Compendium 6
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Questions and Answers

What are the three main components of the cardiovascular system?

Heart, blood vessels, and blood.

Explain the primary function of the heart in the cardiovascular system.

The heart acts as a pump to generate pressure in the blood, facilitating its movement through the blood vessels.

What are the differences between the atria and ventricles in terms of wall thickness?

Atria have thinner walls, while ventricles have thicker walls.

What role do valves play in the heart?

<p>Valves prevent the backflow of blood, ensuring one-way flow through the heart.</p> Signup and view all the answers

Describe the significance of the pericardium in protecting the heart.

<p>The pericardium surrounds the heart, preventing overdistension and anchoring it to surrounding tissues.</p> Signup and view all the answers

What is cardiac output and how is it calculated?

<p>Cardiac output is the volume of blood ejected from the heart per minute, calculated as heart rate multiplied by stroke volume.</p> Signup and view all the answers

What is the purpose of the trabeculae carneae found in the ventricles?

<p>Trabeculae carneae create turbulence in the blood and help in muscular contraction.</p> Signup and view all the answers

How does the autonomic nervous system influence the cardiovascular system?

<p>The autonomic nervous system regulates blood pressure and flow by controlling heart rate and blood vessel diameter.</p> Signup and view all the answers

What is the primary role of epinephrine in the cardiovascular system during stress?

<p>Epinephrine increases heart rate and stroke volume while causing vasoconstriction to redirect blood flow.</p> Signup and view all the answers

Describe the function of the sinoatrial node in the heart.

<p>The sinoatrial (SA) node acts as the pacemaker, generating action potentials at regular intervals to initiate heart contractions.</p> Signup and view all the answers

How does blood composition differentiate between plasma and formed elements?

<p>Plasma comprises 55% of blood and contains water, proteins, and solutes, while formed elements, making up 45%, include red and white blood cells and platelets.</p> Signup and view all the answers

What is the significance of a biconcave shape in erythrocytes?

<p>The biconcave shape of erythrocytes increases the surface area to volume ratio, enhancing their oxygen-carrying capacity.</p> Signup and view all the answers

Explain the term 'auto-rhythmicity' in the context of cardiac muscle.

<p>'Auto-rhythmicity' refers to the ability of cardiac muscle cells to contract rhythmically without external stimulation, primarily driven by the SA node.</p> Signup and view all the answers

What are the primary components of the blood's plasma?

<p>Blood plasma consists of about 91% water, 7% proteins (including albumins, globulins, and fibrinogen), and 2% other solutes like ions and nutrients.</p> Signup and view all the answers

Describe the difference in blood volume between an average male and female.

<p>Typically, males have 5-6 liters of blood, while females have 4-5 liters.</p> Signup and view all the answers

What role do leukocytes play in the body's defense mechanisms?

<p>Leukocytes, or white blood cells, are crucial in identifying and combating infections and foreign substances in the body.</p> Signup and view all the answers

How do action potentials affect cardiac muscle contraction?

<p>Action potentials serve as electrical signals that trigger cardiac muscle cells to contract, enabling the heart to pump blood.</p> Signup and view all the answers

What is the pH range of healthy human blood?

<p>The pH of healthy human blood ranges from 7.35 to 7.45.</p> Signup and view all the answers

What is the role of osmolarity in fluid movement outside the capillary?

<p>Osmolarity increases osmotic pressure outside the capillary, drawing more fluid from the capillary into the interstitial fluid.</p> Signup and view all the answers

Explain why a pulse can only be felt in certain areas of the body.

<p>A pulse can be felt in areas where blood vessels are superficial and large enough to be pressed against tissue without bone obstructing the vessel.</p> Signup and view all the answers

Describe the change in heart rate observed during the experiment after 5 minutes of recovery.

<p>After 5 minutes of recovery, the heart rate returned to normal at 68 BPM, showing a decrease from the post-exercise rate.</p> Signup and view all the answers

What factors contribute to an increase in stroke volume as exercise intensity increases?

<p>As exercise intensity increases, stroke volume rises due to improved heart muscle contractility and increased venous return.</p> Signup and view all the answers

What anatomical structures are involved in controlling blood flow from the left ventricle?

<p>The bicuspid and tricuspid valves, along with the aorta and pulmonary trunk, control blood flow from the left ventricle.</p> Signup and view all the answers

What are the primary functions of neutrophils in the immune system?

<p>Neutrophils are mainly responsible for phagocytosis and the immune response, including both cell-mediated and antibody-mediated immunity.</p> Signup and view all the answers

Why are platelets not considered true cells?

<p>Platelets are not true cells because they are cytoplasmic fractions of very large cells, specifically megakaryocytes.</p> Signup and view all the answers

Describe the structural differences between arteries and veins.

<p>Arteries have thicker walls and carry blood under high pressure, while veins have thinner walls and carry blood under low pressure.</p> Signup and view all the answers

What are precapillary sphincters and their function?

<p>Precapillary sphincters are muscular valves that regulate blood flow into capillaries, directing blood to essential areas when needed.</p> Signup and view all the answers

What is the significance of the tunica media in blood vessels?

<p>The tunica media contains smooth muscle and elastic tissue that allow for the regulation of blood vessel diameter through vasoconstriction and vasodilation.</p> Signup and view all the answers

How do capillaries facilitate the exchange of substances?

<p>Capillaries have thin walls composed of endothelial cells, allowing for the efficient exchange of oxygen, nutrients, and waste between blood and tissues.</p> Signup and view all the answers

Contrast the types of blood carried by arteries and veins.

<p>Arteries primarily carry oxygenated blood, except for pulmonary arteries, while veins mainly carry deoxygenated blood, except for pulmonary veins.</p> Signup and view all the answers

Explain the role of valves in veins.

<p>Valves in veins prevent the backflow of blood, ensuring it returns to the heart despite lower pressure and the effects of gravity.</p> Signup and view all the answers

What happens to blood flow when smooth muscles in the tunica media contract?

<p>When smooth muscles in the tunica media contract, vasoconstriction occurs, leading to a decrease in the diameter of the vessel and a reduction in blood flow.</p> Signup and view all the answers

What are the main layers of a blood vessel from innermost to outermost?

<p>The main layers are the tunica intima, tunica media, and tunica externa.</p> Signup and view all the answers

What are fenestrated capillaries and where are they commonly found?

