TRANSPORT IN HUMANS GRADE 9.2025.pptx

Transport in Humans

The Importance of a Transport System

  • Need for Transport Systems

    • Essential in large, multicellular organisms.

    • Enables the movement of materials necessary for cellular function.

  • Types of Materials Transported in Animals

    • Nutrients, oxygen, hormones, and waste products.

Importance of Transport Systems

  • Living organisms must exchange materials with their environment.

  • Cells require:

    • Constant supply of nutrients and oxygen.

    • Removal of waste products such as carbon dioxide.

  • Substances needing transport in humans include:

    • Digested Food: Absorbed in the ileum and sent to body cells.

    • Nitrogenous Waste (Urea): Produced from excess amino acids in the liver, excreted by kidneys.

    • Oxygen: Obtained from lungs and utilized in body cells during respiration.

    • Carbon Dioxide: Produced in cells during respiration, exhaled via lungs.

    • Hormones: Produced in endocrine glands, exert effects on target organs.

Transport Mechanisms

  • Unicellular Organisms:

    • E.g., Amoeba, jellyfish have a high surface area to volume ratio.

    • They rely on diffusion across their surface for material exchange.

    • Quick nutrient supply and waste removal due to proximity to environment.

  • Multicellular Organisms (Humans):

    • Cells are located deeper in the body, requiring an efficient transport system.

    • Diffusion is too slow for adequate transport across body tissues.

    • Specialized systems are necessary for efficient transport of materials.

The Circulatory System in Humans

  • Components of the Circulatory System:

    • Blood: Transports materials.

    • Blood Vessels: Interconnected tubes throughout the body.

    • Heart: Muscular pump maintaining blood flow.

Structure of the Heart

  • Location and Weight:

    • Located behind the sternum and between the lungs.

    • Weighs approximately 300g, size of a fist.

  • Muscle Type:

    • Composed of cardiac muscle.

  • Protection:

    • Encased in the pericardium, which contains lubricating fluid.

Heart Structure

  • Coronary Arteries:

    • Seen on the surface, supplying glucose and oxygen to cardiac muscles.

Chambers of the Heart

  • Division: Heart divided into right and left sides by septum.

  • Chambers:

    • Each side has two chambers: atria (upper) and ventricles (lower).

  • Blood Flow Mechanism:

    • Veins: Return blood to heart (superior/inferior vena cava).

    • Arteries: Carry blood away from heart (aorta, pulmonary artery).

    • Valves: Prevent backflow during contraction, ensuring one-way blood flow.

Blood Flow through the Heart

  • Deoxygenated Blood:

    • Returns to right atrium via vena cava, pumped to lungs via right ventricle.

  • Oxygenated Blood:

    • Returns from lungs to left atrium, pumped to body via left ventricle.

  • Valves: Atrioventricular and semilunar valves ensure unidirectional flow.

Double Circulation

  • Definition: Blood passes through the heart twice for one complete circuit.

  • Components:

    • Pulmonary Circulation: Pumps deoxygenated blood to lungs for oxygenation.

    • Systemic Circulation: Pumps oxygenated blood to the rest of the body at high pressure.

    • Importance for maintaining metabolic rate in mammals and birds.

Blood Vessels

  • Types:

    • Arteries: Carry blood away, thick walls for high pressure.

    • Veins: Carry blood towards the heart, thinner walls, contain valves.

    • Capillaries: Connect arteries and veins, allow material exchange.

Composition of Blood

  • Volume: Humans have 4-5 liters.

  • Components:

    • Plasma (55%): 90% water, rest proteins, salts, hormones.

    • Blood Cells (45%): Red blood cells, white blood cells, platelets.

Functions of Blood Components

  • Plasma: Transports heat and dissolved substances.

  • Red Blood Cells (Erythrocytes):

    • Transport oxygen via hemoglobin, lifespan of approx. 120 days.

  • White Blood Cells (Leukocytes):

    • Protect against infection, includes phagocytes and lymphocytes.

  • Platelets:

    • Involved in blood clotting, adhere to damaged vessels.

Blood Transfusions and Groups

  • Mixing incompatible blood can cause agglutination.

  • Blood groups determined by the presence of antigens and antibodies (A, B, AB, O).

Blood Pressure

  • Definition: Force of blood against vessel walls.

  • Measurement: Sphygmomanometer used to measure arterial pressure.

  • Normal Ranges: Systolic under 120, Diastolic under 80.

Factors Affecting Blood Pressure

  1. Physical Activity: Strengthens heart, lowers pressure.

  2. Body Weight: Obesity increases resistance, leads to higher pressure.

  3. Sleep Patterns: Poor sleep raises blood pressure.

  4. Diet: High sodium increases pressure; potassium-rich diet lowers it.

  5. Age and Genetics: Blood pressure increases with age and family history.

  6. Stress: Affects overall health and blood pressure levels.

Blood Diseases

  1. Genetic Disorders: Sickle cell disease causes pain and organ damage.

  2. Nutritional Deficiencies: Iron deficiency leads to anemia.

  3. Bone Marrow Disorders: Leukemia results in uncontrolled white blood cell growth.

  4. Heart Diseases: Atherosclerosis causes chest pain and risk of heart attacks.

  5. Aneurysm: Bulge in artery walls leading to potential ruptures.

Hypertension Effects

  • Often asymptomatic until severe, can cause headaches and blurred vision.

  • Leads to complications such as kidney disease, heart disease, and stroke.

  • Increases the risk of premature death from cardiovascular complications.