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

The Journey of Pregnancy: From Conception to Birth

Gestation, commonly known as pregnancy, commences with fertilization and culminates in childbirth. This remarkable process brings about profound changes. What begins as a single cell, the zygote, progressively develops into an embryo, then a fetus, and ultimately a fully formed human being.

Typically lasting around nine months, pregnancy involves significant physiological transformations for the mother. These changes are driven by the fetus's development and growth, the vital exchange of nutrients and waste through the placenta, and the mother's body preparing for childbirth and lactation.

Early embryonic development is primarily regulated by estrogen and progesterone, initially produced by the... Continue reading "Human Reproduction: Pregnancy, Childbirth, Contraception, and Fertility" »

These measures are designed to protect individuals from electrical hazards. They can be implemented at the facility or personal level. Protection must be provided against direct contact (accessible parts or insulation failure) and indirect contact from arcing. Measures must also be taken to prevent power surges or over-current, high voltage drops, burns due to overloading, etc.

Protection Against Direct Electrical Contacts

These measures are designed to prevent the risk of contact with live parts (according to Standard 20460-4-41):

• Protection by insulation of live parts: This must be an insulator that can only be removed by destroying it; lacquer varnish is not sufficient.
• Protection by barriers or enclosures: All equipment and connections must

Breathing Process

Breathing: The process of obtaining energy in which we inhale oxygen and exhale carbon dioxide.

Respiratory System

Processes:

• Nostrils: Air enters through the two nostrils. Hair inside warms the air. The interior is lined by:
  • Pituitary Mucosa: Mucus-secreting glands capture dust and moisten the air.
  • Pituitary Yellow: Mucosa has nerve endings that detect odors.
• Pharynx: A duct that connects the nostrils, oral cavity, larynx, esophagus, and middle ear. Muscles and elastic fibers direct air into the trachea.
• Larynx: Formed by cartilage. The mucosa of the larynx has folds that form the vocal cords.
• Trachea: Composed of cartilage and lined by ciliated epithelium that produces mucus. This removes impurities from the outside through the cough

Fetal Development Stages

Overview

Fetal development primarily involves rapid body growth, tissue differentiation, and the formation of organs and systems. The fetal period is marked by significant growth, especially in the final weeks.

Viability

Fetal viability refers to the ability of a fetus to survive outside the uterus (after premature birth). Fetuses weighing less than 500g at birth typically do not survive. With postnatal care, some fetuses born weighing less than 500g may survive. Many term pregnancies with low birth weight result from intrauterine growth retardation (IUGR). The majority of fetuses born weighing between 1500g and 2500g survive but may experience complications. Prematurity is a common cause of morbidity and perinatal death.... Continue reading "Fetal Development Stages: A Comprehensive Guide" »

Seasonal Isolation

Response:

Species: The name given to each of the groups that divide the sexes, i.e., the limitation of the generic in a particular field of morphology. In biology, a species is the basic unit of biological classification.

Variations: These are the distinctive features that occur in individuals of the same species. These changes or differentials in characteristics of individuals relate to those who show up. Even though their heredity plays an important role in the transmission of hereditary or genetic characteristics, there is no chance, or a very remote one, that there are individuals the same as those around us.

Adaptation: A biological adaptation is an anatomical structure, physiological process, or behavioral trait of an organism... Continue reading "Understanding Biological Species and Genetic Concepts" »

Ammonia: Upper Respiratory Irritant and Health Risks

Certain substances primarily affect the upper respiratory tract, without impacting the lower respiratory tract (throat or bronchi). Due to their extraordinary solubility in water, these substances are completely absorbed by the nose and throat, allowing air to reach the lungs practically pure. Ammonia is a prime example of such an irritant.

Ammonia: Chemical Profile and Characteristics

Formula: NH₃
Synonym: Anhydrous Ammonia

Characteristics: A colorless gas with a pungent, hot, and suffocating odor. It can be liquefied under pressure.

Sources of Exposure

• Chemical Manufacturing: Used in the manufacture of fertilizers, as a solvent in textiles, leather, pulp, and paper manufacturing, and as a stabilizer

Gases, Vapors, and Associated Risks

A gas is matter neither liquid nor solid at room temperature and normal atmospheric pressure, expanding to fill any container. A vapor is the gaseous state of a substance typically solid or liquid. Fumes result from volatilization or sublimation. Gases and vapors diffuse freely, remaining mixed with air.

Lead Poisoning

Metabolism

Inhaled lead is 40-60% retained in the lungs, entering circulation. Ingested lead absorption is about 10%. Blood lead distributes to liver, kidneys, brain, and bone. Elimination occurs via respiratory tract, gastrointestinal system (bile, feces), urine, and generalized discharges (colic).

Pathological Effects

• Hematologic: Altered metabolism via enzyme changes and metabolite accumulation.

Intramuscular Drug Administration and Receptor Binding

Explains what a circuit is: a drug that is administered intramuscularly until it reaches the receptor. It exits the bloodstream through the capillary endothelium, traveling through the interstitial fluid, and crosses the cell membrane of its target cells.

Morphine Effects in Elderly Patients

Explains why an old man, who is administered morphine in doses equal to a middle-aged person, may be at increased risk of sleepiness, even after the drug's effects should have worn off. The elderly, like children, have decreased hepatic activity, so the drug takes longer to metabolize and be disposed of by the body, which can cause drowsiness in the case of morphine.

Drug Molecule Characteristics for Barrier

Coordination Systems: Nervous and Hormonal

When a body is small (one cell or more), its component cells are capable of capturing different environmental stimuli and responding to them. When the body is complex and has organs and organ systems, they must act together to perform their roles effectively. The nervous and hormonal systems carry out the coordination function.

Nervous System

Structure of the Neuron: Neurons are highly specialized cells that make up the different tissues and organs of the nervous system. These cells have different morphologies but share common features:

• Soma: Contains the nucleus and cytoplasm with all organelles.
• Axon: A long, unbranched extension with a widened end called the synaptic button.
• Dendrites: Highly branched,

Cellular Response

Cellular response - Cell-mediated immunity is a form of adaptive immune response mediated by T lymphocytes. It acts as an attack mechanism against intracellular microorganisms, such as viruses and some bacteria, that can survive and proliferate inside phagocytes and other host cells. The defense against such infections depends on cellular immunity, which induces the destruction of the organism living in phagocytes or infected cells.

A phagocyte captures an element, becoming a macrophage. After several processes, helper T cells are created and activated, which perform cytotoxicity (lysis of target cells by cytotoxic T cells) and regulation of the immune response by T helper cells.

Primary and Secondary Immune Response

Primary and