<p>Fenestrated capillaries are characterized by pores in their endothelial cells, allowing for high permeability. They are commonly found in the intestinal villi and glomeruli of the kidney.</p> Signup and view all the answers

Explain the concept of capillary exchange and its importance.

<p>Capillary exchange refers to the movement of substances into and out of capillaries, crucial for delivering nutrients and removing waste products. It relies on concentration gradients and interstitial fluid for effective transfer.</p> Signup and view all the answers

Describe how oxygen and carbon dioxide exchange occurs at the cellular level.

<p>Oxygen diffuses from the capillaries to the cells as it moves from an area of high concentration to low, while carbon dioxide diffuses out of cells into the blood following a similar concentration gradient. This exchange is driven by metabolic activity.</p> Signup and view all the answers

What role does interstitial fluid play in nutrient delivery?

<p>Interstitial fluid bathes cells, allowing substances to diffuse between capillaries and cells. It serves as a medium for the exchange of nutrients, gases, and waste.</p> Signup and view all the answers

How do lipid-soluble substances diffuse across capillary membranes?

<p>Lipid-soluble substances like O2, CO2, and steroid hormones diffuse directly through the plasma membrane of endothelial cells due to their compatible chemical properties. They can easily pass through the lipid bilayer.</p> Signup and view all the answers

What consequences arise if the lymphatic system fails to function properly?

<p>If the lymphatic system fails, it can lead to fluid accumulation causing edema, thickened blood, and reduced blood volume. These conditions can severely impact overall health and homeostasis.</p> Signup and view all the answers

What is the difference between fenestrated and sinusoidal capillaries?

<p>Fenestrated capillaries have pores that facilitate high permeability, while sinusoidal capillaries have large diameters and irregular walls that allow for the passage of larger molecules. Sinusoidal capillaries have less basement membrane compared to fenestrated types.</p> Signup and view all the answers

How does osmotic pressure affect fluid movement in capillaries?

<p>Osmotic pressure helps draw fluid back into capillaries from the interstitial space, counteracting the hydrostatic pressure that pushes fluid out. This balance is essential for maintaining blood volume.</p> Signup and view all the answers

Identify factors that can lead to edema in tissues.

<p>Edema can be caused by problems with capillaries, heart failure, kidney disease, and excessive salt intake, among others. These factors disrupt fluid balance and can lead to increased interstitial fluid accumulation.</p> Signup and view all the answers

What is the significance of the blood-brain barrier in relation to capillary structure?

<p>The blood-brain barrier consists of specialized capillaries that have very tight junctions, allowing only certain substances to pass through while protecting the brain from harmful agents. This selectivity is crucial for maintaining neural health.</p> Signup and view all the answers

What effect does exercise have on blood pressure?

<p>Exercise generally leads to an increase in blood pressure.</p> Signup and view all the answers

How does epinephrine affect heart rate and stroke volume?

<p>Epinephrine increases heart rate and stroke volume by triggering vasoconstriction.</p> Signup and view all the answers

What is the role of the sinoatrial node in the cardiac conduction system?

<p>The sinoatrial node acts as the primary pacemaker, initiating action potentials at regular intervals.</p> Signup and view all the answers

Why do erythrocytes (red blood cells) lack organelles?

<p>Erythrocytes lack organelles to increase their surface area, enhancing oxygen transport capacity.</p> Signup and view all the answers

Describe the composition of blood plasma.

<p>Blood plasma consists of 91% water, 7% proteins (like albumins and globulins), and 2% other solutes.</p> Signup and view all the answers

What defines the term 'auto-rhythmicity' in cardiac muscles?

<p>'Auto-rhythmicity' refers to the heart's ability to generate impulses and contract rhythmically without external signals.</p> Signup and view all the answers

How do leukocytes respond to an infection?

<p>Leukocytes typically increase in number, indicating an immune response to infection.</p> Signup and view all the answers

What is the significance of the biconcave shape of erythrocytes?

<p>The biconcave shape maximizes the surface area for gas exchange, allowing efficient oxygen transport.</p> Signup and view all the answers

What is the function of fibrinogen in blood?

<p>Fibrinogen aids in blood clotting by forming fibrin threads that stabilize the clot.</p> Signup and view all the answers

What is the typical blood volume for an average adult male?

<p>An average adult male typically has 5-6 liters of blood.</p> Signup and view all the answers

What is the primary physiological phenomenon driving fluid exchange out of capillaries into interstitial fluid?

<p>Osmotic pressure or osmolarity outside of the capillary causes fluid to be drawn out.</p> Signup and view all the answers

Why is it possible to palpate a pulse in certain areas of the body?

<p>A pulse can be felt where blood vessels are superficial and of sufficient size to transmit the pressure wave.</p> Signup and view all the answers

How does heart rate change during physical activity, according to the provided experiment data?

<p>Heart rate increases with physical activity, peaking at 112 BPM and then returning toward baseline.</p> Signup and view all the answers

What happens to the stroke volume during exercise, based on the experiment's findings?

<p>Stroke volume remains consistent despite increases in heart rate during exercise.</p> Signup and view all the answers

What is the function of the bicuspid and tricuspid valves in the heart?

<p>These valves prevent backflow of blood from the ventricles into the atria during contraction.</p> Signup and view all the answers

What structural characteristic of fenestrated capillaries facilitates their permeability?

<p>Fenestrated capillaries have pores called fenestrae in their endothelial cells, which enhance permeability.</p> Signup and view all the answers

Explain the importance of interstitial fluid in capillary exchange.

<p>Interstitial fluid is crucial because it allows substances to diffuse from capillaries to cells, acting as a medium for nutrient delivery.</p> Signup and view all the answers

How do pressure gradients affect the diffusion of gases like oxygen and carbon dioxide in capillaries?

<p>Pressure gradients drive the diffusion of gases, with oxygen moving from areas of high concentration in blood to lower concentrations in tissues, and vice versa for carbon dioxide.</p> Signup and view all the answers

Describe the role of the lymphatic system in maintaining fluid balance within the body.

<p>The lymphatic system picks up excess fluid from tissues and returns it to the circulatory system, preventing fluid accumulation.</p> Signup and view all the answers

What consequences arise from failure in the lymphatic system?

