hala cardiovascular system

Pulmonary Circuit

Circuit that carries blood from the heart to the lungs and back to the heart

Systemic Circuit

Circuit that carries blood from the heart to the body tissues and back to the heart

Heart Functions

Creates blood pressure, keeps blood flowing in one direction, and circulates blood according to body needs

Mixing of Oxygen-Rich and Oxygen-Poor Blood

Not a normal function of the heart

Atrial Natriuretic Hormone (ANH)

Hormone secreted by the heart that helps lower blood pressure and blood volume

Fibrous Pericardium

Outermost layer of the pericardium that anchors the heart within the mediastinum

Epicardium

Outermost layer of the heart wall; also called the visceral serous pericardium

Heart Wall Layers (Innermost to Outermost)

Endocardium → Myocardium → Epicardium

Heart Coverings (Inner to Outer)

Epicardium (Visceral Pericardium) → Parietal Pericardium → Fibrous Pericardium

Left Ventricle

Chamber with the thickest wall; pumps oxygen-rich blood to the body

Right Atrium

Chamber that receives oxygen-poor blood from the body

Coronary Sinus, Superior Vena Cava, and Inferior Vena Cava

Vessels that return blood to the right atrium

Pulmonary Veins

Vessels that return oxygen-rich blood to the left atrium

Pulmonary Semilunar Valve

Prevents blood from flowing back from the pulmonary trunk into the right ventricle

Aorta

Largest artery; carries oxygen-rich blood from the left ventricle to the body

Chordae Tendineae

Tendinous cords that anchor AV valves to papillary muscles

Papillary Muscles

Ventricular muscles that prevent AV valves from inverting into the atria

First Heart Sound (Lub)

Produced by closure of the atrioventricular valves

Coronary Arteries

Supply oxygen and nutrients directly to the heart muscle

Heart Murmur

Abnormal heart sound usually caused by leaky or narrowed valves

Atherosclerosis

Thickening and hardening of artery walls caused by plaque buildup

Risk Factors for Atherosclerosis

Smoking, diabetes mellitus, artery wall injury, hypertension, and elevated blood lipids

Cardiac Conduction Pathway

SA Node → AV Node → AV Bundle (Bundle of His) → Purkinje Fibers

SA Node

Natural pacemaker located in the upper posterior wall of the right atrium

AV Node Delay

Allows atria to finish contracting before ventricles contract

Heart Block

Condition in which electrical signals fail to reach the ventricles

P Wave

Represents atrial depolarization

QRS Complex

Represents ventricular depolarization

T Wave

Represents ventricular repolarization

Fibrillation

Rapid, uncoordinated contractions of cardiac muscle

Atrial Systole

Atria contracting, ventricles relaxing, AV valves open, semilunar valves closed

Ventricular Systole

Ventricles contracting, atria relaxing, AV valves closed, semilunar valves open

Semilunar Valve Opening

Occurs when ventricular pressure exceeds pressure in the pulmonary trunk and aorta

Cardiac Output (CO)

Volume of blood pumped by each ventricle per minute

Stroke Volume (SV)

Volume of blood pumped by a ventricle during one contraction

Cardiac Output Formula

CO = Heart Rate × Stroke Volume

Cardioregulatory Center

Located in the medulla oblongata

Baroreceptor Reflex (Low Blood Pressure)

Sympathetic stimulation increases heart rate and cardiac output

Sympathetic Nervous System

Increases heart rate, contraction strength, and stroke volume

Frank-Starling Law

Increased venous return causes stronger ventricular contractions

Blood Vessel Pathway

Artery → Arteriole → Capillary → Venule → Vein

Capillaries

Exchange vessels for gases, nutrients, and wastes

Tunica Intima (Interna)

Innermost blood vessel layer consisting of endothelium and basement membrane

Tunica Media

Middle muscular layer responsible for vasoconstriction and vasodilation

Tunica Externa (Adventitia)

Outermost connective tissue layer

Blood Vessel Layers (Inner to Outer)

Tunica Intima → Tunica Media → Tunica Externa

Arteries

Carry blood away from the heart

Arterioles

Small arteries that regulate blood pressure and blood flow

Veins

Carry blood toward the heart and often contain valves

Tissue Fluid

Fluid surrounding body cells

Diffusion

Movement of substances from high concentration to low concentration

Osmosis

Movement of water across a selectively permeable membrane

Filtration

Movement of water and dissolved substances driven by blood pressure

Arterial End of Capillary

Blood pressure causes filtration of water and nutrients out of capillaries

Venous End of Capillary

Osmotic pressure causes water to move back into capillaries

Carbon Dioxide Exchange

Occurs by diffusion

Phlebitis

Inflammation of a vein

Blood Flow Velocity

Fastest in arteries and slowest in capillaries

Blood Pressure Gradient

Highest in the aorta and lowest in the vena cavae

Mean Arterial Blood Pressure (MABP)

Average arterial pressure over time

Peripheral Resistance

Resistance to blood flow determined mainly by arterial diameter and vessel length

Blood Pressure Determinants

Cardiac Output and Peripheral Resistance

Venous Return

Return of blood to the heart; depends on skeletal muscle contraction, respiration, and blood volume

Skeletal Muscle Pump

Skeletal muscles compress veins to increase venous return

Respiratory Pump

Pressure changes during breathing increase venous return

Vasomotor Center

Located in the medulla oblongata; controls blood vessel diameter

Low Blood Pressure Response

Increased heart rate and arteriole constriction

High Blood Pressure Response

Decreased heart rate and arteriole dilation

ANH (Atrial Natriuretic Hormone)

Decreases blood volume and blood pressure by increasing sodium and water excretion

ADH (Antidiuretic Hormone)

Increases blood volume and blood pressure by increasing water reabsorption

Aldosterone

Increases blood volume and blood pressure by increasing sodium and water reabsorption

Angiotensin II

Raises blood pressure by causing vasoconstriction and stimulating aldosterone release

Renin-Angiotensin-Aldosterone Pathway

Renin → Angiotensin II → Aldosterone → Sodium and Water Reabsorption → Increased Blood Volume

Pulse

Alternating expansion and recoil of an artery

Common Pulse Sites

Common Carotid Artery and Radial Artery

Brachial Artery

Artery commonly used to measure blood pressure with a sphygmomanometer

Systemic Circulation

Begins when the left ventricle pumps blood into the aorta

Aorta Sections

Ascending Aorta → Aortic Arch → Descending Aorta

Coronary Arteries

Branch from the ascending aorta

Aortic Arch Branches

Brachiocephalic Artery, Left Common Carotid Artery, Left Subclavian Artery

Common Iliac Arteries

Branches at the end of the descending aorta

Common Carotid Arteries

Deliver oxygen-rich blood to the head and neck

External Iliac Arteries

Deliver oxygen-rich blood to the lower limbs

Common Iliac Arteries

Part of the systemic circuit

Umbilical Vein

Carries oxygen-rich blood from the placenta to the fetus

Foramen Ovale

Opening between the fetal atria that bypasses the lungs

Ductus Arteriosus

Vessel connecting the pulmonary trunk and aorta to bypass the fetal lungs

Fetal Lung Bypass Structures

Foramen Ovale and Ductus Arteriosus

Aging and the Cardiovascular System

Heart size generally increases while resting heart rate decreases with age