Respiratory and Cardiovascular Systems

What are the functions of circulatory systems?

transportation of essential substances throughout the body and maintaining homeostasis. 

What are the main types of circulatory systems? What does an organism that lacks a circulatory system do (how do they exchange gases, get nutrients to cells, etc.)?

Main types of circulatory systems:

1. Open circulatory system – blood-like fluid (hemolymph) bathes organs directly; found in insects and many invertebrates.

2. Closed circulatory system – blood stays in vessels; found in vertebrates, earthworms, squid, etc.

Organisms that lack a circulatory system (like flatworms, jellyfish, sponges) use diffusion:

• Gases, nutrients, and wastes move directly between cells and the environment.

• Their bodies are thin or have large surface areas to make diffusion fast enough for survival.

You should know what types of blood vessels occur in the circulatory system, what function they have and how they are structured to reflect that function (for red blood cells).

• Arteries: Carry blood away from heart; thick, muscular walls for high pressure.

• Veins: Carry blood to the heart; thin walls, have valves to prevent backflow.

• Capillaries: 1 cell thick for easy diffusion; connect arteries → veins.

You should understand how materials are transferred between the blood in the capillaries and the cells in the surrounding tissues (basically – how does this transfer take place and that it happens at capillary beds).

Material exchange

• Happens in capillary beds by diffusion, osmosis, and pressure (fluid forced out, reabsorbed).

You should be able to label the parts of the heart and trace the flow of blood through the heart.

Right atrium → right ventricle → lungs → left atrium → left ventricle → body.

You should know which parts of the heart and blood vessels (associated with the heart) carry oxygenated vs. deoxygenated blood.

• Oxygenated: Pulmonary veins, left atrium, left ventricle, aorta.

• Deoxygenated: Vena cavae, right atrium, right ventricle, pulmonary arteries.

You should be able to describe what occurs during the cardiac cycle

Atria contract, push blood into ventricles → ventricles contract, pump blood out → diastole (heart relaxes and refills).

You should be able to describe how the heartbeat is initiated and coordinated. What is the function of the sinoatrial (SA) node? The atrioventricular (AV) node? What are the other parts of the conduction system?

• SA node: “Pacemaker,” starts heartbeat (atria contract).

• AV node: Delays signal, sends to Bundle of His, Purkinje fibers → ventricles contract in sync.

You should be able to compare and contrast the organization of the circulatory system in different animals (open vs. closed). Also those that have 2-chambered vs. 3 & 4 chambered hearts (how does the blood flow, oxygenated, deoxygenated and mixed).

• Open: Hemolymph bathes organs (insects).

• Closed: Blood stays in vessels (vertebrates).

• 2-chamber (fish): Single loop; blood goes heart → gills → body.

• 3-chamber (amphibians/reptiles): Some mixing of O₂ & no-O₂ blood.

• 4-chamber (birds/mammals): Complete separation of O₂ and no-O₂ blood.

What is blood pressure, how do you measure it?

• The force of blood against artery walls.

• Measured with cuff as systolic/diastolic.

You should be able to describe the various components of the blood. What is plasma?

• Plasma: Mostly water; carries nutrients, wastes, hormones.

• Cellular parts:

  • RBCs: Carry oxygen; no nucleus; filled with hemoglobin.

  • Leukocytes (white blood cells): Fight infection.

  • Platelets: Help clot blood.

What are the gas exchange systems we discussed?

Gills (fish), tracheal system (insects), lungs (vertebrates)

How is pressure involved with gas exchange and movement of air?

• Air moves from high pressure → low pressure.

• Breathing changes pressure inside the chest.

What adaptations help maximize the rate of diffusion of respiratory gases? Think particularly about form related to function.

Large surface area, thin membranes, moist surfaces, lots of capillaries.

Describe how air is brought into and out of the human lungs? What structures are involved and what happens during inhalation and exhalation? What is tidal breathing?

• Inhalation: Diaphragm contracts & moves down → chest expands → air in.

• Exhalation: Diaphragm relaxes → chest gets smaller → air out.

• Tidal breathing: We inhale and exhale through the same path.

Describe how gas exchange occurs in the alveoli and in the body tissues.

• In alveoli: O₂ diffuses into blood, CO₂ diffuses out.

• In tissues: O₂ leaves blood, CO₂ enters blood.

Describe how gases (O₂ and CO₂) are transported around the body.

• O₂: Mostly carried by hemoglobin.

• CO₂: Mostly as bicarbonate (HCO₃⁻) in the blood.

Why is hemoglobin important?

Greatly increases the amount of O₂ blood can carry.

How is breathing controlled (basics)?

• Controlled by the medulla, which monitors CO₂ levels (not O₂).

How does tobacco smoke affect the cardiovascular system? 

Damages blood vessels, raises blood pressure, increases clotting.

How do blood clots cause problems?

Can block vessels, leading to stroke or heart attack.

Be able to define/recognize hypertension and atherosclerosis. How are they related? What can cause them?

• Hypertension: High blood pressure.

• Atherosclerosis: Plaque buildup in arteries.

• Related because plaque makes arteries stiffer, raising blood pressure.

What does ETS stand for? What is it? What is the difference between and active smoker and a passive smoker? What is the most abundant gas in ETS? What else is in it?

(Environmental Tobacco Smoke)

• Secondhand smoke from cigarettes.

• Active smoker: Smokes directly.

• Passive smoker: Breathes ETS.

• Main gas in ETS: Carbon monoxide.

• Also contains carcinogens and irritants.

How are e-cigarettes different? Do you think this means they are safe? (that's more of a thought question). Note that they do still contain nicotine and nicotine is addictive - so be sure to know that part.

• No smoke, but still contain nicotine and chemicals.

• Not “safe”; still addictive.

Most deaths due to smoking result from what?

Due to cardiovascular disease, lung cancer, and COPD.

What is nicotine? What does it do? How is nicotine linked to addiction/how is it addictive?

• A stimulant drug.

• Increases heart rate & blood pressure.

• Addictive because it increases dopamine in the brain.

Be able to describe (very basically) stroke and heart attack.

• Stroke: Blood flow to the brain is blocked.

• Heart attack: Blood flow to the heart muscle is blocked.

What cells are found in the cellular components? What is special about red blood cells? What are the functions of leukocytes? What do we commonly call them? What is the function of platelets?

• Red blood cells (RBCs / erythrocytes): Carry oxygen; no nucleus, full of hemoglobin.

• White blood cells (WBCs / leukocytes): Fight infection; many types (neutrophils, lymphocytes, etc.).

• Platelets: Cell fragments that help blood clot.

• Plasma: Mostly water, carries nutrients, wastes, hormones.