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Biology 20 IB > D3. Exretory System > Flashcards

D3. Exretory System Flashcards

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1
Q

Excretion

A
  • Process of removing waste and excess water from the body
  • One of the major ways the body maintains homeostasis
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2
Q

Key Organs Involved in Excretion

A
  • Kidneys (filter blood and produce urine)
  • Lungs (expel CO2 during respiration)
  • Skin (sweating)
  • Liver (excretion of certain metabolic products)
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3
Q

Principle Organs of the Excretory System

Kidney

A
  • Main organ of the excretory system
  • Excretes waste products and regulates water and salt balance
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4
Q

Principle Organs of the Excretory System

Ureter

A

Tube extending from each kidney that carries urine to the urinary bladder

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5
Q

Principle Organs of the Excretory System

Urinary Bladder

A

Sac that stores urine until it is eliminated from the body

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6
Q

Principle Organs of the Excretory System

Urethra

A

Tube leading from the urinary bladder through which urine exits the body

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7
Q

Functions of the Excretory System

A
  • Filtration of blood (remove waste and extra stuff)
  • Balancing water and minerals (like sodium and potassium)
  • Blood pressure regulation
  • Balanced blood pH
  • Makes blood cells (produces a hormone that tells your body to make red blood cells)
  • Getting rid of waste (like urea and creatinine)
  • Helping with detoxicification (help get rid of drugs/toxins)
  • Small part in regulating blood sugar by managing how much glucose is kept or released
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8
Q

Urine

A

Liquid waste product produced by the kidneys through the filtration of blood

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9
Q

Urine Composition

A
  • Water ~95%
  • Urea
  • Creatinine
  • Uric Acid
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10
Q

Urea

A

A nitrogenous waste product resulting from the breakdown of proteins

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11
Q

Creatinine

A

A waste product from muscle metabolism

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12
Q

Uric Acid

A

Formed during the breakdown of DNA and RNA

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13
Q

Importance of Urea Formation

Nitrogen Elimination

A

Urea is a non-toxic compound that carries excess nitrogen, a by-product of protein breakdown, out of the body

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14
Q

Importance of Urea Formation

Prevents toxicity

A

Ammonia, an intermediate in deamination, is toxic to cells. Converting it to urea in the liver prevents harmful effects on cellular function

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15
Q

Importance of Urea Formation

Safe Excretion

A

Urea can be safely transported in the bloodstream to the kidneys for excretion in urine, efficiently eliminating nitrogen waste

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16
Q

The Kidney

A
  • About the size of your clenched fist
  • The Cortex - outer layer
  • The Medulla - inner layer
  • Covered by a layer of connective tissue called the capsule
  • The pelvis recieves urine from the collecting ducts and funnels it to the ureter
17
Q

The Kidney

Renal Artery

A

Oxygenated blood from the heart is transported to the kidneys through the renal artery

18
Q

The Kidney

Renal Vein

A

Dexoygenated blood is carried away from the kidney through the renal veins, returning to the circulatory system

19
Q

The Formation of Urine

Filtration

A

Mass movement of water and solutes from blood into the renal tubule

20
Q

The Formation of Urine

Reabsorption

A

Movement of water and essential solutes from the tubule back into the blood

21
Q

The Formation of Urine

Secretion

A

Movement of materials from capillary back to the tubule

22
Q

Glomerulus

A

A network of capillaries surrounded by a cuplike structure, Bowman’s capsule

23
Q

Flow Through a Nephron

Part A: Blood Filtration

A
  1. Blood enters the glomerulus through the afferent arteriole
  • Blood pressure pushes water and dissolved solutes from the capillary into Bowman’s capsule
  • The filtration membrane is selectively permeable, blocking plasma proteins, erythrocytes and platelets from passing through, thus remaining in the blood
  1. Fluid in the Bowman’s capsule is now called filtrate
  2. What isn’f filtered out - moves out the glomerulus into the efferent arteriole
24
Q

Flow Through a Nephron

Part B: Reabsorption in the Proximal Tube

A
  • The proximal convoluted tubule is the tubule that is neartest to the glomerulus
  • Selective reabsorption by both active and passive transport occurs
  • Sodium ions are actively reabsorbed
  • Cl- and HCO3- follow by electrostatic attraction
  • Stops when threshhold is reached
  • Glucose/amino acids are actively reabsorbed
  • Solutes and proteins in the blood create an osmotic pressure that pulls water back into the blood
  • Concentrates solutes in the nephron
  • Some uric acid and urea returns to the blood
25
Q

Reabsorption

A
  • Process that moves solutes and water out of the filtrate and back into your bloodstream
  • They are “reabsorbed” because the first time they were absorbed was when they went into your bloodstream via the digestive tract after your meal
26
Q

Flow Through a Nephron

Part B: Loop of Henle - Descending Limb

A
  • Reabsorption of water by osmosis (lots of aquaporins)
  • High osmotic pressure in medulla forces water out
  • Membrane permeable to water but not to salt or other small solutes
  • No sodium channels to transport sodium out
  • Filtrate becomes highly concentrated
27
Q

Flow Through a Nephron

Part B: Loop of Henle - Ascending Limb

A
  • Membrane permeable to salt but not water
  • Thin segment - NaCl diffuses out
  • Thick segment - NaCl reabsorbed
28
Q

Flow Through a Nephron

Part C: Secretion in Distal convoluted tubule

A
  • Occurs along the distal tubule by active transport
  • Nitrogen wastes, histamines, excess H+, and mineral levels are balanced
  • The secreted ions combine with the remaining filtrate becomes urine
29
Q

Flow Through a Nephron

Part D: Water Reabsorption - Collecting Duct

A
  • Water and urea may be reabsorbed (back into the blood)
  • Water reabsorption is controlled by hormones
  • If someone is dehydrated, more water must be reabsorbed back into the blood
30
Q

Kidneys and Blood pH

A
  • The blood pH is maintained by acid-base buffer systems
  • The most important acid-base buffer system is bicarbonate-carbon dixoide buffer system:
    H+ + HCO3- ↔ H2CO3 ↔ H2O + CO2
  • The kidneys help to maintain this balance by balancing H+ and HCO3-
  • If the blood is too acidic, H+ is excreted amd HCO3- is reabsorbed and returned to the blood
31
Q

Antidiuretic Hormone (ADH)

A
  • Made in your hypothalamus and stored and releases from your pituitary gland
  • Helps regulate the water balance by controlling the amount of water your kidneys reabsorb
  • More ADH released when dehydrated, excess salt intake or losing blood pressure
  • Makes the collecting duct more permeable to water
  • Kidneys hold onto more water instead of releasing it in your urine
32
Q

Aldosterone

A
  • Released from the adrenal glands in response to a drop in Na+ concentration, or an increase in potassium ions
  • Stimulates the distal tubule and collecting ducts to reabsorb Na+. The reabsorption of Na+ is followed by Cl- and water, therefore has a net effect of retaining both salt and water
  • Also promotes the secretion of K+ into the tubule

Biology 20 IB (10 decks)

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