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Excretion

Excretion. Revision of Excretion 5 th Year Biology Nicola Sheehan. What you need to know:. Link excretion to homeostasis . Function and location of excretory organs. Products of excretion. Importance of carbon dioxide in gaseous exchange. What you need to know:.

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Excretion

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  1. Excretion Revision of Excretion 5th Year Biology Nicola Sheehan

  2. What you need to know: • Link excretion to homeostasis. • Function and location of excretory organs. • Products of excretion. • Importance of carbon dioxide in gaseous exchange.

  3. What you need to know: • Macrostructure of urinary system. • Role of kidney in osmoregulation. • Structure and function of the nephron. • Description of formation of urine. • Role of ADH.

  4. Homeostasis • The maintenance of a constant internal environment. • Body temperature. • Osmoregulation. • Body fluid concentration. • Removal of metabolic waste.

  5. What do the lungs excrete? The level of carbon dioxide is monitored in the body. When it is too high, it is excreted through the alveoli of the lungs. The lungs

  6. The skin

  7. The skin • Protection (epidermis, dermis, melanin, sebum). • Vitamin D production. • Food storage. • Sense receptor. • Excretion (Water and salt = sweat). • Temperature regulation.

  8. What are the functions of each of the components of the urinary system? What is the waste product excreted made up of? The urinary system

  9. Where are the kidneys located? Name some functions of the kidney. Where does filtration occur? Where does reabsorption occur? How many nephrons are in the kidneys? The kidney

  10. The nephron • The functional unit of the kidney. • 3cm long. • Located in the cortex and medulla. • Blood arrives in the afferent arteriole. • Blood exits in the efferent arteriole. • Glomerulus located in the Bowman’s capsule. Click for image

  11. Filtration • Blood arrives in the afferent arteriole. • Small particles are removed at glomerulus. • Small particles and plasma forced into Bowman’s capsule. • Called glomerular filtrate. • What makes the glomerulus so suited to filtration? Click for image

  12. Reabsorption • Proximal tubule: Most useful materials, water and salt. • Descending loop of Henle: 5% water, no salt. • Ascending loop of Henle: No water, some salt. • Distal tubule: 10% water, some salt. • Collect. duct: 4.9% water, no salt. Click for image

  13. Increased water consumption leads to increase in blood water volume. No ADH produced. Distal tubule allows more water to pass to bladder. Large volume of dilute urine. ADH not needed

  14. Decrease in blood volume causes high solute concentration. ADH produced. Most of filtered fluid reabsorbed. Thirst sensation. Small volume of concentrated urine. ADH needed

  15. The Nephron • Diagram of the nephron.

  16. To summarise: • Skin, lungs and kidneys involved in excretion. • Kidneys main function is excretion. • Nephron: the functional unit of the kidney. • Urine produced via filtration and reabsorption. • Hormone ADH plays a vital role.

  17. Images courtesy of: • Lakemichigancollege.edu/dept/…./anat/urin.html • gerstner.felk.cvut.cz/.../cepek/SkinSchema.jpg • www.coolschool.ca/lor/BI12/unit14/U14L01.htm • www.britannica.com/eb/art-99769/The-lungs-ser... • www.uic.edu/.../bios100/lecturesf04am/lect21.htm

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