anatomy part 2

ECG P-wave

represents atrial depolarization, which is the electrical activity associated with the contraction of the atria in the heart.

ECG PR interval

(0.12–0.20 s) the time between atrial depol to ventricular depol.

ECG QRS complex

>0.12s

ventricular depolarization (atrial repol hidden).

ECG T-wave

represents ventricular repolarization, reflecting the recovery of the ventricles after contraction.

ECG QT wave

ventricular depol + repol.

ECG RR interval

• determines Heart rate

Diastole

Ventricles relax, AV valves open, filling occurs.

atrial systole

phase where atria contract, pushing blood into ventricles.

Atria contract, topping off ventricular volume.

isovolumentric contraction

Ventricles contract, AV valves close (S1), no volume change yet.

ventricular ejection

Semilunar valves open, blood ejected.

pressure volume loop

preload, afterload, stroke volume, EF .

arteries

Blood vessels that carry oxygenated blood away from the heart, except for the pulmonary arteries.

distribution, high pressure.

Arterioles

Small blood vessels that branch off arteries and regulate blood flow into capillaries.

resistance, regulate flow & pressure.

Capillaries

exchange

of oxygen, carbon dioxide, and nutrients between blood and tissues.

veins/venules

capacitance, reservoirs .

Blood vessels that carry deoxygenated blood back to the heart, except for the pulmonary veins. Venules are small veins that collect blood from capillaries.

blood pressure

force on arterial walls

Systolic

peak during LV contraction.

diastolic

pressure during relaxation.

Pulse pressure (PP)

systolic – diastolic.

Mean arterial pressure (MAP)

diastolic + 1/3(PP).

Venous pressure

very low; aided by skeletal/respiratory pumps.

Central venous pressure

right atrial pressure

R =

(8ηL)/(πr⁴) → radius most important.

Local resistance

O₂, CO₂, metabolites.

Hormonal resistance

angiotensin II, epinephrine, vasopressin.

Neural resistance

sympathetic (alpha-1 adrenergic constrict, beta-2 adrenergic dilate) .

hemodynamics equation

Flow (Q) = ΔP / R.

blood flow = pressure difference/ resistance

Explains how blood moves based on pressure gradient & resistance

cardiact output equation

HR × SV.

HR = heart rate (beats per minute)

SV = stroke volume (mL per beat).

Multiplying them gives CO (cardiac output), the total blood pumped per minute.

Stem cells

Hematopoietic stem cells → myeloid & lymphoid progenitors.

Erythropoiesis

Stimulated by EPO (kidneys, hypoxia). Reticulocyte = immature RBC, marker of marrow output.

Leukopoiesis

Driven by CSFs (G-CSF, M-CSF).

Thrombopoiesis

Megakaryocytes → platelets; regulated by thrombopoietin .

Vascular Phase

Endothelin release → vasoconstriction.

Platelet Phase

Platelets adhere (via vWF), activate, release factors, aggregate → plug.

Coagulation Phase

Extrinsic (tissue factor) + Intrinsic (contact) → converge on common pathway.

Prothrombin → thrombin → fibrin clot.

Vitamin K

Required for factors II, VII, IX, X

Fibrinolysis

• Plasminogen → plasmin (via tPA).

• Plasmin digests fibrin → clot breakdown .

This process is essential for removing blood clots after healing occurs. It helps restore normal blood flow and prevents excessive clotting.

extrensic factor

: Systemic regulation (nerves + hormones).

• Sympathetic nerves: α1 = constrict, β2 = dilate

• Hormones:

  • Epi/NE → reinforce SNS

  • Angiotensin II, ADH → constrict

  • ANP → dilate

intrinsic factor

Local regulation. Vessels adjust to tissue needs.

• Low O₂ / high CO₂ / metabolites → dilation

• Myogenic (stretch → constrict)

• Endothelium: NO dilates, endothelin constricts