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Biology

Biology. Mr. Karns. Excretory system. Each kidney Is supplied with blood by a renal artery and drained by a renal vein. Posterior vena cava. Renal artery and vein. Kidney. Aorta. Ureter. Urinary bladder. Urethra. (a) Excretory organs and major associated blood vessels.

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Biology

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  1. Biology Mr. Karns Excretory system

  2. Each kidney Is supplied with blood by a renal artery and drained by a renal vein Posterior vena cava Renal artery and vein Kidney Aorta Ureter Urinary bladder Urethra (a) Excretory organs and major associated blood vessels Figure 44.13a

  3. 38–3 The Excretory System

  4. Functions of the Excretory System • Functions of the Excretory System • Every cell produces metabolic wastes. • The process by which these wastes are eliminated is called excretion.

  5. Functions of the Excretory System • The skin excretes excess water and salts in the form of sweat. • The lungs excrete carbon dioxide. • The kidneys also play a major role in excretion.

  6. Functions of the Excretory System • The Kidneys • What are the functions of the kidneys?

  7. Functions of the Excretory System • The kidneys: • remove waste products from the blood. • maintain blood pH. • regulate the water content of the blood and, therefore, blood volume.

  8. The Kidneys • The kidneys are located on either side of the spinal column near the lower back. • A tube, called the ureter, leaves each kidney, carrying urine to the urinary bladder. • The urinary bladder is a saclike organ where urine is stored before being excreted.

  9. The Kidneys • Structure of the Kidneys Nephron Kidney

  10. The Kidneys • Blood enters the kidney through the renal artery. • The kidney removes urea, excess water, and other waste products and passes them to the ureter. • The clean, filtered blood leaves the kidney through the renal vein and returns to circulation.

  11. The Kidneys • Kidney Structure  • A kidney has two distinct regions: • The inner part is called the renal medulla. • The outer part is called the renal cortex.

  12. The Kidneys Cortex Renal artery Medulla Renal vein Ureter To the bladder

  13. The Kidneys • The functional units of the kidney are called nephrons. • Nephrons are located in the renal cortex, except for their loops of Henle, which descend into the renal medulla.

  14. The Kidneys Capillaries Bowman’s capsule Glomerulus Collecting duct Vein Artery To the ureter Loop of Henle

  15. The Kidneys Capillaries • Each nephron has its own blood supply: • an arteriole • a venule • a network of capillaries connecting them Collecting duct Vein Artery To the ureter

  16. The Kidneys Capillaries • Each nephron releases fluids to a collecting duct, which leads to the ureter. Collecting duct Vein Artery To the ureter

  17. The Kidneys • How is blood filtered and removed?

  18. Excretory Processes Capillary Filtration. The excretory tubule collects a filtrate from the blood. Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule. 1 Excretory tubule Filtrate 2 Reabsorption. The transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids. Secretion. Other substances, such as toxins and excess ions, are extracted from body fluids and added to the contents of the excretory tubule. 3 4 Excretion. The filtrate leaves the system and the body. Urine • Most excretory systems (4 basic parts) • Produce urine by refining a filtrate derived from body fluids Figure 44.9

  19. What are the 4 parts? • Say it outloud

  20. Key functions of most excretory systems are • 1. Filtration, pressure-filtering of body fluids producing a filtrate • 2. Reabsorption, reclaiming valuable solutes from the filtrate • 3. Secretion, addition of toxins and other solutes from the body fluids to the filtrate • 4. Excretion, the filtrate leaves the system

  21. The Kidneys • As blood enters a nephron through the arteriole, impurities are filtered out and emptied into the collecting duct. • The purified blood exits the nephron through the venule.

  22. The Kidneys • The mechanism of blood purification involves two distinct processes: filtration and reabsorption.

  23. The Kidneys • Filtration  • Passing a liquid or gas through a filter to remove wastes is called filtration. • The filtration of blood mainly takes place in the glomerulus. • The glomerulus is a small network of capillaries encased in the top of the nephron by a hollow, cup-shaped structure called Bowman's capsule.

  24. The Kidneys • Fluid from the blood flows into Bowman’s capsule. • The materials filtered from the blood include water, urea, glucose, salts, amino acids, and some vitamins. • Plasma proteins, cells, and platelets remain in the blood because they are too large to pass through the capillary walls.

