Notes, summaries, assignments, exams, and problems for Biology

NSAIDs: Therapeutic Groups

NSAIDs are categorized into three primary therapeutic groups:

• Analgesic
• Antipyretic
• Anti-inflammatory

Classification of NSAIDs

A. Nonselective COX Inhibitors (Traditional NSAIDs)

• Salicylates: Aspirin
• Propionic acid derivatives: Ibuprofen, Naproxen, Ketoprofen, Flurbiprofen
• Anthranilic acid derivative: Mefenamic acid
• Aryl-acetic acid derivatives: Diclofenac, Aceclofenac
• Oxicam derivatives: Piroxicam, Tenoxicam
• Pyrrolo-pyrrole derivative: Ketorolac
• Indole derivative: Indomethacin
• Pyrazolone derivative: Phenylbutazone, Oxyphenbutazone

B. Preferential COX-2 Inhibitors

• Nimesulide, Meloxicam, Nabumetone

C. Selective COX-2 Inhibitors

• Celecoxib, Etoricoxib, Parecoxib

D. Analgesic-Antipyretics (Poor Anti-inflammatory Action)

• Para-aminophenol

The Menstrual and Ovarian Cycles

Menstruation: This phase begins on the first day of the cycle and lasts 5 to 7 days. If fertilization does not occur, the corpus luteum breaks down and stops producing progesterone. This causes the endometrium to shed, along with the oocyte, resulting in menstruation. If fertilization occurs, the embryo produces a hormone similar to LH (Luteinizing Hormone) to keep the corpus luteum active. It continues producing hormones, preventing menstruation. The oocyte is fertilized and completes oogenesis.

Proliferative Phase: This starts after menstruation and lasts until ovulation. Estrogens from the ovarian follicle stimulate the thickening of the endometrium and the growth of blood vessels.

Secretory Phase: This occurs... Continue reading "Menstrual and Ovarian Cycle Phases and Hormonal Changes" »

Mendel's Pea Plants: Ideal Study Subjects

Mendel chose pea plants for genetic studies due to several key advantages:

1. They produce a large number of offspring, allowing for more data collection.
2. The plants can be easily grown in a small space.
3. They have a simple genetic structure, making it easier to study inheritance patterns.

Understanding the Test Cross

A test cross is used to determine the genotype of an individual exhibiting a dominant phenotype by crossing it with a homozygous recessive individual. This method reveals the genetic makeup of the dominant organism.

Test Cross Outcomes (Example)

• If all offspring are red, the red plant is probably homozygous (RR).
• If you get both red and white offspring, the red plant is heterozygous (Rr).

Genetic Probability

Light and Pigments

• Absorbed: Blue and Red light
• Reflected: Green (chloroplasts appear green)
• Other pigments: Carotenoids, Xanthophylls
• Fall colors: Chlorophyll breaks down, revealing other pigments

Photosynthesis

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

• CO₂: Carbon source for glucose
• H₂O: Source of hydrogen and electrons
• Light: Energy source
• Performed by: Plants, algae, and cyanobacteria

Chloroplast Structure

• Outer and inner membrane
• Stroma: Fluid-filled space
• Thylakoid: Flat sacs forming grana
• Chlorophyll located in the thylakoid membrane

Light Reactions (Thylakoid Membrane)

• PSII absorbs light, exciting electrons
• Water splits, releasing O₂
• ETC pumps H⁺ to create ATP (chemiosmosis)
• PSI re-excites electrons to produce NADPH
• Products: ATP, NADPH,

Species Concepts

• Biological Species Concept (BSC)

  Species are groups of interbreeding natural populations that are reproductively isolated from other groups. This means no viable, fertile offspring with members of other species.

• Phylogenetic Species Concept

  A species is the smallest group that shares a common ancestor and can be distinguished by unique traits.

• Ecological Species Concept

  Defines a species by the ecological niche it occupies, including interactions with the environment and other species.

• General Lineage Concept

  Considers species as independently evolving metapopulations.

Isolating Barriers

• Geographic (Extrinsic) Barriers

  Landscape features physically prevent gene flow (e.g., mountain ranges, oceans).

