Circulatory System Overview

In a closed circulatory system, blood remains confined within blood vessels, allowing for a continuous and efficient flow of nutrients and oxygen to all parts of the body. The blood is pumped faster, enabling a quicker distribution of essential substances and a higher metabolic rate. This system also allows for the regulation of blood flow to different organs based on their needs, unlike open circulatory systems where blood directly enters the body cavity.

A double circulatory system separates oxygenated blood from deoxygenated blood, ensuring that oxygen-rich blood is delivered to all parts of the body. This system also maintains high blood pressure, allowing for a rapid and efficient delivery of nutrients. Single circulatory systems, on the other hand, typically have lower blood pressure, which restricts the delivery of nutrients and oxygen to the body's tissues.

Arteries, which carry blood away from the heart, have thicker muscular walls and more elastic fibers compared to veins. This structure allows arteries to withstand the higher pressure of blood pumped from the heart. Veins, on the other hand, have thinner walls and valves to prevent the backflow of blood as it returns to the heart.

<p>Capillaries possess thin, permeable walls composed of a single layer of endothelial cells. This structure enables efficient diffusion of nutrients, oxygen, and waste products across the capillary walls, allowing for the exchange of materials between the blood and surrounding cells.</p> Signup and view all the answers

<p>The two main types of circulatory systems are open and closed. Open systems have blood that flows freely in a body cavity called the hemocoel before returning to the heart, while closed systems have blood confined within vessels. Open systems are less efficient than closed systems in delivering oxygen and nutrients to tissues.</p> Signup and view all the answers

<ol> <li>The outermost layer of an artery or vein is composed of inelastic protein or collagen, which prevents over-expansion of the wall and provides structural support.</li> <li>The middle layer contains muscle and elastic fibers, allowing the vessel to constrict or dilate to regulate blood flow.</li> <li>The innermost layer, called the endothelium, is a smooth lining that reduces friction and allows for the smooth flow of blood.</li> </ol> Signup and view all the answers

<p>Smaller organisms have a high surface area to volume ratio, allowing for efficient diffusion of materials across their cell membranes. Larger organisms, on the other hand, have a lower surface area to volume ratio, making diffusion inefficient for transporting materials to distant cells. Therefore, they require a circulatory system to distribute nutrients and oxygen effectively.</p> Signup and view all the answers

<p>Insects, like grasshoppers, have an open circulatory system, where blood flows freely through the hemocoel, the body cavity. In contrast, humans have a closed circulatory system, where blood is confined within vessels and is pumped by the heart throughout the body.</p> Signup and view all the answers

<p>Veins are under low pressure, so they need valves to prevent backflow of blood. Arteries are under high pressure, so they don't need valves.</p> Signup and view all the answers

<p>An ECG measures the electrical activity of the heart by placing electrodes on the body. It detects changes in electrical impulses as they travel through the heart, providing information about the heart's rhythm, rate, and any abnormalities in electrical conduction.</p> Signup and view all the answers

<p>Endothelium is the inner lining of blood vessels, forming a single layer of living cells that facilitates the exchange of materials between blood and surrounding tissues.</p> Signup and view all the answers

<p>Sleep and alcohol consumption both decrease heartbeat rate.</p> Signup and view all the answers

<p>Capillaries have thin walls, a large surface area, and a narrow lumen, which facilitates rapid entry and exit of materials.</p> Signup and view all the answers

<p>Ventricular systole is the contraction of the ventricles, which forces blood out of the heart into the pulmonary artery and aorta. This process is essential for pushing blood throughout the body, delivering oxygen and nutrients to tissues.</p> Signup and view all the answers

<p>Coronary arteries are blood vessels that supply the heart muscle with oxygenated blood, branching from the aorta.</p> Signup and view all the answers

<p>The 'lub' sound is produced by the closing of the tricuspid and bicuspid valves during ventricular systole, preventing blood backflow into the atria. The 'dub' sound occurs when the semilunar valves close during ventricular diastole, preventing backflow of blood from the aorta and pulmonary artery.</p> Signup and view all the answers

<p>The pulmonary circuit carries deoxygenated blood from the heart to the lungs and back to the heart, while the systemic circuit carries oxygenated blood from the heart to the body and back to the heart.</p> Signup and view all the answers

<p>A pulse is the expansion and contraction of an artery caused by the pressure of blood being forced through it. It occurs as the left ventricle contracts, pushing blood into the aorta, causing the artery to temporarily expand.</p> Signup and view all the answers

<p>Blood pressure is the force exerted by the blood against the walls of the arteries. Systolic pressure is the highest pressure measured during ventricular contraction (systole), while diastolic pressure is the lowest pressure measured during ventricular relaxation (diastole).</p> Signup and view all the answers

