UNIT 16 (CH. 22)GAS EXCHANGE & EXCRETION

How do organisms:

Obtain oxygen and eliminate carbon dioxide?(or vice versa…in plants?)

Maintain osmotic balance?

Excrete nitrogenous waste products? 300

GAS EXCHANGE (CH 22.1)

♦What gases are exchanged ?♦O2

♦CO2

♦By which process are gases exchanged?♦diffusion

GAS EXCHANGE♦What conditions are required for gas exchanged?♦gas must be dissolved in a liquid♦large surface area

♦Why?♦to maximize exchange

♦protection of structures

♦Which system does the respiratory system often work with in animals?♦circulatory (transport) system

GAS EXCHANGE IN UNICELLULAR & SIMPLE MULTICELLULAR ORGANISMS♦How is gas

exchange carried out in simple organisms?♦diffusion

directly with moist environment

GAS EXCHANGE IN PLANTS♦Where does gas exchange occur in plants?♦no specialized gas transport

system b/c occurs @ different locations♦ roots

♦root hairs♦ stems

♦lenticels♦ leaves

♦ gases enter/exit through stomata and move into air spaces of spongy layer♦exchange occurs at moist surface of cells

surrounding air spaces

GAS EXCHANGE IN MORE COMPLEX ANIMALS♦Usually carried out by respiratory system.♦acquire O2 from

environment, distribute it through body, & discharge CO2

♦“respiration”

GAS EXCHANGE IN ANIMALS♦3 “types” of respiration:

♦external respiration:♦breathing

♦internal respiration:♦exchange of O2 & CO2 between air sacs & capillaries (or cells)

♦cellular respiration: ♦C6H12O6 + 6O2 → 6H2O + 6CO2

+ energy (ATP)

EARTHWORM♦gases diffuse through moist skin

GRASSHOPPER♦air enters spiracles (openings)

♦lead to tracheae (tubes)♦tracheae branch repeatedly

♦ending in moist tracheoles (air sacs)♦gas exchange (diffusion) – aided by muscle mvmt

FISH♦operculum or gill cover♦protection

♦H2O enters mouth & flows over gills♦CO2 diffuses

blood H2O

♦O2 diffuses H2O blood

♦ How does the amount of O2 dissolved in water change in relation to water temp.?

FISH

♦ Which of these descriptions best explains the decrease in the breathing rate of the goldfish?a) The demand for O2 increased. b) The rate of metabolic activity

decreased. c) The demand for CO2 decreased. d) The fish's activity levels

increased.

Virtual Fish Respiration Lab

RESPIRATION IN HUMANS♦What path does air follow when inhaling?♦nose → pharynx → larynx → trachea →

bronchi → bronchioles → alveoli♦gas exchange: alveoli ↔ capillaries

capillaries

How are alveoli an adaptation?

Gas Exchange Animation 1

Respiration Animation

Epiglottis

prevents food from

entering trachea.

What is the function of

the cartilaginou

s rings around the trachea?

HUMAN RESPIRATORY SYSTEM

capillaries

♦What happens in the lungs during gas exchange?♦alveoli have high level of O2 &

low level CO2

♦O2 diffuses from alveoli blood in capillaries (combines w/ hemoglobin in red blood cells)

♦blood in capillaries has high level of CO2 & low level of O2 ♦CO2 diffuses from blood alveoli

♦& is exhaled

RESPIRATION IN HUMANS

♦What happens in the cells/ tissues during gas exchange?♦cells/tissues have high level of

CO2 & low level of O2

♦CO2 diffuses from cells/tissues blood in capillaries

♦blood in capillaries has high level of O2 & low level of CO2

♦O2 diffuses from blood in capillaries cells/tissues

RESPIRATION IN HUMANS

Gas Exchange Animation 3

Gas Exchange Animation 2

Gas Exchange Animation 1

♦Do you have to remember to breathe?♦No, medulla

(brain stem) controls breathing.♦responds to blood’s CO2 levels♦CO2 too high breathe faster

RESPIRATION IN HUMANS

♦What happens to your breathing rate when you exercise? Why?

♦increases to adjust rate of gas exchange to needs of cells♦b/c CO2 levels increase & O2 decrease

RESPIRATION IN HUMANS

♦What happens to the diaphragm and ribs during inhalation?♦diaphragm contracts (pulls down/flattens)♦ribs raised (move up/out)

♦Does the chest cavity gets bigger or smaller?♦bigger (expands)

♦What happens to air pressure in the lungs?♦becomes lower inside than outside

♦Which way does air move?♦air rushes in

RESPIRATION IN HUMANS

♦ What happens to the diaphragm and ribs during exhalation?♦diaphragm is relaxed (pushes up/arches)♦ribs lowered (move down/in)

♦Does the chest cavity gets bigger or smaller?♦smaller (compresses)

♦What happens to air pressure in the lungs?

♦becomes higher inside than outside

♦Which way does air move?♦air rushes out

RESPIRATION IN HUMANS

RESPIRATION IN HUMANS: CONTROL OF BREATHING

Pressure higher inside, lower outside

Pressure higher outside, lower inside

Remember… “High, low…”

RESPIRATION IN HUMANS: CONTROL OF BREATHINGKid's Health Respiratory System & Breathing