Cardiovascular Physiology Notes

What is the primary function and main components of the cardiovascular system?

Transports oxygen, nutrients, hormones, and waste products throughout the body. It includes the heart, blood vessels (arteries, veins, capillaries), and blood.

What is cardiac output (CO)?

The amount of blood pumped by the heart per minute. CO = SV \times HR, where SV is stroke volume (mL) and HR is heart rate (beats/min).

Resting CO for humans ~5 L/min

Define stroke volume (SV).

The amount of blood ejected by the heart with each beat.

What factors influence heart rate (HR)?

Autonomic nervous system (sympathetic increases, parasympathetic decreases), hormones (e.g., epinephrine), body temperature, and physical activity.

Describe the Frank-Starling mechanism.

The heart's ability to increase its force of contraction (and thus stroke volume) when venous return increases, stretching the ventricular muscle. This ensures the heart adapts to varying volumes of blood returning to it.

What is blood pressure (BP)?

The force exerted by circulating blood on the walls of blood vessels, expressed as systolic (ventricular contraction) over diastolic (ventricular relaxation) pressure (e.g., 120/80 mmHg).

What factors regulate blood pressure?

Cardiac output, peripheral resistance, blood volume, and hormones (e.g., angiotensin II, atrial natriuretic peptide).

Define total peripheral resistance (TPR).

The resistance to blood flow in the systemic circulation, influenced by vessel diameter, blood viscosity, and the number of vessels.

How does the autonomic nervous system regulate blood pressure?

Sympathetic increases BP by increasing heart rate, contractility, and vasoconstriction. Parasympathetic decreases BP by decreasing heart rate and promoting vasodilation.

What is the role of baroreceptors in blood pressure regulation?

Pressure-sensitive receptors in blood vessel walls and the heart detect changes in blood pressure and signal the brainstem to adjust autonomic output.

Describe the renin-angiotensin-aldosterone system (RAAS).

A hormonal system that regulates blood pressure and fluid balance. Renin converts angiotensinogen to angiotensin I, then to angiotensin II, which causes vasoconstriction and stimulates aldosterone release (increased sodium and water retention).

What is the function of capillaries?

Facilitates the exchange of oxygen, carbon dioxide, nutrients, and waste products between the blood and tissues.

What is venous return?

The rate of blood flow back to the heart, influenced by skeletal muscle contraction, respiratory movements, and venous valves.

How does exercise affect cardiovascular physiology?

Increases heart rate, stroke volume, cardiac output, and blood pressure. Leads to vasodilation in active muscles and increased venous return.

What are the main functions and components of blood?

Transport of oxygen and nutrients, regulation of body temperature and pH, protection against infection, and clotting. Includes plasma (liquid), red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Define hematopoiesis.

The process of blood cell formation, primarily in the bone marrow.

What are erythrocytes and hemoglobin?

Red blood cells (RBCs) responsible for oxygen transport via hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen and contains iron.

Define hematocrit.

The percentage of blood volume occupied by erythrocytes.

What are leukocytes?

White blood cells (WBCs) involved in immune responses and defense against pathogens.

What is the role of platelets in blood clotting?

Cell fragments that play a crucial role in blood clot formation.

Describe the main plasma proteins: Albumins, Globulins, and Fibrinogen.

Plasma proteins that contribute to osmotic pressure and transport of various substances. Globulins include antibodies and transport proteins. Fibrinogen is essential for blood clotting.

What are multipotent hematopoietic stem cells?

Stem cells in bone marrow that can differentiate into all types of blood cells.

Where does erythropoiesis occur?

The production of red blood cells, primarily in the bone marrow.

What are reticulocytes and bilirubin?

Immature red blood cells recently released from the bone marrow. Bilirubin is a product of hemoglobin breakdown, excreted in bile.

What are ferritin and transferrin?

Ferritin stores iron, primarily in the liver and spleen. Transferrin is a plasma protein that transports iron in the bloodstream to the bone marrow.

What is the role of folic acid and vitamin B12 in erythropoiesis?

