Class 11 Biology Chapter 15 Body Fluids And Circulation

Key Concept: Role of Calcium

c) Calcium

[Solution Description] Calcium ions are essential in various steps of the blood clotting process, including the activation and functioning of thrombokinase. They help in stabilizing and binding various components involved in the cascade reaction.

Key Concept: Basic Definition

c) Interstitial fluid

[Solution Description] When blood flows through capillaries, a portion of water along with small solutes is forced out of the vessel walls due to pressure differences. This results in the formation of a fluid known as interstitial fluid, which fills the spaces between cells in tissues.

Key Concept: Basic Function

d) It acts as a pacemaker

[Solution Description] The sino-atrial node (SAN), located in the right atrium of the heart, acts as the pacemaker. It initiates and regulates the heartbeat by generating the highest number of action potentials per minute.

Key Concept: Blood Group Basics

b) Antigen B

[Solution Description] Blood group B has the presence of antigen B on the surface of red blood cells (RBCs). The ABO blood grouping system is based on the presence or absence of antigens A and B. In this case, since it is blood group B, antigen B will be present.

Key Concept: Role of Calcium

c) They are essential for activating clotting factors

[Solution Description] Calcium ions are crucial as they participate in multiple steps of the coagulation cascade, particularly in activating various factors, including the conversion of prothrombin into thrombin.

Key Concept: Clotting Factors

b) Inactive

[Solution Description] Clotting factors in plasma are present in an inactive form. These factors become active during the clotting process to aid in the formation of a blood clot.

Key Concept: Blood Components

d) Plasma

[Solution Description]

Formed elements in blood include red blood cells (RBCs), white blood cells (WBCs), and platelets. Plasma, however, is not considered a formed element; it is the liquid portion of blood containing water, proteins, and other substances.

Key Concept: Major Proteins

c) Fibrinogen

[Solution Description] Fibrinogen is the protein in plasma that plays a crucial role in the process of blood clotting by forming fibrin threads.

Key Concept: Basic Transport

b) Water circulation

[Solution Description] Coelenterates, like sponges, rely on water circulation through body cavities for the transport of substances. This simple mechanism allows them to distribute nutrients and other necessary molecules throughout their body.

Key Concept: Basic Function

b) Return excess fluid to veins

[Solution Description] The primary function of the lymphatic system is to collect excess interstitial fluid from tissues and return it to the bloodstream through veins.

Key Concept: Basic Function

b) Decreases heart rate

[Solution Description] The parasympathetic nervous system primarily acts to slow down the heart rate by releasing neurotransmitters such as acetylcholine, which reduce the frequency of cardiac contractions.

Key Concept: Plasma Composition

c) Fibrinogen

[Solution Description] Fibrinogen is the main protein involved in the blood clotting process. It converts into fibrin threads that form a mesh, essential for the final step of coagulation.

Key Concept: Basic Function

b) Increases heart rate

[Solution Description] The sympathetic nervous system increases the heart rate when activated. This is achieved by releasing norepinephrine which acts on the cardiac pacemaker, increasing its firing rate.

Key Concept: Blood Groups

c) Presence of Rh antigen

[Solution Description] Blood groups are categorized into ABO and Rh systems based on specific surface antigens present on the red blood cells. The presence of the Rh antigen on the surface of erythrocytes indicates an Rh-positive blood group.

Key Concept: Definition Recall

c) The heart is not pumping blood effectively enough

[Solution Description] Heart failure means the state of the heart when it is not pumping blood effectively enough to meet the needs of the body.

Key Concept: Definition Recall

c) Blood pressure higher than 120/80 mm Hg

[Solution Description]

The normal blood pressure reading is 120/80 mmHg. Hypertension is defined as blood pressure that is higher than this normal value.

Key Concept: Blood Flow Regulation

b) Precise regulation of blood flow

[Solution Description] A closed circulatory system offers precise regulation of blood flow. It allows blood to be directed efficiently to various organs where needed, ensuring better nutrient and gas exchange, unlike an open system where the fluid is not confined within vessels.