<p>Failure of the lymphatic system can lead to edema, which is swelling due to fluid accumulation, and can also cause thickened blood and reduced blood volume.</p> Signup and view all the answers

Why is the structure of sinusoidal capillaries important for their function?

<p>Sinusoidal capillaries have large diameters and irregular walls, allowing for the passage of large molecules and even whole cells.</p> Signup and view all the answers

Identify how capillary exchange impacts the delivery of nutrients and removal of waste.

<p>Capillary exchange involves the diffusion of nutrients from blood to cells and the removal of waste products, ensuring cellular health.</p> Signup and view all the answers

How do water-soluble molecules traverse the capillary wall?

<p>Water-soluble molecules, such as glucose and amino acids, diffuse through intercellular spaces or fenestrations of capillaries.</p> Signup and view all the answers

What is the significance of maintaining a pressure gradient in capillary function?

<p>Maintaining a pressure gradient is significant for driving fluid and solute exchange between capillaries and tissues.</p> Signup and view all the answers

In what way does the metabolic activity of cells impact the concentration gradient in tissue fluid?

<p>As cells metabolize, they consume oxygen and produce carbon dioxide, which alters the concentration gradient, facilitating oxygen uptake and carbon dioxide release.</p> Signup and view all the answers

What anatomical feature prevents backflow of blood from the ventricles into the atria?

<p>The atrioventricular valves prevent backflow of blood from the ventricles into the atria.</p> Signup and view all the answers

What is the role of the pericardial fluid, and where is it located?

<p>Pericardial fluid reduces friction and distributes pressure on the heart, located in the pericardial cavity between the fibrous and serous pericardium.</p> Signup and view all the answers

How do trabeculae carneae contribute to heart function?

<p>Trabeculae carneae create turbulence in the ventricular blood flow, which helps in optimizing the ejection of blood.</p> Signup and view all the answers

What separates oxygenated and deoxygenated blood in the heart's anatomy?

<p>The interventricular septum separates oxygenated blood in the left ventricle from deoxygenated blood in the right ventricle.</p> Signup and view all the answers

In which part of the heart does the majority of oxygenated blood enter?

<p>Majority of oxygenated blood enters the left atrium via the pulmonary veins.</p> Signup and view all the answers

What is the significance of the fossa ovalis in heart anatomy?

<p>The fossa ovalis is a remnant of the foramen ovale, a fetal structure that allowed blood to bypass the lungs.</p> Signup and view all the answers

Describe the primary function of pulmonary circulation.

<p>Pulmonary circulation transports deoxygenated blood from the heart to the lungs for oxygenation.</p> Signup and view all the answers

What are the two types of valves in the heart and their respective functions?

<p>The two types of valves are atrioventricular valves, which prevent backflow into the atria, and semilunar valves, which prevent backflow into the ventricles.</p> Signup and view all the answers

What is the primary function of platelets in the circulatory system?

<p>Platelets primarily function in blood clotting by adhering to damaged blood vessels and forming a plug.</p> Signup and view all the answers

How do arterioles regulate blood flow to capillaries?

<p>Arterioles regulate blood flow through vasoconstriction and vasodilation, adjusting the diameter of their lumen.</p> Signup and view all the answers

What distinguishes elastic arteries from muscular arteries?

<p>Elastic arteries have a higher proportion of elastic tissue to withstand high pressure, while muscular arteries contain more smooth muscle for regulating blood flow.</p> Signup and view all the answers

What are the structural characteristics of capillaries that facilitate their function?

<p>Capillaries have thin walls made of simple squamous epithelium, allowing for efficient exchange of materials between blood and tissues.</p> Signup and view all the answers

How do veins prevent the backflow of blood?

<p>Veins have valves that prevent backflow by ensuring blood flows in one direction toward the heart.</p> Signup and view all the answers

What is the significance of blood vessel lumen shape in arteries and veins?

<p>Arteries have a round lumen to maintain shape under high pressure, while veins have a flatter lumen, which collapses easily.</p> Signup and view all the answers

What role do the tunica media and tunica externa play in blood vessels?

<p>The tunica media consists of smooth muscle and elastic tissue, allowing for changes in vessel diameter, while the tunica externa provides structural support.</p> Signup and view all the answers

What prevents bleeding from minor cuts in the circulatory system?

<p>By forming a platelet plug at the site of injury, platelets prevent excessive bleeding.</p> Signup and view all the answers

How do precapillary sphincters impact blood distribution in the body?

<p>Precapillary sphincters reduce blood flow to certain capillary beds when not needed, redirecting blood to essential areas.</p> Signup and view all the answers

Describe the function of neutrophils in the blood.

<p>Neutrophils are white blood cells that play a critical role in phagocytosis, helping to eliminate pathogens during the immune response.</p> Signup and view all the answers

Study Notes

Cardiovascular System Components

  • Heart: A muscular pump responsible for generating pressure to move blood throughout the body.
  • Blood Vessels: Conduits for blood transportation. Include arteries, veins, and capillaries.
  • Blood: A connective tissue consisting of plasma, formed elements (red and white blood cells), and platelets. Responsible for transporting substances throughout the body.

Cardiovascular System Functions

  • Transport: Carries gases (oxygen, carbon dioxide, nitrogen), nutrients (glucose, amino acids), metabolic waste (urea, uric acid), regulatory molecules (hormones, enzymes), and processed molecules (proteins, enzymes, carbohydrates, lipids).
  • Protection: Involves inflammation, phagocytosis, antibodies, and platelets for clotting.
  • Regulation: Maintains fluid balance, pH, body temperature, blood pressure, and exchange between blood, extracellular fluid, and cells.

Heart Anatomy and Function

  • Location: Situated in the thoracic cavity, obliquely in the mediastinum, medial to the lungs, and superior to the diaphragm.
  • Size: The size of a closed fist weighing approximately 300g (250-350g), slightly smaller in women.
  • Shape: Blunt cone-shaped, with 2/3 towards the left side of the midline.
  • Function: Pumps blood through the circulatory system.
  • Routs blood: Separate pulmonary and systemic circulation. This is achieved through its design, separating deoxygenated blood from oxygenated blood.
  • One-way flow: Achieved through pressure gradients.
  • Regulates blood supply: Influenced by cardiac output and the heart adjusts to the body's needs (homeostasis).