<p>The hepatic portal vein carries blood rich in digested nutrients directly from the intestines to the liver without passing through the heart, functioning as a portal system.</p> Signup and view all the answers

<p>The SA node, located in the wall of the right atrium, acts as the pacemaker of the heart, initiating and regulating the rate of heartbeats.</p> Signup and view all the answers

<p>Atherosclerosis is the hardening and narrowing of blood vessels due to fatty deposits (cholesterol) accumulating under the inner lining of arteries. These deposits restrict blood flow, increasing resistance and leading to higher blood pressure.</p> Signup and view all the answers

<p>A blood clot (thrombosis) can form when an atheroma disrupts the artery lining or if blood flow is slowed significantly. If the clot blocks an artery completely or breaks away and blocks another vessel, it can lead to serious consequences such as stroke (impaired brain blood supply) or heart attack (blockage in coronary arteries).</p> Signup and view all the answers

<p>The SA node generates an electrical impulse, which spreads through the atria and reaches the AV node. The AV node delays this signal before transmitting it through the Purkinje fibers to the ventricles.</p> Signup and view all the answers

<p>Exercise strengthens the heart muscle, improves blood circulation, and helps to lower blood pressure.</p> Signup and view all the answers

<p>The SA node sets the heart's natural rhythm by initiating electrical impulses that travel through the heart. This rhythm can be influenced by nervous stimulation from the brain (e.g., during exercise) or by hormones (e.g., adrenaline).</p> Signup and view all the answers

<p>High intake of saturated fats increases cholesterol levels in the blood, leading to plaque buildup in arteries and increasing the risk of heart disease.</p> Signup and view all the answers

<p>A cardiac cycle begins with both atria and ventricles relaxed (diastole), allowing blood to fill the heart. The atria then contract (atrial systole), pushing blood into the ventricles. Next, the ventricles contract (ventricular systole), forcing blood out of the heart into the pulmonary artery and aorta. Finally, the atria and ventricles relax again, starting the cycle anew.</p> Signup and view all the answers

<p>Smoking increases heart rate and blood pressure, reduces oxygen content in the blood, and increases the risk of blood clots.</p> Signup and view all the answers

<p>Coronary bypass surgery involves replacing blocked coronary arteries with healthy blood vessels taken from other parts of the body, restoring blood flow to the heart muscle.</p> Signup and view all the answers

<p>The left ventricle pumps oxygenated blood to the entire body, which is a longer and higher-pressure circuit than the right ventricle, which only pumps blood to the lungs.</p> Signup and view all the answers

<p>The septum separates the left and right sides of the heart, ensuring that oxygenated and deoxygenated blood do not mix.</p> Signup and view all the answers

<p>The bicuspid valve (left side) and tricuspid valve (right side) prevent backflow of blood from the ventricles into the atria during ventricular contraction.</p> Signup and view all the answers

A system where blood leaves vessels and flows into body cavities.

A system where blood remains enclosed in vessels throughout the body.

A closed, double circulatory system composed of blood, heart, and vessels.

Part of the circulatory system that carries blood to and from the lungs.

Carries oxygenated blood to the body and returns deoxygenated blood to the heart.

Blood vessels that carry blood away from the heart.

Blood vessels that carry blood back to the heart.

Tiny blood vessels that connect arteries and veins, allowing material exchange.

A record of the electrical activity of the heart.

The sequence of events during one heartbeat.

The contraction phase of the heart.

The relaxation phase of the heart.

Blood is pumped from atria to ventricles.

Blood is ejected from the ventricles.

Expansion and contraction of an artery.

Force exerted by blood on artery walls.

High blood pressure condition.

Hardening of blood vessels due to fatty deposits.

Muscle that operates without conscious control, can change vessel size.

A single layer of living cells lining blood vessels, surrounding the lumen.

Structures that ensure blood flows in one direction, preventing backflow.

Elevated pressure in blood vessels; related to diet, obesity, and smoking.

Exercise that increases oxygen intake over a long period; beneficial for heart health.

Heart valve with two flaps, located between left atrium and left ventricle.

Involuntary muscle that makes up the heart; does not tire easily.

Arteries supplying blood to the heart muscle, branching from the aorta.

The heart's natural pacemaker that controls heartbeat rhythm.

Blood vessels that connect organs without going through the heart.

The wall separating the left and right sides of the heart; divides blood types.

The route blood takes from the heart to the lungs and back for oxygenation.

An extra sound during heartbeat, often indicating a defect.

Part of the heart pumping deoxygenated blood to the lungs.