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

Female Reproductive Tract: Anatomy and Function

• Oviducts (Fallopian Tubes or Uterine Tubes)

  These are two small tubes with a funnel-shaped opening at the end closest to the ovaries. They are responsible for collecting the eggs released by these organs. Fertilization occurs in the fallopian tubes. The innermost layer of these tubes consists of ciliated cells that enable the movement of the eggs along them. They also secrete a fluid that facilitates the movement of the zygote before it reaches the uterus.

• Uterus

  A conical-shaped cavity into which the fallopian tubes lead. Its wall has a thick muscular layer, the myometrium, and is lined internally by a mucous layer, the uterine lining (endometrium). At its lower end, called the neck or cervix, the

Mechanisms of Defense: The Immune System

The immune system consists of a set of organs, cells, and molecules dispersed throughout the body that is responsible for its defense. This defense system operates through internal and external defenses.

External Defenses

They consist of physical and chemical barriers and are the first line of defense to prevent the entry of pathogens. These barriers are mainly the skin and mucous membranes.

Internal Defenses

In the interior of the body, we can distinguish two types of defenses:

• Nonspecific Defenses

  Are so called because they do not depend on the nature of the pathogen. The most important are the inflammatory reaction and the nonspecific cellular defense:

  • Inflammatory reaction. It is a local reaction involving

Stress and the Nervous System

In alarming situations, the nervous and hormonal systems trigger a series of processes that provoke reactions such as increased heart rate, elevated blood pressure, and heightened tension. This tension typically subsides when the alarming situation ends. However, if the situation persists, it can lead to anxiety, distress, depression, and insomnia.

To reduce these effects, consider the following:

• Adequate sleep
• Regular exercise
• Balanced diet
• Avoid consumption of tranquilizers, drugs, and sleep aids

Hormonal Coordination: The Endocrine System

The endocrine system is a set of glands formed by specialized cells that secrete hormones. Glands are classified as:

• Endocrine: Release hormones into the bloodstream.
• Exocrine: Discharge

The Process of Fertilization

1. The female gamete, or egg, is captured by the fimbriae (finger-like extensions) of the fallopian tube. Thanks to the muscular contractions of the tube's walls and the movement of its cilia, the egg is gently propelled towards the uterus.
2. Sperm that have entered the vagina begin their ascent through the reproductive tract.
3. The surviving sperm continue their journey to the cervix. This region contains glands that produce a specialized mucus fluid. This discharge facilitates the passage of some sperm while trapping others and removing seminal fluid remnants.
4. Once through the cervix, sperm penetrate the uterine cavity, traverse it, and begin their ascent into the fallopian tubes.
5. The meeting of sperm and egg, known as fertilization,

Genetics

Core Concepts

Genetics is the study of biology that focuses on genes and biological inheritance related to characteristics.

Chromosomes are components that appear as cylindrical or rod-shaped bodies during cell division: mitosis and meiosis.

Genetic engineering involves manufacturing techniques.

The world lives thanks to bacteria and other antibiotic substances they produce. These products prevent the growth of bacteria and fungi.

Cellular Biology and Cloning

Stem cells and blastocysts are cells in the body with no specialized function. They can multiply while maintaining that state and can be transformed into over 200 cell types in an adult individual. They are fundamental.

Cloning:

• Therapeutic cloning: Obtaining stem cells to regenerate tissues

Biological Macromolecules: Proteins, Enzymes, and Nucleic Acids

Proteins: Structure and Function

Proteins are essential biological macromolecules (biomolecules) composed primarily of Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). They are polymers formed by the linkage of subunits called amino acids (AAs).

Amino Acid Composition

Each amino acid consists of a central carbon atom bound to four groups:

• A carboxyl group (COOH)
• An amino group (NH₂)
• A hydrogen atom (H)
• A variable side chain or radical (R group)

There are 20 distinct amino acids that form proteins. These subunits are linked together by a peptide bond, which forms through a dehydration reaction between the amino group of one AA and the carboxyl group of another, releasing a molecule... Continue reading "Essential Biomolecules: Protein Structure, Enzyme Action, and Nucleic Acids" »

Infectious Diseases: Stages and Characteristics

Infectious diseases manifest through various symptoms, including fever, malaise, and fatigue. These diseases typically progress through three stages:

1. Incubation Period: The time between the pathogen's entry and the appearance of the first symptoms. During this period, the pathogen multiplies. The incubation period varies depending on the disease.
2. Development Period: Characteristic symptoms appear.
3. Convalescence: The body recovers from the disease.

Medical Terminology and Definitions

Symptoms, Signs, and Treatments

Symptom: A subjective experience reported by a patient, perceived as abnormal and potentially caused by a disease.

Sign: An objective, observable indication of a disease or health impairment.... Continue reading "Understanding Infectious Diseases, Symptoms, and Treatments" »

Photosynthesis: Key Reactions and Processes

Oxygen Release in Photosynthesis: Oxygen is released during the light-dependent reactions of photosynthesis, specifically when water molecules are split (photolysis).

Organelles Involved: The organelles represented are the mitochondria and chloroplast. Photosynthesis occurs in the chloroplast, and cellular respiration occurs in the mitochondria.

Oxygen as a Waste Product: Oxygen (O2) is produced as a byproduct during photosynthesis and is consumed during cellular respiration.

Anabolic and Catabolic Processes: Photosynthesis is an anabolic process (building complex molecules), while cellular respiration is a catabolic process (breaking down complex molecules).

Photosystems: Structure and Location

Photosystems... Continue reading "Photosynthesis: Key Reactions and Processes Explained" »

Endocrine, Exocrine, and Mixed Glands

The endocrine system is composed of glands that secrete hormones. Hormones are chemical messengers that travel through the blood and exert specific actions on certain organs, known as target organs.

• Endocrine glands discharge hormones directly into the bloodstream.
• Exocrine glands discharge substances onto the body's surface through excretory ducts.
• Mixed glands combine the features of both endocrine and exocrine glands.

Endocrine System Functions

Hormones are key regulators of metabolism, reactions, and responses to states of alarm.

Endocrine Gland Characteristics

• Lack excretory ducts
• Generally small in size
• Act in small doses
• Can be formed as independent bodies, arranged in clusters, or within other organs

Pituitary

Understanding Rock Formation

How Igneous Rocks Form

All igneous rocks are formed by the cooling and solidifying of magma. Magma characteristics include its chemical composition, temperature, and density. Crystallization occurs as magma cools and solidifies. This process is called crystallization because the various materials within the magma form crystals. The location where magma solidifies on the Earth's crust influences the type of rock formed.

Igneous rock types:

• Extrusive
• Intrusive
• Plutonic
• Filonian

Sedimentary Rock Formation

Sedimentary rocks form through compaction and cementation.

Sedimentary rock types:

• Detritic
• Rocks formed from precipitation
• Organic rocks

The Dynamic Rock Cycle

The rock cycle is the set of processes and transformations continually... Continue reading "Understanding Rocks and Cell Organelles" »