Gas ExchangeRespiratory System – Chapter 22

Bozeman – Intro to the Respiratory System

Surviving Thin Air

The high mountains of the Himalayas

Have claimed the lives of even the world’stop mountain climbers

The air at the height of the world’s highest peak,Mt. Everest

Is so low in oxygen that mostpeople would pass outinstantly if exposed to it

Surviving Thin Air

Twice a year, flocks of geese migrate over the Himalayas

They are able to fly at such a high altitude because

of the efficiency of their lungs

These birds have blood with hemoglobin with a very

high affinity for oxygen

This adaptation allows them to carry large amounts

of oxygen to their tissues to exchange with carbon

dioxide

Standards

Core

I can outline the 4 major aspects of the process

respiration.

I can describe structure and function of the airway.

I can describe structure and function of alveoli.

I can describe the processes of inhalation and exhalation.

Advanced

I can outline the nervous control of breathing.

So what is Respiration?

The process of gas exchange,

often called respiration is the

interchange of O2 and CO2

between an organism and its

environment

Crash Course – Respiratory System Pt. 1

Mechanisms of Gas Exchange

There are three sequences of gas exchange; how

respiration occurs

1. Breathing

2. Transport of gases by the circulatory system

3. Exchange of gases with body cells

The Four major aspects of respiration

1. Breathing (inhaling and exhaling)

2. External respiration (gas exchange at the lungs)

3. Internal respiration (gas exchange at the tissues)

4. Cellular respiration (making ATP in cells)

22.2 – Animals exchange O2 and CO2

across moist body surfaces Animals have a respiratory surface which is

often moist.

This moist layer allows O2 and CO2 to

diffuse easily and quickly into the

circulatory system

Some animals, like the earthworm, use their

entire skin as a gas-exchange organ

In most animals specialized body parts

provide large respiratory surfaces for gas

exchange

22.3 Gills are adapted for gas exchange

in aquatic environments

In a fish, gas exchange is enhanced by ventilation and the countercurrent flow of

water and blood

22.4 The tracheal system of insects provides

direct exchange between the air and body

cells Land animals exchange gases

by breathing air

Tracheal systems in insects

Transport O2 directly

to body cells through a

network of finely

branched tubes

22.5 Terrestrial vertebrates have lungs

In mammals, air inhaled

through the nostrils, nasal

cavity, passes through the

pharynx and larynx into

the trachea, bronchi, and

bronchioles

22.5 Terrestrial vertebrates have lungs

The bronchioles end in clusters of tiny sacs called

alveoli and this is where gas exchange occurs

Connection: 22.6 Smoking is a deadly assaults

on our respiratory system

Mucus and cilia in the respiratory passages

Protect the lungs

Can be destroyed by smoking

A single drag on a cigarette exposes a person to over 4000 chemicals, 50 of

which are known carcinogens. People die 13-14 years younger.

Smoking can also cause emphysema; alveoli loose their elasticity and

deteriorate reducing lung capacity

22.7 Breathing ventilates the lungs

Breathing: is the alternation of inhalation and

exhalation

The contraction of rib muscles and the

diaphragm

Expands the chest cavity and reduces air

pressure in the alveoli (negative pressure

breathing)

Vital capacity is the maximum volume of air

we can inhale and exhale but our lungs still

hold a residual volume

22.7 Breathing ventilates the lungs

Air flows in one direction; through the more efficient lungs of birds

22.8 - Breathing is automatically

controlled

We can control some of our breathing but we

have automatic control centres that ensure

coordination between the circulatory system

and the respiratory system.

In your brain, there are areas called

Pons

Medulla Oblongata

The Medulla control centre signal the

diaphragm and rib muscles to contract

The pons smooths out the basic rhythm of

breathing set by the medulla

PH and CO2 levels

The medulla control centre monitors the CO2 levels in

the blood and regulates breathing rate in response.

The way it regulates the CO2 levels is by monitoring

pH levels

When CO2 increases your blood and Cerebralspinal Fluid

pH drop slightly

This is because the CO2 goes into the blood and reacts

with water to produce carbonic acid

This results in your medulla control centre sending a

signal to increase respiration and eliminate more CO2

pH and buffers – Negative Feedback Loop

Secondary control over breathing in the

Aorta!

There are sensors in your aorta and carotid artery that monitor

concentrations of O2 and CO2 that send messages to nerves which relay the

information to the medulla.

This may result in conditions of low oxygen, like high elevation.

Hyperventiation – suspends breathing because too much CO2 has removed

from the blood.

22.9 Blood transports respiratory gases

Transport of gases in the body

The heart pumps oxygen-poor blood to the lungs

Where it picks up O2 and drops off CO2

Then the heart pumps the oxygen-rich blood to body cells

Where it drops off O2 and picks up CO2

Gas transport and exchange in the body

Gases diffuse down partial-pressure gradients In the

lungs and the tissues

22.10 Hemoglobin carries O2 and helps

transport CO2 and buffer the blood

Hemoglobin in red blood cells

Consists of four polypeptides chains of two types

Attached to each polypeptide is a chemical group

called heme (green) at which the centre is a iron

group (black)

Every hemoglobin can carry up to four O2

molecules

Transports oxygen, helps buffer

the blood and carries some CO2

The partial pressure of oxygen in the tissue reflects

how much oxygen the cells are using

Crash Course – Respiratory System pt. 2

22.10 Hemoglobin carries O2 and helps

transport CO2 and buffer the blood

Most CO2 enters the red blood cells, where some combines with hemoglobin.

The rest reacts with water molecules forming carbonic acid

Red blood cells contain an enzyme that accelerates this reaction to break

them apart into hydrogen ion and a bicarbonate ions

Hemoglobin will then bind the H+ ion, minimizing the change in blood pH

Is transported as bicarbonate ions in the plasma, where they are carried to

the lungs

This process is reversed in the lungs so the CO2 diffuses from the alveoli to

the exhaled air

Words to know!

Oxyhemoglobin: O2 attached to hemoglobin

Carbaminohemoglobin – CO2 attached to hemoglobin

Reduced hemoglobin – once oxygen is released into

tissues from hemoglobin

Bicarbonate ions – is alkaline and helps buffering pH

Carbonic anhydrase – enzyme that balances the pH

of blood by converting CO2 and H20 into bicarbonate

ions and hydrogen ions

Connection - 20.11 – The human fetus exchanges gases

with the mother’s bloodstream

A human fetus exchanges gases with

maternal blood in the placenta

Fetal hemoglobin has a higher affinity

for oxygen transfer from maternal blood

At birth, increasing CO2 in the fetal

blood

Stimulates the breathing control

centers to initiate breathing

because the baby’s lungs are filled

with amniotic fluid.