AHP Unit 5

1. DIGESTIVE AND URINARY
SYSTEMS
UNIT 5

2. TOPICS TO BE COVERED
 Organs of Digestive System
 Digestion
 Absorption
 Structure of Kidney and Nephron
 Mechanism of Urine Formation
 Regulation of Blood Pressure by Urinary System
 Urinary Reflex

3. DIGESTIVE SYSTEM

4. DIGESTIVE SYSTEM

5. •Glucose.
•Fructose (a.k.a. fruit sugar)
•Sucrose (a.k.a. table sugar)
•Lactose (a.k.a. dairy sugar)

6. ORGANS OF DIGESTIVE
SYSTEMS

8. Mouth

12. Layers of Alimentary Canal

15. Stomach

17. Pancreas
 The pancreas is an organ located in the abdomen. It plays an essential role in
converting the food we eat into fuel for the body's cells. The pancreas has two
main functions: an exocrine function that helps in digestion and an endocrine
function that regulates blood sugar.

19. Exocrine glands
 A gland that makes substances such as sweat, tears, saliva, milk, and digestive
juices, and releases them through a duct or opening to a body surface. Examples
of exocrine glands include sweat glands, lacrimal glands, salivary glands,
mammary glands, and digestive glands in the stomach, pancreas, and intestines.
Endocrine glands
 Endocrine glands are ductless glands of the endocrine system that secrete their
products, hormones, directly into the blood. The major glands of the endocrine
system include the pineal gland, pituitary gland, pancreas, ovaries, testes,
thyroid gland, parathyroid gland, hypothalamus and adrenal glands.

21. Small Intestine

22. Large Intestine
The large intestine includes the appendix, cecum, colon, and rectum.

24. DIGESTION &
ABSORPTION

31. URINARY SYSTEM

32. URINARY SYSTEM
• Performs excretion functions
• Acts as essential regulators
of volume and chemical
makeup of blood
• Maintain proper balance
between water and salts and
between acid and base
• Comprises of pair of Kidney,
Urinary Bladder, a pair of
Ureters and Urethra

34. The 7 functions of the kidneys
•A - controlling ACID-base balance.
•W - controlling WATER balance.
•E - maintaining ELECTROLYTE balance.
•T - removing TOXINS and waste products from the body.
•B - controlling BLOOD PRESSURE.
•E - producing the hormone ERYTHROPOIETIN.
•D - activating vitamin D.

35. STRUCTURE OF KIDNEY
AND NEPHRON

36. Structure of Kidney – Location & External Anatomy
 A pair of Bean Shaped Structure
 Present in the retroperitoneal position ie between the
dorsal body wall and the parietal peritoneum in
superior Lumbar region
 Right kidney is crowded by liver so it is slightly lower
than the left one
 An Adults kidney has mass of 150g and average
dimensions are 12cm long, 6 cm wide, 3cm thick
 Lateral surface is convex, medial surface is concave and
has a vertical clift – Renal Hilum (point where ureter,
renal blood vessels, lymphatics, nerves join kidney
 Atop each kidney, an adrenal gland is present
(Endocrine Gland)
 Layers Around Kidney - Renal Fascia, Perirenal Fat
Capsule, Fibrous Capsule

37. Structure of Kidney –Internal Anatomy
 Frontal Section – Cortex, Medulla, Pelvis
 Renal Cortex – Most superficial region,
light in color and granular appearance
 Renal Medulla – Deep into cortex,
reddish brown structure tissue masses
called Medullary or Renal pyramids
 Renal Pyramids – cone shaped, broad
base faces cortex, apex called Papilla
points internally, appears striped as it
contains parallel bundles of microscopic
urine collecting tubules and capillaries
 Renal Columns – inward extension of
cortical tissue, separates pyramids
 Renal Pelvis – A funnel shaped tube
 Major Calyces
 Minor Calyces – Cup shaped areas to
enclose papilla
 Calyces – Collect urine from papilla and
empty it into pelvis
 Walls of Calyces, pelvis and ureter
contains smooth muscles

41. Structure of Nephron
 Structural and functional units of kidneys
 Blood processing units helps in formation of urine
 Each kidney contain 1 million nephrons
 Consist of Glomerulus and a renal tubule

