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Defense Mechanism In Plants

Introduction

• Plants provide protection from various threats.

• Modified parts are essential for defense.

• Defense mechanisms target herbivores, insects, and egg-laying pests.

Types Of Defense Mechanisms

1. Thorns

   • Definition: Modified branches or stems with sharp points.

   • Example: Carissa bispinosa.

2. Spines

   • Definition: Modified leaves or stipules.

   • Examples:

     • From leaves: Opuntia sp.

     • From stipules: Acacia erioloba.

3. Prickles

   • Definition: Modified epidermal extensions.

   • Examples:

     • From stem: Rose.

     • From leaves: Solanum pyracanthum.

4. Shrinkage

   • Description: Loss of turgidity in cells.

   • Effect: Deterrents to animals; perceived as danger.

   • Example: Mimosa pudica.

5. Milky Latex

   • Definition: Aqueous, poisonous secretion.

   • Examples: Euphorbia pulcherrima, Opium poppy.

6. Trichomes

   • Definition: Hair-like epidermal projections.

   • Types:

     • Glandular (poisonous).

     • Non-glandular (irritating).

   • Examples: Capsicum pubescens (non-glandular), Cannabis sp. (glandular).

7. Volatile Organic Compounds (VOC’s)

   • Definition: Chemical defenses produced by plants.

   • Example: Quisqualic acid from Geraniums, which paralyzes insects.

PLANT HORMONES

Overview of Plant Hormones

• Plant hormones guide plant growth and development.

Functions of Plant Hormones

• Plant hormones act as chemical messengers:

  • Produced in one part of the organism.

  • Stimulate or suppress activity in other parts.

Types of Plant Hormones

Gibberellins

• Gibberellins promote:

  • Ending of seed dormancy.

  • Stem elongation.

  • Germination and flowering.

  • Cause dramatic increases in plant size.

Ethylene

• Ethylene is important for:

  • Ripening of fruits, often applied to fruits picked before ripening.

  • Fruits are sprayed with ethylene to ensure ripening upon reaching their destination.

Cytokinins

• Cytokinins are involved in:

  • Stimulating cytokinesis (final stage in cell division).

  • Produced in growing roots, seeds, and fruits.

  • Growth of side branches.

Auxins

• Auxins affect:

  • Lengthening of plant cells in the growing tips.

  • Growth of primary stems.

  • Control certain forms of tropism (response to environmental stimuli).

Types of Tropisms Controlled by Plant Hormones

Phototropism

• Phototropism is the growth of plants toward light:

  • Auxins accumulate on the shaded side of the stem, leading to:

    • Lengthening of cells on that side.

    • Bending of the stem toward the light source.

Thigmotropism

• Thigmotropism is a plant's response to touch-like stimuli:

  • Seen in climbing plants and vines that grow in the direction of constant wind.

Gravitropism

• Gravitropism is how plants respond to gravity:

  • Positive gravitropism: downward growth (roots).

  • Negative gravitropism: upward growth (shoots).

Photoperiodism

• Photoperiodism is a response to seasonal changes in day length:

  • Triggers flowering in certain plants.

  • Influences fall coloration and winter dormancy in deciduous trees.

ABSCISIC ACID

Definition:

• Abscisic Acid (ABA) is a plant hormone that regulates various physiological processes, primarily associated with stress responses and growth inhibition.

Functions of Abscisic Acid:

1. Seed Dormancy:

   • Prevents premature germination.

   • Helps seeds survive unfavorable conditions.

2. Stomatal Closure:

   • Reduces water loss during drought by closing stomata.

3. Stress Response:

   • Enhances plant tolerance to drought, salinity, and cold stress.

4. Inhibits Growth:

   • Suppresses shoot growth during unfavorable conditions.

5. Fruit Ripening and Senescence:

   • Regulates leaf fall (abscission) in some plants.

Synthesis and Transport:

• Synthesized in plastids from carotenoids.

