This document discusses the principles of physiology, focusing on the urinary system. It describes the key functions of the kidneys as excretion of wastes, regulation of homeostasis, and secretion of substances like rennin and erythropoietin. The basic structures and functions of nephrons are explained, including the three stages of filtration, reabsorption and secretion in urine formation. Various conditions that can impact urine output like diabetes and kidney diseases are also summarized.

1. Principles of physiology
 Nutrition, Digestion & Metabolism
 Blood
 Respiration
 Excretion
 Muscular system
 Nervous system
 Endocrine system

2. EXCRETION

3. LUNG
 Excrete carbon
dioxide and water
The wastes of cellular
respiration

4.  Removes
toxic substances
from the blood
 Converts
hemoglobin from
old RBC’s to bile
pigments
eliminated in the
feces
LIVER

5.  Disposal of nitrogenous wastes
 Breaks down excess
amino acids (deamination)
 Amino group ammonia urea
Urea transported to the kidneys by the blood

6. Skin
 sweat
glands
excreto
structur
of the s

7. URINARY SYSTEM
 kidneys,
 ureters,
 urinary
bladder
 urethra

8. URINARY SYSTEM
kidneys (2) are bean
shaped organs ,
10 cm long ,
located below the
diaphragm near
the back

9. 3 main functions:
1. Excretion(remove wastes of cellular
metabolism from the blood)
2. Regulation, homeostasis
(concentrations of substances found in
body fluids,plasma,pH, blood pressure)
3. Secretion (rennin, and erythropoietin)

12. Kidney Structure
 Kidneys consist of
microscopic
structures called
 NEPHRONS.

13. A NEPHRON
Made of :
1- Glomerulus: a network of
capillaries
2- Bowman’s
capsule:
cup-like structuresurrounding the
glomerulus
3- Renal tubule

14.  Proximal convoluted
tubule (PCT)
 longest, most coiled,
simple cuboidal with
brush border
 Nephron loop - U
shaped; descending +
ascending limbs
 Distal convoluted tubule
(DCT)
 cuboidal, minimal
microvilli

15. Juxta-glomerular apparatus:
 A group of spindle shaped cells in the media
of afferent glomerular arterioles
 -Secrete rennin ( increase renal blood flow ).
 -Secrete erythropoietine, a hormonal agent
necessary for production of red blood cells
by bone marrow.
 -Secrete chemical factor ,regulate the output
of aldosterone.

16. A nephron works in 3 stages:
 1- Filtrations stage: water, minerals,
salts, urea, amino acids and glucose are
filtered out of the blood

17. Filterate
170-180L/day
resemble blood plasma (except RBCs,plasma
protein
3 forces :
 High glomerular capillaries pressure
 High glomerular osmotic pressure
 Low filterate pressure

18.  2- Reabsorption
stage:
 water, minerals,
amino acids and
glucose are
reabsorbed by
active transport
from the renal
tubule into the
capillaries
 3- Secretion stage

21. Urine Formation Preview

22. Urine Volume
 Normal volume - 1 to 2 L/day
 Polyuria > 2 L/day
 Oliguria < 500 mL/day
 Anuria - 0 to 100 mL

23. DiabetesChronic polyuria
 With hyperglycemia and glycosuria
 diabetes mellitus I and II, insulin
hyposecretion/insensitivity
 gestational diabetes, 1 to 3% of pregnancies
 pituitary diabetes, hypersecretion of GH
 adrenal diabetes, hypersecretion of cortisol
 With glycosuria but no hyperglycemia
 renal diabetes, hereditary deficiency of glucose
transporters
 With no hyperglycemia or glycosuria
 diabetes insipidus, ADH hyposecretion

24. URETERS
 Tubes
carry urine
from the
kidney to the
bladder

25. URINARY BLADDER
 Stores urine

26. URETHRA
 Tube that
carries urine
from the
bladder to the
outside of the
body

27. Function - Homeostasis
 Acid-Base Balance
 Kidneys regulate the pH, mineral ion concentration,
and water composition of the blood.
 By exchanging hydronium ions and hydroxyl ions,
the blood plasma is maintained by the kidney at pH
7.4.
 Urine, becomes either acidic at pH 5 or alkaline at
pH 8.
 Water Balance
 Aldosterone
 Plasma Volume
 ADH

28. Aldosterone
 A steroid hormone (m alocorticoid)
 It is formed in the outer-section (zona
glomerulosa) of the adrenal cortex
 It diminishes the excretion of Na+ ions and
therefore water, and stimulates the excretion
of K+ ions by the kidneys.

29. ADH (VASOPRESSIN)
 when the body is low on water.
kidneys conserve water
 osmotic activity increase
con. urine.
 → stimulate OSMOTIC RECEPTORS in the
hypothalamus
 → stimulation of posterior pituitary lobe


→ activation of VASOPRESSIN
→ increase collecting ducts permeability for water
 → reabsorption
 →HYPERTONIC URINE

30. Malfunctions
Kidney Diseases:
 Various conditions in which the
kidneys are unable to properly
excrete nitrogenous wastes

31. Kidney stones:
 Substances crystalize out of the urine
in the urinary tract or in the kidney
 Some pass out in the urine on their
own
 Some can be shattered with lasers or
sound waves
 Some are surgically removed

32.  Dialysis - can
some times be used
to treat various
kidney diseases
 Kidney
transplants