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

Heart Muscle

The heart is the ultimate aerobic tissue. Its activity depends heavily on glucose oxidation. It utilizes the following fuels and metabolic pathways:

• Glucose: Oxidation
• Fatty Acids: Beta-oxidation
• Ketone Bodies: Oxidation of acetoacetate

The heart also plays a role in the clearance of lactic acid produced by muscles.

Nervous System

The nervous system primarily utilizes:

• Glucose: Oxidation
• Ketone Bodies: Oxidation of acetoacetate

Adipose Tissue

Adipocytes serve as the body's energy reserves, storing free fatty acids as triacylglycerols. Because these cells lack the enzyme to catalyze the conversion of glycerol to glycerol-3-phosphate, they must utilize glucose.

Glucose concentration is a determinant factor in the esterification and release of... Continue reading "Metabolic Pathways and Energy Substrates in Human Tissues" »

Circulatory System: Blood and Lymph

The circulatory system is responsible for distributing food (nutrients) and oxygen throughout the body. Blood, lymph — HCH-HCH.

Circulatory Blood

Circulatory blood (a tissue of cells suspended in a liquid medium) includes several components:

Plasma

Plasma: acellular liquid (about 90% water) containing dissolved substances, including:

• Nutrients: glucose, amino acids, lipids, water and minerals — transported from the digestive tract to the rest of the body;
• Waste products: transported from cells to the excretory organs (e.g., urea), excess salts and carbon dioxide;
• Hormones: carried from producing glands to the organs where they are used;
• Other substances dissolved in plasma.

Red Blood Cells / Erythrocytes

Red blood

Biological Contaminants in Indoor Environments

Biological contaminants are living or once-living organisms that can negatively affect indoor air quality and human health. Key types include:

• Bacteria: Carried by people, animals, soil, and plant debris.
• Viruses: Primarily transmitted by people and animals.
• Moulds: Grow on water-damaged materials or wet surfaces.
• Pollens: Originate from plants.
• Animal Dander: Sources include household pets.
• Saliva: Mainly from cats and rabbits.
• Dust Mites: Thrive in damp, warm environments.
• Insects and Pests: Including ants, cockroaches, mice, and rats.

Humans as Sources of Indoor Contamination

Human activities significantly contribute to indoor biological contamination:

• During sneezing, between 4,000 and 40,000 small drops

Carbohydrates: Primary Energy Source

Carbohydrates are chemical compounds of oxygen, carbon, and hydrogen, synthesized by plants through the action of solar energy. Sugars are found in bread, grains, fruits, and vegetables.

They serve as the first major energy substrate, providing between 50% and 60% of the total energy necessary for movement and basic functions. They are also essential to feed the brain.

Fats (Lipids)

Fats (lipids) consist of hydrogen, oxygen, and carbon that form a chain, categorized as saturated or unsaturated fatty acids.

Sources of Fats

• Saturated Fats: Meat, eggs, and dairy.
• Unsaturated Fats: Olive oil or sunflower oil.

Fats are indispensable; they serve as an energy source, help regulate body temperature (Tª), and transport... Continue reading "Essential Nutrients: Macronutrients, Vitamins, and Diet" »

Laryngeal Skeleton and Hyoid Bone

The hyoid bone is located in the skeleton of the larynx and is formed by various cartilages.

Key Laryngeal Cartilages

• Hyoid Bone: An irregular bone featuring two processes on each side.
• Thyroid Cartilage: Shaped like an "open book" with a prominent thyroid notch. It features superior and inferior prolongations on its side plates.
• Cricoid Cartilage: An unpaired cartilage that articulates posteriorly with the arytenoid cartilage.
• Epiglottic Cartilage: Shaped like a bicycle saddle.

These structures are reinforced by membranes, tendons, and laryngeal muscles, all covered by the laryngeal mucosa.

Hyoid Muscle Groups

The hyoid muscles are located in the anterior neck and are divided into suprahyoid and infrahyoid groups.

Infrahyoid

Understanding Health & Disease

Health initiatives are often geared toward reducing exposure to various factors that are carcinogens, such as alcohol, tobacco, and diet. Recent years have spawned a new area of scientific knowledge: epigenetics, which studies the influence of the environment on gene expression.

Mental Health Conditions

Some diseases of the nervous system are due to malfunctioning neurons or injuries provoked by varied causes, such as high blood pressure, strokes, or lack of blood supply. The most important mental health challenges include:

• Depression

  Characterized by deep sadness and an incapacity to lead a normal life.

• Schizophrenia

  A disease that can present from adolescence, provoking serious personality disorders and disconnecting

Biological Organization: From Subatomic to Organismal Levels

Matter is organized into different degrees of complexity, forming the hierarchical structure of life. These levels include:

• Subatomic Level: Particles that make up atoms (e.g., protons, neutrons, electrons).
• Atomic Level: Formed by individual atoms (e.g., carbon, oxygen, hydrogen).
• Molecular Level: Resulting from the linkage of different atoms. Molecules can be inorganic (e.g., water, salts) or organic (e.g., proteins, carbohydrates, lipids, nucleic acids), with organic molecules being fundamental to living material.
• Cellular Level: The first level of life; the smallest unit capable of independent existence.
• Tissue Level: A network of specialized cells with the same function and origin.

The Heart: Structure and Function

The heart is a contractile, muscular organ, roughly the size of a fist and conical in shape. Its primary function is to pump blood to reach all parts of the body. The heart is situated above the diaphragm, nestled between the lungs.

The heart is composed of two distinct halves, separated by a septum, which ensures the right and left halves do not communicate directly. Each half of the heart has two cavities:

• An upper, thinner-walled cavity called an atrium.
• A lower, muscular-walled cavity called a ventricle, which drives the blood.

Understanding the Cardiac Cycle

The period between the end of one contraction and the end of the subsequent one is called the cardiac cycle. It includes two main phases:

• Diastole: An expansion

The Fundamental Units of Life: Cells and DNA

The Cell: The cell is the basic unit of life. It can be divided into two distinct areas: the cytoplasm and the nucleus. The cytoplasm contains various cellular organelles, while the nucleus contains the genetic information that determines the characteristics of every individual: DNA.

Chromosomes and Genes

Chromosomes:

• Tiny threadlike structures found in the nucleus of eukaryotic cells.
• Contain nucleic acids, specifically DNA (deoxyribonucleic acid), and proteins.
• Divided into smaller units called genes.
• The number of chromosomes is characteristic of each species. For example, human cells have 46 chromosomes grouped in pairs, while reproductive cells (gametes) have 23.

Genes:

• The basic unit of heredity in

Common Foodborne Pathogens and Their Sources

• Clostridium botulinum: Causes botulism, often found in soil or dust.
• Vibrio cholerae: Causes cholera, transmitted by fecal matter.
• Salmonella enterica subsp. enteritidis: Causes salmonellosis.
• Salmonella enterica subsp. Typhi: Causes typhoid fever.
• Shigella: Causes shigellosis.
• Brucella melitensis: Causes brucellosis, transmitted by infected animals.
• Bacillus cereus: Found in soil and dust.
• Campylobacter jejuni: Transmitted by infected animals.
• Clostridium perfringens: Found in soil and dust.
• Escherichia coli: Associated with fecal contamination.
• Listeria monocytogenes: Transmitted by infected animals.
• Yersinia enterocolitica: Transmitted by infected animals.
• Vibrio parahaemolyticus: Transmitted by infected animals.