Pericardium

  • Fibrous Pericardium: Tough outer layer that prevents overdistension and anchors the heart.
  • Serous Pericardium: Thin inner layer with two continuous parts:
    • Parietal Pericardium: Lines the fibrous outer layer.
    • Visceral Pericardium: Covers the surface of the heart (epicardium).
  • Pericardial Cavity: Space between the two layers containing pericardial fluid, which reduces friction and distributes pressure.
  • Pericarditis: Infection of the pericardium.

Heart Morphology

  • Sulci (Grooves):
    • Coronary Sulcus: Separates the atria and ventricles.
    • Anterior Interventricular Sulcus: Separates the right and left ventricles on the anterior side.
    • Posterior Interventricular Sulcus: Separates the right and left ventricles on the posterior side.
  • Pericardial and Epicardial Fat:
    • Pericardial Fat: Located between the visceral and parietal pericardium.
    • Epicardial Fat: Located between the outer layer of the myocardium and visceral pericardium (epicardium).
  • Chambers:
    • Atria (Superior Chambers): Thin-walled collecting chambers.
    • Ventricles (Inferior Chambers): Thick-walled discharging chambers.

Heart Wall Layers

  • Epicardium: Outer layer composed of serous membrane, simple squamous epithelium over areolar tissue.
  • Myocardium: Middle layer, thickest layer, composed of cardiac muscle cells responsible for contractility.
  • Endocardium: Inner layer, smooth inner surface of heart chambers, simple squamous epithelium over areolar tissue, covers valve surface and continuous with endothelium.

Heart Anatomy

  • Interventricular Septum: The separation between the two ventricles.
  • Interatrial Septum: The wall between the atria, containing the fossa ovalis, a remnant of the fetal opening (foramen ovale) between the atria.
  • Left Ventricle Wall: Significantly thicker than the right ventricle wall.
  • Pectinate Muscles: Muscular ridges in the auricle and atrial walls, aiding in contraction.
  • Trabeculae Carnae: Muscular ridges and columns on the inside of the ventricle wall, creating turbulence in the blood.

Heart Chambers

  • Right Atrium: Thin-walled receiving chamber, mostly on the posterior side.
  • Right Ventricle: Pumping chamber, mostly on the anterior side.
  • Left Atrium: Thin-walled receiving chamber, mostly on the posterior side.
  • Left Ventricle: Pumping chamber, forms the apex and posteroinferior aspect.

Great Blood Vessels of the Heart

  • Blood into the Heart:
    • Right Atrium: Receives deoxygenated blood through the superior and inferior vena cava from systemic circulation and the coronary sinus from the coronary circulation.
    • Left Atrium: Receives oxygenated blood through four pulmonary veins from the pulmonary circulation.
  • Blood Out of the Heart:
    • Right Ventricle: Sends deoxygenated blood through the pulmonary trunk (which splits into two pulmonary arteries) to the pulmonary circulation.
    • Left Ventricle: Sends oxygenated blood through the aorta to the systemic circulation.

Heart Valves

  • Atrioventricular Valves:
    • Located between atria and ventricles.
    • Have leaf-like cusps.
    • Attached to papillary muscles by chordae tendineae.
    • Right side: Three cusps (tricuspid, right AV valve).
    • Left side: Two cusps (bicuspid, left AV valve).
  • Semilunar Valves:
    • Located at the base of large blood vessels (exit of ventricles).
    • Cup-shaped valves.
    • Pulmonary SL valve: At the base of the pulmonary trunk.
    • Aortic pulmonary valve: At the base of the aorta.

Blood Flow through the Heart

  • Superior and inferior vena cava and coronary sinus -> right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk -> pulmonary arteries -> lung tissue -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> aorta -> coronary arteries or body tissues

Heart as a Pump

  • Pulmonary Circulation:
    • Deoxygenated blood is transported to the lungs for oxygenation and then returned to the heart.
    • Deoxygenated blood enters the right atrium, flows into the right ventricle, exits through the pulmonary trunk, and travels through the pulmonary arteries to the lungs for gas exchange.
    • Oxygenated blood returns to the heart through the pulmonary veins into the left atrium.
  • Systemic Circulation:
    • Oxygenated blood is transported to the body tissues and then returned to the heart.
    • Oxygenated blood enters the left atrium, flows into the left ventricle, exits through the aorta, and is delivered to body cells for exchange.
    • Deoxygenated blood returns to the heart through the vena cava into the right atrium.
  • Coronary Circulation: A part of systemic circulation that supplies blood to the heart.

Cardiac Cycle

  • Contraction and Relaxation: Repetitive contraction (systole) and relaxation (diastole) of the heart chambers, moving blood through the heart and body.
  • Blood flow: Proportional to the metabolic needs of tissues.
  • Cardiac Output: The amount of blood ejected from the heart per minute (heart rate x stroke volume).
  • Nervous System Control: The autonomic nervous system maintains blood pressure and blood flow, rerouting blood flow as needed.
  • Hormonal Control: Epinephrine (adrenaline) increases heart rate and stroke volume by inducing vasoconstriction, a stress response.

Conducting System

  • Cardiac Conducting System: Internal pacemaker and nerve-like pathways through the myocardium that trigger heart contractions.
  • Action Potential: A rapid change in membrane potential that acts as an electrical signal.
  • Auto-rhythmicity: Repetitive contractions caused by autorhythmic contractile cells:
    • Sinoatrial Node (SA Node): Located in the atrial wall, acts as the pacemaker, generating action potentials at regular intervals.
    • Atrioventricular Node (AV Node): Located at the junction of the atrium and ventricles.
    • Atrioventricular Bundle (Bundle of His): Nerve tissue that continues from the AV node.
    • Right and Left Bundle Branches: Branches of the AV bundle that extend to the apex of the heart and through the myocardium.
    • Purkinje Fibers: Branches given off by the right and left bundle branches, extending throughout the ventricular walls.

Blood Composition

  • Plasma: Extracellular matrix of blood, composed of water, proteins, and other solutes.
  • Buffy Coat: Contains white blood cells and platelets.
  • Formed Elements: Composed of erythrocytes (red blood cells).
  • Erythrocytes (Red Blood Cells): Biconcave disc-shaped cells that lack a nucleus and organelles. They transport oxygen and carbon dioxide.
  • Leukocytes (White Blood Cells): Complete cells with a nucleus and organelles. They are involved in protection and immune responses.
  • Platelets: Cytoplasmic fragments of large cells that are essential for blood clotting.