Folic acid (Vitamin B9) is required for DNA synthesis in dividing cells, including erythrocyte precursors. Vitamin B12 is necessary for red blood cell production and requires intrinsic factor for absorption.

Define anemia.

A condition characterized by a decreased ability of the blood to carry oxygen, often due to a reduced number of erythrocytes or decreased hemoglobin content.

Describe sickle cell disease.

A genetic disorder characterized by abnormal hemoglobin, causing red blood cells to become rigid and sickle-shaped.

Define polycythemia.

A condition characterized by an abnormally high number of erythrocytes in the blood.

What is the function of neutrophils and monocytes/macrophages?

Neutrophils are phagocytic leukocytes essential during inflammation. Monocytes differentiate into macrophages, which are phagocytic cells that engulf bacteria and cellular debris.

What is the function of basophils and eosinophils?

Basophils secrete heparin (anticoagulant) and histamine (vasodilator). Eosinophils combat parasitic infections and modulate allergic responses.

What are megakaryocytes?

Large bone marrow cells that produce platelets by pinching off fragments of their cytoplasm.

What are Hematopoietic growth factors?

Hormones that stimulate the growth and differentiation of progenitor cells into mature blood cells and prevent apoptosis.

Define pulmonary and systemic circulation.

The part of the circulatory system where deoxygenated blood is pumped to the lungs and oxygenated blood returns to the heart. Systemic circulation is where oxygenated blood is pumped to the body and deoxygenated blood returns to the heart.

Define: Arteries, Veins, and Microcirculation.

Arteries carry blood away from the heart, while veins carry blood back to the heart. Microcirculation involves blood flow through arterioles, venules, and capillaries, where exchange occurs.

Heart Anatomy: what are the three layers?

Pericardium (protective), epicardium, myocardium (muscle mass), and endocardium (lining blood vessels).

What is the interventricular septum?

The wall that separates the left and right ventricles of the heart.

What are the left and right AV valves also known as?

The left AV valve is known as the bicuspid or mitral valve. The right AV valve is called the tricuspid valve.

What are papillary muscles and Chordinae tendineae?

Muscles located in the ventricles that attach to the chordae tendineae, which hold the AV valves in place. Dysfunction can lead to prolapse.

Name the two semilunar valves.

Pulmonary and aortic valves.

What is the conduction system?

Cardiac muscle with gap junctions that propagate electrical signals.

What are the Vagus nerves and describe the sympathetic nervous system's effect on the heart.

Parasympathetic: Affects only the atrium and SA node, releasing muscarinic acetylcholine. Sympathetic: Affects the whole heart via B1 receptors, releasing NE and E.

What is the role of the coronary arteries/blood flow?

Supplies blood to the myocardium, emptying into the atrium.

What is Monoamine oxidase and which receptors do NE and E bind to?

Breaks down dopamine and serotonin (low = depression, high = ADHD). NE binds to alpha 1,2 and beta 1,3. E binds to alpha 1,2 and beta 1,2,3.

Conduction Pathway: SA node, AV node, Internodal pathways, Bundle of His, and Purkinje fibers function

SA node: initial depolarization starts. AV node: delays signal to prevent tetany. Internodal pathways: SA -> AV. Bundle of His: interventricular septum branches & apex. Purkinje fibers: rapidly through myocytes throughout ventricles.

P wave and QRS complex - ECG meaning

P wave: atrial depolarization. QRS complex: ventricular depolarization.

How is Partial and Complete av block presented on a ECG?

Partial AV block: damages AV node - every other QRS. Complete AV block: no matching between P and QRS.

Pacemaker potential and Automaticity

Slow depolarization of SA node. Automaticity is the ability to excite spontaneously.

What happens in the excite SA phase? What is Ectopic pacemaker?

Dec K+ permeability, F type Na+ opens, T type Ca opens, L type Ca opens - action potential. Ectopic pacemaker is when nodes manifest own rhythm.

What does systole and diastole mean? Isovolumetric ventricular contraction?

systole - contraction. diastole - relaxation. Isovolumetric ventricular contraction: ventricles contract.

Stroke volume and Stroke volume equation:

Blood ejected from each ventricle. SV = EDV - ESV.