• Reproductive (Intrinsic) Barriers

  Biological

Benign Epithelial Lesions

Squamous Cell Papilloma

Age: Mid-age
Site: Palate, uvula, cheek, lip, tongue, gingiva
Characteristics:

• Color: White to pinkish (depending on keratinization)
• Shape: Cauliflower-like
• Surface: Rough, irregular (finger-like projections)
• Texture: Firm or soft (depending on keratinization)
• Sessile or pedunculated

Histological Features:

1. Hyperplastic stratified squamous epithelium
2. Acanthosis and hyperkeratosis
3. Intact basal layer
4. Thin central branching core of connective tissue carrying nutrition

Verruca Vulgaris (Wart)

Reactive lesion, autoinoculation
Etiology: HPV 2, 4, 6
Histological Features:

1. Intranuclear inclusion bodies
2. Koilocytes
3. Cupping effect of rete ridges
4. Granular cell layer

Keratoacanthoma

True, self-limiting lesion
Age: Older males
... Continue reading "Benign Epithelial and Mesodermal Lesions of the Oral Cavity" »

Excretory System Notes

Excretion

Excretion: Process of eliminating waste substances from metabolic reactions.

Although the kidneys are the main organs of excretion, several other organs also excrete wastes. They include the liver, skin, and lungs. All of these organs of excretion, along with the kidneys, make up the excretory system. This lesson focuses on the role of the kidneys in excretion. The roles of the other excretory organs are summarized below:

• Kidneys: Responsible for filtering the blood and forming urine.
• Lungs: Expel carbon dioxide produced during cell respiration.
• Sweat glands: Excrete sweat, a liquid with a composition similar to urine.
• Liver: Expels waste that comes from toxins, medicines, and digestion of food.

Urinary System

The kidneys... Continue reading "Excretory System and Kidney Function: Urine, Nephrons, Diseases" »

Core Ecology Concepts

Biodiversity

• Definition: Variety of all living things in one area.
• Importance: Increases stability and health of ecosystems.
• Threats: Pollution, deforestation, climate change, invasive species.

Ecosystems

• Definition: A system of living (biotic) and nonliving (abiotic) things interacting.
• Biotic Components: Plants, animals, fungi.
• Abiotic Components: Water, sunlight, soil, air, temperature.
• Producers' Role: Make food from sunlight (photosynthesis).
• Balance: All parts depend on each other.

Energy Pyramid

• Purpose: Shows how energy moves through trophic levels.
• Trophic Levels: Producer → Primary → Secondary → Tertiary.
• Energy Transfer: Only 10% passed to the next level; 90% is lost as heat.
• Fewer Top Predators: Less energy is available

Q — Classify antihistaminic drugs and their therapeutic uses.

Classification of Antihistamines and Therapeutic Uses

1. Introduction to Antihistamines

Antihistamines are drugs that block or reduce the effects of histamine, a chemical involved in allergic reactions, gastric acid secretion, and neurotransmission. They are primarily classified based on the histamine receptor subtype they act on:

• H₁ receptor antagonists (H₁ antihistamines)

• H₂ receptor antagonists (H₂ blockers)

• H₃ and H₄ antagonists (experimental/limited clinical use)

2. Classification of Antihistamines

A. H₁ Receptor Antagonists (H₁ Blockers)

1. First-Generation H₁ Antihistamines

• Cross the blood–brain barrier → cause sedation

• Have anticholinergic and antiemetic effects

Examples:

• Diphenhydramine

• Chlorpheniramine

• Hydroxyzine

• Promethazine

• Dimenhydrinate

• Meclizine

2.

Mendel's Laws of Inheritance and Genetic Crosses

Mendel's Laws of Inheritance

1. Law of Segregation: Each parent contributes only one of their two alleles for a specific trait to their offspring.
2. Law of Independent Assortment: Alleles for different traits are passed down independently of one another during gamete formation.
3. Law of Dominance: When an organism inherits two different alleles for a trait, the dominant allele will be expressed in the phenotype, masking the effect of the recessive allele.

Analyzing Monohybrid Inheritance

Case Study: Earlobes (Monohybrid Cross)

The results of the cross show:

• Mr. Jones: aa (Attached earlobes, recessive)
• Mrs. Jones: Aa (Free earlobes, heterozygous dominant)

Their children exhibit the following genotypes and phenotypes:... Continue reading "Genetic Inheritance: Mendel's Laws, Crosses, Ratios, and Probability" »