Blood flowing through the heart creates movement and turbulence, especially when the valves close. These normal sounds are described as “lub” and “dub,” and they occur with each heartbeat.
Topics
Cell - The Structural and Functional Unit of Life [For Revision Only]
- Cell: Structural and Functional Unit of Life
- Organisms Show Variety in Cell Number, Shape and Size
- Structure of the Cell > Plasma Membrane / Cell Membrane
- Structure of the Cell > Cell Wall: “Supporter and Protector”
- Structure of the Cell > Cytoplasm: “Area of Movement”
- Structure of the Cell > Nucleus: “Brain” of the Cell
- Cell Organelles
- Endoplasmic Reticulum (ER)
- Mitochondria - “Power House of the Cell”
- Golgi Apparatus - "The delivery system of the cell"
- Ribosomes - "The sites of protein synthesis"
- Lysosome - “Suicidal Bag”
- Centrosome and Centrioles
- Plastids
- Non-living Substances Or Cell Inclusion
- Plant Cell Vs Animal Cell
- Microscopic Examination of Onion Peel
Basic Biology
Structure of Chromosomes, Cell Cycle and Cell Division
- Chromosomes - The Carriers of Heredity
- Chromatin
- Deoxyribonucleic Acid (DNA)
- Histone Proteins
- Genes and Genetic
- Need for New Cells
- Cell Cycle - "Divide, Grow and Redivide"
- Interphase
- Cell Division: an Essential Life Process
- Mitosis > Karyokinesis (Division of Nucleus)
- Mitosis > Karyokinesis (Division of Nucleus)
- Mitosis > Cytokinesis (Division of Cytoplasm)
- Significance of Mitosis
- Comparison of Mitosis in Plant and Animal Cells
- Mitochondria and Chloroplasts in Cell Division
- Meiosis: Reduction Division
- Stages of Meiosis: Meiosis I
- Stages of Meiosis: Meiosis II
- Significance of Meiosis
- Mitosis Vs Meiosis
Plant Physiology
Human Anatomy and Physiology
Genetics: Some Basic Fundamentals
- Gregor Johann Mendel – Father of Genetics
- Genes and Genetic
- Heredity
- Inheritance in Humans
- Chromosomes - The Carriers of Heredity
- Autosomes and Sex Chromosomes
- Sex Determination
- Genes and their Alleles
- Genotype and Phenotype
- Inheritance of Human Traits and Their Genetic Basis
- Sex-Linked Inheritance in Human Beings
- Monohybrid Cross
- Applications of Mendel's Laws
Absorption by Roots: The Processes Involved
- Plant Physiology
- Concept of Absorption by the Roots
- Need of Water and Minerals for Plants
- Characteristics of Roots for Absorbing Water
- Absorption and Conduction of Water and Minerals
- Imbibition
- Diffusion
- Osmosis
- Osmotic Pressure
- Active Transport
- Passive Transport
- Turgidity and Flaccidity (Plasmolysis)
- Uses of Turgidity to Plants
- Comparison of Diffusion, Osmosis and Active Transport
- Root Pressure
- Importance of Root Hairs and Upward Transport
- Experiments on Absorption and Conduction of Water in the Plants
- Forces Contributing to Ascent of Sap
Human Evolution
Population
Transpiration
- Concept of Transpiration
- Demonstration of Transpiration
- Measurement of Transpiration > Weighing Method
- Measurement of Transpiration > Potometer Method
- Kinds of Transpiration
- Stomatal Transpiration
- Cuticular Transpiration
- Lenticular Transpiration
- Factors Affecting the Rate of Transpiration
- Plant Adaptations to Reduce Transpiration
- Significance of Transpiration
- Guttation and Bleeding
- Traspiration Vs Bleeding
Pollution
Photosynthesis
- Concept of Photosynthesis
- Chlorophyll: The Vital Plant Pigment
- Regulation of Stomatal Opening for Carbon Dioxide Intake
- Opening and Closing of Stomata
- Process of Photosynthesis
- Light-Dependent Phase of Photosynthesis
- Light-Independent Phase of Photosynthesis
- Adaptations in Leaves to Perform Photosynthesis
- Products of Photosynthesis
- Factors Affecting Photosynthesis
- Experiments on Photosynthesis
- Significance of Photosynthesis
- The Carbon Cycle
Chemical Coordination in Plants
Physical Health and Hygiene
Health Organisations
- International Bodies: WHO (World Health Organisation)
- Common Health Problems in India
Aids to Health
- First Aid and Emergency Action
- Antiseptics and Disinfectants
- Antibiotics
The Circulatory System
- Need for Transport in the Body
- Fluids in Our Body
- Blood
- Functions of Blood
- Composition of Blood > Plasma (The Liquid Portion of Blood)
- Composition of Blood > Cellular Elements: Red Blood Cells (Erythrocytes)
- Composition of Blood > Cellular Elements: White Blood Cells (Leukocytes)
- Erythrocytes vs Leukocytes vs Thrombocytes – A Comparative Overview
- Composition of Blood > Cellular Elements: Blood Platelets (Thrombocytes)
- Blood Transfusion and Blood Groups (ABO and Rh system)
- Blood Circulatory System
- Human Heart
- Blood Vessels Entering and Leaving The Heart
- Valves of the Heart
- Circulation of Blood in the Heart (Functioning of Heart)
- Heart Beat
- Pacemaker
- Blood Vessels
- Arteries Vs Veins
- Pulmonary and Systemic Circulation (Double Circulation)
- Hepatic Portal System
- The Pulse
- Blood Pressure (B.P.)
