Gas Exchange

By:An indian and a

jew

Respiratory structures are adapted for gas exchange in air or water. ◦ External Gas exchange, creature uses their body surface for gas

exchange◦ Gills are adapted for respiration in water◦ Trachea and lungs are adapted for terrestrial respiration

All respiratory systems must be: (1) Moist (2)Thin(3)Large in relation to the body.

How it all started

Cell respiration releases energy in the form of ATP so that this energy can be used inside the cell.

Cell respiration occurs in the mitochondria and cytoplasm of cells.

Oxygen is used in this process and carbon dioxide is produced.

Cellular Respiration

Small animals with a large body surface use this and exchange gas externally

Is not very efficient but is good enough to support small animals.

Hydras and worms use this.

External Gas Exchange

Gills are outward extensions of the pharynx

Adapted by marine animals for gathering oxygen in water.

Fish use Countercurrent exchange-O2 rich water goes in the opposite

direction of O2 poor blood.

Concurrent Exchange- O2 rich water goes in the same direction as O2

poor blood.

Countercurrent Exchange is more effective in extracting H2O.

Uses much more energy than lungs.

Fish Lungs A.K.A Gills

Fish Lungs A.K.A Gills

Tracheae- Tiny air tubes that take oxygen directly to the cells.

Tracheoles- tinnier air tubes that branch off from Tracheae

Walls lined with chitin for support.

Used by bugs and other small terrestrials.

Not very efficient

Tracheal System

It is fairly effective and costs very little energy to operate since oxygen is abundant in the air

Uses some muscles and pressure to easily manipulate gases.

Actually has more surface area than most body parts.

Is controlled by the brain.

Lungs

Respiration- The sequence of events that result in gas exchange between the body’s

cells and the environment.

External Respiration- The gas exchange between the air and the blood within the

lungs. Blood transports oxygen from the lungs to the tissues.

Internal Respiration- The gas exchange between the blood and the tissue fluid. Blood

then transports CO2 to the lungs.

Ventilation- The inspiration and expiration of air. The exchange of gas between the

lungs and the atmosphere. (A.K.A Breathing)

Inspiration-The act of moving air into the lungs.

Expiration-The act of moving air out of the lungs.

Some words you need to know.

Cont.…

 Ventilation Organs

1. The Nasal Cavity takes in air.2. The pharynx  filters, warms, and moistens air and conducts it into

the lungs.3. Air goes to the glottis (when the epiglottis is closed), then to the larynx,

and then into the trachea.4. Then it splits into 2 Bronchi which enter the Lungs, and then they split

into many bronchioles with alveoli at the ends.5. There is a huge capillary network in the lungs that surrounds the

alveoli for gas exchange.6. Blood delivers the oxygen to the tissues and bring back CO2 to lungs.

It is involuntary and the respiratory centers in the medulla oblongata control it. Can be influenced by nervous and chemical input.

Ventilation

Is located in the medulla oblongata and controls respiration.

It is sensitive to H+. When the pH decreases from an increase in H+ it increases our breathing rate.

It detects H+ through receptors in the body.

Chemoreceptors called Carotid bodies (Carotid arteries) and Aortic bodies (Aorta).

Respiratory Centers

It is a horizontal muscle that divides the thoracic cavity from the abdominal cavity.

Inspiration- It contracts and goes down and the chest moves up.

Expiration- It relaxes and goes up and the chests moves down.

Plays an important function in maintaining pressure in the lungs.

Diaphragm

Inhalation:

The external intercostal muscles contract. This moves the ribcage up and out. 

The diaphragm contracts. As it does so it moves down and becomes relatively

flat. 

Both of these muscle contractions result in an increase in the volume of the

thorax which in turn results in a drop in pressure inside the thorax.

Pressure eventually drops below atmospheric pressure. 

Air then flow into the lungs from outside the body, through the mouth or nose,

trachea, bronchi and bronchioles. 

Air continues to enter the lungs until the pressure inside the lungs rises to

the atmospheric pressure.

