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15. BODY FLUIDS AND CIRCULATION

The chapter discusses the essential role of blood and lymph in transporting nutrients and waste in vertebrates. It describes the composition of blood, including plasma and formed elements, along with the mechanisms of circulation including the functions of the heart and the differences between open and closed circulatory systems. Additionally, it addresses the regulation of cardiac activity and the common disorders of the circulatory system.

Sections

BODY FLUIDS AND CIRCULATION

This section covers the composition of blood and lymph, their functions, and the human circulatory system's structure and mechanisms.

15 Section Overview

Start current section content and materials

15.1 Blood

Blood is a vital connective tissue consisting of plasma and formed elements, crucial for nutrient transport and waste removal in living organisms.

15.1.1 Plasma

Plasma is the liquid component of blood, accounting for 55% of its composition, which primarily consists of water, proteins, and various solutes.

15.1.2 Formed Elements

Formed elements of blood include erythrocytes, leucocytes, and platelets, each serving essential functions in gas transport, immunity, and blood clotting.

15.1.3 Blood Groups

Blood groups in humans are categorized primarily by the presence of specific antigens on red blood cells, notably the ABO and Rh systems.

15.1.4 Coagulation of Blood

Coagulation of blood is a critical mechanism that prevents excessive blood loss following injury through a series of biochemical reactions.

15.2 Lymph (Tissue Fluid)

Lymph, also known as tissue fluid, is crucial for nutrient and waste exchange between blood and cells and plays a key role in immune function.

15.3 Circulatory Pathways

Circulatory pathways, including open and closed systems, describe how blood is circulated in different organisms.

15.3.1 Human Circulatory System

The human circulatory system comprises a muscular heart and closed vessels that transport blood throughout the body.

15.3.2 Cardiac Cycle

The cardiac cycle is the sequence of events in which the heart contracts and relaxes to pump blood effectively, comprising both systole and diastole phases.

15.3.3 Electrocardiograph (ECG)

The Electrocardiograph (ECG) is a vital diagnostic tool that records the electrical activity of the heart during a cardiac cycle, providing insight into heart function.

15.4 Double Circulation

Double circulation refers to the distinct pathways of blood flow in the human body, consisting of pulmonary and systemic circuits.

15.5 Regulation of Cardiac Activity

Regulation of cardiac activity involves intrinsic mechanisms like nodal tissue and external influences through the autonomic nervous system and hormonal signals.

15.6 Disorders of Circulatory System

This section covers various disorders associated with the circulatory system, including hypertension, coronary artery disease, angina, and heart failure.

15.7 SUMMARY

This section summarizes the critical aspects of body fluids and circulation, particularly blood and lymph, and the function of the circulatory system.

15.8 EXERCISES

This section contains a variety of exercises designed to test knowledge about blood components, circulation, and the human circulatory system.

Learning Objectives

  • Blood is a fluid connective tissue comprising plasma and formed elements that include red blood cells, white blood cells, and platelets.

  • The composition of blood groups is determined by specific antigens, and the Rh factor's presence or absence is crucial for blood transfusion compatibilities.

  • The circulatory system in vertebrates is primarily closed, with double circulation allowing for efficient oxygenation and nutrient delivery throughout the body.

Key Concepts

Plasma

The liquid component of blood, constituting about 55% of its volume, primarily made of water, electrolytes, and proteins.

Cardiac Cycle

The sequence of events in one heartbeat, including systole (contraction) and diastole (relaxation) of the heart chambers.

Double Circulation

A circulatory system in which blood passes through the heart twice within one complete circuit: once for oxygenation in the lungs and once for distribution to the body.

SinoAtrial Node (SAN)

The heart's natural pacemaker located in the right atrium, responsible for initiating the heart's rhythmic contractions.

Electrocardiogram (ECG)

A graphical representation of the electrical activity of the heart during a cardiac cycle, used for diagnosing heart conditions.

Practice Exercises

Total Questions

5

Estimated Time

10 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting