Respiration

Principles of Gas Exchange in Animals

Gases diffuse across a moist respiratory surface (easy when aquatic--> various adaptations for life on land)

Gases move from areas of high partial pressure to areas of low partial pressure

Rate of diffusion related to surface area

Uptake of O2 from environment and discharge of CO2 to environment

Gas Exchange in Animals

Fish

LUNGS

Insects

O2/CO2 exchange completed in trachea

Works great because insects are small--> don't have to expend a lot of energy--> can get away with this kind of system

Trachea: air tubes that branch out through the body

Branches found close to every cell in body (like capillaries)

connected to environment by pores (how O2 comes in)

Hemolymph lacks red blood cells, distributes nutrients, and collects waste

Gas exchange separate from circulatory system

Processing of Accessing oxygen through water

Gills have a large surface area for gas exchange--> makes it efficient

Countercurrent exchange

Water contains less O2 than air--> adaptations for efficient gas exchange

water travels across pharyngeal slits, over the gills, and out

Water going over gills leads to gas exchange

water comes in through mouth

Blood and water travel in opposite directions

O2 content in blood always lower than in water--> water always diffusing into blood and CO2 always out

Maximizes gas exchange efficiency

Partial or sole means of gas exchanges for tetrapods (no trachea but some can still breathe through skin like amphibians)

Linked with circulatory system for delivery of O2 and disposal of CO2

Breathing on Land

Localized gas exchange in one part of the body

Mammalian Respiratory Sytem

Breathing in Birds

2 cycles of inhalation and exhalation to complete circuit

Air flow is unidirectional--> oxygenated and deoxygenated air barely interact

Air sacs act as bellows to keep air moving

Air forced into lungs

breathe in again--> air goes into anterior air sacs

Air goes into posterior air sacs

Breathe out

Breathe in--> air in through thracea

Alveoli: air sacs at tips of bronchioles

Epithelium in bronchioles covered in cilia and mucus

Negative Pressure Breathing

Air enters, filtered by nose hairs

See gas exchange with circulatory system occur here

O2 out of lungs into blood, CO2 out of blood into lungs

Covered in capillary beds

Air rushes into lungs (inhalation!)

Muscles relax

Gas flows from high pressure to low pressure

Thoracic cavity shrinks (rib cage in and diaphragm up)

Leads to lower pressure in lungs (relative to environment)

Forces CO2 rich air out of body (exhalation)

Muscular contractions expand thoracic cavity

Negative Pressure is Made By

Diaphragm pulls thoracic cavity down

Muscles in rib cage pull thoracic cavity out

Circulation and Gas Exchange

Regulating gas exchange in Mammals

Circulation and Gas Exchange

Distributing Oxygen: Hemoglobin

Binding changes affinity of hemoglobin for O2--> once one binds more are more likely to start binding

Each iron atom bonds a single oxygen molecule: 4 oxygen molecules can be moved with one unit of hemoglobin

CO2 production promotes O2 unloading

4 subunits have heme group that has iron atom

Removing CO2

Found in all vertebrates, and some invertebrates

iron is binding site for oxygen

Iron atom does all the work

Lots of CO2 in organs, not a lot in capillaries

Change in blood pH increases release of O2 from hemoglobin

Gradient differs in body parts than in lungs

Process of Removal:

CO2 is the waste product of Cellular Respiration

~20% binds to proteins in hemoglobin (NOT TO IRON)

~73% diffuses into red blood cells, converts to HCO3, travels to lungs this way

~7% dissolves into plasma and will travel to lungs that way

Breathed out

converted back into CO2 at lungs

pH of cerebrospinal fluid indicates CO2 levels (H from HCO3 lowers pH)

As metabolic activity increases, decrease in pH leads to signal to increase breathing

Breathing is controlled by medulla oblongata

O2 diffuses into interstitial fluid then into tissue itself (determined by gradient)

CO2 diffuses into interstitial fluid then into blood (determined by gradient)

O2 rich blood travels through body and encounters O2 poor tissue

O2 poor blood + CO2 travels back to heart

CO2 diffuses into Alveoli based on gradient

Blood in capillaries have a higher CO2 concentration than blood in alveoli--> diffuse based on gradient

Oxygen diffuses into capillaries based on gradient

O2 diffuses into blood from alveoli based on gradient

Air in alveoli: higher in oxygen than capillaries

Air exhaled: high in CO2

Air inhaled: high in oxygen