• Transported through the xylem and phloem.

Significance in Agriculture:

• Used in seed storage and drought-resistant crops.

• Helps regulate water usage in plants.

RESPIRATORY SYSTEM

Human Respiration

• Definition: The human respiratory system is responsible for obtaining oxygen and eliminating carbon dioxide.

• Phases of Breathing:

  • Inspiration: Taking in air (O2).

  • Expiration: Blowing out air (CO2).

Structure of the Human Respiratory System

Upper Respiratory Tract

• Nose: Passageway for air; warms, moistens, and filters air.

• Mouth: Passageway for both food and air.

• Epiglottis: Covers larynx during swallowing to prevent food entry.

• Nasal Cavity: Filters, warms, and moistens air.

• Pharynx (Throat): Common passageway for air, food, and liquids.

• Larynx (Voice box): Involved in sound production.

Lower Respiratory Tract

• Pleural Membranes: Cover the lungs and line the chest cavity.

• Lungs: Organs responsible for gas exchange.

• Intercostal Muscles: Move ribs during respiration.

• Rib Cage: Provides structure and protection for the lungs.

• Diaphragm: Skeletal muscle crucial for breathing.

• Trachea (Windpipe): Main airway leading to the lungs.

• Bronchi: Branching airways that lead from trachea to lungs.

• Alveoli: Air sacs where gas exchange occurs.

Functions of the Respiratory System

Specific Organs and Their Functions

• Nose/Nasal Cavity: Warms, moistens, filters inhaled air.

• Pharynx: Pathway for air leading to trachea.

• Larynx: Voice production and route for air and food.

• Trachea: Maintains open airway and filters air with cilia.

• Bronchi: Directs air to the lungs.

• Bronchioles: Smaller branches leading to alveoli.

• Alveoli: Primary site for gas exchange in the lungs.

Upper Respiratory Tract Functions

• Passage for Respiration: Facilitates air movement.

• Receptors for Smell: Contains sensory structures for olfaction.

• Air Filtering: Filters larger particles from incoming air.

• Moistening and Warming Air: Prepares air for lung entry.

• Voice Resonance: Functions as resonating chambers for voice.

Lower Respiratory Tract Functions

• Larynx:

  • Maintains open airway.

  • Routes food and air appropriately.

  • Assists in sound production.

• Trachea:

  • Transports air to and from the lungs.

• Bronchi and Bronchioles: Branching structures that direct air into lungs.

• Lungs: Facilitate gas exchange in alveoli.

Gas Exchange Process

• In Alveoli:

  • Blood flow indicates process location.

  • Oxygen (O2) enters blood, Carbon Dioxide (CO2) exits blood.

• Pulmonary Circulation: Coordination between air in alveoli and blood in capillaries.

Respiratory Cycle

• Phases of Breathing:

  1. Relaxed State: No air movement.

  2. Inspiration: Diaphragm contracts and flattens, ribcage expands.

  3. Expiration: Diaphragm relaxes, lung volume decreases.

Types of Respiration

• Breathing (Ventilation): Movement of oxygen into and carbon dioxide out of the lungs.

• External Respiration: Gas exchange between air and blood.

• Internal Respiration: Gas exchange between blood and tissues.

• Cellular Respiration: Oxygen used to produce ATP; carbon dioxide as a waste product.

Malfunctions and Diseases of the Respiratory System

• Asthma: Severe allergic reaction causing bronchioles constriction.

• Bronchitis: Inflammation of the lining of bronchioles.

• Emphysema: Deterioration of alveoli, losing lung elasticity.

• Pneumonia: Infection causing alveoli to fill with fluid, impairing gas exchange.

• Lung Cancer: Uncontrolled growth of tumors within lung tissue.

