Notes, summaries, assignments, exams, and problems for 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" »

Nervous vs. Endocrine System Coordination

Living organisms utilize different systems for coordination. These include:

• Nervous System: Receives information and processes it for a fast response. It utilizes nerve impulses, and its effects are generally short-lasting.
• Endocrine System: Elaborates hormones for communication. Its response is typically very slow but durable.

Nervous System Response Pathway

The nervous system's response to stimuli involves several key components:

Receptor, Center, and Effector

• Receptor: The organ or structure responsible for perceiving stimuli from the internal or external environment.
• Nervous Center: Receives information from receptors and transmits processed information, producing a series of organized responses.
• Effector:

Cranial Bones

Frontal Bone

The Frontal Bone is an unpaired, flat bone located on the top and front of the head. It forms the "roof" of the orbits and the root of the nose.

Sphenoid Bone

The Sphenoid Bone is an unpaired bone located in the anterior base of the skull. It has a body and six extensions: two greater wings, two lesser wings, and two pterygoid processes. Through these, it is inserted like a wedge between the other bones of the skull.

Occipital Bone

The Occipital Bone is an unpaired bone located posteroinferiorly in the skull. Its lowest part, which forms part of the skull base, features the foramen magnum. This opening connects the cranial cavity, housing the brain, to the spinal canal, which contains the spinal cord, thus allowing the... Continue reading "Human Skull Bones: Anatomy and Functions" »

Nucleic Acids: Life's Genetic Blueprint

What Are Nucleic Acids?

Nucleic acids are vital macromolecules that store and transmit genetic information. They are polymers formed by the union of repeating monomeric units called nucleotides.

Understanding Nucleotides: Building Blocks

Nucleotides, the fundamental components of nucleic acids, are composed of three parts:

• Carbohydrate (Pentose Sugar): This is a five-carbon sugar. In RNA (Ribonucleic Acid), the sugar is ribose. In DNA (Deoxyribonucleic Acid), the sugar is deoxyribose.
• Phosphate Group (P): A molecule containing phosphorus and oxygen.
• Nitrogenous Base (BN): A nitrogen-containing molecule with basic properties. The main nitrogenous bases are:
  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T) - primarily

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" »

Understanding Plant Fundamentals

Plants are multicellular organisms characterized by being anchored to the ground by roots, which absorb water and mineral salts. Chlorophyll, a green pigment, captures light energy. The primary products of photosynthesis are carbohydrates, with oxygen produced as a secondary byproduct.

Plant Transport Systems

Most plants, with the exception of mosses, possess vascular tissues, similar to human blood vessels, through which sap flows. There are two main types of sap:

• Raw sap: A mixture of water and dissolved minerals, it rises from the roots through the xylem.
• Elaborate sap: Containing carbohydrates produced during photosynthesis, it flows through the phloem.

Plant Classification

Plants are broadly categorized into two... Continue reading "Plant Biology: Structure, Function, and Diversity" »

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" »