The urinary system part 3

Lecture Objectives
By the end of this lecture, students are expected to:
1. List and describe the blood supply of kidney.
2. Outline the histological features of the nephron .
3. Compare the local function and histological features of proximal
and distal convoluted tubules.
4. Outline the different types of epithelium within urinary passages.
5. Summarize the functional and histological structure of medulla of
kidney.
6. Relate the functional to histological feature of the of cells of
proximal and distal convoluted tubules.
7. Outline the structural and functional adaptations of the
gastroesophageal glands.
8. Outline the difference in histological features of outer layer of
esophagus along its course.
The Urinary System
Introduction
The Urinary System consists of
? paired kidneys and ureters.
? unpaired bladder and urethra.
The function of Urinary System:
Function
1. filter blood and reabsorb nutrients.
2. control the water, ion, and salt balance of the body.
3. maintain the acid-base balance of the blood.
Histology URINARY SYSTEM Dr. Hameda A.Gazi
2
4. excrete metabolic wastes (urea and uric acid), toxins, and drug
components.
5. secrete hormones, such as renin and erythropoietin.
6. produce calcitriol (an active form of vitamin D) to help the body
absorb dietary calcium into the blood.
Kidneys
The kidneys are bean-shaped organs located in the posterior
abdominal region on each side of the vertebral column. The kidney can
be divided into the renal cortex, the renal medulla, and the hilum.
The renal cortex is composed of renal corpuscles and various
cortical tubules, which include
1. proximal convoluted tubules.
2. distal convoluted tubules.
3. cortical collecting tubules.
The renal medulla is located deep to the cortex , and its tubules
extend as medullary rays into the cortex region. The medulla comprises
10 to 18 renal pyramids; each pyramid contains the loops of Henle,
collecting ducts, and papillary ducts. The apical projection of a renal
pyramid is called the renal papilla. The papillary ducts empty urine at
the tip of a renal papilla onto its surface, which is called the area
cribrosa (perforated area). Each renal papilla is surrounded by a space,
the minor calyx; several minor calices unite to form a major calyx.
There are two or three major calyces for each kidney.