Circulatory System Flashcards

Circulatory Systems

• Some animals lack a circulatory system, relying on diffusion for transport.

  • Sponges: Utilize simple diffusion.
  • Jellyfish: Employ diffusion in the epidermis and gastrovascular cavity, with pulsing movements aiding fluid exchange.

• Complex animals require a circulatory system for nutrient and waste transport due to their size.

  • The system consists of a heart and a network of vessels.
  • Circulatory systems are classified as open or closed.

Open Circulatory Systems

• Circulatory fluid is pumped into a body cavity (hemocoel).
• Blood is termed hemolymph and mixes with interstitial fluid.
• The heart's beating and body movements facilitate hemolymph circulation around organs.
• Hemolymph re-enters the heart via ostia (openings).

Closed Circulatory Systems

• Blood remains within blood vessels and flows unidirectionally.
• Blood travels from the heart, through the systemic circulatory route, and back to the heart.

Varieties of Circulatory Systems

• Vertebrates exhibit variations in heart structure and blood circulation.

Fish

• Possess a two-chambered heart.
• Feature a single circuit for blood flow.
  • Atrium: Blood collection.
  • Ventricle: Blood pumping.
  • Gill circulation: Blood movement between the heart and gills.
  • Systemic circulation: Blood movement between the body and the heart.
• Unidirectional blood flow generates an oxygenation gradient in the systemic circuit.

Amphibians

• Exhibit two blood flow circuits.
  • Pulmonary circulation: Blood flow through the lungs and back to the heart.
  • Pulmocutaneous circulation: Gas exchange through the skin.
  • Systemic circulation: Blood flow to the rest of the body.
• Have a three-chambered heart (two atria and one ventricle).
• Mixing of blood occurs in the ventricle, reducing oxygenation efficiency.

Reptiles

• Also possess a three-chambered heart with pulmonary and systemic circuits.
• A partial septum in the ventricle reduces the mixing of oxygenated and deoxygenated blood.

Mammals and Birds

• Feature four-chambered hearts (two atria and two ventricles).
• Separate oxygenated and deoxygenated blood, enhancing circulation efficiency.
• The four-chambered heart evolved independently in birds and mammals (convergent evolution).

Blood

• Blood composition:
  • Plasma with dissolved solutes (proteins, salts, lipids, glucose).
  • Cells (red and white blood cells).
  • Platelets (cellular fragments).
• Cellular components make up approximately 45% of blood volume, while plasma constitutes about 55%.
• Adult humans have 4-6L of blood volume.

Homeostasis

• Blood plays a crucial role in regulating body systems and maintaining homeostasis.
  • Regulates blood pH, temperature, and osmotic pressure.
  • Distributes nutrients and hormones to support growth.
  • Eliminates waste products.
  • Transports clotting factors and white blood cells.

Red Blood Cells (Erythrocytes)

• Specialized cells that transport oxygen throughout the body.
• Contain hemoglobin, an iron-containing protein that gives blood its color.
• Primary function involves carrying oxygen and, to a lesser extent, carbon dioxide.
• Small size and large surface area facilitate rapid diffusion of oxygen and carbon dioxide.
• Hemoglobin also binds carbon monoxide.

White Blood Cells

• Constitute about 1% of blood cells by volume.
• Possess nuclei but lack hemoglobin.
• Include neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

Lymphocytes

• Primary cells of the immune system.
  • B cells: Produce antibodies.
  • T cells: Directly attack infected and cancerous cells or activate other immune cells.
  • Natural killer cells: Target infectious microbes and certain tumor cells.

Platelets

• Essential for blood clotting to prevent excessive blood loss.
• Attracted to wound sites, where they adhere and interact with coagulation factors to form a clot (positive feedback).

Blood Plasma

• Liquid fraction of blood, consisting of 90% water and various substances for maintaining pH and osmotic load.
• Plasma without coagulation factors is termed serum.
• Serum's electrolyte composition is vital for normal muscle and nerve function.

