This document provides information about the urinary system. It discusses the key functions and components of the urinary system, including the kidneys, ureters, urinary bladder, and urethra. It also provides detailed information about kidney anatomy, the internal structures of the kidney like the renal cortex and medulla, and the nephron, which is the functional unit of the kidney. Furthermore, it explains the multi-step process of urine formation within the nephron and kidney.

1. Urinary system
Lab Work
Muhammad Iqbal Khan
SS Biology
Email ID:mikhan1313@yahoo.com
0923135448175

2. Announcements
• Urinary system
• Lab Practical Week after Spring Break
• Practical Review this Sunday 23rd at 3-5
pm

3. Functions of Urinary System
• Kidneys carry out four functions
– Filter nitrogenous wastes, toxins, ions, etc. from blood
to be excreted as urine.
– Regulate volume and chemical composition of blood
(water, salts, acids, bases).
– Produce regulatory enzymes.
• Renin – regulates BP/ kidney function
• Erthropoeitin – stimulates RBC production from marrow.
– Metabolism of Vitamin D to active form.

4. Urinary System
• Two Kidneys
– Perform all functions except actual excretion.
• Two Ureters
– Convey urine from Kidneys to Urinary Bladder
• Urinary Bladder
– Holds Urine until excretion
• Urethra
– Conveys urine from bladder to outside of body

5. Complete System

6. Kidney general info
• Lie against posterior abdominal wall at level of
T12-L3.
• Right kidney is lower than left kidney due to the
shape of the liver.
• Lateral surface of kidney is convex while medial
is concave.
– Concave side has a cleft – Renal Hilus
– Inside hilus is Renal sinus
• Where kidneys receive renal vessels and nerves.

7. Kidney External Anatomy
• Average size – 12cm x 6cm x 3 cm
• Weights 150 grams or 5 oz
• Surrounded by three membranes (deep to
superficial)
– Renal capsule – fibrous barrier for kidneys.
– Adipose capsule – fatty tissue designed for protection /
stability.
– Renal fascia – dense fibrous CTP anchors kidneys/
adrenals/ membrane 1 and 2 to surroundings.

8. Kidney Anatomy
• Renal arteries and veins
• Renal cortex
• Renal medulla
• Nephron
• Renal pyramids (6-10)
• Renal papilla
• Calyx (ces)
• Renal pelvis
• Ureter

9. Kidney- External Anatomy
• Lateral surface- convex
• Medial is concave-
– Renal Hilum
• Opening to Kidney
– Renal Sinus
• Space within hilus
• Kidneys receive blood vessels and nerves.

10. Kidney Internal Anatomy I
• Renal arteries and veins
– Bring blood in and out of kidney
• Renal cortex
– Outer layer of Kidney
• Renal medulla
– Inner layer of Kidney
• Nephron

11. Kidney Internal Anatomy II
• Renal Pyramids
• Renal Columns
– Space between pyramids
within the medula
• Renal Papilla
– Narrow end of pyramid
• Calyx (ces)
– Collecting tubes
• Renal Pelvis
– Collecting vessel prior to
ureter

12. Human Kidney

13. Nephron
• Blood processing unit which serves to
produce urine
• 1 million per kidney
• Consists of a glomerulus and tubules

14. Nephron: Vascular System
• Afferent arteriole
• Glomerulus
• Efferent arteriole
• Peritubular capillaries
– Capillary beds
reabsorb in cortex
• Vasa recta
– Capillary beds
reabsorb in medulla

15. Nephron
• Tubular system
– Glomerular Capsule
– Proximal convoluted tubule
– Loop of Henle (nephron loop)
• Descending limb
• Ascending limb
– Distal convoluted tubule
– Collecting duct

16. Nephron

17. Dynamic Human
Gross Anatomy
Urinary system
Kidney
Nephron

18. Urine Formation I
• Glomerular filtration
• Water, ions, amino
acids, and glucose get
into capsular space
from blood
• Proteins stay in blood
– too big to leave
capillaries.

19. Urine Formation II
• Proximal convoluted
tubule and Peritubular
capillary
• Na+ goes down
gradient and brings
glucose, amino acids,
etc. back into blood
stream (cotransport).
• Reabsorbs about 65%
of filtrate.

20. Urine Formation III
• Descending limb
• Goes into medulla
- increasing salt
gradient
• Water leaves
• Fluid concentrates
• Ascending limb
• Goes up toward cortex
- decreasing salt
gradient
• Na+ pumped out
• Fluid relatively diluted
Countercurrent Multiplication
in the Nephron Loop

21. Nephron Loop

22. Urine Formation IV
• Collecting duct
• Travels down into medulla
• Water leaves tubule and enters blood
• Urine becomes concentrated and enters
renal papilla
• ADH controls water channel
• ADH – Antidiuretic hormone

23. Collecting duct

24. Dynamic Human
Urine Formation

25. Micturition
• Ureters
– 25 cm long
– Enters on the floor of bladder
• Urinary Bladder
– Muscular sac on floor of pelvic cavity
– Muscle layer formed by detrusor muscle
– Average bladder volume is 500 ml
– Max capacity is 700-800 ml

26. Micturition
• Urethra
– Conveys urine out of body
– Female urethra – 3 - 4 cm
– Opens into external urethral oriface
– Lies between vaginal oriface and clitoris
– Male urethra – 18 cm
– 3 regions
• Prostatic urethra – 2.5 cm
• Membranous urethra – 0.5 cm
• Penile urethra – 15 cm

27. Micturition Reflex
Bladder with >= 200 ml of urine
Sensory input to parasympathetic system
Contraction of detrusor muscle and
relaxation of internal urethral sphincter
Relaxation of external urethral sphincter

28. Micturition

29. Kidney stones
• A hard granule of calcium, phosphate, uric acid
and protein.
• Form in renal pelvis and get lodged in pelvis or
ureter.
• Caused by urinary tract infections, dehydration,
pH imbalances, or an enlarged prostate gland.
• Treated with stone dissolving drugs, surgical
removal, or lithotripsy (ultrasonic vibrations)

30. Dynamic Human
Visualizing the Urinary System
Intravenous pyelography
Ultrasound

31. Dissection
• Be able to identify layers of the kidney on
human material
• Be able to locate kidneys, ureters, urinary
bladder, and urethra on cat.

32. Next Week – Spring Break
Week After - Practical II
• Material over lymphatic, respiratory, and
urinary systems
• Review Sunday (end of break) at 3-5pm
• Remember – some questions will be based
on identifying structures on the cats.