GEN BIO 2 | Gas Exchange

Note: flashcards about gas circulation are in the circulatory system set.

Gas Exchange

uptake of molecular O2 from the environment and the discharge of CO2 to the environment

External Respiration

gas exchange between the air and the blood within the lungs

Internal Respiration

gas exchange between the blood and tissue through the interstitial fluid

Respiratory Surfaces

• each consists of a thin, moist membrane

• the surface area must be relatively large

• rate of diffusion varies in air and in water

  • aquatic animals have to expend more energy for oxygen compared to terrestrial animals

Respiratory Medium

environmental substance with which an animal exchanges gases can be either water or air

Water as the Respiratory Medium

• high viscosity; more difficult to move

• slower diffusion rates for gases

• low O2 concentration; varies with flow rate and temperature

  • warm water and stagnant water holds less oxygen compared to cold water and flowing water

Air as the Respiratory Medium

• low viscosity, easier to move

• higher diffusion rate for gases

• higher O2 concentration

• O2 concentration constant at a given altitude

Fish Kill

sudden and unexpected death of aquatic animals in a short period of time

Respiratory Surfaces in Hydras

the cells are close enough to the external environment as the outer layer of its cells in contact with the environment and the inner layer can exchange gases with the water in the gastrovascular cavity

Respiratory Surfaces in Earthworms

they use their body surface/skin as the capillaries between the skin come close to the surface and facilitate gas exchange, they secrete mucus to keep their skin moist

Respiratory Surfaces in Insects

insects have a system of air tubes called tracheae where oxygen is delivered directly to the cells without entering the blood, air sacs are located at the abdomen, wings, and legs

Spiracles

tracheae connect to the atmosphere through these

Respiratory Surfaces of Aquatic Vertebrates

they have gills that extract oxygen from a watery environment

Gills

outfoldings of the body surface that are suspended in the water that exchange gases across a thin layer of epithelium

Respiratory Surfaces in Humans and Terrestrial Vertebrates

their lungs, sac-like organs, contains a moist internal respiratory surface, not in direct contact with all parts of the body, allowing the circulatory system to aid in gas exchange

Ventilation

process of air flowing into the lungs during inspiration/inhalation and out of the lungs during expiration/exhalation

Positive Pressure Breathing

• for amphibians, inflation of the lungs with forced air flow

• the floor of their oral cavity is lowered as air is drawn into its nostrils with its mouth shut

• floor of the oral cavity is raised and forces air into the lungs

• air is expelled when the body wall contracts and the lungs recoil

One-Way Ventilation

• for birds, one-way flow of air through a bird’s lungs increases the efficiency of gas exchange

• air is inhaled into the posterior air sacs

• during exhalation, air moves through tiny tubes

• as air is inhaled again, air goes into the anterior lungs

• air exits the air sacs

Negative Pressure Breathing

• the breathing done by mammals

  • pulling air into the lungs

Respiratory Cycle | Inhalation

• low pressure in the lungs

• rib cage expands chest cavity

• lungs expand to draw in air

• muscles in diaphragm contract

Respiratory Cycle | Exhalation

• high pressure in the lungs

• lungs and chest cavity go back to original pressures and positions

• rib cage allows lungs to recoil to expel air

• muscles in diaphragm relax

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Respiratory Pigment

any molecule that increases the oxygen carrying capacity of blood

Blood Proteins

• hemoglobin

• hemocyanin

• chlorocruorin

• hemorythrin

Hemoglobin

• red in color

• most common in humans and vertebrates

• each contains four polypeptide chains, folded around the iron-containing group heme

• oxygen diffuses into the blood and binds to this molecule

• 250 million of them in one blood cell

Oxyhemoglobin

a molecule where oxygen is bound to one or more of the heme groups

Hemocyanin

blue in color

Chlorocruorin

green in colorH

Hemorythrin

purple to pink in color

Olfaction

breathing moves air across the nose’s olfactory epithelium, which detects odors

Production of sounds

movement of air across the vocal cords in the larynx

Maintenance of homeostasis

breathing volume and rate determine the concentration of CO2 in blood, which balances and affects blood pH

Human Respiratory Tract

1. Nasal Cavity

2. Pharynx

3. Larynx

4. Trachea

5. Bronchi

6. Bronchiole

Nasal Cavity

how air enters the respiratory tract and where it is moistened and warmed

Pharynx

Also known as the throat, air continues here after the nasal cavity.

Larynx

Also known as the voice box, it is where the vocal chords are located. It also directs food towards the esophagus.

Glottis

A slit-like opening where air passes through and causes the vocal chords to vibrate

Epiglottis

covers the glottis while swallowing to ensure food does not enter the lungs

Trachea

Also known as the wind pipe, it is located below the larynx. Cilia and mucus coat the inside surface to trap debris and moisten the air.

Bronchi

one main branch in each lung that is connected to the trachea

Bronchiole

The bronchi further branch into these, where the alveoli are located

Alveoli

The additional branching always delivers air to these, where gases are exchanged with pulmonary capillaries

Pulmonary Capillaries

exchanges gases with the alveoli

Gas Exchange

Oxygen and carbon dioxide diffuse through the thin walls of the alveoli and the neighboring capillaries.

Respiratory Adaptations

• Organisms in higher altitudes have adaptations to facilitate the uptake of oxygen as there is less air in such altitudes (e.g. hemoglobin that is more efficient at binding oxygen).

• Animals with long dives have adaptations that allow them to store oxygen and shift the distribution of blood flow during a dive due to the higher water pressure.