Circulatory System Overview

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Questions and Answers

The circulatory system is responsible for transporting ______ throughout the body.

blood

The three types of blood vessels are arteries, veins, and ______.

capillaries

The ______ is a hollow, muscular organ that circulates blood through vessels.

heart

Red blood cells are also known as ______.

erythrocytes Signup and view all the answers

Blood includes white blood cells, red blood cells, platelets, and ______.

plasma Signup and view all the answers

Blood regulates body ______ and electrolyte composition.

temperature Signup and view all the answers

Platelets help minimize blood loss when a blood vessel is ______.

damaged Signup and view all the answers

The straw-colored, sticky fluid portion of blood is called ______.

plasma Signup and view all the answers

Hematopoiesis is the process of ______ blood cells.

producing Signup and view all the answers

The absence of a nucleus in red blood cells makes them ______.

anucleate Signup and view all the answers

The primary function of hemoglobin is the transport of ______ and carbon dioxide.

oxygen Signup and view all the answers

Most carbon dioxide is transported in the form of ______.

HCO3- Signup and view all the answers

Red blood cells are normally destroyed in the ______.

spleen Signup and view all the answers

A person's hematocrit indicates the percentage of ______ cells in blood.

red blood Signup and view all the answers

Erythropoietin is released from the kidneys and liver in response to low ______ levels.

oxygen Signup and view all the answers

Vitamins B12 and folic acid are essential for ______ synthesis.

DNA Signup and view all the answers

Anaemia refers to a reduction of haemoglobin or red cell ______ in the blood.

concentration Signup and view all the answers

Neutrophils comprise ______ to 70% of white blood cells.

60 Signup and view all the answers

Eosinophils play a role in ending ______ reactions.

allergic Signup and view all the answers

Basophils release substances that are involved in inflammatory ______.

responses Signup and view all the answers

Study Notes

Introduction

The circulatory system functions as a transport system within the body.
This system plays a crucial role in body defenses, blood clotting, and temperature regulation.
Key components of the circulatory system include blood, blood vessels, and the heart.
Blood serves as the primary transport medium.
Blood vessels encompass arteries, veins, and capillaries.
The heart is the central organ responsible for pumping blood through the circulatory system.
Key characteristics of the heart include being a hollow, muscular organ.
It is comprised of cardiac muscle, which possesses the ability to contract simultaneously due to synchronized depolarization.
The heart exhibits automaticity, meaning it can initiate its own electrical impulses for contraction.

Blood Vessel Components

Blood vessels are crucial for transporting blood throughout the body.
White blood cells (WBCs), red blood cells (RBCs), and platelets are the primary cellular components found in blood.
Plasma, a straw-colored fluid, makes up the majority of blood volume.

Functions of Blood

Blood performs essential functions within the body:
- Transportation: Transports dissolved gases (oxygen and carbon dioxide), nutrients, hormones, and metabolic waste products.
- Protection: Restricts fluid loss from damaged vessels. Platelets and clotting factors minimize blood loss during vessel injury. Blood also plays a role in defending against foreign substances.
- Regulation: Regulates the pH and electrolyte balance within interstitial fluids. Additionally, blood helps regulate body temperature.

Blood Composition

Blood is a specialized type of connective tissue, composed of cells, chemicals, and fluids.
Its primary function is to transport substances and maintain a stable internal environment.
Blood comprises formed elements, including red blood cells, white blood cells, and platelets.
Plasma is the liquid component of blood.

Blood Plasma

Blood plasma is a straw-colored, sticky fluid constituting a significant portion of blood.
Nearly 90% of plasma is water.
The composition of plasma includes various components:
- Ions: Sodium (Na+) and Chloride (Cl-) ions are present in significant amounts.
- Nutrients: Includes sugars, amino acids, lipids, cholesterol, vitamins, and trace elements.
- Proteins: Albumin, globulin, and fibrinogen are the three main protein types found in plasma.
- Dissolved Gases: Including oxygen (O2) and carbon dioxide (CO2).
- Waste Products: Other protein waste products such as urea and bilirubin.

Formed Elements

Formed elements are the cellular components of blood.
These elements include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets.

Red Blood Cells (RBC)

Erythrocytes (RBCs) constitute the most abundant type of blood cell, making up about 99% of the total blood cell count.
Structure: RBCs are biconcave and lack a nucleus. They have a diameter of approximately 8µm.
Components: RBCs contain hemoglobin, lipids, ATP, and carbonic anhydrase.

Function of RBCs

Oxygen and Carbon Dioxide Transport: RBCs are primarily responsible for transporting oxygen and carbon dioxide throughout the body.
pH Homeostasis: The majority of carbon dioxide is transported as bicarbonate ions (HCO3-) within RBCs.
Carbonic Anhydrase: Carbonic anhydrase is an enzyme present in RBCs that facilitates the conversion of CO2 and water into bicarbonate ions and hydrogen ions (CO2 + H2O → HCO3- + H+).
Capillary Passage: RBCs are flexible enough to bend and pass through small capillaries due to their biconcave shape.
Destruction: Old RBCs are normally destroyed in the spleen.
Phagocytosis: Phagocytic WBCs remove cellular debris from the blood.

Hematocrit

Hematocrit represents the percentage of red blood cell volume within a blood sample.
Hematocrit values vary between men and women:
- Men: 5 million cells/mm3
- Women: 4.5 million cells/mm3

Regulation of Red Blood Cell Production

The production of RBCs is tightly regulated by a negative feedback mechanism involving the hormone erythropoietin.
Erythropoietin is released from the kidneys and liver in response to low oxygen levels detected in the blood.
This hormone stimulates the production of new RBCs, increasing oxygen-carrying capacity.

Dietary Factors Affecting Red Blood Cells Production

Vitamins B12 and Folic Acid: These vitamins contribute to DNA synthesis, which is essential for the replication of all body cells, particularly in hematopoietic tissue.
Iron: Iron is required for the synthesis of hemoglobin.

Red Blood Cell Disease

Anemia: Anemia is a condition characterized by a decreased concentration of hemoglobin or red blood cells in the blood.
Polycythemia: Polycythemia refers to an excess of red blood cells in the blood. It can be caused by cancer, tissue hypoxia (low oxygen levels), dehydration, or occur naturally at high altitudes.

White Blood Cells

White blood cells (WBCs), also known as leukocytes, play a critical role in the immune system, defending the body against pathogens and infections.
Types of WBCs:
- Neutrophils: Most abundant WBCs, comprising 60-70% of total WBC count. They have a multi-lobed nucleus and blue granules. Their primary function is to phagocytose and destroy bacteria.
- Eosinophils: Represent 2-4% of WBCs and possess bilobed nuclei. They contain red or yellow granules with digestive enzymes. They play a key role in resolving allergic reactions.
- Basophils: These cells are less common, comprising less than 1% of WBCs. They have a bilobed nucleus and contain dark blue granules with histamine and heparin.

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Description

Explore the vital roles and components of the circulatory system in this quiz. Learn about the heart's function, blood vessels, and the importance of blood in transporting essential substances throughout the body. Test your knowledge on the basics of this crucial system.