- Tissue Fluid (Or Intercellular Fluid)
- Lymph and Lymphatic System
- The Spleen
The Excretory System
The Nervous System
- Human Nervous System
- Neuron (Or Nerve Cell)
- Transmission of Nerve Impulse
- Synapse
- Types of Neurons
- Nerves
- Kinds of Nerves
- Major Division of the Nervous System
- The Human Brain
- Parts of the Brain > Cerebrum
- Parts of the Brain > Cerebellum
- Parts of the Brain > Medulla Oblongata
- Primary Regions of the Brain
- The Spinal Cord
- Peripheral Nervous System > Somatic Nervous System
- Peripheral Nervous System > Autonomic Nervous System
- Reflex Action
- Involuntary Actions Vs Voluntary Actions
- Types of Reflexes
- Pavlov's Experiment on a Dog
- Reflexes in Humans
- Nervous Pathways in Reflexes
- Reflex Arc
- Complex Reflex Action
Sense Organs
- Concept of Sense Organs
- Sensory Receptors
- The Human Eye
- Structure of the Eyeball
- Yellow Spot and Blind Spot
- Rods Vs Cones
- Eye Donation
- Lens
- Light and Dark Adaptation
- Colour Vision
- Defects of Vision and Their Corrections > Myopia
- Defects of Vision and Their Corrections > Hypermetropia
- Defects of Vision and Their Corrections > Presbyopia
- Eye Defect and Its Correction: Astigmatism
- Common Defects of the Eye
- Stereoscopic (Binocular) Vision
- Colour Blindness Assessment
- After-Images and Visual Illusions of Vision
- Human Ear
- Functions of the Ear
The Endocrine System
- Human Endocrine System
- Hormonal Control Vs Nervous Control
- Concept of Hormone
- General Properties of Hormones
- Adrenal Gland (Suprarenal Gland)
- Pancreas (Islets of Langerhans)
- Thyroid Gland
- Pituitary Gland or Hypophysis Gland
- Control of Hormonal Secretions
- Summary of Hormones and Their Actions
The Reproductive System
Human Evolution
- Evolution
- Theories of Biological Evolution
- Evidence of Evolution > Vestigial Organs
- Lamarck's Theory Vs Darwin's Theory
- Human Ancestors
- Homo Sapiens Sapiens (Modern Man)
Population: The Increasing Numbers and Rising Problems
- Rising Population - A Global Threat
- World Population Through the Ages
- Rapid Rise in Population
- Population Explosion- A Serious Global Concern
- Simplified Model Of Population Growth
- Concept of Population in India
- Factors Responsible For The Population Explosion In India
- Rising Population - Pressure on Natural Resources
- Population Growth And Urbanisation: Pressure On Resources
- Need To Reduce Population Growth Rate
- Need For Adopting Control Measures
- Population Education And Population Control
Pollution: A Rising Environmental Problem
- Waste
- Pollution
- Water Pollution
- Soil Pollution
- Sources of Soil Pollution
- Radiation
- Noise Pollution
- Sources of Noise Pollution
- Acid Rain
- Greenhouse Effect and Global Warming
- Ozone Layer Depletion
- Effects on Human Health
- Control of Pollution
- Swachh Bharat Abhiyan (Clean India Movement)
- Plastic Pollution
- Definition: Cardiac Cycle
- Heart Beat Rate
- Heart Beat Sounds
- Key Points: Heart Beat
CISCE: Class 10
Definition: Cardiac Cycle
The complete sequence of events that occurs during one heartbeat, including contraction and relaxation of the atria and ventricles, is called the cardiac cycle.
Maharashtra State Board: Class 8
Heart Beat Rate
Heartbeat is the rhythmic contraction and relaxation of the heart muscles, which enables the heart to pump blood throughout the body.
- A healthy person's heart beats around 72 (ranges between 60 and 100) times per minute under normal conditions. With each heartbeat, the heart pumps approximately 75 ml of blood. This pumping action ensures that oxygen and nutrients are circulated to all parts of the body efficiently.
- Heartbeat is measured in terms of beats per minute (bpm) and can be recorded through medical instruments like an electrocardiogram (ECG).
The rate of heartbeat can change based on activity or emotions.
- It increases with physical exercise, stress, or strong emotions.
- It decreases during rest or sleep.
Infants have a higher heart rate compared to adults, meaning they have more beats per minute.
Maharashtra State Board: Class 8
Heart Beat Sounds
- “Lubb”: The first sound, created when the atrioventricular valves (between the upper and lower chambers) close. This occurs when the heart muscles contract to pump blood out.
- “Dub”: The second sound, produced when the semilunar valves (between the heart and the arteries) close as the heart relaxes and refills with blood.
CISCE: Class 10
Key Points: Heart Beat
- One heartbeat lasts about 0.85 seconds and includes atrial contraction, ventricular contraction, and relaxation of all chambers.
- The first sound "LUBB" is caused by the closure of tricuspid and bicuspid valves at the start of ventricular contraction.
- The second sound "DUP" is due to the closure of semilunar valves at the start of ventricular relaxation.
- Smaller animals and newborns have faster heart rates because of higher metabolism and heat loss.
- The full sequence of contraction and relaxation in a heartbeat is called the cardiac cycle.
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Series: Heart Beat - Heart Sounds "LUBB" and "DUP"
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