Why?
- All living things obtain the energy they need by metabolizing energy-rich compounds (e.g. carbohydrates and fats).
- In the majority of organisms, this metabolism takes place by respiration.
- Respiration requires oxygen to be transferred from the atmosphere into cells.
- Respiration also produces carbon dioxide gas as a waste product with needs to be exchanged from cells to atmosphere.
How?
Oxygen and carbon dioxide move by diffusion across moist membranes
Gas Exchange in Simple animals:
Gas Exchange in Simple animals:
- Directly from environment
- Skin must be moist
- Animals typically quite small
- e.g. Earth worms:
- Earthworms exchange oxygen and carbon dioxide directly through their skin.
- The oxygen diffuses into tiny blood vessels in the skin surface, where it combines with the red pigment hemoglobin.
- Hemoglobin binds loosely to oxygen and carries it through the animal’s bloodstream.
- Carbon dioxide is transported back to the skin by the hemoglobin.
Gas Exchange in Terrestrial Arthropods:
- Terrestrial arthropods have a series of openings called spiracles at the body surface.
- Spiracles open into tiny air tubes called tracheae,
- Tracheae expand into fine branches that extend into all parts of the arthropod body.
Gas Exchange in Fish:
A fish out of water:
How do Fish "Breathe"?
Two methods:
Anatomy of Gills:
Operculum: the covering over the gills (bony fish)
Opercular Cavity: The cavity beneath the operculum where filaments are located.
Gill Slits: slits in sides of cartilagenous fish such as sharks. Usually have 6 or 7 slits. (no operculum).
Filaments: leaf-like structures which project from the gill arch. Have a large surface area for diffusion.
Gill Plates: sheets of filaments, there are numerous of these to increase surface area.
Gill Arch: contains a large blood vessel to supply cappillaries that branch from it towards filaments
- There is less gaseous oxygen in water (approx. 10 parts per million) than in air (210000 parts per million).
- Fishes use outward extensions of their body surface called gills for gas exchange.
- Gills are flaps of tissue richly supplied with blood vessels.
- As a fish swims, it draws water into its mouth and across the gills.
- Oxygen diffuses out of the water into the blood vessels of the gill,
- Carbon dioxide leaves the blood vessels and enters the water passing by the gills.
A fish out of water:
- If fish are taken out of the water, their fine filaments clump together and the surface area is drastically reduced.
- The fish cannot diffuse enough oxygen and will suffocate.
How do Fish "Breathe"?
Two methods:
- Move through the water with their mouths open so that oxygenated water flows in, over their gills, and then out.
- Fish fill their mouths with water and then close their mouth and lift the floor of the mouth to force water over gills and out
Anatomy of Gills:
Operculum: the covering over the gills (bony fish)
Opercular Cavity: The cavity beneath the operculum where filaments are located.
Gill Slits: slits in sides of cartilagenous fish such as sharks. Usually have 6 or 7 slits. (no operculum).
Filaments: leaf-like structures which project from the gill arch. Have a large surface area for diffusion.
Gill Plates: sheets of filaments, there are numerous of these to increase surface area.
Gill Arch: contains a large blood vessel to supply cappillaries that branch from it towards filaments
Gas Exchange in Terrestrial Vertebrates:
Amphibians:
Reptiles:
Birds:
Mammals:
Salamander Frog Lizard Mammal Bird
Amphibians:
- Swallow air into their lungs, where oxygen diffuses into the blood to join with hemoglobin in the red blood cells.
- Can also exchange gases through their skin.
Reptiles:
- Have folded lungs to provide increased surface area for gas exchange.
- Rib muscles assist lung expansion and protect the lungs from injury.
Birds:
- Birds have large air spaces called air sacs in their lungs.
- When a bird inhales, its rib cage spreads apart and a partial vacuum is created in the lungs.
- Air rushes into the lungs and then into the air sacs, where most of the gas exchange occurs.
- This system is birds’ adaptation to the rigors of flight and their extensive metabolic demands.
Mammals:
- The lungs of mammals are divided into millions of microscopic air sacs called alveoli (the singular is alveolus).
- Each alveolus is surrounded by a rich network of blood vessels for transporting gases.
- In addition, mammals have a dome-shaped diaphragm that separates the thorax from the abdomen.
- Diaphragm provides a separate chest cavity for breathing and pumping blood.
- During inhalation, the diaphragm contracts and flattens to create a partial vacuum in the lungs.
- The lungs fill with air, and gas exchange follows.
Salamander Frog Lizard Mammal Bird
Mammalian Respiratory System:
The organs and tissues that comprise the human respiratory system include the:
Nose:
Pharynx:
Trachea:
Lungs:
The organs and tissues that comprise the human respiratory system include the:
Nose:
- Where air is conditioned by warming and moistening.
- Bone partitions separate the nasal cavity into chambers,
- Air swirls about in currents within chambers (getting warmer, moister and purified).
- Hairs and hairlike cilia trap dust particles and purify the air.
Pharynx:
- The nasal chambers open into a called the pharynx.
- From the pharynx, two tubes called Eustachian tubes open to the middle ear to equalize air pressure there.
- The pharynx also contains tonsils and adenoids, which are pockets of lymphatic tissue used to trap and filter microorganisms.
Trachea:
- The trachea has a framework of smooth muscle with about 16 to 20 open rings of cartilage shaped like a C.
- These rings give rigidity to the trachea and ensure that it remains open.
- The opening to the trachea is a slitlike structure called the glottis.
- A thin flap of tissue called the epiglottis folds over the opening during swallowing and prevents food from entering the trachea,
- The trachea branches into two large bronchi (singular, bronchus).
- Bronchi also have smooth muscle and cartilage rings.
- The bronchi branch into smaller bronchioles, forming a bronchial “tree.” The bronchioles terminate in the alveoli.
Lungs:
- Composed of approximately 300 million alveoli.
- Red blood cells pass through the capillaries in single file.
- Oxygen from each alveolus enters the red blood cells and binds to hemoglobin.
- Carbon dioxide contained in the plasma and red blood cells leaves the capillaries and enters the alveoli.
- Most carbon dioxide reaches the alveoli as bicarbonate ions.
- Rib muscles and diaphragm contract on inhalation - increasing the volume of the chest cavity, reducing air pressure so air rushes into the alveoli.
- Nerve activity controls breathing: A high carbon dioxide concentration leads to an increased number of nerve impulses and a more rapid breathing rate.
Take an Online Quiz:
Mechanisms for gas exchange:
https://www.cliffsnotes.com/study-guides/biology/biology/gas-exchange/quiz-mechanisms-for-gas-exchange
Human Respiratory System:
https://www.cliffsnotes.com/study-guides/biology/biology/gas-exchange/quiz-human-respiratory-system
COMPLETE:
Mechanisms for gas exchange:
https://www.cliffsnotes.com/study-guides/biology/biology/gas-exchange/quiz-mechanisms-for-gas-exchange
Human Respiratory System:
https://www.cliffsnotes.com/study-guides/biology/biology/gas-exchange/quiz-human-respiratory-system
COMPLETE:
- Read through pages 275-278 and take down any additional notes.
- Question set 11.3.
- Move onto Gas Exchange in Plants and then you can complete WACE Study guide Pages 123-125.
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