Mammalian Circulation

• Divisions:
  • Coronary circulation: Blood supply to the heart muscle.
  • Pulmonary circulation: Blood flow from the heart to the lungs.
  • Systemic circulation: Blood flow from the heart to the body.
• Lungs are located close to the heart in the thoracic cavity.

Heart Structure

• Asymmetrical, with the right side smaller than the left.
• Four chambers: two atria and two ventricles.
• Atria receive blood, and ventricles pump blood.

Heart Tissue Layers

• Endocardium: Inner layer.
• Myocardium: Middle layer.
• Epicardium: Outer layer.
• Pericardium: Membranous layered sac around the heart.
• Pericardial fluid lubricates the heart to minimize friction.
• Excessive pericardial fluid buildup is called pericardial effusion.

Heart as a Muscle

• Requires its own blood supply from coronary arteries, which branch off the aorta.
• Coronary veins return deoxygenated blood to the right atrium.
• Atherosclerosis: Blockage due to fatty plaque buildup.
• Myocardial infarction: Death of cardiac muscle tissue due to complete blockage (heart attack).

Heart Pumping Action

• Function of cardiac muscle cells (cardiomyocytes).
• Cardiomyocytes: Striated muscle cells that pump rhythmically and involuntarily.

Blood Flow

• Deoxygenated blood enters the right atrium via:
  • Superior vena cava (upper body).
  • Inferior vena cava (lower body).
  • Coronary sinus (heart itself).
• Blood moves from the right atrium to the right ventricle through the tricuspid valve.
• The right ventricle pumps blood through the pulmonary arteries (via the semilunar valve) to the lungs for reoxygenation.
• Oxygen-rich blood returns from the lungs to the left atrium via the pulmonary veins.
• Blood flows through the bicuspid valve to the left ventricle, which pumps blood through the aorta to the body (double circulation).

Heart as a Double Pump

• Systole: Active contraction.
• Diastole: Rest between contractions.
• Atrial contraction forces blood into the ventricles (

Circulatory Systems

Some animals lack a circulatory system, relying on diffusion for transport.

Sponges: Utilize simple diffusion. Water enters through pores, and nutrients are absorbed directly by cells.

Jellyfish: Employ diffusion in the epidermis and gastrovascular cavity, with pulsing movements aiding fluid exchange. The gastrovascular cavity acts as both a digestive and circulatory system.

Complex animals require a circulatory system for nutrient and waste transport due to their size. Diffusion alone is insufficient to meet metabolic needs.

The system consists of a heart and a network of vessels. These vessels include arteries, veins, and capillaries.

Circulatory systems are classified as open or closed.

Open Circulatory Systems

Circulatory fluid is pumped into a body cavity (hemocoel). This cavity directly bathes the internal organs.

Blood is termed hemolymph and mixes with interstitial fluid. Therefore, it's difficult to distinguish between blood and interstitial fluid.

The heart's beating and body movements facilitate hemolymph circulation around organs. This circulation is less efficient than in closed systems.

Hemolymph re-enters the heart via ostia (openings). These openings have valves to prevent backflow.

Closed Circulatory Systems

Blood remains within blood vessels and flows unidirectionally. This allows for more efficient delivery of oxygen and nutrients.

Blood travels from the heart, through the systemic circulatory route, and back to the heart. The systemic route involves arteries, capillaries, and veins.

Varieties of Circulatory Systems

Vertebrates exhibit variations in heart structure and blood circulation. These variations are adaptations to different metabolic needs and environments.

Fish

Possess a two-chambered heart. This is the simplest heart structure among vertebrates.

Feature a single circuit for blood flow. Blood passes through the heart once per circuit.

Atrium: Blood collection. The atrium receives blood from the body.

Ventricle: Blood pumping. The ventricle pumps blood to the gills.

