Excretory System

• Lungs eliminate carbon dioxide
• The liver breaks down indigested toxins
• The kidneys eliminate indigested toxins, and helps maintain pH and water balance in the bloodstream
• Three main roles of the excretory system:

  1. Removes waste from the blood (ex. urea, drugs)
  2. Maintains chemical composition of the blood

  • Regulates levels of Na+ and K+
  • Maintains blood pH of 7.4, by H+

  3. Maintains water balance in blood
• Urinary tract (Renal System) consists of the, bladder, kidney, ureters and urethra
• Label:

  A) Vena Cava

  B) Renal Vein

  C) Aorta

  D) Renal Artery

  E) Renal pelvis

  F) Medulla

  G) Cortex

  H) Ureter

  I) Renal Artery

  J) Renal Vein

  K) Ureter

  L) Urinary Bladder

  M) Urethra

  
• Aorta carries oxyenated blood to kidneys through the renal arteries
• After wastes and excess water get filtered from the blood by the kidneys, they are conducted through the ureters to the bladder.
• The bladder temporarily stores the urine.
• Ureters are the long tube attatched to each kidney, transports urine to bladder by peristalsis.
• When the bladder begins filling, recptors in the brain are activated, urine exits the body through the urethra
• An outside layer of connective tissue known as the cortex encircles the kidney.
• What contains the Bowman's capsule?

  The Kidney
• Label:

  A) Renal Artery

  B) Renal pelvis

  C) Medulla

  D) Cortex

  E) Renal Vein

  F) Ureter

  
• Inner layer in the Kidneys are known as the medulla, which contains collecting ducts
• The renal pelvis is a hollow chamber (funnel like), this joins the kidney with the ureter
• Kidneys are composed of slender tubes, called nephrons
• Nephrons span the cortex and medulla and are responsible for the filtration of wastes and other solutes from the blood
• Nephrons allow the reabsoption of water and solutes back into the blood stream; maintaining homeostasis
• Solutes and water that are not reabsorbed are excreted in the form of urine
• Afferent arterioles are small branches from the renal artery which supplies nephrons with blood
• Afferent arterioles branch into a group of capillaries called the glomerulus
• Blood leaves the glomerulus through the efferent arterioles. Then it is moved through the peritubular capillaries, and exits the kidney via renal vein
• Bowman's capsule surrounds the glomerulus
• The Bowman's capsule, afferent arteriole and efferent arteriole are located in the cortex of the kidney
• What are the steps for fluid becoming urine?

  Filtration, reabsorption, secretion, excretion.
• Urine is carried from the proximal tube to the Loop of Henle, which then descends into the medulla of the kidney
• Urine movies through the distal tubule, last segment of the nephron into the collecting ducts. Ducts gather urine from many nephrons, which then merge them into the pelvis of the kidney
• Which organs are used as a filter in the Nephron?

  Bowman's Capsule

  Renal artery, which splits into glomerus
• Which organ is impermeable to large mollecules (ex. protiens) but permeable to small particles (urea, water, ions,-> filtrates)


  Glomerulus
• From Bowman's capsule, filtrates travel through reabsorption tubule with three sections.


  Proximal tubule, loop of Henle, distal tubule.
• Tubule empties into collecting ducts, it reabsorbs water, filtrates that remains (waste solutes) which is Urine.
• Solute and water that is reabsorbed goes back to the body by renal veins
• Label:

  A) Proximal Tubule

  B) Bowman's Capsule

  C) Glomerulus

  D) Distal Tubule

  E) Loop of Henle

  F) Collecting duct

  G) Renal Pelvis

  
• Label:

  A) Bowman's Capsule

  B) Proximal Tubule

  C) Distal Tubule

  D) Glomerulus

  E) Capillary Network

  F) Renal Vein

  G) Renal Artery

  H) Collecting duct

  I) Loop of Henle

  J) Ascending Loop

  K) Descending Loop

  
• Nephron: A functional unit of the kidney responsible for filtering blood and producing urine.
• Hypothalamus a structure in the brain that contains specialzed cells called osmorecpetors, which monitors osmotic blood pressure
• Osmoreceptors are cells in the brain specialized in monitoring osmotic pressure
• When a person is dehydrated, blood is too concentrated and osmotic pressure increases which signal pituitary in the brain to release ADH (anti pee hormone).
• What does the ADH hormone do?

  It increases premeability, and decreases urine output. Water is getting put back into the blood