory fibres connect renal fascia to kidney and limit movement of kidney Start development in the pelvis then rise upwards

Adrenal Glands 

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Cortex - Corticosteroids, aldosterone - Sodium and water retention BP and volume Medulla - Adrenaline and noradrenaline - ‘Fight or flight’

Structure         

150g (largest 1.8kg) : 10cm long, 5cm wide, 2.5cm thick Indented ovoid – bean shaped Hilum – located medially (structures enter and leave) Cortex surrounds pyramids Large blood supply – 20-25% of cardiac output Its internal features can be divided into the outer renal cortex which is in contact with the fibrous renal capsule Renal columns divide the inner renal medulla into 8 – 16 pyramidal shaped structures called the renal pyramids The pyramids and their associated cortex are collectively known as a renal lobe The boundaries of these lobes can be seen during foetal development, and some evidence of these may persist in some even after birth

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Renal pyramids collectively form the medulla

Renal Lobe

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Contains the functional unit = nephron The renal cortex of a lobe contains the filtration equipment (the cortical nephrons) and their associated collecting ducts While the renal pyramids contain the loops of Henle, where water is reabsorbed from the filtration system, and the majority of the collecting ducts which deliver urine to the tip of the pyramid The tip of each pyramid, known as the renal papilla is the point at which urine is excreted

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Renal cortex – proximal and distal parts of the nephron and collecting ducts (medullary rays)

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Renal medulla (pyramids) – Loop of Henlé and collecting ducts (collection and delivery of urine)

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Minor calyx – collects urine from pyramids

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Major calyx – where 2 minor calyxes meet

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Urine drains in major calyx the renal pelvis

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Urine passes out through the ureter

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Ureters 

Hollow muscular tubes 25-30cm in length which propel urine from the kidney to the bladder

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Located in both the abdomen and pelvis

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Retroperitoneal throughout their length

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Enter the bladder obliquely

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Backflow into the ureters is prevented when the bladder is full; compression closes off the ureters – valves

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1 of 125 people have a duplex ureter

Urinary Bladder    

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Lined superiorly by peritoneum When empty the bladder is roughly tetrahedral in shape Shaped like the bow of a boat when empty 4 surfaces - Superior - Inferolateral x2 - Posterior = base/ fundus Have folds (rugae) that allow for expansion

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Internally, the points at which these structures enter or exit the bladder mark the 3 corners of a region of thickened mucosa known as the smooth trigone Named as such because of its smooth triangular appearance The trigone has a different appearance to the rest of the bladder due to its differing developmental origin The trigone is thought to acts as a funnel, which channels urine into the urethra during micturition Made of smooth muscle (detrusor muscle) Usually capacity of around 0.75 litres

Female Urethra  

Short 4-5cm Passes through the pelvic floor and opens anterior to the vagina

Male Urethra   

20cm in length Prostate S-shaped = 4 regions - Pro-prostatic - Prostatic - Membranous - Penile

Urethral Sphincters  

Internal sphincter – junction of the bladder with the urethra (involuntary) External sphincters – inferior to the prostate (voluntary)...