8.2 The Mammalian Respiratory System

The Respiratory System

Respiration: The exchange of oxygen & carbon dioxide between an organism & its external environment.

The respiratory system supplies oxygen to cells & removes carbon dioxide.

Components of Respiration

Breathing (Ventilation) External Respiration Internal Respiration Cellular Respiration

Breathing (Ventilation) Inhalation: Oxygen is taken in from the

external environment. Exhalation: Carbon dioxide is removed

from the internal environment.

External Respiration

Gas exchange between the alveoli & blood. Oxygen diffuses into the alveoli & carbon

dioxide diffuses out. The alveoli must be

moist to allow for diffusion.

The blood carries the oxygen from the lungs to the body cells.

External Respiration

Internal Respiration

Gas exchange between the blood &the body cells.

Oxygen diffuses out of the blood & carbon dioxide diffuses in.

Allows cellular respiration to occur.

Cellular Respiration

Occurs in the mitochondria of every cell. Cells produce energy (ATP) when glucose

is broken down in the presence of oxygen. Byproducts

include carbon dioxide & water

Anatomy of the Respiratory System

Analogous to an upside-down tree. Components:

Nose Nasal & oral cavities Pharynx Larynx Trachea Bronchi & bronchioles Alveoli

Respiratory Basics - Learning Activity - Flash Player Installation

The Upper Respiratory Tract1. NoseStructure: Two nostrils separated

by cartilage and soft bone

Functions: Air that is breathed in through the nose is:

a) Warmed by heat in the capillaries in the nose

b) Dampened when it passes over the mucus lining of the nose

c) Cleaned by cilia that sweep dirt into the mucus

d) Filtered by hairs that remove large particles

2. Pharynx (throat)Structure: a muscular tubeFunction: the pharynx is necessary for:

a) breathing: the pharynx connects the 2 nasal passages to the larynx which leads to the tracheab) maintaining air pressure: the Eustachain tube is found in the middle ear and opens into the pharynx and is able to equalize the pressure inside the ear to atmospheric pressurec) Swallowing: during swallowing, the soft palate rises to block the opening to the nose. A small flap of cartilage, the epiglottis, slides closed to cover the entrance to the trachea.

3. LarynxStructure: -the first part of the trachea

- contains tightly stretched cords (vocal cords)

- while breathing they lie against the wall, while speaking they move forward

Function: forcing air over them causes the cords to vibrate and allows us to speak

the loudness is determined by how hard we breathe out

the pitch is determined by how tight the cords are

the quality is determined by amplifiers (mouth, nose, lungs)

N.B. Men have longer vocal cords therefore their voices are lower

4. TracheaStructure: a 10 cm tube extending from the

larynx to the branches of the bronchi

All breathing tubes are held open by C-shaped rings of cartilage that prevent the tubes from collapsing

Function: passage way

for air

The Lower Respiratory Tract5. BronchiStructure: the base of the

trachea divides into 2 tubes called bronchi

-one bronchus goes into the left lung and one to the right lung

-inside the lungs, the bronchi branch out into smaller tubes called bronchioles which spread all over the lungs

Function: passageway for air

6. AlveoliStructure: inside of our two lungs are 300

million air sacs called alveoli, found in clusters at the ends of bronchioles (allows more surface area)- each alveolus is surrounded by blood capillaries- each alveolus is covered in a film of moisture

Function: the oxygen in the air that enters the alveoli during inhalation dissolves in the moisture and diffuses into the capillaries- the O2 is absorbed by molecules of hemoglobin, a pigment in red blood cells, and transported to the heart.- CO2 dissolved in water, passes from the capillaries into the alveoli to be breathed out

Therefore, this process is called gas exchange, and the two systems involved are the alveoli and the capillaries.

Alveoli

7. LungsStructure: 2 large spongy organs

that fill nearly the entire thoracic

cavity (chest)

- the left lung is slightly smaller

(2 lobes) b/c the heart sits on it,

whereas the right lung has 3 lobes

- the lungs contain the bronchi, bronchioles, alveoli, and capillaries

- enveloped in layers of tissue called pleura

Function: expand and contract to fill up with gas

8. Pleura

Structure: a membrane (sac) that covers the lungs

- between the pleura and the lungs is a fluid that acts as a lubricant

Function: applies pressure equally to all parts of the lungs allowing inhalation and exhalation

Animation: The Pleural Membranes

Pleurisy: Inflammation of the pleura that causes when you take a breath or cough; the smooth lining of the lungs becomes rough

Pleural effusion: fluid collecting around

the lungs; resulting

from TB infections

How is O2 taken up?1. Oxygen diffuses to the cells

of the capillaries, to the blood plasma, and then across the cell membranes of red blood cells

2. In the red blood cells, the oxygen forms a bond with hemoglobin.

Hemoglobin + O2 oxyhemoglobin (HbO2 -)

3. The red blood cells circulate rapidly in the bloodstream transporting oxygen to all body cells. (A very small amount of dissolved O2 is carried in blood plasma)

How is CO2 removed?1. Diffusion from cells to the

blood ~ 9% is held in the plasma

2. About 27% attaches to hemoglobin and is carried by RBCs to lungs

3. 64% combines with water to form bicarbonate (HCO3) and hydrogen ions (H+)

CO2 + H2O H2CO3

H2CO3 H+ + HCO3

Hydrogen ions are very reactive and can be fatal in high concentrations therefore they must be removed

The H+ is taken up by oxyhemoglobin. When this happens, the oxygen is released by the oxyhemoglobin and goes into the cells to be used for cellular respiration.

The H+ then react with HCO3 releasing CO2 and H2O which are both released by the lungs.

Respiratory system | Flash simulation, Animation, Illustration, Picture, Diagram