44. MECHANISM OF URINE
FORMATION

45.  Urine formation is a result of three processes:
 Glomerular filtration
 Tubular reabsorption
 Tubular secretion

46. GLOMERULAR FILTRATION:
 The glomerulus acts as a filter.
 Glomerular filtration is a nonselective, passive process in which fluid passes from
the blood into the glomerular capsule part of the renal tubule.
 Once in the capsule, the fluid is called filtrate  it is essentially blood plasma
without blood proteins.
 Both proteins and blood cells are normally too large to pass through the filtration
membrane, and when either of these appears in the urine, there is usually a
problem with the glomerular filters

47. TUBULAR REABSORPTION:
 Besides wastes and excess ions that must be removed from the blood, the filtrate
contains many useful substances including water, glucose, amino acids, and ions,
which must be reclaimed from the filtrate and returned to the blood.
 Tubular reabsorption begins as soon as the filtrate enters the proximal
convoluted tubule
 The tubule cells are “transporters,” taking up needed substances from the filtrate

48.  Some reabsorption is done passively (for example, water passes by osmosis), but
reabsorption of most substances depends on active transport processes, which
use membrane carriers, require ATP, and are very selective.
 Needed substances (for example, glucose and amino acids) are usually entirely
removed from the filtrate.
 Most reabsorption occurs in the proximal convoluted tubules, but the distal
convoluted tubule and the collecting duct are also active

49. TUBULAR SECRETION:
 Tubular secretion is essentially tubular reabsorption in reverse.
 Some substances, such as hydrogen and potassium ions (H+ and K+) and
creatinine, also move from the blood of the peritubular capillaries through the
tubule cells or from the tubule cells themselves into the filtrate to be eliminated
in urine.
 This process seems to be important for getting rid of substances not already in
the filtrate, such as certain drugs or excess potassium ions, or as an additional
means for controlling blood pH

50. NITROGENOUS WASTES:
 Nitrogenous waste products are poorly reabsorbed
 Tubule cells have few membrane carriers to reabsorb these substances because we do not
need them.
 They tend to remain in the filtrate and are found in high concentrations in urine excreted
from the body.
 Common nitrogenous wastes include the following:
 Urea, formed by the liver as an end product of protein breakdown when amino acids are used to
produce energy
 Uric acid, released when nucleic acids are metabolized
 Creatinine, associated with creatine metabolism in muscle tissue

52. REGULATION OF BLOOD
PRESSURE BY URINARY
SYSTEM

54. URINARY REFLEX

55.  Micturition or voiding, is the act of emptying the bladder. Micturition reflex is a spinal reflex
influenced by higher centres
 Two sphincters or valves control the flow of urine from the bladder
 The internal urethral sphincter (more superiorly located)
 The external urethral sphincter (more inferiorly located)
 Ordinarily, the bladder continues to collect urine until about 200 ml have accumulated and at
this point, stretching of the bladder wall activates stretch receptors.
 Impulses transmitted to the sacral region of the spinal cord and then back to the bladder via
the pelvic splanchnic nerves cause the bladder to go into reflex contractions.
 As the contractions become stronger, stored urine is forced past the internal urethral
sphincter (the smooth muscle, involuntary sphincter) into the upper part of the urethra.
 The person will then feel the urge to void.

56.  Because the lower external sphincter is skeletal muscle and is controlled
voluntarily, we can choose to keep it closed and postpone bladder emptying
temporarily.
 However, if it is convenient, the external sphincter can be relaxed so that urine is
flushed from the body.
 When a person chooses not to void, the reflex contractions of the bladder stop
within a minute or so, and urine collection continues.
 After 200 to 300 ml more have been collected, the micturition reflex occurs
again.
 Eventually, micturition occurs whether the person wills it or not.

57. Accumulation of
sufficient quantity of
urine
Stimulates stretch
receptors in the
bladder
Sensory signals reach
sacral segments of
spinal cord through
pelvic nerve
Motor response
reaches bladder
through
parasympathetic fibers
Contraction of detrusor
muscle- micturition
reflex
Once micturition reflex
becomes powerful,
inhibits external
sphincter
Relaxation of perineal
muscles, urine passes
through urethra
If condition not
suitable, higher centers
exhibit control over
lower centers
Temporarily postpone
micturition