Blood Vessels

  • Arteries: Carry blood away from the heart, containing blood under pressure.
    • Elastic Arteries: Large arteries like the aorta and pulmonary trunk, able to withstand high pressure.
    • Muscular Arteries: Facilitate vasoconstriction and vasodilation.
    • Arterioles: Smaller arteries that feed into capillaries.
  • Precapillary Sphincters: Regulate blood flow to specific areas.
  • Capillaries: The site of exchange with tissues.
  • Veins: Carry blood towards the heart, containing blood under low pressure.
    • Venules: Smallest veins.
    • Valves: Prevent backflow of blood.

Histology of Blood Vessels

  • Tunica Intima: Innermost layer composed of simple squamous endothelium, a basement membrane, lamina propria, and elastic tissue.
  • Tunica Media: Middle layer with smooth muscle cells and elastin arranged circularly. Responsible for vasoconstriction and vasodilation.
  • Tunica Externa: Outer layer of connective tissue that merges with surrounding tissue.

Blood Vessels Comparison

Characteristic Arteries Veins
Direction Carries blood away from the heart to the tissues Carries blood to the heart from the tissues
Location Located deep in the muscle Located closer to the surface of your body
Wall Thickness Have very thick walls Have thinner walls than arteries
Blood Type Carry mainly oxygenated and some deoxygenated blood Carry mainly deoxygenated and some oxygenated blood
Valves Have no valves due to high pressure Have valves to prevent backflow of blood as there is low pressure
Pressure Carry blood under very high pressure Carry blood under very low pressure
Lumen Round lumen (holds its shape) Flat lumen (looks collapsed)

Capillaries

  • Structure: Composed of endothelial cells, a basement membrane, and a delicate layer of loose connective tissue.
  • Types:
    • Continuous Capillaries: No gaps between endothelial cells, less permeable to large molecules.
    • Fenestrated Capillaries: Windows in endothelial cells allow for greater permeability.
    • Sinusoidal Capillaries: Large gaps and irregular lumen allow free exchange of large protein molecules.

Capillary Types

  • Fenestrated Capillaries: Have pores in the endothelial cells (fenestrae) and highly permeable. Found in intestinal villi and the glomeruli of the kidney.
  • Sinusoidal Capillaries: Have a large diameter and irregular, incomplete walls of endothelial cells with less basement membrane. Found in endocrine glands and the liver as large molecules cross their walls.

Capillary Structure

  • Capillaries only have tunica intima, no media or externa.
  • Capillaries have a diameter of 7-9 microns, smaller than red blood cells (7.5 microns).

Capillary Exchange

  • Substances must pass through the interstitial fluid to reach their destinations.
  • Diffusion is driven by pressure gradients.
  • Source and Sink Principle:
    • Cells use oxygen, lowering its concentration. Freshly oxygenated blood flowing through capillaries maintains a concentration gradient, driving oxygen movement out of blood and into cells.
    • Cells produce carbon dioxide, increasing its concentration. Freshly oxygenated blood with low CO2 levels maintains a concentration gradient, driving carbon dioxide movement out of cells and into blood.

Transport Across Capillaries

  • Lipid-soluble substances like oxygen, carbon dioxide, steroid hormones, and fatty acids diffuse through the plasma membrane of endothelial cells.
  • Water-soluble molecules like glucose and amino acids diffuse through intercellular spaces or fenestrations.
  • The small spaces between cells restricts movement of large molecules in most capillaries.
  • The blood-brain barrier is a specialized capillary system with tight junctions that restrict the passage of most substances into the brain.
  • Larger spaces between endothelial cells in the liver or spleen allow proteins and even whole cells to pass.

Lymphatic System

  • Lymphoid Organs: Spleen, thymus, tonsils.
  • Lymphoid Tissues & Cells: MALT, Peyer's patches, lymphocytes (B and T cells).
  • Lymph: Fluid that circulates through lymphatic vessels.
  • Lymph Nodes: Filter and trap foreign substances from the lymph.

Connection between Cardiovascular and Lymphatic Systems

  • Capillary permeability, blood pressure, and osmotic pressure influence fluid movement from capillaries.
  • Fluid leaks out of capillaries into the interstitial space, and most returns to the capillaries due to osmotic pressures.
  • The lymphatic system collects the remaining fluid in tissues and carries it back to venous circulation.
  • Importance of the Lymphatic System:
    • Prevents fluid accumulation (edema) and swelling.
    • Maintains blood volume and pressure.
    • Regulates fluid balance.

Edema

  • Swelling caused by excess fluid in tissues (interstitial space).
  • Causes: Capillary leakiness, heart failure, kidney disease, liver problems, pregnancy, lymphatic system problems, standing/walking in hot weather, high salt intake.
  • Leaky capillaries can allow proteins into the interstitial fluid, increasing its osmotic pressure and drawing more fluid out of capillaries.

Cardiovascular System Components

  • Heart: A muscular pump that generates pressure within blood to circulate it throughout the body.
  • Blood Vessels: Conduits for blood transport, including arteries, veins, and capillaries.
  • Blood: Carries dissolved and suspended substances, delivering them to various locations throughout the body.

Cardiovascular System Functions

  • Transport:
    • Gases: Oxygen, carbon dioxide, and nitrogen.
    • Nutrients: Glucose, amino acids, vitamins, proteins, and lipids.
    • Metabolic Waste: Urea, uric acid, creatine, and ammonium ions.
    • Regulatory Molecules: Hormones and enzymes.
    • Processed Molecules: Proteins, enzymes, carbohydrates, and lipids.
  • Protection:
    • Inflammation: Triggered by infections or injuries.
    • Phagocytosis: The process where cells engulf and destroy foreign particles.
    • Antibodies: Proteins that identify and neutralize pathogens.
    • Platelets: Small cell fragments that help with blood clotting.
  • Regulation:
    • Fluid Balance: Regulates water content in the body.
    • pH: Maintains the body's pH level.
    • Body Temperature: Regulates body temperature through blood flow.
    • Blood Pressure: Maintains blood pressure for efficient blood circulation.
    • Exchange: Facilitates exchange between blood, interstitial fluid, and cells.

