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Teacherâs Instructions:
Pre-read pages 1 and 2 to become familiar with the teacherâs instructions, objectives, student tasks and references.
Activate studentsâ prior knowledge of respiration by guiding a class discussion as follows:
- ask students to breathe in and out deeply,
- ask âWhy do we breathe?â (answer: to get oxygen),
- ask âWhy do we need oxygen?â (answer: to live),
- help students arrive at the understanding that our bodies and cells need oxygen to convert the food that we eat into energy and use this energy to carry out our life processes,
- ask âWhat is respirationâ (answer: from âbreathingâ to âthe process by which living organisms take up oxygen, release carbon dioxide and produce energyâ).
Inform students that they will be learning the different parts of respiration (external, internal and cellular) while learning how fish and humans breathe.
Hand out copies of pages 2-15 to each student. Have students read page 2 to 4 (Objectives, Tasks and Key Terms).
Read the Background on pages 5-9 as a class pausing whenever necessary to clarify points or draw diagrams on the board.
Have students complete Activity A (pages 10, 11, 12) and Activity B (pages 10, 13, 14).
Have students complete the assignment on page 15.
Correct the activities and assignment using the Answer Keys on page 16-18.
Respiration:
External, Internal and Cellular
Fish vs. Human
Objectives:
Student Tasks:
- to distinguish between cellular, internal and external respiration.
- to identify major structures and functions of fish and human respiratory systems from a diagram, model or specimen.
- Participate in the class discussion.
- Read the background on pages 5-9 as a class and ask questions as necessary.
- Complete activities A and B on pages 10-14.
- Complete the assignment on page 15.
Respiration:
External, Internal and Cellular
Fish vs. Human
Freudenrich, C. How Your Lungs Work. Retrieved August 4, 2004 from: http://www.howstuffworks.com/lung.htm
Maastricht University: Department of Respiratory Medicine. Respiration. Retrieved August 4, 2004 from: http://www.pul.unimaas.nl/respir.htm
Maslin, P. (2000). Respiration in Fishes. Retrieved August 4, 2004 from: http://www.csuchico.edu/~pmaslin/ichthy/fshrsp.html
Taylor, M. (2002). Understanding Cellular Respiration. Retrieved August 4, 2004 from: http://tx.essortment.com/cellularrespira_rmpr.htm
References:
External, Internal and Cellular
Key Terms: (continued...)
interpleural fluid
pleura
interpleural fluid
pleura
ribs ribs
KEY TERM DEFINITION
interpleural fluid the fluid in between the pleural membranes of the lungs.
lamella a thin layer of bone or tissue in the gills.
larynx voice box where the vocal chords are located.
lungs elastic structures that bring air into the body.
nasal cavity a chamber located above the mouth and below the floor of the cranium that is enclosed by bone or cartilage.
pharynx section of the respiratory system that extends from the mouth and nasal cavity to the larynx.
pleura a thin membrane in mammals that surrounds each lung and folds back to (pleural membranes) make a lining for the chest cavity.
pulmonary capillaries small blood vessels that surround the alveoli.
respiratory system lungs, airways leading to lungs and chest, and structures responsible for the movement of air into and out of them.
ribs a series of long curved bones that extend from the spine to the sternum.
trachea rigid tube that connects the mouth with the bronchi, also called âwindpipeâ.
uvula a small, conical, fleshy mass of tissue suspended at the back of the mouth (the âhangy thingâ at the back of your mouth).
Background: Refer to the diagrams below and on page 6.
Respiration is a biochemical process by which living organisms take up oxygen, release carbon dioxide and produce energy. There are three main stages of respiration: external, internal and cellular.
For a yellow perch (or any species of fish), respiration begins when it opens its mouth to take in water. The water passes over a set of gills and the lamella direct the water over filaments. These filaments are attached to the gills and supplied with blood. The concentration of oxygen is higher in the water than in the blood so oxygen enters the blood and carbon dioxide leaves it. This is called external respiration.
The newly oxygenated blood is carried throughout the fishâs body. As this blood comes into contact with tissues that are low in oxygen, internal respiration occurs. Oxygen leaves the blood and enters the tissue. At the same time, carbon dioxide leaves the tissue and enters the blood.
Cells in the tissue use the oxygen to produce energy through cellular respiration. The energy produced is in the form of ATP (adenosine triphosphate) molecules. The balanced equation of cellular respiration is:
The carbon dioxide produced by cellular respiration enters the blood during internal respiration. The blood carries it to the filaments in the gills. Carbon dioxide leaves the blood during external respiration and is expelled in the water.
C H O 6 12 6 + 6H O + 6O 2 2 6CO 2 + 12H O + energy 2
gill capillaries
artery
heart
ventricle
atrium vein
tissue capillaries
External, Internal and Cellular
lung capillaries
left right
atrium^ atrium
ventricle^ ventricle
tissue capillaries
heart
For humans, respiration begins when we inhale. The chest cavity expands as the diaphragm and intercostal muscles contract. Air enters the lungs since the air pressure inside the lungs is less than the air pressure of the atmosphere. The chest cavity and lungs are surrounded with membranes called pleura. In between these membranes is a substance called interpleural fluid. These membranes and fluid preserve a vacuum in the chest and enables us to breathe. This vacuum ensures that our lungs inflate and deflate as the chest cavity expands and contracts.