  25. The Kidneys • Reabsorption  • Most of the material removed from the blood at Bowman's capsule makes its way back into the blood. • The process in which liquid is taken back into a vessel is called reabsorption.

  26. The Kidneys • Almost 99% of the water that enters Bowman’s capsule is reabsorbed into the blood. • When the filtrate drains in the collecting ducts, most water and nutrients have been reabsorbed into the blood.

  27. The Kidneys • Remaining material, called urine, is emptied into a collecting duct. • Urine is primarily concentrated in the loop of Henle. • The loop of Henle is a section of the nephron tubule in which water is conserved and the volume of urine minimized.

  28. The Kidneys • As the kidney works, purified blood is returned to circulation while urine is collected in the urinary bladder. • Urine is stored here until it is released from the body through a tube called the urethra.

  29. Control of Kidney Function • Control of Kidney Function “Homeostasis” • The activity of the kidneys is mostly controlled by the composition of the blood. • In addition, regulatory hormones are released in response to the composition of blood. This is controlled by a hormone ADH from the Pituitary Gland.

  30. Pituitary Gland feedback system • Pituitary Gland • What is the function of the pituitary gland?

  31. Pituitary Gland – master control • The pituitary gland secretes nine hormones that directly regulate many body functions and controls the actions of several other endocrine glands.

  32. Pituitary Gland • The pituitary gland is a structure at the base of the skull. • The gland is divided into two parts: the anterior pituitary and the posterior pituitary. • Remember anterior – front side or ventral • posterior- toward the rear / dorsal side

  33. Pituitary Gland • The Pituitary Gland Hypothalamus Posterior pituitary Pituitary gland Anterior pituitary

  34. Pituitary Gland

  35. Control of Kidney Function • When you drink a liquid, it is absorbed into the blood through the digestive system. • As a result, the concentration of water in the blood increases. • As the amount of water in the blood increases, the rate of water reabsorption in the kidneys decreases. • Less water is returned to the blood, and excess water is sent to the urinary bladder to be excreted as urine.

  36. Control of Kidney Function • When the kidneys detect an increase in salt, they respond by returning less salt to the blood by reabsorption. • The excess salt the kidneys retain is excreted in urine, thus maintaining the composition of the blood.

  37. Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH Increased permeability Pituitary gland Distal tubule H2O reab- sorption helps prevent further osmolarity increase STIMULUS: The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Collecting duct Homeostasis: Blood osmolarity • Antidiuretic hormone (ADH) • Increases water reabsorption in the distal tubules and collecting ducts of the kidney Figure 44.16a (a) Antidiuretic hormone (ADH) enhances fluid retention by makingthe kidneys reclaim more water.

  38. Kidney Disorders • Kidney Disorders • Humans have two kidneys, but can survive with only one. • If both kidneys are damaged by disease or injury, there are two options: • a kidney transplant • kidney dialysis

  39. Kidney Disorders • Kidney dialysis works as follows: • Blood is removed by a tube and pumped through special tubing that acts like nephrons. • Tiny pores in the tubing allow salts and small molecules to pass through. • Wastes diffuse out of the blood into the fluid-filled chamber, allowing purified blood to be returned to the body.

  40. Kidney Disorders • Kidney Dialysis Blood in tubing flows through dialysis fluid Blood pump Vein Artery Shunt Used dialysis fluid Fresh dialysis fluid Compressed air Dialysis machine Air detector

  41. 38–3

  42. 38–3 • A dialysis machine performs the function of which structure in the excretory system? • nephron • ureter • urethra • glomerulus

  43. 38–3 • In the human body, the kidneys play an important role in • producing digestive enzymes. • circulating the blood. • destroying old red blood cells. • maintaining homeostasis.

  44. 38–3 • In the nephron, most filtration occurs in the • renal tubule. • capillaries. • glomerulus. • loop of Henle.

  45. 38–3 • Urine leaves the body through the • loop of Henle. • glomerulus. • urethra. • bladder.

  46. 38–3 • Materials filtered out of the blood include all of the following EXCEPT: • water. • urea. • amino acids. • plasma proteins.

  47. END OF SECTION

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