Comprehensive Review: Cardiovascular, Hematologic, and Endocrine Systems

A comprehensive question-and-answer flashcard set covering cardiac anatomy and conduction (Chapter 22), hematology, blood typing, and hemostasis (Chapter 21), and the endocrine glands, hormone mechanisms, and regulatory feedback loops (Chapter 20).

Arteries

Blood vessels that transport blood away from the heart, regardless of oxygenation.

Veins

Blood vessels that transport blood toward the heart, regardless of oxygenation.

Three cardiovascular circuits

The pulmonary circuit (lungs), systemic circuit (body tissues), and coronary circuit (heart muscle).

Pulmonary circuit pathway

Right atrium → right ventricle → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium.

Systemic circuit pathway

Left atrium → left ventricle → aorta → systemic tissues → superior and inferior venae cavae → right atrium.

Pericardium layers (superficial to deep)

Fibrous pericardium, parietal pericardium, pericardial cavity, and visceral pericardium (epicardium).

Heart wall layers (superficial to deep)

Epicardium, myocardium, and endocardium.

Pectinate muscles

Comb-like muscular ridges situated within the walls of the atria and auricles.

Trabeculae carneae

Muscular ridges and bridges located along the inner walls of the ventricles.

Vessels entering the right atrium

Superior vena cava, inferior vena cava, and coronary sinus.

Right coronary artery branches

Marginal branch and posterior interventricular branch (mnemonic: RPM).

Left coronary artery branches

Anterior interventricular branch and circumflex branch (mnemonic: LEFTAC).

Coronary artery and cardiac vein pairs

Great cardiac vein with anterior interventricular branch; middle cardiac vein with posterior interventricular branch; small cardiac vein with marginal branch.

Chordae tendineae

Fibrous cords connecting AV valve cusps to papillary muscles to prevent valve eversion and prolapse into the atria during ventricular contraction.

First heart sound ("lub")

The sound generated by blood reverberating against the closing atrioventricular (AV) valves at the onset of ventricular systole.

Second heart sound ("dub")

The sound generated by blood slamming against the closing semilunar (SL) valves at the onset of ventricular diastole.

Intercalated disc junctions

Gap junctions allow direct electrical transmission between cells; desmosomes mechanically anchor adjacent cells against physical strain.

Three stages of the cardiac cycle

1. Mid-to-late ventricular diastole (ventricular filling), 2. Ventricular systole (ventricular ejection), 3. Early ventricular diastole (isovolumetric relaxation).

Cardiac conduction sequence

Sinoatrial (SA) node → atrioventricular (AV) node → atrioventricular (AV) bundle (bundle of His) → bundle branches → Purkinje fibers.

ECG waves: P, QRS, and T

P wave represents atrial depolarization; QRS complex represents ventricular depolarization; T wave represents ventricular repolarization.

Normal resting heart rate

$60\text{--}100\,\text{beats per minute}$.

Centrifuged blood layers and fractions

Plasma (top layer, $>50\%$ volume), buffy coat (middle layer, $<1\%$ volume), and erythrocytes (bottom layer, $<50\%$ volume).

Normal blood pH range

$7.35\text{--}7.45$.

Major plasma proteins (abundance order)

Albumin (most abundant), globulins (second), and fibrinogen (least abundant).

Blood serum

Blood plasma from which clotting factors and proteins (such as fibrinogen) have been removed.

Mature erythrocyte characteristics

Biconcave disc shape, lacking a nucleus and most organelles (retaining only ribosomes), and packed with hemoglobin.

Hemoglobin structure

Composed of four globin protein chains, each carrying an iron-containing heme group that binds one oxygen molecule.

Hematocrit

The percentage of total blood volume composed of erythrocytes, typically $38\%\text{--}56\%$.

Erythrocyte lifespan

Approximately $120\,\text{days}$.

ABO blood group antigens and antibodies

Type A has A antigens and anti-B antibodies; Type B has B antigens and anti-A; Type AB has both antigens and no antibodies; Type O has no antigens and both antibodies.

Rh incompatibility mechanism

Sensitization occurs when an Rh-negative mother is exposed to Rh-positive fetal blood, producing anti-Rh antibodies that can cross the placenta in a subsequent Rh-positive pregnancy.