Heart

  • Function:

    • Pump: Creates pressure for blood movement through blood vessels.
    • Routing: Separates pulmonary and systemic circulatory pathways.
    • One-way flow: Achieved through pressure gradients.
    • Regulation: Blood supply adjusted to meet body demands (homeostasis).

  • Protection:

    • Rib cage, protective membranes, and fluid (pericardium): Provide a physical barrier for the heart.

  • Location:

    • Thoracic cavity, within the mediastinum, medial to the lungs, and superior to the diaphragm.
    • Size: Approximately the size of a closed fist, weighing around 300g (250-350g), with females having slightly smaller hearts.
    • Shape: Blunt-cone shaped, with 2/3rd towards the left side of the midline.
      • Apex: Rounded end, pointing anteriorly and inferiorly, above the diaphragm.
      • Base: Broader end, directed posteriorly and slightly superiorly.
    • Position: Sits between the second rib and the 5th intercostal space.

Pericardium

  • Fibrous Pericardium: Tough outer layer that prevents over-distension and anchors the heart to surrounding tissues.

  • Serous Pericardium: Thin inner layer, composed of simple squamous epithelium.

    • Parietal: Lines the fibrous outer layer.
    • Visceral: Covers the heart's surface, resembling cling film.
    • Pericardial Cavity: Space between parietal and visceral layers, filled with pericardial fluid which reduces friction and distributes pressure.

  • Protection: The pericardium provides protection for the heart.

  • Attachments: Attached to the large blood vessels (aorta and pulmonary trunk).

  • Pericarditis: Infection of the pericardium.

Heart Morphology

  • Anterior & Posterior Sides: Contain major blood vessels.

  • Sulci (Grooves):

    • Coronary Sulcus: Separates the atria and ventricles.
    • Anterior Interventricular Sulcus: Separates the right and left ventricles (anterior side).
    • Posterior Interventricular Sulcus: Separates the right and left ventricles (posterior side).

  • Pericardial & Epicardial Fat:

    • Pericardial Fat: Between visceral and parietal pericardium.
    • Epicardial Fat: Between outer layer of myocardium and visceral pericardium (epicardium).

  • Superior Chambers (Collecting): Atria with thinner walls.

  • Inferior Chambers (Discharging): Ventricles with thicker walls.

Heart Wall

  • Epicardium: (Visceral Pericardium) Outer layer, serous membrane, simple squamous epithelium over areolar tissue, providing a smooth surface.
  • Myocardium: Middle layer, thickest layer, composed of cardiac muscle cells, responsible for contractility, branched cells, and uninucleate.
  • Endocardium: Inner layer, smooth, simple squamous epithelium over areolar tissue, covers the valve surface, continuous with endothelium, and very smooth.

Heart Anatomy

  • Interventricular Septum: Wall separating the two ventricles.
  • Interatrial Septum: Wall separating the atria, containing the fossa ovalis, a remnant of the fetal opening (foramen ovale) between the atria.
  • Left Ventricle Wall: Significantly thicker than the right ventricle wall.
  • Pectinate Muscles: Muscular ridges in the auricle and atrial walls, allowing for muscle stretching during blood inflow and aiding in contraction.
  • Trabeculae Carnae: Muscular ridges and columns on the ventricle wall's inner surface, creating turbulence within blood.

Chambers

  • Right Atrium: Thin-walled receiving chamber, primarily on the posterior side.

    • Auricles: Extensions increasing volume.
    • Pectinate Muscles: Allow for large force of contraction.
    • Blood Inflow: Receives deoxygenated blood through three openings:
      • Superior and inferior vena cava
      • Coronary Sinus

  • Right Ventricle: Pumping chamber, mainly on the anterior side.

    • Wall Thickness: Thicker than the atria.
    • Blood Flow: Receives deoxygenated blood from the right atrium, and pumps blood to the pulmonary trunk.
    • Trabeculae Carnae: Present within this chamber.

  • Left Atrium: Thin-walled receiving chamber, predominantly on the posterior side, forming the heart's base.

    • Auricles: Extensions increasing volume.
    • Pectinate Muscles: Allow for Large force of contraction.
    • Blood Inflow: Receives oxygenated blood through four openings:
      • Four Pulmonary Veins

  • Left Ventricle: Pumping chamber, forms the apex and posteroinferior aspect.

    • Wall Thickness: Thickest chamber of the heart.
    • Blood Flow: Receives oxygenated blood from the left atrium and pumps blood to the aorta.
    • Trabeculae Carnae: Present within this chamber.

Great Blood Vessels of the Heart

  • Blood into the Heart:
    • Right Atrium: Receives blood from:
      • Superior and Inferior Vena Cava (Systemic Circulation): Deoxygenated blood.
      • Coronary Sinus (Coronary Circulation): Deoxygenated blood.
    • Left Atrium: Receives blood from:
      • Four Pulmonary Veins (Pulmonary Circulation): Oxygenated blood.
  • Blood out of the Heart:
    • Right Ventricle: Blood exits through the pulmonary trunk (dividing into two pulmonary arteries for each lung) to the pulmonary circulation (deoxygenated).
    • Left Ventricle: Blood exits through the aorta to the systemic circulation (oxygenated).

Valves of the Heart

  • Atrioventricular (AV) Valves: Between atria and ventricles.

    • Leaf-like Cusps: Structure of the valves.
    • Chordae Tendineae: Tendons attaching cusps to papillary muscles.
    • Atrioventricular Canal: Canal formed by open valves.
    • Right Side (Tricuspid Valve): Three cusps.
      • Left Side (Bicuspid or Mitral Valve): Two cusps.
    • Function: Allow blood flow from atrium to ventricle when open, and close to prevent blood flow back into the atrium when the ventricle contracts.

  • Semilunar (SL) Valves: At the base of large blood vessels (exit of ventricles).

    • Cup-shaped Structure: Their shape.
    • Pulmonary SL Valve: Located at pulmonary trunk base.
    • Aortic SL Valve: Located at aorta base.
    • Function:
      • Close when cups are filled, preventing blood backflow into the heart.
      • Open when cups are empty allowing blood flow freely out of the heart.

  • Specific Valve Functions:

    • Chordae Tendineae: Prevent atrioventricular valves from bulging into the aorta.
    • Papillary Muscles: Pillar-like muscles in ventricles, preventing atrioventricular valve prolapse.

