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

Human Heart: Structure and Function

The heart is a vital muscular organ responsible for pumping blood throughout the body. Its walls are primarily composed of a specialized muscle tissue called the myocardium.

Heart Anatomy: Key Components

The heart is divided into four main chambers:

• Two Atria: These are the upper chambers. They have thin, elastic walls and receive blood returning to the heart via veins.
• Two Ventricles: These are the lower chambers. They possess thick, powerful walls, especially the left ventricle, which pumps blood to the entire body. Arteries exit from the ventricles.

The left ventricle is connected to the left atrium, while the right side is separated by a partition (septum). Blood enters the atria from veins and leaves the ventricles... Continue reading "Human Heart: Structure, Circulation, and Health" »

Habitat and Ecological Niche Defined

A habitat is the physical place where a species lives. It provides the natural conditions the species needs to survive. An ecological niche is the way a species relates to the biotic and abiotic factors in an ecosystem.

Two species can share the same habitat, although they do not usually occupy the same ecological niche.

Understanding Trophic Dynamics

Trophic dynamics is the system that describes the position of a living being in a food chain. The system uses trophic levels to explain what an organism eats or is eaten by.

Trophic Pyramids: Graphic Representations

A trophic pyramid is a graphic representation of a particular characteristic at each trophic level. These pyramids are specific to individual ecosystems.... Continue reading "Ecosystem Dynamics: Trophic Levels, Pyramids, and Energy Flow" »

Nervous System Actions: Reflexes and Voluntary Acts

Reflex acts are fast and automatic, and do not involve conscious brain processing. These acts occur when a quick response is needed.

Neurons Involved in Reflexes

• Sensory neurons: Come from the skin and their axons enter the spinal posterior roots.
• Interneurons: Synapse with sensory neurons and transmit nerve impulses to other neurons.
• Motor neurons: They leave the spinal cord by the anterior roots and reach muscles, causing contraction and reflex.

Voluntary acts are varied, changing, and more elaborate than reflexes, involving the cerebral cortex.

Autonomic Nervous System

Also called the involuntary nervous system, it is responsible for the proper regulation and coordination of internal organs.

Types

Carnitine: An Essential Nutrient

Carnitine is a nutrient synthesized in the liver, kidneys, and brain from two essential amino acids: lysine and methionine. Carnitine is responsible for transporting fatty acids into the mitochondria, cellular organelles responsible for energy production.

Some individuals need carnitine supplements to maintain normal metabolism, which indicates that carnitine should be considered an essential nutrient.

Carnitine Deficiency

Carnitine deficiency is classified into two major groups: systemic deficiency (rare) and myopathic (more common). The systemic form affects the whole body, while the myopathic form affects only muscle tissue.

Causes of Carnitine Deficiency

Known causes of carnitine deficiency include:

• Deficiency

Population, Community, and Ecosystem

A population is a group of individuals of the same species living in a specific area. A community is a set of populations inhabiting the same area. The biotope is the physical environment occupied by a community, characterized by specific environmental conditions. An ecosystem encompasses both the community (biocenosis) and the biotope, including the interactions of organisms with each other and their environment.

Habitat and Optimal Conditions

A habitat is the specific environment where an organism finds the necessary conditions for life. Optimal conditions, regarding a given environmental factor, are the values at which a species thrives, reproduces effectively, and experiences high offspring survival.... Continue reading "Understanding Ecosystems: Species, Niches, and Interactions" »

In the early 1990s, research on the human being began with the Human Genome Project. In April 2003, the entire nucleotide sequence of the human genome was completed. Today, we know that:

• Our haploid genome (all 23 different chromosomes that we possess) contains 3,000 million pairs of nitrogenous bases, which equates to about 30,000 genes.
• 99.9% of these genes are the same in all people: the differences between us do not represent more than 0.1% of the genome.
• 90% of the genome has no known coding function, which does not mean it has no function, such as gene regulation or various biological controls. It is thought that some of this DNA may correspond to genetic remains of our ancestors.

Applications of the Human Genome Project

The practical applications... Continue reading "Decoding the Human Genome: Applications and Biotechnology" »

Biotic Relationships

Biotic relationships are the interactions among living organisms in an environment. There are two main types of biotic relationships:

Interspecific Relationships

Interspecific relationships occur between organisms of different species. These include:

• Mutualism: A relationship where both species benefit. Example: Bees pollinating flowers.
• Commensalism: A relationship where one species benefits, and the other is unaffected. Example: Beetles feeding on mammal excrement.
• Inquilinism: A specific type of commensalism where one organism uses another for housing.
• Parasitism: A relationship where one species (the parasite) benefits at the expense of the other (the host). Example: Cochineals feeding on cacti.
• Predation: A relationship where

Non-Infectious Diseases

In addition to diseases caused by microorganisms, other diseases are caused by different reasons:

a) Diseases Affecting the Functioning of the Equipment

These include circulatory diseases, which affect the respiratory tract (such as asthma or bronchitis), and those that affect bones or joints (osteoarthritis and osteoporosis).

b) Cancer

This occurs when certain cells, for reasons not yet fully clarified, undergo a metamorphosis that makes them divide rapidly and uncontrollably. As a result, it creates a mass of abnormal cells, called a tumor, which causes the destruction of nearby tissue.

c) Deficiency Diseases

These are caused by a poor diet lacking in certain nutrients. Examples include vitamin deficiency or anemia.

d) Traumatic

Dental Pathology & Caries Vocabulary

• Pathology: The study of the effects of disease as seen in the structure and function of the body.
• Pathogen: Any organism capable of causing disease.
• Etiology: The study of the causes of disease, including all factors that may be involved in its development.
• Clinical Data: A collection of information gathered about a patient's disease.
  • Symptom: A subjective experience reported by the patient.
  • Sign: An objective finding observed by a clinician (e.g., blood pressure, swelling).
• Diagnosis: The identification of a disease through scientific evaluation of its physical signs, symptoms, medical history, laboratory tests, and other procedures.
• Prognosis: The predicted outcome of a disease, based on the patient's condition