Heart and Lungs Lecture Notes

Flashcards about the heart and lungs, covering anatomy, function, and related processes.

What is the cardiovascular system and its functions?

Distributes blood between the heart and the rest of the body through pumping and regulation of blood vessel diameter; transports O2, water, and nutrients to all cells; transports CO2 and other metabolic wastes out of the body; transports hormones; transports immune cells; distributes heat to regulate body temperature

What is the function of the atria?

Thin-walled structure that transfers blood into the ventricles

What is the role of the right atria?

Receives blood from the superior/inferior vena cava and pumps it to the right ventricle

What is the role of the left atria?

Receives blood from the pulmonary veins and pumps it to the left ventricle

What is the function of the ventricles?

Thick-walled/muscular structure that pumps blood further distances

What is the role of the right ventricle?

Pumps deoxygenated blood to the lungs

What is the role of the left ventricle?

Pumps oxygenated blood throughout the rest of the body; most muscular chamber

What is the function of atrioventricular (AV) valves?

Allow blood flow from the atria into the ventricles while preventing atrial backflow

What is the tricuspid valve?

Separates the right atrium and right ventricle

What is the bicuspid/mitral valve?

Separates the left atrium and left ventricle

What is the function of the semilunar valves?

Allow blood flow from the ventricles into blood vessels (arteries) while preventing ventricular backflow

What is the pulmonary semilunar valve?

Accepts blood from the right ventricle and sends it to the pulmonary artery

What is the epicardium?

Outermost layer; holds a thin layer that protects the heart and anchors it to surrounding tissue (visceral pericardium)

What is the myocardium?

Thickest layer comprised of cardiac muscle tissue; responsible for contractions

What are intercalated discs?

Connect cardiac muscles in heart walls end-to-end; hold gap junctions and desmosomes

What are gap junctions?

Allow ion passage from cell to cell; allows action potentials to spread rapidly across the heart

What are desmosomes?

Prevent cardiac muscles from pulling away from each other during contraction

What is myogenic activity?

Electrical signals that stimulate heart contraction derive from self-depolarizing cells in the heart muscle itself (not an outside source)

What is the sinoatrial (SA) node?

Origination of electrical signal for contraction in the right atria; spreads across both atria via gap junctions causing atria contraction

What is the atrioventricular (AV) node?

Inferior portion of the interatrial septum; cells hold structural adaptations that delay signal passage into the ventricles

What is the bundle of His (AV bundle)?

Site after the AV node; only structure that electrically links the atria to the ventricles

What is the function of the purkinje fibers?

Carry the signal superiorly within ventricular walls, triggering ventricular contraction from the apex to the atria

What is the endocardium?

Innermost layer that lines heart chambers and valves; holds a thin layer for efficient blood flow

What is the QRS complex?

Ventricular depolarization; APs spread through the ventricles and induce ventricular contraction

What is the T wave?

Ventricular repolarization; ventricles depolarize to resting membrane potential

What is an electrocardiogram (ECG)?

Records electrical activity within the heart as the heart beats

What is the P wave?

Atrial depolarization; APs fired from the SA node cause atrial contraction

What is the PR segment?

Signal transmission is slowed; APs reach AV node and are delayed

What is blood?

Fluid connective tissue composed of formed elements (living cells) and an extracellular matrix (nonliving)

What are the formed elements of blood?

Erythrocytes, leukocytes, and thrombocytes

What are Hematopoietic stem cells?

Produce blood cells in the bone marrow

What are the different blood types?

A, B, AB, or O

What are erythrocytes?

Red blood cells with membranes that hold antigens (basis for human blood groups/types); carry oxygen and carbon dioxide

What is the function of the spleen?

Removes aged or damaged RBCs and platelets via phagocytosis through macrophages in the spleen

What are Rh groups?

Based on the presence or absence of the Rh factor antigen; follows an autosomal dominant inheritance pattern

What is hemoglobin?

Four polypeptide chains/subunits attached to an iron-containing heme group that reversibly binds one O2

What is hematocrit?

Fraction of a blood sample's total volume that consists of RBCs (37%-52% in adults)

What are leukocytes?

White blood cells; provide immune defense

What is plasma?

Liquid matrix that suspends blood cells; ~55% of blood's volume

What are thrombocytes?

Platelets/cell fragments derived from megakaryocytes; involved in blood clotting

What is an oxygen-hemoglobin dissociation curve (OHDC)?

Shows the fraction of hemoglobin present in a blood sample saturated with O2 when blood is exposed to different O2 partial pressures (PO2)

What is the Bohr effect?

Right shift in the OHDC caused by increased PCO2 and/or decreased pH

What is fetal hemoglobin?

Hemoglobin F; holds a different amino acid sequence from hemoglobin A (adult hemoglobin), causing a higher O2 affinity

What is the chloride shift?

Transport proteins bring in Cl- to prevent an electric charge imbalance from the loss of HCO3-

What is the cardiac cycle?

Process of the heart pumping blood

What is systolic pressure?

Arterial blood pressure from ventricular systole; elastic arteries near the heart stretch, allowing arteries to store energy

What is diastolic pressure?

Ventricles relax, allowing stored artery energy to generate pressure through pushing on blood; maintains forward blood movement in the vasculature

What is a sphygmomanometer?

Measures systemic blood pressure as systolic/diastolic via an inflatable cuff and pressure gauge

What occurs during diastole?

Cardiac muscle relaxes, lowering pressure within the heart and allowing blood to enter the heart

What is mean arterial pressure (MAP)?

Average pressure in an artery during one cardiac cycle via diastolic pressure + pulse pressure/3

What is pulse pressure?