Key Concept: Heart Valves

b) Prevents backflow into ventricles

[Solution Description] The semilunar valves, including the aortic and pulmonary valves, prevent backflow of blood from the arteries into the ventricles after ventricular systole. They ensure that blood flows in a forward direction towards the systemic or pulmonary circuit.

Key Concept: Real-World Application, Pathway Integration

c) Assertion is true, but Reason is false.

[Solution Description] The assertion states that inefficiencies in pulmonary circulation can result in systemic hypoxia due to insufficient oxygen transfer into the bloodstream. This is a true statement because pulmonary circulation is responsible for oxygenating the blood. If this process is inefficient, it can indeed cause systemic hypoxia. However, the reason provided is false. Pulmonary veins actually deliver oxygenated blood to the left atrium, not the right atrium.

Key Concept: Basic Pathway

d) Right ventricle

[Solution Description] The right ventricle is responsible for pumping deoxygenated blood into the pulmonary artery, which then carries it to the lungs for oxygenation.

Key Concept: Blood Flow Pathway

b) Body tissues

[Solution Description]

In fishes with single circulation, the heart pumps deoxygenated blood to the gills where gas exchange occurs. After being oxygenated in the gills, the blood directly proceeds to the body tissues without returning to the heart. Hence, the next stop for blood after the gills is the body tissues.

Key Concept: Blood Grouping

c) AB

[Solution Description]

Blood group AB is considered the universal recipient because individuals with this blood type can receive red blood cells from any ABO blood group without risk of incompatibility reactions.

Key Concept: Blood Content

b) Nutrient-rich blood from the intestines

[Solution Description]

The hepatic portal vein carries blood from the intestines to the liver, which is rich in nutrients absorbed from the food we consume. Thus, the blood in the hepatic portal vein is nutrient-rich.

Key Concept: Vascular Connections

b) To transport blood from the intestine to the liver

[Solution Description]

The hepatic portal system is a vascular connection that transports nutrients-rich blood from the digestive organs directly to the liver. This allows the liver to process and detoxify substances absorbed from the intestines before they enter the general circulation.

Thus, the primary function is to transport blood from the intestine to the liver.

Key Concept: Hormone Function

b) Increases cardiac output

[Solution Description] Epinephrine increases both heart rate and stroke volume, leading to an increase in cardiac output. The formula for cardiac output is $$\text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate}$$. When either stroke volume or heart rate increases, the overall cardiac output increases.

Key Concept: Basic Function

d) Sympathetic nerves

[Solution Description] Sympathetic nerves are part of the autonomic nervous system and play a role in increasing the heart rate by stimulating the cardiac muscle, leading to stronger contractions.

Key Concept: Definition Check

c) Blood pressure consistently above 140/90 mm Hg

[Solution Description] Hypertension is a condition where blood pressure in the arteries is persistently elevated. The systolic and diastolic pressures are typically higher than normal.

Key Concept: Blood Group Basics

b) Antigen B

[Solution Description] Blood group B has antigen B on the surface of its red blood cells.

Key Concept: WBC Count

c) 6000-8000

[Solution Description] The syllabus states that leucocytes, or white blood cells, are present in the range of 6000-8000 per mm$^{3}$ of blood.

Key Concept: Plasma Components

c) Fibrinogen

[Solution Description] Fibrinogen is present in plasma and is essential for blood clotting as it is converted into fibrin by thrombin.

Key Concept: Basic Function

b) It delays the impulse between atria and ventricles

[Solution Description] The atrioventricular node (AVN) is responsible for delaying the electrical impulse from the sinoatrial node (SAN) before it passes to the ventricles. This delay allows the atria to contract and complete the filling of the ventricles with blood. Hence, its primary function is to act as a relay point that slows down the conduction speed from the atria to the ventricles.