Isovolumetric ventricular relaxation and Ventricular filling?

no blood entering or leaving. Ventricular filling: blood flows in from atria.

Lub and Dub

av valves close (S1). Dub: pulmonary/aortic valves close (S2).

End diastolic volume and End systolic volume

Vol of blood before contraction. End systolic volume: vol of blood after contraction.

Dicrotic notch

Rebounding of aortic pressure and elastic recoil.

Atrial fibrillation, Heart murmurs

Atria contracts unrhythmically. Heart murmurs are weird sounds indicating heart disease.

Laminar flow and Stenosis flow/Insufficiency

blood going through smooth valves. Stenosis flow sound: blood going through narrow causing high pitch sound. Insufficiency: blood backwards in damaged valve causing low pitch sound.

Septal defect

Blood btw atria or ventricles.

Cardiac Output

HR * SV, vol of blood a ventricle pumps w time.

Chronotropic and Dromotropic effects

Chronotropic: Parasym HR dec w vagus nerves, inc K+ permeability so slow depolarization & Sym HR inc , more F type Na+ release so fast depolarization. Dromotropic: Parasym : dec rate of spread through AV & Sym: inc conduction velocity.

Preload, SV, and Ventricular function curve:

Vol of blood just before contraction. SV: B1 receptors and NE drive muscle fibers & Thyroid - inc force of contraction : permissive of B1 receptors. Ventricular function curve: SV proportional to EDV.

Frank Starling Mechanism

relation btw SV & Endv -> inc filling, inc stretching, inc contraction & Inc venous return, inc end diastolic vol, inc SV.

Stretching - for cardiac muscle function

dec thick and thin fil spacing during a twitch, inc Ca2+ release in SR.

Contractility and Ionotropic

strength of contraction at any time: inc by NE on B receptors. Ionotropic: extrinsic factor that inc force contraction.

Ejection fraction

SV/EDV.

Afterload

how hard heart has to work to eject blood: pressure downstream.

Endothelium, Venules, Elastic arteries

Single cell layered lining. Venules: endothelium and connective tissues. Elastic arteries: near heart.

Pressure reservoirs, Passive recoil

⅔ blood is held in arteries and pushed out during diastole : more consistent flow. Passive recoil: drive blood into arteriols during diastole.

Compliance and Muscular arteries

how easily it can be stretched: dif vol / dif pressure. Muscular arteries: carry blood to mesenteric artery.

Hypertension and Mean arterial pressure

inc BP. Mean arterial pressure: average pressure during the cycle = DP + ⅓(SP - DP).

Sphygmomanometer and Korotkoff’s sounds

arm cuff. Korotkoff’s sounds: when arm pressure > cuff pressure and high velocity blood makes noise.

Arterioles function in capillary flow, Locals controls

control min/min flow in capillary beds : determines mean arterial pressure. Locals controls: how nervous/hormone alter own arteriolar resistance.

Active hyperemia, Bradykinin, kininogen, kallikrein, prekallikrein

inc BP when metabolic activity is Inc. Flow autoregulation - arterioles change their resistance in response to BP to maintain constant amount.

If stretched, arteriole will… and Sym postganglionic neurons

If stretched, arteriole will contract. Sym postganglionic neurons Releases NE - received by alpha receptors: vasoconstrict & Dec sym to basal level = vasodilation.

Autonomic postganglionic, Angiotensin II funciton, Vasopressin

release NO - gastro inst - mediate erection. Angiotensin II funciton: contracts most arterioles. Vasopressin: constriction - responds to dec BP from posterior pituitary.

Atrial natriuretic peptide, NO from endothelial cells, Prostaglandin, Endothelin

vasodilator from cardiac atria. NO from endothelial cells: vasodilator. Prostaglandin: vasodilator. Endothelin: vasoconstriction.

Diffusion and Starling forces

only important means of net movement of important stuff. Starling forces: capillary blood pres (favored) vs interfluid blood pres.

capacitance vessels and Veins

large capacity for blood. Veins: low resistance conduits for blood flow & Diameters alter in response to changes in blood volume & Constriction increases forward flow.

