Pressure & Pathogens
This passive process is how tiny, single-celled organisms exchange nutrients, but it is too slow for large, complex multicellular bodies.
What is Simple diffusion?
This is the primary function of the circulatory system that involves moving hormones, oxygen, and metabolic wastes throughout the body.
What is Transportation?
This fluid, a mix of blood and interstitial fluid, is what pumps through an open circulatory system.
What is Hemolymph?
These microscopic vessels feature walls that are only a single cell layer thick to allow for rapid nutrient and gas exchange.
What is Capillaries?
This cluster of specialized cells in the right atrium acts as the heart's natural pacemaker by initiating electrical impulses.
What is the Sinoatrial (SA) Node?
This is the medical term for chronically elevated blood pressure, which can be worsened by stress and stimulants
What is Hypertension?
An increase in this specific factor (the amount of blood pumped per beat) allows physically fit individuals to have a lower resting heart rate.
What is Stroke Volume?
Humans and earthworms share this type of structural system, where blood is completely enclosed within a continuous network of vessels.
What is a closed circulatory system?
Because veins carry blood under very low pressure, they require these structural features to stop blood from flowing backward.
What are one-way valves?
These blood components are actually irregular cell fragments that trigger the clotting process when a vessel is damaged.
What are platelets (Thrombocytes)?
Chemical stimulants like caffeine and nicotine mimic or amplify this branch of the autonomic nervous system to speed up the heart.
What is the sympathetic nervous system
This diagnostic tool allows a doctor to listen to internal heart sounds to check for faulty, leaking valves or heart murmurs.
What is a stethoscope?
This closed circulatory loop specifically takes blood from the right ventricle, sends it to the lungs, and returns it to the left atrium.
What is the pulmonary circuit?
To travel safely to the lungs, most carbon dioxide waste in the blood is converted into these specific ions inside red blood cells.
What are Bicarbonate ions (HCO_3-)?
Leaving the right ventricle, blood passes through a semilunar valve and directly enters these specific blood vessels on the way to the lungs.
What are Pulmonary Arteries?
These specific proteins are mass-produced by plasma B-cells to physically bind to and target foreign pathogens.
What are antibodies?
This diagnostic procedure uses a special injected dye and X-rays to map out physical blockages inside coronary arteries.
What is an Angiogram?
In an open circulatory system, hemolymph leaves the vessels and directly bathes the organs inside these fluid-filled cavities.
What is Sinuses (or Hemocoel)?
This largest artery in the human body must have highly elastic, thick muscular walls to withstand intense systolic pressure from the left ventricle.
What is the aorta?
This region of the brain stem houses the cardiovascular center responsible for regulating unconscious heart rate.
What is the medulla oblongata?
These general types of physical factors—such as blood thickness (viscosity), total blood volume, and vessel diameter—directly dictate blood pressure.
What are viscosity, blood volume, and vessel radius (arteriole diameter)?
These specialized nervous system receptors, located in the aorta and carotid arteries, constantly monitor changes in physical blood pressure to help regulate it.
What are baroreceptors?
This specific loop of systemic circulation branches right off the base of the aorta to feed the tissues of the heart muscle itself.
What is the Cardiac (Coronary) circuit?
Hemoglobin binds to oxygen tightly in the lungs, but releases it easily near hardworking body tissues due to these two environmental factors being higher/altered in active tissues.
What is Temperature and Acidity (Lower pH / Higher CO_2 concentration)?
This is the scientific term for the biological creation of all blood cell types, occurring entirely within red bone marrow.
What is Hematopoiesis?