Universal blood donor

$O^-$ blood, because its red blood cells lack A, B, and Rh surface antigens.

Universal blood recipient

$AB^+$ blood, because its plasma lacks anti-A, anti-B, and anti-Rh antibodies.

Leukocyte abundance order

Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils (mnemonic: Never Let Monkeys Eat Bananas).

Granulocytes

Neutrophils (bacteria destruction via lysozyme), Eosinophils (parasite defense), and Basophils (histamine and heparin release).

Lymphocytes

Agranulocytes driving adaptive immunity, including T cells (direct cellular attack), B cells (antibody secretion via plasma cells), and natural killer cells.

Monocytes

Large agranulocytes that migrate into tissues to differentiate into phagocytic macrophages.

Platelets (thrombocytes)

Cell fragments shed from bone marrow megakaryocytes that mesh with fibrin to form hemostatic plugs.

Hemophilia

A hereditary bleeding disorder caused by a clotting factor deficiency (such as factor IX), resulting in impaired coagulation.

Thrombocytopenia

A bleeding condition defined by an abnormally low circulating platelet count.

Erythropoiesis developmental stages

Myeloid stem cell → erythroblast (nucleated) → reticulocyte (anucleated, organelles present) → mature erythrocyte.

Polycythemia

An abnormal elevation in erythrocyte count and hematocrit above $56\%$, causing dangerous blood viscosity.

Peptide hormones

Water-soluble (hydrophilic) signaling molecules that bind to plasma membrane receptors to initiate intracellular signal transduction.

Steroid hormones

Lipid-soluble (hydrophobic) signaling molecules that diffuse across cell membranes to bind intracellular receptors.

Three types of endocrine stimuli

Humoral stimuli (blood ion or nutrient levels), neural stimuli (direct nerve signals), and hormonal stimuli (tropic hormones from other glands).

Hypothalamic regulation of pituitary lobes

Regulates the anterior pituitary via releasing and inhibiting hormones through the hypophyseal portal system, and regulates the posterior pituitary via direct neural innervation.

Posterior pituitary hormones

Oxytocin (stimulates uterine contractions and bonding) and antidiuretic hormone (ADH; stimulates water reabsorption by the kidneys).

Tropic hormones of the anterior pituitary

Follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), and thyroid-stimulating hormone (TSH) (mnemonic: FLAT).

Pituitary dwarfism

Proportionate short stature resulting from hyposecretion of growth hormone (GH) during childhood development.

Achondroplastic dwarfism

Disproportionate short-limbed stature resulting from premature closure of limb epiphyseal growth plates.

Hypothalamic-pituitary-thyroid axis

Hypothalamic TRH stimulates anterior pituitary TSH release, prompting thyroid secretion of $T_3$ and $T_4$ to raise metabolic rate and heat production.

Calcitonin

Hormone secreted by thyroid parafollicular (C) cells in response to hypercalcemia, acting to lower blood calcium by activating osteoblasts.

Parathyroid hormone (PTH)

Hormone secreted by parathyroid chief cells in response to hypocalcemia, acting to elevate blood calcium by activating osteoclasts.

Nutritional goiter

Thyroid enlargement resulting from dietary iodine deficiency, which prevents thyroid hormone synthesis and causes compensatory TSH hypersecretion.

Adrenal cortex

The outer glandular region of the adrenal gland that synthesizes and secretes steroid hormones.

Adrenal medulla

The inner neuroendocrine core of the adrenal gland that secretes epinephrine and norepinephrine upon sympathetic stimulation.

Adrenal cortex zones (superficial to deep)

Zona glomerulosa (mineralocorticoids/aldosterone), zona fasciculata (glucocorticoids/cortisol), and zona reticularis (gonadocorticoids/androgens).

Pancreatic alpha cells

Endocrine cells within pancreatic islets that secrete glucagon to raise blood glucose levels.

Pancreatic beta cells

Endocrine cells within pancreatic islets that secrete insulin to lower blood glucose levels.

Melatonin

Hormone secreted by the pineal gland that promotes sleepiness and entrains circadian rhythms, inhibited by light exposure.

Thymus gland

Endocrine and lymphatic organ that secretes thymosin to stimulate T lymphocyte maturation and undergoes atrophy with age.