CIRCULATORY

Circulatory System Overview

• Major components of the circulatory system include:

  • Superior vena cava

  • Inferior vena cava

  • Aorta

  • Pulmonary veins

  • Pulmonary arteries

  • Femoral artery

  • Femoral vein

  • Descending aorta

Functions of the Circulatory System

• Main Functions:

  • To carry nutrients to all body cells (e.g. glucose, amino acids, oxygen)

  • To carry wastes away from all body cells (e.g. ammonia, carbon dioxide)

• Circulating Fluid:

  • Blood flows through flexible pipe-like structures called vessels to move throughout the body.

Components of the Human Circulatory System

• Consists of:

  • Heart: Pumps the blood

  • Blood Vessels: Conduct blood flow

  • Blood: Substance that carries materials being transported.

The Heart

• Location: Near the center of the chest

• Size: Approximately the size of a clenched fist

• Chambers: Four chambers

  • Atrium: Upper chambers receiving blood

  • Ventricle: Lower chambers pumping blood

Cardiac Circulation

• The heart acts as two separate pumps:

  • Right Side: Pumps blood from the heart to the lungs (pulmonary circulation)

    • In lungs, CO2 leaves blood and O2 is absorbed.

  • Left Side: Pumps blood from the heart to the rest of the body (systemic circulation).

Blood Flow and Valves

• Blood flow pathway includes:

  • Right Atrium (RA) -> Tricuspid valve -> Right Ventricle (RV) -> Pulmonary Valve -> Pulmonary Arteries (PA) -> Lungs

  • Left Atrium (LA) -> Mitral Valve -> Left Ventricle (LV) -> Aortic Valve -> Aorta (AO).

• Blood types: Oxygen-rich and oxygen-poor blood.

Blood Vessels

• Three Types:

  • Arteries: Carry blood away from the heart (except pulmonary arteries, which carry oxygen-poor blood).

    • Thick walls withstand pressure from heart contractions; contain connective tissue, smooth muscle, and endothelium.

  • Veins: Carry blood toward the heart; usually carry oxygen-poor blood.

    • Walls contain connective tissue and smooth muscle; valves present to keep blood flowing toward the heart.

  • Capillaries: Smallest blood vessels connecting arteries and veins.

    • Walls are one cell thick; blood cells pass through in single file.

Diseases of the Circulatory System

• Known as: Cardiovascular diseases.

• Major Concerns: Heart disease and stroke are leading causes of death and disability, particularly in the Philippines.

Specific Diseases

• High Blood Pressure (Hypertension):

  • Forces the heart to work harder, can weaken heart muscle and blood vessels.

  • Increases risk of coronary heart disease, heart attack, or stroke.

• Heart Disease:

  • Narrowing of blood vessels can lead to heart attacks (symptoms: nausea, shortness of breath, severe chest pain).

  • Blood clots resulting from atherosclerosis can cause strokes due to oxygen deprivation in the brain.

Preventing Diseases

• Healthy Lifestyle Recommendations:

  • Regular exercise

  • Balanced diet:

    • Fruits & Vegetables (33%)

    • Cereal, Bread & Potatoes (33%)

    • Milk and Dairy Foods (15%)

    • Meat, Fish & Alternatives (12%)

    • Fatty & Sugary Foods (7%)

  • Avoid smoking

Blood Composition

• Overall Volume: Human body contains 4-6 liters of blood.

  • Components:

    • Red Blood Cells (RBCs)

    • White Blood Cells (WBCs)

    • Platelets

    • Plasma (55% of blood volume; straw-colored fluid)

Plasma

• Composed of:

  • 90% Water

  • 10% dissolved gases, salts, nutrients, enzymes, hormones, wastes, and plasma proteins.

Red Blood Cells (Erythrocytes)

• Most numerous cells in blood, transport oxygen.

• Color derived from hemoglobin (iron-containing protein that binds with oxygen).

• Shape: Round plates with a central indentation.

White Blood Cells (Leukocytes)

• No hemoglobin; produced in bone marrow.

• Important for fighting diseases by targeting pathogens.

Platelets

• Essential for blood clotting, playing a key role in preventing excessive bleeding.

IMMUNE SYSTEM

Immune System Overview

• Instructor: Ms. Melody S. Dalag

Body Defenses

General Overview

• Viruses and bacteria are ubiquitous; some seek to invade the body.

• The body uses various mechanisms to defend itself against these pathogens.

• Key principle: WORK TOGETHER to ensure effective defense.

Defense Against Disease

• If external barriers are breached, the body employs different responses:

  • Innate Immune Response: Quick, non-specific defense mechanisms.

  • Adaptive Immune Response: Specific and long-lasting immunity developed through:

    • Cell-mediated immunity

    • Humoral immunity

• Key components of defense:

  • Nonspecific External Barriers:

    • Skin

    • Mucous membranes

  • Innate Immune Response:

    • Phagocytic cells

    • Natural killer cells

    • Inflammatory response

    • Fever

First Line of Defense

• The non-specific defenses include:

  • Intact skin: Physical barrier against pathogens.

  • Mucus and Cilia: Trap and expel invaders from respiratory tract.

  • Phagocytes: Target and destroy pathogens.

Role of Phagocytes

• Phagocytes are types of white blood cells (e.g., macrophages, neutrophils).

• Function: Seek and destroy foreign invaders and damaged body cells.

• Phagocytes activation: Stimulated by inflammatory signals from damaged cells.

Role of Inflammation

• Inflammation response initiated by mast cells releasing histamine:

  • Histamine helps fluids accumulate around injuries, diluting toxins and causing swelling.

  • Elevated tissue temperature may help eliminate temperature-sensitive microbes.

Role of Fever

• Fever is a defensive mechanism against infections:

  • Can destroy various pathogens.

  • Enhances viral infection resistance by boosting interferon production.

  • Caution: Extremely high fevers can be dangerous; moderate fevers are often allowed without treatment.

Specific Defenses

• Specific defenses provide immunity to certain diseases:

  • The immune system creates a chemical "memory" of pathogens, facilitating rapid responses to repeat infections to minimize symptoms.

Major Players in the Immune System

• Key components of the immune response include:

  • Macrophages

  • T cells: Helper T cells, Cytotoxic T cells, Memory T cells

  • B cells: Plasma cells, Memory B cells

  • Antibodies

Antibodies

• Composed of protein chains; various configurations create unique antibodies.

Helper T Cells

• Recognize antigens through specific receptors and stimulate B-cell division via cytokines.

• Critical for signaling an immune response:

  • Disability (e.g., in AIDS) leads to impaired immune response.

B Cells

• Function primarily to produce antibodies:

  • B cells with matching antibodies undergo rapid division and differentiation into:

    • Plasma cells: Produce antibodies quickly.

    • Memory B-cells: Maintain memory of the invader for future encounters.

Role of Antibodies

• Antibodies bind to specific antigens in the bloodstream:

  • May disable pathogens or encourage agglutination.

  • Tag pathogens for recognition and destruction by other white blood cells.

“Killer” T Cells

• T cells also proliferate and differentiate:

  • Some develop into cytotoxic or “killer” T cells which seek out and destroy any recognized antigens and microbes marked by antibodies.

  • Capable of targeting cancer cells.

Supporting the Immune System

• Medical interventions to bolster immune defenses include:

  • Antibiotics: Target bacterial infections (not the same as antibodies).

  • Vaccines: Train immune system for future encounters with pathogens.

How Vaccines Work

• Created using killed microbes or protein fragments:

  • Recognized as antigens, inducing a mild immune response.

  • Leads to production of memory T-cells and B-cells for future protection against the illness.

Autoimmune Disorders

• Occur when the immune system incorrectly identifies body proteins as foreign:

  • Examples: Multiple sclerosis, lupus, rheumatoid arthritis.

