Part 10: Human Excretory system; Structure of Nephron скачать в хорошем качестве

Part 10: Human Excretory system; Structure of Nephron

A nephron is the structural and functional unit of the kidney.Each kidney contains approximately 1 million nephrons. Blood flow pathway: Heart → Artery → Arterioles → Capillaries → Venules → Vein → Heart Arteries: carry blood away from the heart (usually oxygenated) under high pressure. Capillaries: tiny, thin-walled vessels connecting arteries and veins. Site of exchange of gases, nutrients, and wastes with tissues. Veins: carry blood toward the heart (usually deoxygenated) Arteries branch into arterioles, which lead to capillaries for exchange; capillaries then join to form venules, which merge into veins returning blood to the heart. Different types of simple epithelial tissue: 1. Simple squamous epithelium -Flat, thin cells -Found in alveoli, capillaries, Bowman’s capsule Function: diffusion and filtration 2. Simple cuboidal epithelium -Cube-shaped cells -Found in kidney tubules, glands Function: secretion and absorption 3. Ciliated cuboidal epithelium Made of cuboidal epithelial cells with cilia on the free surface Cilia help push materials along the surface Function: movement of substances by ciliary action Location: bronchioles of lungs, some ducts 4. Brush-bordered cuboidal epithelium -Made of simple cuboidal epithelial cells -Free surface has a brush border of microvilli -Microvilli are microscopic finger-like projections Location- Proximal convoluted tubule (PCT) of nephron Function- Increases surface area for absorption 5. Simple columnar epithelium -Tall, pillar-like cells -Found in stomach and intestine Function: absorption and secretion 6. Ciliated columnar epithelium -Columnar cells with cilia -Found in respiratory tract, fallopian tubes Function: movement of substances 7. Brush-bordered columnar epithelium Made of simple columnar epithelial cells Free surface has microvilli forming a brush border Location- Small intestine Function- Increases surface area for absorption Brush border = microvilli (for absorption) Cilia = for movement