Body Fluids and Circulation — Revision Notes

⚡ 30-Second Revision

Blood Components: — Plasma (55%), Formed Elements (45% - RBCs, WBCs, Platelets).
RBCs: — $5-5.5,\text{million/mm}^3$, hemoglobin, $120,\text{day}$ lifespan.
WBCs: — $6000-8000/\text{mm}^3$, immunity. Neutrophils (60-65%), Lymphocytes (20-25%), Monocytes (6-8%), Eosinophils (2-3%), Basophils (0.5-1%).
Platelets: — $1.5-3.5,\text{lakhs/mm}^3$, clotting.
Blood Groups: — ABO (A, B, AB, O), Rh factor. Universal Donor: O, Universal Recipient: AB.
Clotting: — Platelets $ightarrow$ Prothrombin activator $ightarrow$ Prothrombin $xrightarrow{Ca^{2+}}$ Thrombin $ightarrow$ Fibrinogen $ightarrow$ Fibrin.
Heart: — 4 chambers (2 Atria, 2 Ventricles). Valves: Tricuspid (R AV), Bicuspid/Mitral (L AV), Semilunar (Aortic, Pulmonary).
Pacemaker: — SAN (Sinoatrial Node), $70-75,\text{beats/min}$.
Cardiac Cycle: — $0.8,\text{s}$. Atrial Systole ($0.1,\text{s}$), Ventricular Systole ($0.3,\text{s}$), Joint Diastole ($0.4,\text{s}$).
Heart Sounds: — 'Lubb' (AV closure), 'Dubb' (SL closure).
ECG Waves: — P (Atrial depolarization), QRS (Ventricular depolarization), T (Ventricular repolarization).
Blood Pressure: — Normal $120/80,\text{mmHg}$. Hypertension $ge 140/90,\text{mmHg}$.
Cardiac Output: — $CO = HR \times SV$ (Heart Rate $imes$ Stroke Volume). Normal $5,\text{L/min}$.

2-Minute Revision

Body fluids and circulation are vital for transport and homeostasis. Blood, composed of plasma and formed elements (RBCs, WBCs, platelets), carries oxygen, nutrients, hormones, and wastes. RBCs, rich in hemoglobin, transport oxygen.

WBCs provide immunity, with neutrophils, lymphocytes, and monocytes being key types. Platelets are essential for blood clotting, a cascade involving fibrinogen and thrombin. Blood groups (ABO, Rh) are determined by antigens on RBCs, crucial for safe transfusions.

Lymph, a fluid similar to plasma but lacking large proteins, circulates in the lymphatic system, returning interstitial fluid, absorbing fats, and playing a significant immune role via lymph nodes. The human heart, a four-chambered muscular pump, drives double circulation: pulmonary (heart-lungs) and systemic (heart-body).

The cardiac cycle, lasting $0.8,\text{s}$, involves atrial and ventricular systole and diastole, producing 'lubb' (AV valve closure) and 'dubb' (semilunar valve closure) sounds. The SA node acts as the heart's natural pacemaker.

ECG records electrical activity (P, QRS, T waves). Blood pressure, normally $120/80,\text{mmHg}$, is regulated by neural and hormonal factors. Disorders like hypertension, CAD, and heart failure are common.

5-Minute Revision

The human body's internal transport system relies on body fluids and circulation. Blood, the primary fluid, consists of a liquid matrix, plasma (90-92% water, proteins, salts), and formed elements.

These include Red Blood Cells (RBCs), which are biconcave, anucleated cells packed with hemoglobin for oxygen transport, having a lifespan of 120 days. White Blood Cells (WBCs) are immune cells, categorized into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

Platelets are cell fragments crucial for blood coagulation, a process where prothrombin is converted to thrombin, which then converts fibrinogen to insoluble fibrin, forming a clot. Blood groups (ABO and Rh) are determined by antigens on RBCs; O is the universal donor, AB the universal recipient.

Lymph, or tissue fluid, is formed from plasma filtering out of capillaries. It circulates through the lymphatic system, returning fluid to the blood, transporting absorbed fats via lacteals, and providing immune surveillance through lymph nodes.

The human heart is a four-chambered, muscular pump. The right side handles deoxygenated blood (right atrium receives from body, right ventricle pumps to lungs via pulmonary artery), while the left side handles oxygenated blood (left atrium receives from lungs via pulmonary veins, left ventricle pumps to body via aorta).

Valves (tricuspid, bicuspid/mitral, semilunar) prevent backflow. The heart's rhythm is set by the Sinoatrial Node (SAN), its natural pacemaker. The cardiac cycle ($0.8,\text{s}$) involves atrial systole ($0.