Gill circulation: Blood movement between the heart and gills. Here, blood is oxygenated.

Systemic circulation: Blood movement between the body and the heart. Oxygenated blood is delivered to organs and tissues.

Unidirectional blood flow generates an oxygenation gradient in the systemic circuit. Organs closer to the gills receive more oxygenated blood.

Amphibians

Exhibit two blood flow circuits. This is an adaptation to life both in water and on land.

Pulmonary circulation: Blood flow through the lungs and back to the heart. Blood is oxygenated in the lungs.

Pulmocutaneous circulation: Gas exchange through the skin. This is especially important when lungs are not fully functional.

Systemic circulation: Blood flow to the rest of the body. Oxygenated blood is delivered to organs and tissues.

Have a three-chambered heart (two atria and one ventricle). This structure is less efficient due to blood mixing.

Mixing of blood occurs in the ventricle, reducing oxygenation efficiency. Deoxygenated and oxygenated blood mix before being pumped out.

Reptiles

Also possess a three-chambered heart with pulmonary and systemic circuits. Similar to amphibians, but with adaptations for a more terrestrial lifestyle.

A partial septum in the ventricle reduces the mixing of oxygenated and deoxygenated blood. This septum partially divides the ventricle, improving efficiency.

Mammals and Birds

Feature four-chambered hearts (two atria and two ventricles). This is the most efficient heart structure.

Separate oxygenated and deoxygenated blood, enhancing circulation efficiency. No mixing occurs, allowing for higher metabolic rates.

The four-chambered heart evolved independently in birds and mammals (convergent evolution). This is due to similar high-energy demands.

Blood

Blood composition:

Plasma with dissolved solutes (proteins, salts, lipids, glucose). Plasma also contains hormones, antibodies, and clotting factors.

Cells (red and white blood cells). Red blood cells carry oxygen, while white blood cells are involved in immune responses.

Platelets (cellular fragments). Platelets are essential for blood clotting.

Cellular components make up approximately 45% of blood volume, while plasma constitutes about 55%. These proportions can vary depending on hydration and health status.

Adult humans have 4-6L of blood volume. Blood volume varies with body size and sex.

Homeostasis

Blood plays a crucial role in regulating body systems and maintaining homeostasis. It ensures a stable internal environment.

Regulates blood pH, temperature, and osmotic pressure. Buffers in blood help maintain stable pH.

Distributes nutrients and hormones to support growth. Nutrients are absorbed from the digestive system, and hormones are secreted by endocrine glands.

Eliminates waste products. Waste products are transported to the kidneys and liver for removal.

Transports clotting factors and white blood cells. These components are essential for wound healing and immune defense.

Red Blood Cells (Erythrocytes)

Specialized cells that transport oxygen throughout the body. Their biconcave shape increases surface area for gas exchange.

Contain hemoglobin, an iron-containing protein that gives blood its color. Hemoglobin binds oxygen in the lungs and releases it in tissues.

Primary function involves carrying oxygen and, to a lesser extent, carbon dioxide. Carbon dioxide is transported back to the lungs for exhalation.

Small size and large surface area facilitate rapid diffusion of oxygen and carbon dioxide. This allows for efficient gas exchange.

Hemoglobin also binds carbon monoxide. Carbon monoxide binding is much stronger than oxygen, leading to carbon monoxide poisoning.

White Blood Cells

Constitute about 1% of blood cells by volume. Their numbers increase during infection and inflammation.

Possess nuclei but lack hemoglobin. This distinguishes them from red blood cells.

Include neutrophils, eosinophils, basophils, monocytes, and lymphocytes. Each type has a specific role in immune defense.

Lymphocytes

Primary cells of the immune system. They recognize and respond to foreign invaders.

B cells: Produce antibodies. Antibodies mark pathogens for destruction.

T cells: Directly attack infected and cancerous cells or activate other immune cells. Helper T cells and cytotoxic T cells are examples.

