Lesson 9.1: The Importance of an Organ Delivery System

Animals require a continuous supply of oxygen (O2) for cellular respiration, and they must expel carbon dioxide (CO2), the waste product of this process.

It is important not to confuse gas exchange, the traffic of O2& CO2 between the animal & its environment, with the metabolic process of cellular respiration.

gas exchange supports cellular respiration by supplying O2& removing CO2

The Earth’s atmosphere is composed of 21% oxygen

the source of oxygen, called the respiratory medium, is air for terrestrial animals, & water for aquatic animals

four activities involved

1. movement of air through the respiratory passages and lungs

2. diffusion of O2 and CO2 between the lungs & the blood in the transport system

3. transportation of the O2 and CO2 by the blood to the body cells

4. diffusion of the O2 and CO2 between the blood and the body cells

Breathing-process of exchange of air between the lungs and the environment

The uptake of O2 and the release of CO2 by cells takes place across a respiratory membrane

Respiration-all processes involved in the exchange of O2 and CO2 between cells and the environment, including breathing, gas exchange, and cellular respiration

Upper Respiratory Tract

oral passage

partial warming & moistening of air

nasal passages

moistens air

warms air

filters air

pharynx

nasal pharynx

oral pharynx

both join to connect to the trachea & esophagus

epiglottis

prevents material from entering the trachea

trachea (upper region)

reinforced with rings of cartilage

prevents the tube from collapsing; i.e. it is always open

larynx

enlarged area of the trachea

contains the vocal cords

Lower Respiratory Tract trachea (lower region) lined with cilia that move particles up

mucous secreting cells that trap foreign matter

moved out by the cilia

bronchi two branches from the trachea

one to left lung, one to right lung

cartilage ring reinforced

bronchioles further divisions of bronchi

no cartilage reinforcement

terminal bronchioles final divisions of bronchioles

alveoli composed of alveolar ducts and sacs at the end

of the terminal bronchioles

site of O2 and CO2 gas exchange

pulmonary capillaries part of the circulatory system

very small and very numerous

great surface area

very intimate contact with alveoli

minimum diffusion distance

Air enters the body through the nasal cavity or the mouth

Foreign particles are blocked entry by nasal hairs (act as a filter)

Nasal cavity warms and moistens incoming air

Mucus traps particles and keeps cells lining the nasal cavity moist

Nasal cavities open into the pharynx

Pharynx branches into 2 openings Trachea

Esophagus

Trachea AKA windpipe

Cilia (hair-like structures) line the trachea

Debris gets swept by cilia from the trachea to the pharynx

Bands of cartilage keep the trachea open

Esophagus

Trachea

Taken from Nucleus medical media

Enlarged section of cartilage (larynx), supports the epiglottis

Larynx (AKA voicebox) The epiglottis is a flap-like structure

which covers the trachea when food is being swallowed

Air from pharynx enters larynx

Contains 2 thin sheets of elastic ligaments (vocal cords)

Cords vibrate as air is forced past them

Larynx is protected by thick cartilage (Adam’s apple)

Inhaled air moves from the trachea to the 2 bronchi

Carry air into the right and left lungs, where they branch into smaller airways called bronchioles Bronchioles-

smallest passageways of the respiratory tract, without cartilage

The lining of the bronchi and bronchioles have ciliated cells and mucus secreting cells.

cilia beat together about 20 times/s to move dirt trapping mucus toward the pharynx

ensures clean air passages & alveoli

Air moves from the bronchioles into tiny sacs, alveoli

Each sac is surrounded by capillaries

Gases diffuse between the air and blood from high concentration to low

Oxygen moves from the air in the alveoli into the capillaries

CO2 moves from the capillaries into the air in the alveoli

Contain one layer of cells to allow rapid gas exchange

150 million/lung

Outer surface of the lungs and the chest cavity are surrounded by the pleural membrane

Space between pleural membranes is filled with fluid to reduce friction during inhalation

Dome shaped muscle, separating the chest cavity from the abdominal cavity

Regulates pressure in the chest

Exhalation Diaphragm relaxes

and returns to dome shape due to the force exerted by the organs in the abdomen

Chest volume decreases and pressure increases

Pressure in lungs is greater than Pat, air moves out of the lungs

Inhalation Diaphragm

contracts, shortens and pulls down

Chest volume increases and pressure in the lungs decreases

Pat is greater than pressure in chest, air moves into lungs

Pg. 287

Questions 1-4, 6-9

Bill Nye-Part 1

9.2

Gases diffuse from high pressure to low pressure

Dalton’s law of partial pressure-each gas in a mixture exerts its own pressure, or partial pressure

Partial pressure of oxygen in the blood depends on location

Atmospheric air follows the following path to enter the blood stream. Oral/Nasal Cavity Pharynx Larynx

Trachea Bronchus Bronchioles Alveoli Blood Stream

Hemoglobin-increases oxygen carrying capacity of the blood Heme (iron) and globin (protein)

Each heme contains an iron atom which binds with oxygen

Oxyhemoglobin-hemoglobin that is bound to oxygen, allows oxygen to be dissolved into the plasma

20 times more soluble than oxygen

Small amount (9%) produced by body is carried in the plasma

27% combines with hemoglobin

Majority (64%) combines with H2O to form carbonic acid H2CO3

Carbonic anhydrase speeds up the conversion of CO2 to H2CO3

Maintains a low partial pressure of CO2, allowing it to diffuse into the blood

Carbonic acid problematic, needs to be buffered

Carbonic acid dissociates into bicarbonate ions (HCO-

3) and hydrogen ions (H+) H2CO3 H+ + HCO-

3

Hemoglobin combines with hydrogen ions, neutralizing the acidity

The venous blood reaches the lungs where oxygen dislodges the H+ from the hemoglobin sites

Free hydrogen and bicarbonate ions combine to form CO2 and H2O

The CO2 is eliminated during exhalation

Three physical factors affects the rate of gas exchange across the respiratory surface...

1. the area of the respiratory surface the larger the area the greater the

exchange

2. the concentration difference the greater the difference between O2

concentrations in the air, the lungs, & in the blood, the more rapid the rate of diffusion (same principle applies for CO2 exchange)

3. the diffusion distance the thinner the respiratory surface, the

faster the rate of diffusion across it... human lung alveoli and capillaries are only

one-cell thick

Pg. 288

Questions 1-2

Pg. 291

Questions1-5

Bill Nye-Part 2