krit.club logo

Body Fluids and Circulation - Human circulatory system

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

The human heart is a mesodermally derived organ, situated in the thoracic cavity, protected by a double-walled membranous bag called the pericardium.

•

The heart consists of four chambers: two small upper atria and two larger lower ventricles. The SASA node (Sino-atrial node) is the 'Pacemaker' that generates action potentials at a rate of 70−7570-75 min−1min^{-1}.

•

The Cardiac Cycle involves sequential events: Atrial systole (0.10.1 ss), Ventricular systole (0.30.3 ss), and Joint Diastole (0.40.4 ss), totaling approximately 0.80.8 ss per beat.

•

Double Circulation consists of two pathways: Pulmonary circulation (RightRight Ventricle→PulmonaryVentricle \rightarrow Pulmonary Artery→Lungs→PulmonaryArtery \rightarrow Lungs \rightarrow Pulmonary Veins→LeftVeins \rightarrow Left AtriumAtrium) and Systemic circulation (LeftLeft Ventricle→Aorta→Tissues→VenaVentricle \rightarrow Aorta \rightarrow Tissues \rightarrow Vena Cava→RightCava \rightarrow Right AtriumAtrium).

•

Electrocardiogram (ECG) is a graphical representation of the electrical activity of the heart. The PP-wave represents atrial depolarization, the QRSQRS complex represents ventricular depolarization, and the TT-wave represents ventricular repolarization.

•

Regulation of Cardiac Activity: The heart is myogenic but can be modulated by the autonomic nervous system (ANSANS). Sympathetic nerves increase the heart rate, while Parasympathetic nerves (vagus nerve) decrease it.

•

Disorders of the circulatory system include Hypertension (BP>140/90BP > 140/90 mmHgmmHg), Coronary Artery Disease (CADCAD or Atherosclerosis), Angina Pectoris (acute chest pain), and Heart Failure (inability to pump blood effectively).

📐Formulae

Stroke Volume (SV)=End Diastolic Volume (EDV)−End Systolic Volume (ESV)Stroke \, Volume \, (SV) = End \, Diastolic \, Volume \, (EDV) - End \, Systolic \, Volume \, (ESV) patterns

Cardiac Output (CO)=Stroke Volume (SV)×Heart Rate (HR)Cardiac \, Output \, (CO) = Stroke \, Volume \, (SV) \times Heart \, Rate \, (HR)

Pulse Pressure=Systolic Blood Pressure−Diastolic Blood PressurePulse \, Pressure = Systolic \, Blood \, Pressure - Diastolic \, Blood \, Pressure

Mean Arterial Pressure (MAP)=Diastolic BP+13(Systolic BP−Diastolic BP)Mean \, Arterial \, Pressure \, (MAP) = Diastolic \, BP + \frac{1}{3} (Systolic \, BP - Diastolic \, BP)

💡Examples

Problem 1:

Calculate the Cardiac Output of an individual if their heart rate is 7272 beats per minute and the amount of blood pumped by each ventricle during a cardiac cycle is 7070 mLmL.

Solution:

CO=SV×HRCO = SV \times HR CO=70 mL×72 beats/min=5040 mL/minCO = 70 \, mL \times 72 \, beats/min = 5040 \, mL/min CO≈5.04 L/minCO \approx 5.04 \, L/min

Explanation:

Cardiac Output is defined as the volume of blood pumped out by each ventricle per minute. It is calculated by multiplying the Stroke Volume (volume per beat) by the Heart Rate (beats per minute).

Problem 2:

During a clinical checkup, a patient's EDVEDV was measured at 120120 mLmL and ESVESV at 5050 mLmL. Determine the Stroke Volume.

Solution:

SV=EDV−ESVSV = EDV - ESV SV=120 mL−50 mL=70 mLSV = 120 \, mL - 50 \, mL = 70 \, mL

Explanation:

The Stroke Volume is the difference between the volume of blood in the ventricle at the end of filling (End Diastolic Volume) and the volume remaining after contraction (End Systolic Volume).

Human circulatory system - Revision Notes & Key Diagrams | CBSE Class 11 Biology