Blood Flow through the Heart

  • Path: Superior and inferior vena cava & coronary sinus - > right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk -> pulmonary arteries -> lung tissue -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> aorta -> coronary arteries or body tissues.

Heart as Pump

  • Pulmonary Circulation: Deoxygenated blood travels to the lungs for oxygenation and returns to the heart, completing a double cycle.

    • Flow: Deoxygenated blood enters the right atrium, moves into the right ventricle, exits through the pulmonary trunk, branches into left and right pulmonary arteries, reaches the lungs for gas exchange, oxygenated blood travels through pulmonary veins back to the left atrium.

  • Systemic Circulation: Oxygenated blood circulates to body tissues and returns to the heart.

    • Flow: Oxygenated blood enters the left atrium, flows into the left ventricle, is pumped out of the heart through the aorta, branches into ascending aorta, aortic arch, and descending aorta, delivers blood to all body cells for gas/nutrient/fluid exchange, deoxygenated blood returns to the heart through the vena cava, entering the right atrium.

  • Coronary Circulation: A part of systemic circulation, supplying blood specifically to the heart.

Cardiac Cycle

  • Contraction: The heart's contraction creates the pressure for blood movement, causing the flow from regions of higher to lower pressure within the circulatory system.

  • Cycle: Repetitive contraction (systole) and relaxation (diastole) of the heart chambers, moving blood through the heart and body.

  • Blood Flow Adjustment: Blood flow is adjusted according to the metabolic needs of different tissues.

    • High Need Tissues: The brain, kidneys, liver, and exercising skeletal muscles require increased blood flow.

  • Cardiac Output (CO):

    • Formula: CO = Heart Rate x Stroke Volume.
    • Stroke Volume: Amount of blood ejected with each heartbeat.
    • Heart Rate: Number of heartbeats per minute.
    • CO Measurement: Usually measured in milliliters per minute (ml/min), ranging from 5-6 L/min at rest in a normal adult.

Cardiac Control

  • Nervous System Control: The autonomic nervous system regulates blood pressure and blood flow:

    • Blood Pressure Maintenance: The autonomic system manages blood pressure.
    • Blood Flow Rerouting: The nervous system redistributes blood flow depending on need, for example, increasing blood flow to the muscles during exercise. Additionally, it reroutes blood away from vital organs and the skin towards the brain and cardiac muscles in emergency situations like blood loss or injury.

  • Hormonal Control: Hormones like epinephrine (adrenaline) released by the adrenal glands increase heart rate and stroke volume, causing vasoconstriction as a response to stress.

Conducting System

  • Cardiac Conducting System: Internal pacemaker and nerve-like pathways within the myocardium.

  • Action Potential: A rapid change in membrane potential that functions as an electrical impulse.

  • Signal Transmission: Action potentials spread through the conducting system, initiating contraction of cardiac muscle cells, ultimately pumping blood.

  • Auto-rhythmicity: The heart's ability to generate its own action potentials, resulting in repetitive contractions.

    • Sinoatrial (SA) Node: This is the pacemaker, located in the right atrial wall. Its role is to generate action potentials at regular intervals.
    • Atrioventricular (AV) Node: Found at the junction of the atrium and ventricle.
    • Atrioventricular Bundle (Bundle of His): Nerve tissue extending from the AV node.
    • Right and Left Bundle Branches: The bundle branches split from the AV bundle as it passes through the atrioventricular septum, extending to the apex of the heart, through the myocardium, and up to the atrioventricular wall.
    • Purkinje Fibers: Branches given off by the right and left bundle branches, known as Purkinje branches. They are responsible for conveying the electrical signals within the ventricles.

Blood Composition

  • Life-sustaining Fluid: Essential for various bodily functions.

  • Diagnostic Tool: Blood analysis is commonly employed for disease diagnosis.

  • Components (Centrifuged Blood):

    • Plasma (55%): The extracellular matrix of blood.
      • Water (91%): The primary component.
      • Proteins (7%):
        • Albumins (58%): Large proteins influencing osmotic balance.
        • Globulins (38%): Transport proteins carrying lipid-soluble molecules and antibodies.
        • Fibrinogen (4%): Fibrous proteins aiding in blood clotting.
      • Other Solutes (2%):
        • Ions: Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg).
        • Nutrients: Glucose, amino acids, lipids, cholesterol.
        • Waste Products: Urea, uric acid, creatine, ammonium ions.
        • Gases: Oxygen, carbon dioxide, nitrogen.
        • Regulatory Substances: Hormones, enzymes.
    • Buffy Coat (Less than 1%): This thin layer contains white blood cells and platelets.
      • White Blood Cells (5-10 thousand/cubic mm): Important for immune responses.
      • Platelets (250-400 thousand/cubic mm): Essential for blood clotting.
    • Formed Elements (45% - Haematocrit): Primarily composed of red blood cells.
      • Red Blood Cells (4.2-6.2 million/cubic mm): Responsible for oxygen transport.

  • Connective Tissue: Blood is classified as a connective tissue due to its few cells with an abundance of extracellular matrix.

  • Blood Volume: Typically 5-6 liters in males, 4-5 liters in females.

  • Blood pH: 7.35-7.45.

Blood Cells

  • Erythrocytes (Red Blood Cells):

    • Shape: Biconcave discs.
    • Size: 7.5 micrometers.
    • Nucleus: Non-nucleate and lack organelles, making them unable to reproduce, with a lifespan of 120 days.
    • Hemoglobin: Contains the protein hemoglobin, which contains iron and carries oxygen.
    • Oxygen Transport: 1.5% oxygen is dissolved in plasma, while 98.5% is bound to hemoglobin.
    • Carbon Dioxide Transport: 7% in plasma, 23% attached to hemoglobin, and 70% exists as bicarbonate ions (HCO3).

  • Leukocytes (White Blood Cells):

    • High Count: Indicates potential infection.
    • Complete Cells: Possess a nucleus and organelles.
    • Types: Neutrophils, lymphocytes, monocytes, eosinophils, basophils.
    • Protection: Responsible for phagocytosis, immune responses (cell-mediated and antibody-mediated), differentiate into macrophages, and release histamine.

