Notes, abstracts, papers, exams and problems of Biology

Tendon Structure

Tendon: A structure composed of collagen fibers arranged parallel to the tendon's axis. These fibers are designed for low flexibility and resistance to extension. Within the tendon, we find loose connective tissue and cells called tenocytes.

The entire structure is termed the endotendon, enclosed within a sheath called the peritenon. The peritenon's extension is continuous with the periosteum at one end and the perimysium at the other.

Some tendinous fibers, known as Sharpey's fibers, penetrate the bone and calcify, forming a strong union between tendon and bone.

The tendon is protected by an outer sleeve consisting of a parietal layer and an inner visceral synovial layer. A space filled with synovial fluid separates these layers.... Continue reading "Tendon, Fascia, and Cranial Bones: Structure and Function" »

The Interaction in Living Things

The interaction functions are those enabling a living being to receive information from the outside to the inside, and respond to it. A stimulus is a change in the environment surrounding a body or inside it.

There are two types of responses:

• Static: There is no movement.
• Dynamic or taxis: Movement occurs in response to a stimulus.

The Interaction in Plants

• Tropism: Movements related to plant growth or its parts. They are slow and irreversible responses.
• Nasties: Rapid and temporary changes in certain parts of the plant.
• Photoperiodism: Responses due to changes in illumination that occur throughout the seasons.

The Relationship in Animals (1)

Many animals have developed sophisticated sensory organs that detect specific... Continue reading "Interaction: Stimulus and Response in Living Things" »

Ecosystems: An Overview

Ecology is the science that studies the characteristics of living beings, their environment, and the relationships they build with each other and their surroundings.

What is an Ecosystem?

An ecosystem consists of a fragment of the biosphere where living organisms interact and form relationships.

Biotope

The biotope is the physical environment or place where living things develop, including the environmental conditions that characterize it.

Biocenosis

Biocenosis refers to the set of living organisms within a given ecosystem.

The Biotope: Terrestrial and Aquatic Environments

The terrestrial environment is located on the surface of the continents, while the aquatic environment is made up of water.

Abiotic Factors

Abiotic factors are... Continue reading "Understanding Ecosystems: Biotope, Biocenosis, and Dynamics" »

Human Tissue Types: Location and Function

Epithelial Tissue: This tissue is found on the body's exterior surfaces, lining internal cavities (such as blood vessels), and in glands. Its cells are directly linked, without any intermolecular substance between them. The primary function is to coat and protect the body's exterior and internal cavities.

Connective Tissue: Located around organs, tendons, ligaments, in the dermis of the skin, and bone marrow. It consists of several cell types and connects other organs, muscles, and bones. It also fuels the dermal tissue and generates red blood cells.

Adipose Tissue: Found under the skin and around certain organs (like the kidney or heart). It is composed of round cells that store fat. Its functions include... Continue reading "Human Tissue Types and Cellular Components: Functions" »

Human Tissue Types

Connective Tissue

Connective tissue consists of specialized cells embedded in an intercellular substance containing fibers like collagen. Key types include:

• Connective Tissue Proper: Binds and supports other tissues and organs, such as tendons and ligaments.
• Adipose Tissue: Composed of adipocytes filled with fat, providing lipid reserves, organ protection, and thermal insulation.
• Cartilage: Made of chondrocytes within a solid intercellular substance, forming structures like the nose, trachea, and ear cartilage.
• Bone Tissue: Composed of osteocytes that develop a strong intercellular substance with mineral salts of calcium and phosphorus, forming bones.
• Blood: Considered by many as a connective tissue with plasma as its intercellular

The Large Intestine

The large intestine is divided into:

• Cecum (Blind): Located after the ileum, contains the appendix.
• Colon: Divided into ascending, transverse, descending, and sigmoid sections.

Functions of the Large Intestine

• Absorbs water, forming feces. Feces consist of undigested food, few nutrients, and bile pigments.
• Synthesizes vitamins created by the intestinal flora. These flora digest substances we cannot and synthesize vitamins for us, a symbiotic relationship.

Rectum and Anal Canal

• Rectum: 15-20 cm in length.
• Anal Canal: 3 cm, opening to the outside through the anus.
• Anus: Contains two sphincters (muscle loops), one involuntary and one voluntary.

The Liver

The liver is located in the upper right quadrant, weighs approximately 1.5 kg, and... Continue reading "Digestive System, Breathing & Oxygen Administration: A Concise Review" »

Key milestones in genetics include:

• James Watson & Francis Crick (1953): Discovery of the helical structure of DNA.
• Gregor Mendel: Pioneering work in Mendelian genetics.
• Genetic Engineering: Development of techniques to manipulate genes.
• Human Genome Project (HGP): Identifying all the genes of a living being.

Steps in Reading the Genetic Code

1. Separation of the two helical chains.
2. Transcription.
3. Using the Genetic Code.
4. Formation of protein-based amino acids.

Genetically Engineered Foods (GMOs)

Genetically engineered foods are obtained through GMOs and were tagged in 2004, with the following exceptions:

• GM foods with less than 0.9% GMO content.
• Products of second or third generations.
• GM foods that use microorganisms for fermentation.

Genetic Engineering

Genetic... Continue reading "Decoding Genetics: DNA, GMOs, and the Human Genome" »

Effects of Heat on Proteins in Food Processing

Functional Properties of Proteins in Foods

• Mass Hydration: Formation
• Solubility: Emulsification
• Viscosity: Foam formation
• Gelification: Flavoring capture
• Texture: Interaction with other food components

Denaturation of Proteins

Physics

Heating, cooling, mechanical treatment, hydrostatic pressure, radiation.

Chemistry

Acids, bases, metals, organic solvents.

Effects of Protein Denaturation

• Changes in solubility by exposure of hydrophilic or hydrophobic peptide units
• Changes in water absorption capacity
• Loss of biological activity
• Increased risk of chemical attack by exposure of other peptide bonds
• Changes in viscosity of solutions
• Decreased ability of crystallization

Color Changes

Red purple myoglobin converts to metmyoglobin... Continue reading "Protein Changes in Food: Heat, Denaturation, and Functionality" »