Module 9: Cardiovascular system

What is the function of the heart valves?

To ensure one-way blood flow between chambers

what causes the heart sound s1 LUB?

Closure of AV valves (start of systole).

what causes the heart sound s2 dub?

Closure of SL valves (start of diastole).

Where is the heart located?

In the thoracic cavity, mediastinum, slightly left of center.

What are the chambers of the heart?

• 2 atria (upper chambers).

• 2 ventricles (lower chambers).

Name the heart valves and their locations.

• AV valves: Right = tricuspid, Left = mitral.

• SL valves: Right = pulmonary, Left = aortic.

Flow of blood in the systemic circulation

Left ventricle → Aorta → Body → Right atrium.

• Delivers oxygen and nutrients to the body

Flow of blood through the pulmonary system

Right ventricle → Pulmonary trunk → Lungs → Left atrium.

• Exchanges gases in the lungs (O₂ in, CO₂ out)

flow of blood through the coronary system

Aorta → Coronary arteries → Myocardium → Cardiac veins → Coronary sinus → Right atrium.

• Feeds the heart muscle itself

What is capillary microcirculation?

The exchange of fluid, nutrients, oxygen, and waste between blood in capillaries and surrounding tissues.

What are the two main pressures in capillary microcirculation?

• Hydrostatic pressure: Pushes fluid out of capillaries (filtration).

• Osmotic pressure: Pulls fluid into capillaries (reabsorption)

Continuous capillaries

🔹 Continuous Capillaries

• Leakiness: Least leaky

• Function: Tight control, slow exchange

• Found in: Brain, Skin

Fenestrated capillaries

• Leakiness: Medium leaky

• Function: Faster exchange, small pores

• Found in: Kidneys, Intestines

Sinusoidal capillaries

• Leakiness: ✅ Super leaky

• Function: Big stuff can pass (cells, proteins)

• Found in: Liver, Bone marrow

What’s the difference between arteries and veins?

• Arteries: thick walls, high pressure, carry blood away

• Veins: thin walls, low pressure, carry blood to heart, have valves

What is cardiac output (CO)?

CO = Heart Rate × Stroke Volume

What influences heart rate?

• Parasympathetic = slows HR

• Sympathetic = increases HR

• Also affected by hormones, ions, temperature

What is blood pressure (BP)?

BP = Cardiac Output × Total Peripheral Resistance

What controls capillary microcirculation?

• Hydrostatic pressure = pushes fluid out (filtration)

• Osmotic pressure = pulls fluid in (reabsorption

What is Mean Arterial Pressure (MAP)?

MAP = DBP + ⅓ (Systolic BP – Diastolic BP); normal = 70–100 mmHg

SBP – DBP = Pulse Pressure

• The difference between systolic and diastolic pressure

• Shows how much pressure the heart generates with each beat

• Example:
  If BP = 120/80
  → SBP – DBP = 120 – 80 = 40 mmHg
  → MAP = 80 + ⅓(40) = 93 mmHg