Skeletal muscle pump, Respiratory pump

inc venous pressure - values make blood go towards heart only. Changes pressure in dif organs so that there is a dif btw peripheral veins and heart so that blood can move forward easier.

Venous return

CO except for brief moments in time & Large amounts of vol veins need to be moments in time.

Lymphatic system and Lymphatic capillaries

lymph nodes & vessels lymph fluids flows. Lymphatic capillaries: 1 layer of endothelium on basement membrane & large water filled channels and permeable returns leaked proteins.

Total peripheral resistance

combined resistance to flow of all blood vessels & Total peripheral resistance inv. Prop. arteriole radius.

Hemorrhage

dec blood loss, dec blood vol, dec CO, dec MAP.

Baroreceptors and Communicates with brainstem through afferent neurons

pressure sensors -> carotid sinus. Communicates with brainstem through afferent neurons: Inc freq of bar receptors firing = inc carotid stimulation = inc mean arterial pressure.

Cushing's phenomenon

Cushing's phenomenon: situation in which increased intracranial pressure causes a dramatic inc in MAP & Inward pressure causes a collapse and greatly releases resistance to blood blow

Hypotension and Silent killer/Vasovagal syncope

low arterial blood pressure. Silent killer: no one pinpoint cause for hypotension. Vasovagal syncope: Higher brain centers involved with emotions inhibit sympathetic activity to the circulatory system and enhance parasympathetic activity to the heart

Shock and Gravity increases pressure in

any loss of blood that damages tissues. Gravity increases pressure in legs.

Exercise affect on blood flow, What happens to Cardiac Output during exercise?

flow diverted to skeletal muscle & heart & away from skin (at first), GI and kidneys & Local factors mediate the vasodilation in skeletal muscle and heart: dec TPR. Inc HR, Inc SV: inc CO & dec TPR so MAP inc a little & Pulse pressure inc bc SV inc and systolic pressure inc

Arterial baroreceptors during exercise

resets system for exercise - dec baroreceptor firing causes dec parasympathetic and inc sympathetic outflow.

Vo2 max

maximal oxygen consumption - when o2 cannot be consumed anymore despite more exercise.

Embolus and Von willebrand factor

blood clot that breaks off and lodges elsewhere : embolism. Platelets adhere to this protein Bridge damaged vessels and platelets

Platelets aggregation:

Platelet plug (using thromboxane A2).

End diastolic volume

clotting product makes blood into a solid gel:

Hypertrophic Cardiomyopathy

A condition typically caused by genetic mutations affecting cardiac contractile proteins, leading to thickening of the left ventricle wall and disrupted organization of heart muscle cells (myocytes).

Angina Pectoris

Chest pain caused by reduced blood flow to the heart muscle, often a symptom of underlying heart disease.

Sudden Deaths from Ventricular Fibrillation

Unexpected cardiac arrest due to rapid, uncoordinated contractions of the ventricles, leading to ineffective pumping of blood. Often associated with underlying heart conditions.

Atherosclerosis

A disease in which plaque builds up inside the arteries, causing them to harden and narrow. This thickening of the artery wall primarily occurs closest to the lumen (the inner space of the artery).

Hypertension

A condition in which there is an increase in systemic arterial pressure. Chronic hypertension can lead to serious health complications, including heart disease, stroke, and kidney failure. It often requires long-term management through lifestyle changes and/or medication.

Heart Failure

A chronic condition in which the heart is unable to pump blood effectively enough to meet the body's needs, leading to symptoms such as fatigue and shortness of breath. Heart failure can result from a variety of underlying cardiovascular conditions, including coronary artery disease, hypertension, and valve disorders. The condition is characterized by not enough Cardiac Output (CO).

Pulmonary Edema

Characterized by lung fluid accumulation due to left ventricular failure. It indicates a decrease in O2 uptake and CO2 removal. Pulmonary edema is a condition in which excess fluid accumulates in the lungs, making it difficult to breathe. It is often caused by congestive heart failure, but can also result from other conditions such as pneumonia or kidney disease.