  • No cure available; treatment focuses on managing symptoms and slowing progression.

ENDOCRINE

Endocrine System Overview

• The endocrine system includes glands and hormones that play a vital role in regulating bodily functions.

• Major Endocrine Glands:

  • Male: Testis

  • Female: Ovary

  • Other glands include the Pituitary, Thyroid, Pineal, Thymus, Adrenal, and Pancreas.

Function of the Endocrine System

• Hormone: A chemical messenger released into the bloodstream targeting specific cells to modify their activity.

• General Function:

  • Secretes hormones directly into the bloodstream.

  • Hormones can either activate or inhibit specific activities in target tissues.

Characteristics of Endocrine Glands

• Ductless Glands:

  • Release hormones directly into circulation.

  • Blood transports hormones throughout the body.

• Each hormone acts on specific tissues known as target tissues:

  • Target Cell: Has receptors for the hormone.

  • Non-Target Cell: Lacks receptors for the hormone, thus unresponsive.

Major Human Endocrine Glands

• Pituitary Gland

• Thyroid Gland

• Parathyroid Glands

• Adrenal Glands

• Pancreas (Islets of Langerhans)

• Testes & Ovaries

Details on Pituitary Gland

• Location: Behind the nose at the base of the brain, pea-sized (~1 cm).

• Hormones Secreted:

  • Total of 9 hormones affecting growth, blood pressure, pregnancy, milk production, sexual organ function, metabolism, and water regulation.

Key Pituitary Hormones and Functions

• Growth Hormone (GH):

  • Increases body size during childhood/adolescence; maintains size in adulthood.

• Thyroid Stimulating Hormone (TSH):

  • Stimulates thyroid to produce thyroxin.

• Follicle Stimulating Hormone (FSH):

  • Regulates puberty and reproductive processes.

• Luteinizing Hormone (LH):

  • Stimulates production of estrogen and testosterone.

Growth Hormone Implications

• Oversecretion:

  • Causes giantism in children; acromegaly in adults (enlargement of bones).

• Undersecretion:

  • Results in dwarfism in children.

Thyroid Gland

• Location: In the neck; releases thyroxin hormone.

• Function: Regulates metabolism, crucial for physical and mental development.

• Thyroxin Imbalance:

  • Oversecretion leads to nervousness and weight loss.

  • Undersecretion can cause cretinism (mental retardation and reduced growth in children).

Thyroid Issues

• Goiter:

  • Caused by iodine deficiency leading to enlargement of the thyroid.

Parathyroid Gland

• Function: Regulates calcium metabolism, critical for nerve function, blood clotting, and bone health.

• Location: Positioned behind the thyroid gland; releases parathormone.

• Health Impacts:

  • Undersecretion leads to nerve disorders, brittle bones, and clotting issues.

Adrenal Glands

• Location: On top of each kidney (shaped like hats).

• Hormones Released: Cortisone and adrenaline.

• Functions:

  • Cortisone: Regulates metabolism of carbohydrates, proteins, and fats.

  • Adrenaline: Raises blood sugar levels, increases heart rate, and breath rate.

Importance of Insulin and Glucagon (Pancreas)

• Insulin and Glucagon: Secreted by the Islets of Langerhans located on the pancreas.

• Blood Sugar Regulation:

  • Oversecretion of insulin leads to low blood sugar.

  • Undersecretion results in high blood sugar, potentially leading to diabetes.

Diabetes Overview

Type 1 Diabetes

• Common in children and young adults; insufficient insulin production.

• Symptoms include:

  • Frequent urination, unusual thirst, extreme hunger, weight loss, fatigue.

Type 2 Diabetes

• Develops in adults; body may not produce enough insulin, or cells become resistant.

• Symptoms include:

  • Similar to Type 1, plus frequent infections, blurred vision, slow healing of cuts/bruises.

Ovaries and Testes Functions

• Detailed exploration is reserved for a later unit on reproduction.