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Unit 16 (Ch. 22) Gas Exchange & Excretion. How do organisms: Obtain oxygen and eliminate carbon dioxide? (or vice versa…in plants?) Maintain osmotic balance? Excrete nitrogenous waste products?. 300. Part 2. Excretion of metabolic waste & Maintenance of Osmotic Balance ch . 22.2.

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unit 16 ch 22 gas exchange excretion

Unit 16 (Ch. 22)Gas Exchange & Excretion

How do organisms:

Obtain oxygen and eliminate carbon dioxide?

(or vice versa…in plants?)

Maintain osmotic balance?

Excrete nitrogenous waste products?

300

Part 2

excretion
Excretion
  • What is excretion?
    • removal of wastes produced from metabolism of nutrients (& other non-useful materials)
      • CO2
      • excess water
      • nitrogenous waste
    • All metabolic wastes removed through excretory organs (nephridia, Malpighian tubules, kidneys)
      • exception = CO2, excreted with water vapor through lungs
excretion1
Excretion
  • Why must cellular wastes be removed?
    • can be toxic
  • Which life characteristic does excretion relate to?
    • homeostasis
nitrogenous waste
Nitrogenous Waste
  • mostly from protein metabolism
    • & some from nucleic acids
  • amino groups quickly pick up H
    • to become ammonia
      • highly toxic
      • may be excreted directly or converted to less toxic forms
        • urea
        • uric acid
nitrogenous wastes

How is the production of urea/uric acid an adaptation to life on land/dry environments?

Nitrogenous Wastes
  • ammonia
    • excreted by aquatic organisms
  • urea
    • excreted in small amount of water
      •  urine
  • uric acid
    • insoluble
    • excreted as crystals
      • in arid environments

H2O conservation

osmotic balance

Importance of H2O: reactions, part of blood, disperse heat

Osmotic Balance
  • concentration of dissolved particles in liquid inside & outside cell is the same (isotonic)
    • What if the concentrations are different?
      • hypotonic
        • cytolysis
      • hypertonic
        • plasmolysis
  • Adaptations for waste removal may also be responsible for maintaining osmotic balance
salt water organisms
excretion

ammonia is soluble

diffuses from (cells) into water

osmotic balance

naturally in balance

no special adaptations needed

SALT WATER ORGANISMS
fresh water organisms
excretion

waste diffuses from (cells) into water

osmotic balance

not naturally in balance (hypotonic environment)

Adaptations to help maintain?

contractile vacuole

ex. Paramecium

Fresh Water Organisms

Video of Paramecium--Contractile Vacuole

fresh water organisms1
Planaria

excretion of wastes & osmotic balance

system of excretory canals & flame cells

canals branch into excretory ducts

open as pores on the surface

Fresh Water Organisms
land animals
Land Animals
  • cannot diffuse ammonia
    • must convert to urea or uric acid
      • can safely build up in body fluids until excreted
  • wastes transported by blood or tissue fluid
  • system excretes N-wastes & is a factor in osmotic balance
    • H2O conservation emphasized

Uric acid

Uric acid

slide13

LAND ANIMALS: EARTHWORM

  • ammonia
    • diffuses through skin
      • into soil moisture
  • urea
    • eliminated through nephridia
      • filtering organs
slide14

LAND ANIMALS: GRASSHOPPER

  • Malpighian tubules
    • filter blood
    • reabsorb water
    • uric acid enters intestine
      • excreted thru anus
  • Why is ammonia converted uric acid (crystals)?
    • H2O conservation
slide15
Habitat?

desert

Can survive without drinking H2O.

How is this possible?

gets water from food

extremely efficient kidneys

reabsorbs almost all water that passes through them

excretes very concentrated urine

Land Animals: Kangaroo Rat

human excretion
Which parts of the human body carryout excretion?

lungs

CO2 & H2O (vapor)

skin

H2O & salts

= sweat

urinary system

urea, H2O, salts

= urine

Human Excretion
human excretion1
HUMAN EXCRETION
  • What are the parts of the urinary system?
        • kidneys (& associated blood vessels)
          • main excretory organ
        • ureters
        • (urinary) bladder
        • urethra
human excretion the kidney
HUMAN EXCRETION: THE KIDNEY
  • main excretory organ
  • 3 parts
    • outer part
      • cortex
    • inner layer
      • medulla
    • inner collecting area
      • pelvis
5 steps to how kidneys work
5 STEPS TO HOW KIDNEYS WORK
  • blood w/ waste brought to kidneys from renal artery
  • blood is filtered by nephrons (by diffusion)
  • wastes pass thru ureters to bladder as urine
  • clean blood sent back to body thru renal vein
  • bladder stores urine (until passes out of body thru urethra)

How Kidneys Work Video

1 million nephrons per kidney!!!

nephron
NEPHRON
  • What is a nephron?
    • functional unit of the kidney
      • responsible for filtration of waste from blood
  • ~1 million nephrons per kidney!!!
nephron structure
nephron consists of:

Bowman’s capsule

cup-shaped

surrounds glomerulus

narrows into coiled tubule

NEPHRON: STRUCTURE
nephron structure1
glomerulus

mass of capillaries in center of Bowman’s capsule that forms from branch of renal artery

carries unfiltered “waste-filled” blood to nephron

another arteriole loops away from glomerulus & divides into capillaries that surround tubule

NEPHRON: STRUCTURE
nephron structure2
capillaries surround tubule

merge to form venules & veins

which merge to form renal vein which returns filtered blood back to body

NEPHRON: STRUCTURE
processes in the nephron
PROCESSES IN THE NEPHRON
  • filtration of blood/ urine production
    • requires three distinct processes:
      • glomerular filtration
      • tubular reabsorption
      • tubular secretion
  • excretion of urine
processes in the nephron1
PROCESSES IN THE NEPHRON
  • 1. filtration
    • “waste-filled” blood brought to kidney by renal artery
      • blood pressure forces plasma from blood in glomerulus into Bowman’s capsule of nephron
        • this liquid =filtrate(water, urea, salts, glucose, amino acids & other dissolved materials)
      • large proteins & blood cells do not enter
processes in the nephron2
PROCESSES IN THE NEPHRON
  • 2. tubular reabsorption
    • filtrate travels through nephron in tubule
      • needed materials are reabsorbed into surrounding capillaries
        • ex. most of water, salts, glucose, vitamins, etc.
          • by active or passive transport
      • excess materials remain in the collecting duct
        • water , urea, salts
          • concentrated fluid = urine

tubule.

processes in the nephron3
PROCESSES IN THE NEPHRON
  • 3. tubular secretion
    • molecules present in blood in great excess (or natural poisons) may be removed from capillaries & transferred to tubules for excretion
      • often by active transport
        • ex. drugs such as antibiotics
      • “clean” blood sent back to body through renal vein
slide29
excretion

urine (urea, excess salt, small amount of water) leaves nephron & passes from collecting duct to renal pelvis

leaves kidney via ureters

to bladder where stored until once filled & urine is excreted through urethra (urination)

PROCESSES IN THE NEPHRON

How Kidneys Work Video

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