Heart Anatomy & Blood Flow
What are the four chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle
Which node is known as the heart’s pacemaker?
SA node
What are the three main types of blood vessels?
Arteries, veins, capillaries
What muscle is primarily responsible for quiet breathing?
Diaphragm
What law explains gas diffusion based on pressure gradients?
Fick’s Law
Which valve separates the left atrium and left ventricle?
Bicuspid (Mitral) valve
What does the AV node do?
Delays conduction to allow atrial contraction before ventricular filling
Which vessels are known as resistance vessels?
Arterioles
What pressure keeps lungs from collapsing?
Negative intrapleural pressure
What percentage of oxygen is carried bound to hemoglobin?
About 98%
What blood vessels return deoxygenated blood to the heart?
Superior and inferior vena cavae
What causes the plateau phase of a cardiac action potential?
Calcium influx through L-type channels
What does MAP stand for and how is it calculated?
Mean arterial pressure = Diastolic + ⅓(Pulse Pressure)
According to Boyle’s Law, how are pressure and volume related?
Inversely related
How is most CO₂ transported in the blood?
As bicarbonate (HCO₃⁻)
Which artery carries deoxygenated blood?
Pulmonary artery
What do Purkinje fibers do?
Distribute depolarization through ventricles for coordinated contraction
What happens to flow when vessel radius decreases?
Flow decreases because resistance increases (1/r⁴ relationship)
What happens to intrapleural pressure during inspiration?
It becomes more negative
Where are central chemoreceptors located?
In the medulla (brainstem)
Trace the full pathway of blood through the heart and lungs starting from the vena cava.
Vena cava → RA → Tricuspid → RV → Pulmonary Valve → Lungs → Pulmonary Veins → LA → Mitral → LV → Aortic Valve → Aorta
How does sympathetic activation affect the heart?
Increases heart rate and contractility via β₁ receptors
What causes edema at the capillary level?
Imbalance in Starling forces (↑ hydrostatic or ↓ osmotic pressure)
What muscles contract during expiration?
internal intercostal muscles
What is the main stimulus for increased breathing rate?
Elevated CO₂ (hypercapnia)