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

Photosynthesis

Photosynthesis is the process by which some cells can capture light energy from the sun and transform it into chemical energy. This process is carried out by plants, green or red algae, and some bacteria. Its purpose is to synthesize organic matter from inorganic matter (CO₂, H₂O, mineral salts) using light energy and releasing molecular oxygen into the atmosphere during the process.

In eukaryotic cells, it occurs in chloroplasts in two phases:

• Light Phase

  This occurs in the thylakoid membrane of chloroplasts, driven by chlorophyll. It captures light energy from the sun and converts it into chemical energy in the form of energy-rich ATP and a molecule with great reducing power, NADPH. The photolysis of water liberates O₂.

• Dark Phase

Physical Assessment of a Patient with Cancer

Skin

• Inspection: Color, integrity, turgor, humidity, temperature.
• Check for: Injuries (type, size, and location), purpura, petechiae, edema, and appearance of nails.

Head and Neck

• Inspect: Face (asymmetry), eyes, mouth, trachea, maxillary sinuses.
• Palpation: Thyroid.

Thorax

• Inspection: Breathing movements and rate.
• Palpation, percussion, auscultation: Tone, intensity, and duration of breath sounds.

Breasts and Armpits

• Inspection and palpation.

Cardiovascular

• Inspection: Tremors and palpitations in the chest.
• Auscultation, palpation, blood pressure.

Musculoskeletal

• Inspection: Hair distribution, abnormal masses or lesions, asymmetries, nodules.
• Palpation: Painful masses, joint range of motion.

Neurologic

• Presence of

Types of Transplants

• Autotransplant: Donor and recipient are the same patient. Used for tissues or organs such as skin portions or bone.
• Isotransplant: Donor and recipient are identical twins. No rejection occurs.
• Xenotransplant: Donor and recipient are distinct species (e.g., using pig heart valves in humans). There is a risk of rejection.
• Allogeneic Transplant: Donor and recipient are of the same species but genetically different. This is the most common type, and there is a risk of rejection.

Immune Rejection Problems

Our immune system distinguishes self from foreign. If it locates foreign tissue, it attempts to destroy it. This is of great importance when dealing with viruses and bacteria, but it also applies to donor tissue. It is crucial that... Continue reading "Medical Transplants and Regenerative Medicine" »

Nutrition: Function and Importance Nutrition includes all processes to get the materials of development and the energy we need to live like .--- La Nutricion: Nutrition is a long process. One step is to take food. Function in the 4 processes involved Nutrition: Circulation - the digestive process, respiration, and excretion Feeding and Nutrients To live, we need the nutrients that food contains. The main groups are carbohydrates, fats, proteins, water, vitamins, and minerals - A diet is complete when it contains all types of nutrients. A balanced diet is when it gives us the necessary amount of each nutrient.

Functions of Muscle Tissue

• Production of body movements
• Stabilization of posture
• Volume regulation of the body
• Movement of chemicals in the body
• Production of heat

Properties of Muscle Tissue

• Electrical excitability
• Contractility
• Extensibility
• Elasticity

Types of Muscle Tissue

There are three types of muscle tissue: striated skeletal, striated cardiac, and smooth.

• Striated skeletal muscle: Called skeletal because the function of these muscles is to move the bones; it often works on a voluntary basis.
• Heart muscle (myocardium): Is located in the heart and is part of its wall. Its movement is involuntary.
• Smooth muscle: Is part of the walls of blood vessels, airways, and some guts. Almost always, this type of muscle movement is involuntary.

Structure of Striated

What is Embryology?

Embryology is the branch of biology that studies the development of an organism from a fertilized egg. It encompasses several key concepts:

• Ontogeny: The transformations that the embryo undergoes during development.
• Phylogeny: The evolutionary history of a species.

Historical Theories of Development

Historically, two main theories attempted to explain embryonic development:

• Preformationism: This theory argued that a miniature version of the organism, called a "homunculus," was present in either the sperm or the egg. Scientists who believed in this were called "animalculists." In 1699, Danlenpatius proposed this theory.
• Epigenesis: This theory proposed that adult body structures were not preformed in the gametes but developed gradually.

Genetics: The Study of Gene Inheritance

Genes are transmitted according to defined rules or laws. Genes are located on chromosomes, which are cellular structures. Sex is determined by specific genes or chromosomes in most living organisms.

Key Genetic Terms

• Genotype: The genetic constitution of an individual, referring to a specific character or the entire set of genes.
• Phenotype: The external expression of the genotype; the observable characteristics of an individual.
• Alleles: Variants that a gene may present. For each gene, an individual has a pair of alleles, often represented by letters.
• Homozygous: An individual having two identical alleles for a specific gene.
• Heterozygous: An individual carrying two different alleles for a specific gene.

Mendelian

Fertilization

Fertilization is the fusion of male and female gametes, initiating the process of reproduction. It's important to note that fertilization of the egg is not immediate upon contact.

Human Fertilization

In humans, fertilization occurs when a sperm and egg unite in the fallopian tubes after sexual intercourse. Humans develop from the union of these two tiny cells. Mature eggs measure approximately 0.135 mm in diameter, while sperm are even smaller. Each ejaculation can contain between 120 and 600 million sperm. The union of these cells has the potential to create a new human being with extraordinary abilities.

Zygote

In biology, a zygote is the cell formed by the union of male and female gametes during sexual reproduction in organisms... Continue reading "Human Reproduction: From Fertilization to Embryonic Development" »

Infectious Diseases

Definition

Temporary or permanent loss of health caused by microorganisms.

Types of Microorganisms

• Bacteria: Unicellular prokaryotic organisms that multiply and can destroy cells and tissues.
• Viruses: Not considered living organisms. They reproduce by entering cells and using their resources, causing damage.
• Protozoa: Single-celled eukaryotes. Some cause disease.
• Fungi: Unicellular and multicellular eukaryotes. Some can cause disease in weakened individuals.
• Parasites: Multicellular organisms that live at the expense of a host, weakening but not killing it.
• Prions: Misfolded proteins that accumulate and cause neuron degeneration.

Non-Infectious Diseases

Nonspecific Defenses

Mechanisms that prevent the entry of microorganisms:

• Skin: Acts

Definition of Infectious Diseases

An infectious disease occurs when a parasite develops and multiplies within a host. The causal agent of transmissible diseases is usually a living organism that moves from one individual to another by contagion. The set of elements that define a communicable disease consists of:

• Reservoir: Where infectious agents are usually found.
• Source of Infection: Animate or inanimate object from which the causative agent originates.
• Mechanism of Transmission: The pathways that allow the causal agent of a transmissible disease to contact the host.
• Host: A person susceptible to contracting a communicable disease upon contact with the source of infection.

Samples arriving at the laboratory for the diagnosis of causative agents... Continue reading "Infectious Diseases: Definition, Transmission, and Diagnosis" »