1, ext{s}$), ventricular systole ($0.3, ext{s}$), and joint diastole ($0.4, ext{s}$). Heart sounds 'lubb' and 'dubb' are due to the closure of AV and semilunar valves, respectively. An ECG records the heart's electrical activity: P-wave (atrial depolarization), QRS complex (ventricular depolarization), T-wave (ventricular repolarization).

Double circulation ensures efficient oxygenation, with separate pulmonary and systemic circuits. Blood pressure (normal $120/80,\text{mmHg}$) is regulated by neural and hormonal mechanisms. Disorders like hypertension ($ge 140/90,\text{mmHg}$), Coronary Artery Disease (CAD), and heart failure are important to understand.

Prelims Revision Notes

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Blood Composition:

* Plasma: 55% of blood. 90-92% water, 6-8% proteins (albumin, globulin, fibrinogen), salts, glucose, amino acids, hormones, wastes. * Formed Elements: 45% of blood. Produced in bone marrow.

* RBCs (Erythrocytes): $5-5.5,\text{million/mm}^3$. Biconcave, anucleated. Hemoglobin for $O_2$ transport. Lifespan $120,\text{days}$. Destroyed in spleen/liver. * WBCs (Leukocytes): $6000-8000/\text{mm}^3$.

Nucleated, immune function. * Granulocytes: Neutrophils (60-65%, phagocytic), Eosinophils (2-3%, allergy/parasites), Basophils (0.5-1%, histamine, serotonin, heparin). * Agranulocytes: Lymphocytes (20-25%, B & T cells, specific immunity), Monocytes (6-8%, phagocytic, become macrophages).

* Platelets (Thrombocytes): $1.5-3.5,\text{lakhs/mm}^3$. Cell fragments. Blood clotting.

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Blood Groups:

* ABO: Antigens A, B on RBCs. Antibodies anti-A, anti-B in plasma. O is universal donor (no antigens), AB is universal recipient (no antibodies). * Rh: Rh antigen (D antigen). Rh incompatibility (Rh- mother, Rh+ fetus) can cause erythroblastosis fetalis.

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Blood Coagulation: — Injury $ightarrow$ Platelets/tissue factors $ightarrow$ Prothrombin activator $ightarrow$ Prothrombin $xrightarrow{Ca^{2+}}$ Thrombin $ightarrow$ Fibrinogen $ightarrow$ Fibrin (clot).
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Lymphatic System:

* Lymph: Tissue fluid entering lymphatic capillaries. Contains lymphocytes, less protein than plasma. * Functions: Returns interstitial fluid, transports absorbed fats (lacteals), immune surveillance (lymph nodes).

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Human Heart:

* Structure: 4 chambers (RA, RV, LA, LV). Pericardium. Septa (inter-atrial, inter-ventricular). * Valves: Tricuspid (RA-RV), Bicuspid/Mitral (LA-LV), Pulmonary Semilunar (RV-Pulmonary Artery), Aortic Semilunar (LV-Aorta). * Conduction System: SAN (pacemaker, $70-75,\text{bpm}$), AVN, Bundle of His, Purkinje fibers.

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Cardiac Cycle: — $0.8,\text{s}$ at $72,\text{bpm}$.

* Joint Diastole ($0.4,\text{s}$), Atrial Systole ($0.1,\text{s}$), Ventricular Systole ($0.3,\text{s}$). * Heart Sounds: 'Lubb' (AV valve closure), 'Dubb' (Semilunar valve closure).

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ECG: — P-wave (atrial depolarization), QRS complex (ventricular depolarization), T-wave (ventricular repolarization).
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Double Circulation: — Pulmonary (heart-lungs-heart) and Systemic (heart-body-heart) circuits.
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Blood Vessels: — Arteries (away from heart, thick, high pressure), Veins (towards heart, thin, low pressure, valves), Capillaries (exchange site).
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Regulation: — Neural (medulla oblongata, sympathetic/parasympathetic), Hormonal (adrenaline, noradrenaline).
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Disorders: — Hypertension ($ge 140/90,\text{mmHg}$), CAD (atherosclerosis), Angina, Heart Failure.

Vyyuha Quick Recall

Let's Have Blood Circulation Every Day!

Lymphatic system: Fluid return, fat transport, immunity.
Heart: 4 chambers, valves, SAN (pacemaker).
Blood: Plasma, RBCs (O2), WBCs (Immunity), Platelets (Clotting).
Cardiac Cycle: $0.8,\text{s}$ (Atrial Systole, Ventricular Systole, Joint Diastole), 'Lubb-Dubb' sounds.
ECG: P, QRS, T waves (depolarization/repolarization).
Double Circulation: Pulmonary & Systemic.