Ventilation Cont.…

Exhalation:  The internal intercostal muscles contract. This moves the ribcage down and in.  The abdominal muscles contract. This pushes the diaphragm up, back into a

dome shape.  Both of these muscle contractions result in a decrease in the volume of the

thorax.  As a result of the decrease in volume, the pressure inside the thorax increases.  Eventually the pressure rises above atmospheric pressure. Air then flows out of the lungs to outside of the body through the nose or mouth.  Air continues to flow out of the lungs until the pressure in the lungs has

fallen back to atmospheric pressure.- http://www.youtube.com/watch?v=dTsUyXXudvA (Breathing)

Ventilation Cont.…

1) To maintain the concentration gradients of oxygen and carbon dioxide in the alveoli. 

2) The body needs oxygen to make ATP via cell respiration.3) The body needs to get rid of carbon dioxide, a product of cell

respiration.4) Oxygen needs to diffuse from the alveoli into the blood. Carbon

dioxide needs to diffuse from the blood into the alveoli.5) To do so there must be a high oxygen concentration and a low

carbon dioxide concentration in the alveoli. 6) A ventilation system makes this possible by getting rid of the carbon

dioxide in the alveoli and bringing in more oxygen.

Why you need to Ventilate

Gas exchange is the biological process of swapping one gas for another. (What happens in the alveoli)

Oxygen diffuses into the capillaries from the air in the alveoli and carbon dioxide diffuses out of the capillaries and into the air in the alveoli. 

It occurs in the alveoli in the lungs.

Gases have partial pressures, which exert pressure on other things.

Gas Exchange

Great numbers of them increase the surface area for gas exchange.

Wall made up of single layer of cells and so are the walls of the

capillaries so diffusion distance is small allowing rapid gas exchange. 

Covered by a dense network of capillaries which have low oxygen

and high carbon dioxide concentrations. This allows oxygen to diffuse

into the blood and carbon dioxide to diffuse out of the blood.  

Some cells in the walls secret fluid allowing gases to dissolve. The

fluid also prevents the sides of alveoli from sticking together.

Alveoli and their Special Features

Hemoglobin (Hb)-A special molecule that has a special part in aiding our

breathing. Commonly forms bonds with oxygen and CO2

Oxyhemoglobin (HbO2)-Used by RBCs to carry oxygen. (Common)

Carbonic anhydrase- is an enzyme that speeds up the breakdown of carbonic

acid and the formation of bicarbonate ions.

Bicarbonate ion (HCO3-)-The from in which Carbon is transported in the blood.

(common)

Carbaminohemoglobin(HbCO2)-Some carbons from bonds with hemoglobin to

form this. (Rare)

Reduced hemoglobin-(HbH+)- maintains your body’s ph.

Reactions with Hemoglobin

Exhale: HbO2 separates when blood reaches the tissues where it

diffuses and releases the oxygen. The CO2 then either attaches to the

Hb and forms HbCO2 or CO2 combines with water to form Carbonic

acid (H2CO3) which dissolves into H+ and a Bicarbonate ion

(HCO3-).

Inhale: The H+ and HCO3- combine into carbonic acid and form water

and CO2, which is catalyzed by carbonic anhydrase, and is then

expired. The O2 comes in and forms HbO2 with the Hemoglobin. http://www.youtube.com/watch?v=QP8ImP6NCk8 (Hemoglobin)

Cont.…

Bicarbonate Ion- HCO3- acts as a buffer so the blood will not get too acidic. The reaction is reversed when the blood reaches the lungs. Bohr Shift: The more CO2 in the blood, the more acidic (low pH) the blood

becomes. Decreasing the pH causes hemoglobin to release its’ oxygen easier. This is needed during exercise to supply the body with O2.

Bohr Shift

Bronchitis-Infection of the Bronchi, treatable. Pneumonia- Your lungs are filled with bacteria due to an infection,

treatable. Pulmonary Tuberculosis- Caused by tubercle bacillus(a

bacterium), treatable. Carbon Monoxide (CO)-poisonous because it forms strong bonds

with Hemoglobin and is difficult to remove, incurable. Asthma- disorder caused by really sensitive airways, causes

spasms, incurable, treatable. Emphysema-Damaged alveoli cause lack of oxygen, incurable,

harmful. Lung Cancer=Some bad cellsTumorMetastasis GG. Smoking=BAD

Dangerous Stuff Bro…

Any questions?