  • Platelets:

    • Not True Cells: Cytoplasmic fragments of large cells.
    • Blood Clotting: Essential for stopping bleeding.
    • Blood Clot Formation: Adhere to fibrin, forming a plug/clot to stop bleeding.

Blood Vessels

  • Arteries: Carry blood away from the heart.

    • Pressure: Blood flows under pressure.
    • Types:
      • Elastic Arteries: Large arteries (aorta and pulmonary trunk), capable of withstanding high pressure due to their proximity to the heart.
      • Muscular Arteries: Facilitate vasoconstriction and vasodilation.
      • Arterioles: Smaller arteries leading to capillaries.

  • Precapillary Sphincters: Control blood flow to certain areas.

  • Capillaries: Sites of exchange between blood and tissue interstitial fluid.

  • Veins: Carry blood towards the heart.

    • Pressure: Low blood pressure.
    • Wall Thickness: Thinner walls compared to arteries, with less elastic tissue and smooth muscle.
    • Valves: Present to prevent backflow of blood due to low pressure, helping to counteract gravity's influence.
    • Types: Venules, small, medium, and large veins, with venules being the smallest.

Blood Vessel Histology

  • Tunica Intima (Interna): Innermost layer, composed of simple squamous endothelium, basement membrane, lamina propria, and elastic tissue.

  • Tunica Media: Middle layer, containing smooth muscle cells and elastin arranged circularly.

    • Smooth Muscle Function: Controls the diameter of the lumen.
    • Elastic Tissue Function: Allows for distension and recoil.
      • Vasoconstriction: Smooth muscle contraction, reducing blood flow.
      • Vasodilation: Smooth muscle relaxation, increasing blood flow.

  • Tunica Externa (Adventitia): Outer layer, composed of connective tissue that transitions from dense to loose, merging with surrounding tissue.

    • Blood Vessels & Nerves: Nerves and blood vessels pass through the tunica externa, supplying the smooth muscle with blood.

  • Lumen: Blood vessel's inner space where blood flows.

  • Variations: The structure of blood vessels can vary based on type and specific requirements.

Blood Vessel Comparison Table

Feature Arteries Veins
Function Carries blood away from the heart to the tissues Carries blood to the heart from the tissues
Location Deep within muscles Closer to the surface of the body
Wall Thickness Thick walls Thinner walls than arteries
Blood Type Mainly oxygenated, but some deoxygenated (pulmonary and umbilical artery) Mainly deoxygenated, but some oxygenated (pulmonary and umbilical vein)
Valves No valves due to high pressure Valves present to prevent backflow due to low pressure
Blood Pressure High pressure Low pressure
Lumen Appearance Round lumen (holds its shape) Flat lumen (collapsed appearance)

Capillaries

  • Size: Smallest blood vessel type.

  • Structure: Walls composed of endothelial cells (simple squamous epithelium), basement membrane, and a delicate layer of loose connective tissue.

  • Types:

    • Continuous Capillaries: Lack gaps between endothelial cells, less permeable to large molecules.
    • Fenestrated Capillaries: Have pores in the endothelial cells, more permeable to smaller molecules.
    • Sinusoidal Capillaries: Have large gaps between endothelial cells, highly permeable to large molecules.

  • Function: Exchange of substances between blood and tissues.

Capillary Types

  • Fenestrated capillaries are highly permeable due to pores called fenestrae in the endothelial cells. These are found in places like intestinal villi and the glomeruli of the kidneys.
  • Sinusoidal capillaries have a large diameter with an incomplete wall of endothelial cells and a reduced basement membrane. These are found in locations such as endocrine glands and the liver, allowing for the passage of large molecules.
  • Capillaries only possess the tunica intima layer, lacking the media and externa layers.
  • Capillaries have a diameter of 7-9 microns, which is comparable to the 7.5 micron diameter of a red blood cell.

Capillary Exchange

  • Capillary exchange involves the movement of substances into and out of capillaries.
  • Diffusion plays a crucial role in the movement of oxygen, hormones, and nutrients from the high concentration within the capillary to the lower concentration in the interstitial fluid.
  • Lipid-soluble substances, such as O₂ , CO₂, steroid hormones, and fatty acids, diffuse directly through the plasma membrane of endothelial cells.
  • Water-soluble molecules, such as glucose and amino acids, diffuse through intercellular spaces or through fenestrations in capillaries.
  • The small spaces between cells restrict the passage of many molecules, as seen in the blood-brain barrier, where specialized capillaries control the substances entering the brain.
  • Larger spaces between endothelial cells allow proteins and even whole cells to pass through, as observed in the liver and spleen.

Lymphatic System

  • The lymphatic system features a network of vessels, tissues, and organs that help maintain fluid balance and immunity.
  • Lymphoid organs include the spleen, thymus, and tonsils.
  • Lymphoid tissues and cells consist of MALT (mucosa-associated lymphoid tissue), Peyer's patches, lymphocytes (B and T cells), and lymph, the fluid circulating through the lymphatic vessels.
  • Lymphatic ducts, trunks, vessels, and capillaries form the network of fluid drainage.
  • Lymph nodes act as filters for the lymph.

Connection Between Cardiovascular and Lymphatic Systems

  • Capillary permeability, blood pressure, and osmotic pressure influence the movement of fluid between capillaries and interstitial space.
  • While most fluid returns to capillaries due to osmotic pressures, some remains in the tissues.
  • Lymphatic capillaries collect this residual fluid and ultimately return it to the venous circulation.
  • The lymphatic system is essential for maintaining blood volume, pressure, and fluid balance.
  • Edema – Swelling due to excess fluid in body tissues. Several factors can contribute to edema, including:
    • Issues with capillaries
    • Heart failure
    • Kidney disease
    • Liver problems
    • Pregnancy
    • Problems with the lymphatic system
    • Standing or walking in hot weather
    • Eating too much salt

Edema

  • If capillaries become leaky to blood, proteins can leak into the interstitial fluid, increasing the osmotic pressure outside the capillary, drawing more fluid into the interstitial space.

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Compendium 6 Cardiovascular System Notes PDF

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Test your knowledge on the key components and functions of the cardiovascular system. From the structure of the heart to the role of blood, this quiz covers essential topics including cardiac output, the sinoatrial node, and the significance of blood composition. Perfect for students studying human anatomy and physiology.

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