Circulation and Gas Exchange

Vocabulary flashcards covering circulatory and gas-exchange concepts from the lecture notes.

Open circulatory system

Blood (hemolymph) is pumped from a heart into open spaces (sinuses) where it directly bathes organs; no complete network of vessels.

Closed circulatory system

Blood is confined to vessels (arteries, veins, capillaries) and the heart pumps it through a connected network for efficient transport.

Hemolymph

The circulating fluid in open circulatory systems that transports nutrients, gases, and wastes and bathes tissues.

Heart

Muscular organ that pumps circulatory fluid through the body.

Blood vessels

Network of tubes (arteries, veins, capillaries) that transport blood.

Atrium

Upper chamber of the heart that receives blood returning to the heart.

Ventricle

Lower chamber of the heart that pumps blood out of the heart.

Ostia

Openings in the heart that allow blood to enter the heart from vessels.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood toward the heart."

Capillaries

Tiny vessels where exchange of oxygen, carbon dioxide, nutrients, and wastes occurs between blood and tissues.

Sinuses

Open spaces in an open circulatory system where hemolymph mixes with interstitial fluid.

Valve

Structure in the heart that prevents backflow and ensures one-way flow of blood.

Counter-current exchange

Gas exchange mechanism where blood and the medium flow in opposite directions, enhancing diffusion efficiency.

Concurrent flow

Gas exchange where blood and the medium flow in the same direction; less efficient than counter-current exchange.

Gill filaments

Thin projections from gill arches that increase surface area for gas exchange.

Lamellae

Folds on gill filaments that increase surface area and host capillaries for diffusion.

Operculum

Flap covering fish gills that helps ventilate by opening and closing.

Gill arches

Bony supports of the gills that host filaments and lamellae.

Two-chambered heart

Fish heart with an atrium and a ventricle in a single circulation.

Three-chambered heart

Amphibian/reptile heart with two atria and one ventricle; double circulation with partial separation.

Four-chambered heart

Birds and mammals heart with two atria and two ventricles; complete separation of pulmonary and systemic circuits.

Pulmonary circulation

Blood flow to the lungs for oxygenation.

Systemic circulation

Blood flow to the rest of the body delivering O2 and nutrients.

Oxygenated blood

Blood rich in oxygen; bright red; typically in arteries (except pulmonary arteries).

Deoxygenated blood

Blood low in oxygen; darker; carried by veins (except pulmonary veins).

Pulmonary artery

Carries deoxygenated blood from the right ventricle to the lungs.

Pulmonary vein

Returns oxygenated blood from the lungs to the left atrium.

Aorta

Largest artery; carries oxygenated blood from the left ventricle to the body.

Superior vena cava

Vein returning deoxygenated blood from the upper body to the right atrium.

Inferior vena cava

Vein returning deoxygenated blood from the lower body to the right atrium.

Right atrium

Upper right chamber that receives deoxygenated blood from the body.

Right ventricle

Lower right chamber that pumps deoxygenated blood to the lungs via the pulmonary artery.

Left atrium

Upper left chamber that receives oxygenated blood from the lungs.

Left ventricle

Lower left chamber that pumps oxygenated blood to the body; has the thickest walls.

Diaphragm

Muscular partition aiding mammalian ventilation by expanding thoracic cavity during inhalation.

Alveoli

Tiny air sacs at the end of bronchioles where gas exchange occurs; moist and surrounded by capillaries.

Bronchioles

Small air passages leading to the alveoli.

Bronchi

Main air passages that branch from the trachea into the lungs.

Parabronchi

Main gas-exchange air tubes in birds' lungs; site of one-way air flow and gas exchange with capillaries.

Air sacs

Birds’ thin-walled sacs that store air and enable one-way flow through the lungs.

Gas exchange surface

Surface area large enough for diffusion, with short diffusion distance and moist lining to enable O2 and CO2 diffusion; maintains concentration gradient.

Gas exchange medium

Environment through which gases diffuse; air provides high O2 concentration, water has lower O2 availability.

Insect tracheal system

Direct system of air tubes (trachea and tracheoles) reaching body cells via spiracles; insect blood does not carry oxygen.

Spiracles

External openings that connect the tracheal system to the environment.

Tracheoles

Fine extensions of the tracheal system that delivery oxygen directly to respiring cells.

Counter-current exchange in birds

One-way flow of air and blood in parabronchi and capillaries, maximizing gas exchange efficiency.

Alveolar gas exchange in mammals

Oxygen diffuses from air in alveoli into blood; carbon dioxide diffuses from blood into alveolar air for exhalation.

Crocodilian heart

Crocodilians have a fully four-chambered heart, like birds and mammals, for high-efficiency separation of circuits.

Disorders of the respiratory system

Asthma (bronchiolar constriction), bronchitis (inflammation and mucus), emphysema (loss of lung elasticity), pneumonia (alveolar fluid), lung cancer (tumor growth).