Key Concept: Heartbeat Rate Calculation

a) 80 beats per minute

[Solution Description]

To calculate the heart rate, multiply the number of QRS complexes by the factor that converts the time period into minutes:

$$\text{Heart rate} = \frac{20 \times 60}{15} = 80 \text{ beats per minute}$$

Key Concept: Basic Definition

b) Atherosclerosis

[Solution Description] CAD is commonly referred to as atherosclerosis because it involves the narrowing of arteries due to deposits such as calcium, fat, cholesterol, and fibrous tissues.

Key Concept: Heart Structure

d) Amphibian

[Solution Description] Amphibians, such as frogs, have a 3-chambered heart consisting of two atria and one ventricle. This is typical among amphibians and most reptiles except for crocodiles.

Key Concept: Basic Definition

d) Colorless

[Solution Description] Lymph is a clear fluid collected by the lymphatic system from interstitial spaces and is typically described as being colorless.

Key Concept: Plasma Proteins

b) Fibrinogen

[Solution Description] Fibrinogen is a key plasma protein involved in blood clotting. During the coagulation process, fibrinogen is converted into fibrin by the action of thrombin, forming a mesh that helps in stopping bleeding.

Key Concept: Cardiac Output Calculation

c) 5600 mL/min

[Solution Description]

The formula for calculating cardiac output (CO) is given by:

$$CO = \text{Stroke Volume} \times \text{Heart Rate}$$

Given that the stroke volume (SV) is 70 mL and the heart rate (HR) is 80 beats per minute, we substitute these values into the equation:

$$CO = 70 \, \text{mL} \times 80 \, \text{beats/min}$$

Performing the multiplication:

$$CO = 5600 \, \text{mL/min}$$

Therefore, the new cardiac output is 5600 mL/min.

Key Concept: Basic Function

b) Transport of nutrients, oxygen, and waste

[Solution Description] The primary function of circulation in living organisms is to transport essential substances such as nutrients and oxygen to cells and remove waste products from the body.

Key Concept: Basic Definition

c) Thrombocytes

[Solution Description] Platelets are also known as thrombocytes. This term comes from the Greek word “thrombos,” which means “clot,” indicating their role in blood clotting.

Key Concept: Definition Recall

d) Angina Pectoris

[Solution Description] Angina, which refers to a symptom of acute chest pain due to insufficient oxygen reaching the heart muscle, is commonly known as “angina pectoris.”

Key Concept: Key Components

c) Fibrinogen

[Solution Description]

Fibrins are formed during the clotting process by the conversion of inactive fibrinogen. Fibrinogen, a soluble plasma protein, is transformed into insoluble fibrin strands through the action of thrombin.

Key Concept: Chambers of Heart

c) Four

[Solution Description] The human heart consists of four chambers: two atria and two ventricles.

Key Concept: Basic Definition

b) Atherosclerosis

[Solution Description] The condition of hardening and narrowing of the arteries due to the build-up of cholesterol, fats, and other substances is commonly referred to as “atherosclerosis.”

Key Concept: RBC Life Span

c) 120 days

[Solution Description]

The average lifespan of red blood cells (erythrocytes) in human blood is approximately 120 days. These cells are formed in the red bone marrow and have a biconcave shape, which aids in gas exchange. After completing their lifecycle, they are typically destroyed in the spleen.

Key Concept: RBC Evolution, RBC and Disease

b) To allow flexibility and maximize hemoglobin accommodation, avoiding anemia due to insufficient RBCs.

[Solution Description] Enucleated RBCs are more flexible and can deform easier as they navigate narrow capillaries, maximizing space for hemoglobin and enhancing gas transport. A deficiency in such cells often leads to anemia, characterized by reduced oxygen transport capacity in the blood.

Key Concept: Basic Definition

d) Rhesus monkeys

[Solution Description] The Rh antigen is named after Rhesus monkeys because it was first discovered in their blood. Thus, the Rh antigen in humans is similar to the one present in Rhesus monkeys.