Air enters the body and is warmed, moistened and filtered though the nasal cavity. Then it moves past the uvula and epiglottis. The exact function of the uvula is unknown. Some specialists say it plays a role in speech, swallowing and snoring. It may prevent food from going back up into your nose when you swallow and/or help prevent choking as it triggers the âgag reflexâ when something touches it. The epiglottis is a flap of tissue that covers the larynx and trachea when you swallow so that you donât choke.
Next the air travels through the pharynx, larynx and into the trachea. The pharynx is located at the back of the throat and leads to the larynx. The larynx contains the vocal chords and leads to the trachea. The trachea is lined with fine hairs called cilia which filter the air before it enters the lungs.
Background: Refer to the diagrams below and on page 9.
ribs
intercostal muscles
diaphragm
External, Internal and Cellular
After the trachea, the air passes through the bronchi and into the lungs. In the lungs, it follows narrower and narrower bronchioles until it reaches the alveoli. Alveoli are grape-like clusters that enable gas exchange to take place.
As air enters the alveoli, the oxygen concentration of the alveoli becomes higher than the oxygen concentration of the blood in the pulmonary capillaries. This allows the oxygen to pass or diffuse across the membrane of the alveoli into the blood. This is called external respiration. The hemoglobin in these capillaries has very little oxygen and a lot of carbon dioxide bound to it. Hemoglobin has an affinity for oxygen so it releases carbon dioxide and takes up the oxygen.
The newly oxygenated hemoglobin is transported in the blood throughout the body. Body tissues that are low in oxygen and high in carbon dioxide will take oxygen from and give carbon dioxide to the hemoglobin. This is called internal respiration.
The oxygen is used by the cells in the tissue to produce energy. This is called cellular respiration. The energy produced is in the form of ATP (adenosine triphosphate) molecules. The balanced equation of cellular respiration is:
The carbon dioxide produced by cellular respiration attaches to hemoglobin in the blood during internal respiration. The blood carries it to the alveoli in the lungs. Carbon dioxide leaves the blood and enters the alveoli during external respiration and is expelled when humans exhale. To exhale, the diaphragm moves up and the intercostal muscles relax. This chest cavity becomes smaller and air is forced out. The entire process of respiration happens very quickly - within seconds.
C H O 6 12 6 + 6H O + 6O 2 2 6CO 2 + 12H O + energy 2
intercostal muscles
diaphragm
ribs
Background: (continued...)
External, Internal and Cellular
Activity A:
Follow these steps to build models of the different parts of a fishâs respiratory system.
- Cut along all dotted lines on page 11.
- Cut out the hole for the gill (the white area on the fish).
- Glue or tape the gill on the spot indicated on the fish. Be sure to only glue part of the gill and leave part of it unglued so that it can move.
- Glue or tape the gill cover (operculum) on top of the gill. Be sure to only glue part of the gill cover and leave part of it unglued so that it can move.
- Arrange the stream water with the fish and gill so that it corresponds to the direction of water flow in the diagram on page 6.
- Fold the lamella on the dots so that they stand at a right angle to the filament, glue them together and arrange the stream of water so that it corresponds to the direction of water flow on the diagram on page 6.
- Use page 12 to glue down the fish and filament.
- Arrange the tissue, blood stream and cell on the paper and glue them down.
- Place oxygen and carbon dioxide arrows at the sites of external respiration, internal respiration and cellular respiration and label each site accordingly.
Activity B:
Follow the steps to build models of the different parts of a humanâs respiratory system.
- Cut along all dotted lines on page 13.
- Glue or tape the pieces in the correct order and location on the body outline or in the appropriate box on page 14.
- Label all the structures and write a brief description of their function on the back of the paper:
- lungs - ribs - nasal cavity - bronchioles
- pleura - epiglottis - bronchi - interpleural fluid
- alveoli - pharynx - diaphragm - pulmonary capillaries
- uvula - trachea - larynx - intercostal muscles
- Draw a âflow of airâ arrow and label the direction of oxygen and carbon dioxide flow.
- Place oxygen and carbon dioxide arrows at the sites of external respiration, internal respiration and cellular respiration and label each site accordingly (hint: one site of respiration will be in the body diagram and the other two sites will be in the boxes).
External, Internal and Cellular
glue gill here cut out
Activity A:
s tr a (^) e m of w ter (^) a
O 2
CO 2
O 2
CO 2
s tr a (^) e m O 2 o watef^ r
CO 2
b o l od s rea (^) t (^) m
cell
tissue
tissue
gill
gill cover
lamella
lamella filament
lamella
filament
lamella filament capillary
External, Internal and Cellular
tissue
Activity B:
O 2
CO 2
O 2
CO 2
O 2
CO 2
cell
b^ lood^ st e mr a
tissue
External, Internal and Cellular
Activity B:
Respiration
Respiration
2 CO
bl od streao (^) m
tissue
O^2
CO
2
Fil mena^
t
Ca illaryp Lam^ ella
W ter Fla^
ow
cell
tissue
CO
O^2
2
Respiration
FISH
Internal Respiration Cellular Respiration
External
Answer Key: Activity A
gill
gill cover
gill
O
2
Respiration
cell
tissue
CO
O^2 2
O
2
CO
2
Answer Key: Activity B
lungs
pleura
nasal cavity
epiglottis
bronchi
alveoli
diaphragm
interpleural fluid
phayrnx
larynx
trachea
uvula
ribs
intercostal muscles
pulmonary capillaries
Cellular
Respiration
tissue
O blood stream 2
CO
2
Internal
External Respiration
bronchiole