Difference between diastolic and systolic pressures in an artery

What occurs during systole?

Cardiac muscle contracts (atria first, then ventricles), increasing pressure within the heart and causing blood to be pumped out of the heart into the attached arteries

What is pulse?

Pressure fluctuations as the heart alternates between systole and diastole

What causes the Lub-dub sound of the heart?

'Lub': Ventricular systole; contracting ventricle pressure is greater than pressure in the relaxed atria, causing AV valves to forcefully close. 'Dub': Semilunar valves close at the beginning of ventricular diastole when ventricle pressure drops below pressure in the arteries.

What is cardiac output?

Blood pumped from one ventricle in one minute; measures the heart's effectiveness at pumping blood

What is stroke volume?

Volume of blood pumped from the ventricle during a single contraction (ventricular systole)

What is the pulmonary circuit?

Carries blood under lower pressure from the right side of the heart to the lungs and back to the left side

What is the systemic circuit?

Transports blood pumped under higher pressure from the heart's left side to all parts of the body; returns to the heart on the right side

What is friction?

Opposition of blood flow

What is total peripheral resistance (TPR)?

Total amount of friction encountered by blood as it passes throughout the circulatory system

What is the aorta?

Artery that pumps blood from the left ventricle into the systemic circuit

What are venae cavae?

Oxygen-poor blood enters the right atrium

What is the endothelium?

Internal lining of a single layer of specialized epithelial cells (endothelial cells) that provides a slick surface to reduce friction between the vessel wall and blood for smooth blood flow through vessels

What are arteries?

Carry blood away from the heart; blood is oxygenated (except pulmonary arteries)

What are arterioles?

Small branches that diverge from arteries

What are veins?

Carry blood toward the heart; blood is deoxygenated (except pulmonary veins)

What are venules?

Small vessels that converge to form veins

What are capillaries?

Smallest blood vessel; extremely thin walls hold a single layer of endothelial cells attached to a basement membrane

What are capillary beds?

Organize capillaries into networks; each receives blood from an arteriole and passes blood to a venule

What is a portal system?

Two capillary beds in series that allow substances to be transported from one region to another without dilution or wide distribution

What is bulk flow (mass fluid transfer)?

Formed by hydrostatic pressure (HP) and oncotic pressure (OP) inside and outside capillaries

What is hydrostatic pressure?

Force a fluid exerts on a vessel wall (blood pressure); due to friction, higher on arteriole end and decreases at venous end

What is oncotic pressure?

Colloid osmotic pressure; presence of large molecules prevents free movement across the capillary wall, causing water to move from low OP to high OP (osmosis)

What is the role of the Lymphatic system?

Lymphoid organs, lymphatic vessels, and fluid within lymphatic vessels (lymph) that return excess interstitial fluid to the blood. Also function in immune defense and transport absorbed lipids to the blood for distribution

What are Lymphatic capillaries?

Lymphatic capillaries closed at one end in blood capillaries and tissue cells that receive interstitial fluid

What are Lymphatic trunks?

Formed when lymph nodes merge and carry lymph to one of two lymphatic ducts (right lymphatic duct or thoracic duct) to empty lymph into veins near the heart

What is the right lymphatic duct?

Receives lymph that drains from the right arm, right side of the head, and right side of the thorax

What is the thoracic duct?

Drains lymph from all other body regions; holds majority of the body's lymph

What is edema?

Higher filtration rate than absorption rate in capillary beds leads to excess interstitial fluid

What is thermoregulation?

Maintenance of internal body temperature via controlling blood flow to distribute heat

What is autoregulation?

Local conditions within an organ or tissue that alter arteriole diameter to control blood flow to surrounding capillary beds

What are extrinsic controls?

Signals in the nervous and endocrine systems that regulate contraction rate and contraction force

What is vasoconstriction?

First step in hemostasis where broken vessels narrow to reduce blood flow/loss in the damaged vessel

What is hemostasis?

Process of platelets (thrombocytes) forming blood clots

What is the platelet plug?

Second step in hemostasis where platelets stick to collagen fibers hidden under the endothelium of undamaged cells that are now exposed in damaged vessels

What is coagulation?

Final step in hemostasis that produces collagen via activation of multiple clotting factors

What is fibrin?

Polymerizes into fibrin strands that cross-link into a mesh to trap platelets and red blood cells and produce a clot that stops additional blood loss

What is fibrinolysis?

Fibrin mesh is digested by plasmin enzyme to dissolve the clot once the damaged blood vessel has healed

What is plasminogen?

Inactive precursor plasma protein that activates to form plasmin

What is hemophilia?

X-linked recessive disorder where the clotting process is impaired and minor injuries can cause life-threatening blood loss

What is the respiratory zone?

Region of gas exchange within the lungs (respiratory bronchioles, alveolar ducts, and alveolar sacs)

What is the conducting zone?

Nose, pharynx, larynx, trachea, and primary bronchi

What is the larynx?

Opening for air flow covered by the epiglottis during swallowing

What are the vocal folds?

Produce sounds via vibration as air passes between them during expiration

What are bronchioles?

Air passageways with diameters less than 1 mm; walls hold smooth muscle and lack cartilage to allow diameter adjustment for airflow regulation

What are terminal bronchioles?

Smaller bronchiole branchings; final section of the conducting zone

What are alveolar ducts?

Short tubes with multiple individually attached alveoli that receive air from respiratory bronchioles and transfer air to alveolar sacs

What are alveolar sacs?

Dead-end structures of small clusters of interconnected alveoli that lack smooth muscle

What are alveoli?

Thin-walled microscopic air pockets that bulge from the bronchioles' surface

What is pleura?

Double-layered saclike membrane that surrounds the lungs