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

• The outer ear: it is formed by the pinna and the auditory canal.
• The middle ear: a cavity in the eardrum that reaches the oval window and the round window.
• The inner ear: formed by the membranous labyrinth.
• Sweat gland: this secretes sweat, cooling the body surface when it is necessary and removing certain waste substances.
• Sebaceous gland: these secretes substances that lubricate the skin and hair.
• Taste buds: are located inside the mouth especially on the tongue.
• Long bones: these are long and contain spongy bone tissue at either end, as well as compact bone.
• Short bones: these are rounded and mostly made up of spongy bone tissue.
• Flat bones: these are plate-shaped. Formed by an inner layer of bone tissue surrounded by two layers of compact bone

Step 1: Glycolysis - What Happens?

1 glucose molecule is split into two 3-carbon molecules called pyruvate.

Who Controls It? Enzymes. Where? Cytosol. Result? Two molecules of ATP are produced.

Step 2: Oxidative Respiration - The pyruvate molecules made during glycolysis still have a lot of potential to make more energy (ATP). What Happens? The 2 pyruvate molecules now go through oxidative respiration where they produce carbon dioxide, water, and 34 ATP! Where? Mitochondria.

Three Metabolic Pathways - Within these two systems, aerobic vs. anaerobic, there are three main metabolic pathways by which ATP energy reserves are restored.

1. The ATP-PC Pathway: Anaerobic Alactic.

2. The Glycolysis Pathway: Anaerobic Lactic.

3. Cellular Respiration: Aerobic - It is

Environmental Factors

Characteristics of the environment that affect living things are called environmental factors. They can be abiotic (related to non-living things) or biotic (related to living things).

Biotic and abiotic factors

⦁ Abiotic factors: Physical and chemical conditions that affect living things.

The main abiotic factors are water, light, temperature, soil, pH, humidity, and nutrients found in water and soil. Some abiotic factors are more important than others depending on the location they are in.

• Sunlight is essential for life on Earth to exist.
• The concentration of oxygen in the atmosphere decreases as altitude increases.
• Temperature is a decisive factor in the physiological activity of living things.
• Water is an essential substance

Core Concepts of Health and Disease

Health and Disease Definitions

• Health: A state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.
• Disease: A disorder or malfunction of the mind or body, which leads to a departure from good health. It can be a disorder of a specific tissue or organ due to a single cause.

Pathogens and Infectious Diseases

Types of Pathogens

• Fungi
• Bacteria
• Viruses

Diseases Caused by Viruses

Influenza (Flu)

Influenza is a virus that causes a severe form of respiratory tract infection with generalized bodily symptoms. While it shares cold-like symptoms, its onset is rapid and violent, often featuring:

• High fever
• Severe aches and pains, often in the back and muscles

Other common viral diseases... Continue reading "Understanding Disease, Immunity, and STIs: Core Concepts" »

Understanding Shigellosis: Causes and Treatment Challenges

What is Shigellosis?

Shigellosis is a significant public health threat in both developed and developing countries. It is an infectious disease caused by a group of bacteria known as Shigella. The genus Shigella includes four pathogenic serogroups: Shigella dysenteriae, Shigella flexneri, Shigella sonnei, and Shigella boydii. Shigellosis typically causes symptoms such as diarrhea, fever, and stomach cramps.

How is Shigellosis Contracted?

Individuals can contract shigellosis by ingesting contaminated food or water, or through direct contact with the stool of an infected person. This highlights the ease of transmission and the importance of hygiene.

Current Treatments and Emerging Resistance

Antibiotic... Continue reading "Sfin-1 Bacteriophage: A Potent Weapon Against Drug-Resistant Shigella" »

The Internal Environment

• Refers to the fluids that surround the cells.
• Temperature and composition must be stable for the correct working of cells.
• This internal environment is maintained by the organ systems of the body.
• Interstitial fluid (plasma): Surrounds and bathes the cells.
• Blood and lymph: Collect and distribute substances for the cells (O2, nutrients) and remove waste.

The Circulatory System

• Carries nutrients and oxygen throughout the body and collects waste (blood): Blood Circulatory System.
• Returns excess interstitial fluid to the blood.
• Transports fat to the blood.
• Defends the immune system (lymph): Lymphatic System.

The Lymphatic System

• Lymph capillaries:
  • Thin vessels closed at one end.
  • Collect excess interstitial fluid.
• Lymphatic vessels:

Human Body Systems

1. Respiratory System: The purpose of this system is to take in air, filter it, and take it to the tissues responsible for gas exchange. Oxygen is then transported by blood to all the tissues in the body. Carbon dioxide, a waste product, is reabsorbed and excreted from the body.
2. Skeletal System: This system forms the basic framework of the body. It supports and protects all internal organs. Bones serve as levers (with the attached muscles) for movement, produce blood cells, and store calcium salts, which can be absorbed into the blood when there is not enough calcium in the diet.
3. Endocrine System: The secretion of hormones, which regulate the body's functions chemically, is the function of this system.
4. Urinary System: This system

Keystone Species

Predators that maintain the balance of other species within the ecosystem.

Trophic Cascade

Ecological phenomenon triggered by the removal or addition of top predators, causing changes in the ecosystem through the food chain.

Green World Hypothesis

Hypothesis stating that predators control the number of herbivores.

Food Chains

Illustrate a single pathway of feeding relationships.

Food Web

Represents the complex relationships between multiple species and their various feeding interactions.

10% Law

As energy transfers through trophic levels, 90% is lost, with only 10% retained. This loss occurs due to metabolic reactions, growth and repair, movement, and heat.

Energy Flow

The movement of energy through the food chain.

Energy Pyramid

Measured

The Cori Cycle: Recycling Lactic Acid

After lactate (often referred to as lactic acid) is produced, it is transported by the blood to the liver. In the liver, most of the lactate is converted back to glucose. During periods of rest, this newly formed glucose is efficiently stored as glycogen through a process known as glycogenesis. Approximately one-sixth of the lactate is oxidized to carbon dioxide.

Essentially, during the Cori Cycle, lactic acid is recycled. It is converted to pyruvate, which can then be used for the future conversion to glucose and subsequently stored as glycogen.

Energy Sources Beyond Carbohydrates

While the primary source of energy during physical activity typically comes from carbohydrates and other glucose sources (like... Continue reading "Cori Cycle, Lactate Metabolism, and Fat Energy Pathways" »