Natural killer cells: Target infectious microbes and certain tumor cells. They induce apoptosis (programmed cell death) in target cells.

Platelets

Essential for blood clotting to prevent excessive blood loss. They are formed from megakaryocytes in the bone marrow.

Attracted to wound sites, where they adhere and interact with coagulation factors to form a clot (positive feedback). This process is tightly regulated to prevent excessive clotting.

Blood Plasma

Liquid fraction of blood, consisting of 90% water and various substances for maintaining pH and osmotic load. It also carries nutrients, hormones, and waste products.

Plasma without coagulation factors is termed serum. Serum is used in many diagnostic tests.

Serum's electrolyte composition is vital for normal muscle and nerve function. Electrolytes include sodium, potassium, and calcium.

Mammalian Circulation

Divisions:

Coronary circulation: Blood supply to the heart muscle. This is essential for heart function.

Pulmonary circulation: Blood flow from the heart to the lungs. This is where blood is oxygenated.

Systemic circulation: Blood flow from the heart to the body. This delivers oxygen and nutrients to tissues.

Lungs are located close to the heart in the thoracic cavity. This proximity minimizes the distance for blood to travel.

Heart Structure

Asymmetrical, with the right side smaller than the left. The left side has to pump blood to the entire body, so it’s larger.

Four chambers: two atria and two ventricles. These chambers work together to pump blood efficiently.

Atria receive blood, and ventricles pump blood. The atria are smaller and thinner-walled compared to the ventricles.

Heart Tissue Layers

Endocardium: Inner layer. This layer is in direct contact with the blood.

Myocardium: Middle layer. This is the thickest layer and contains cardiac muscle.

Epicardium: Outer layer. This layer protects the heart and reduces friction.

Pericardium: Membranous layered sac around the heart. It consists of two layers: the visceral and parietal pericardium.

Pericardial fluid lubricates the heart to minimize friction. This fluid is located between the visceral and parietal pericardium.

Excessive pericardial fluid buildup is called pericardial effusion. This can compress the heart and impair its function.

Heart as a Muscle

Requires its own blood supply from coronary arteries, which branch off the aorta. Blockage of these arteries can lead to heart attack.

Coronary veins return deoxygenated blood to the right atrium. This blood then enters the normal circulatory route.

Atherosclerosis: Blockage due to fatty plaque buildup. This reduces blood flow to the heart muscle.

Myocardial infarction: Death of cardiac muscle tissue due to complete blockage (heart attack). This can cause permanent damage to the heart.

Heart Pumping Action

Function of cardiac muscle cells (cardiomyocytes). These cells are interconnected by intercalated discs.

Cardiomyocytes: Striated muscle cells that pump rhythmically and involuntarily. Their contraction is coordinated to ensure efficient pumping.

Blood Flow

Deoxygenated blood enters the right atrium via:

Superior vena cava (upper body). This vein carries blood from the head, neck, and upper limbs.

Inferior vena cava (lower body). This vein carries blood from the trunk and lower limbs.

Coronary sinus (heart itself). This drains blood from the heart muscle.

Blood moves from the right atrium to the right ventricle through the tricuspid valve. This valve prevents backflow of blood.

The right ventricle pumps blood through the pulmonary arteries (via the semilunar valve) to the lungs for reoxygenation. The semilunar valve prevents backflow into the ventricle.

Oxygen-rich blood returns from the lungs to the left atrium via the pulmonary veins. There are typically four pulmonary veins.

Blood flows through the bicuspid valve to the left ventricle, which pumps blood through the aorta to the body (double circulation). The bicuspid valve, also known as the mitral valve, prevents backflow.

Heart as a Double Pump

Systole: Active contraction. This is when the heart chambers are contracting and pumping blood.

Diastole: Rest between contractions. This is when the heart chambers are filling with blood.

Atrial contraction forces blood