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

Unit 5: Cell Nutrition

All living beings need food used as follows:

• For growth: it provides the substances needed for making new cells and tissues.
• As a source of energy: required for the chemical reactions which take place in living organisms to keep them alive.
• For replacement: of worn and damaged tissues, for example, red blood cells that break down each day and to replace the skin which is worn away and to repair wounds.

Nutrition can be defined as obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Several systems are involved in cell nutrition: this process is carried out by organ systems which working together allow cells to obtain matter and energy.

• Digestive

Health and Disease: A Comprehensive Overview

Health Encompasses: Sickness absence and well-being in physical, mental, emotional, social, spiritual, sexual, and environmental aspects.

Risk Factors for Health

• Food rich in fat and/or sugar
• Tobacco and/or drug use
• Lack of hygiene
• Stress

International Sanitary Conference (Paris, 1851)

Accomplishments:

• Development of public health policies with laws governing food handling and potable water.
• Creation of the National Institute of Health.
• Methods for preventative health planning, including vaccination and infection control.
• Improved diagnostic techniques.
• Drug development.
• Promotion of better nutritional habits for a healthy life.

Infectious Diseases

Infectious diseases are caused by microorganisms and are transmitted... Continue reading "Health and Disease: Factors, Prevention, and Immunity" »

Asexual Reproduction in Cormophytes

Asexual reproduction in cormophytes involves specific vegetative organs such as stolons, rhizomes, tubers, and bulbs.

• Runners: These are side branches emerging from the base of the stems with horizontal growth. Roots emit buds, giving rise to new independent individuals.
• Rhizomes: Underground stems that grow horizontally in the soil and accumulate reserve substances. Ground stems can emerge from buds, eventually taking root and separating from the main rhizome.
• Tubers: Very enlarged underground stems that store food. They can be separated from the main plant to form separate plants.
• Bulbs: Underground stems that are more or less spherical, with fleshy, layered storage. Smaller bulbs are often formed with buds

As a result of cephalocaudal and lateral folding, a portion of the yolk sac lined by endoderm is incorporated into the embryo to form the primitive gut. The primitive gut is divided into three parts: foregut, midgut, and hindgut. The midgut communicates with the yolk sac through the temporary omphalomesenteric duct.

Foregut Development

It extends from the oropharyngeal membrane to the second portion of the duodenum (ampulla of Vater).

Esophagus Formation

Its primordium arises from the tracheoesophageal septum around the 4th week. The endoderm proliferates to temporarily occlude the lumen. At the end of the embryonic period, the lumen recanalizes, and the endoderm differentiates into stratified squamous epithelium. The muscle of the upper 1/3 is... Continue reading "Digestive System Embryology" »

Desenvolvemento Embrionario Inicial

Implantación e Primeiras Etapas

A implantación no endometrio ocorre de forma temperá. Unha vez implantado, o embrión continúa crecendo e desenvolvéndose.

Formación do Sistema Nervioso e Órganos

Prodúcese a formación inicial do sistema nervioso. Arredor dos tres meses, o embrión convértese nun feto e os seus órganos comezan a funcionar.

Reprodución Humana Asistida: Técnicas

Inseminación Artificial

A inseminación artificial consiste en introducir artificialmente o esperma no tracto reprodutor feminino.

Fecundación In Vitro (FIV)

A fecundación in vitro (FIV) consiste en fecundar o óvulo co esperma fóra do corpo, no laboratorio. O termo in vitro fai referencia ao uso de material de laboratorio, como... Continue reading "Embrións, Reprodución Asistida e Células Nai" »

Endocrine System

The endocrine system is formed by cells and glands that secrete specific hormones. These hormones are effective messengers that regulate various bodily functions through feedback mechanisms.

Endocrine Glands

Pituitary Gland

Anterior Lobe

• GH (Somatotropin)
• ACTH (Adrenocorticotropin)
• TSH (Thyroid Stimulating Hormone)
• PRL (Prolactin)
• FSH (Follicle-Stimulating Hormone)
• LH (Luteinizing Hormone)

Posterior Lobe

• Vasopressin (ADH - Antidiuretic Hormone)
• Oxytocin

Hypothalamus

The hypothalamus controls the neurohypophysis through nerve fibers and releases or inhibits pituitary factors.

Adrenal Glands

Cortex

• Glucocorticoids: Regulate carbohydrate and protein metabolism and inhibit the immune response.
  • Cortisol
  • Corticosterone
• Mineralocorticoids: Regulate Na-

Puberty: Hormonal Changes

Boys: Sperm production, increased bone thickness and muscle mass, voice deepening, beard growth, and the appearance of pubic and axillary hair.

Girls: First menstruation, breast growth, widened hips, and the appearance of pubic and axillary hair.

Female Reproductive System

Ovaries, Fallopian tubes, uterus, vagina, clitoris, labia majora, and labia minora.

Male Reproductive System

Testes, prostate, urethra, epididymis, vas deferens, seminal vesicles, penis, and scrotum.

Key Definitions in Human Development

• Embryo: The second phase of zygote development occurs when it attaches to the endometrium.
• Fetus: The third stage of embryonic development, starting in the second trimester.
• Nidation: The moment when the zygote attaches to

Muscular System

Muscle Characteristics

Involuntary. Located in the heart. Striated fibers are present inside longitudinal filaments called myofibrils. Muscle cells are made of two proteins: actin and myosin. Some form rhabdomyosarcoma.

Types of Muscles

• Long or Fusiform: (spindle-shaped)
• Flat or Planar: (e.g., diaphragm)
• Orbicular: (round body, e.g., orbicularis oculi)

Tendons join muscles to bones. Two muscles are involved in any movement: agonist (contracts) and antagonist (relaxes).

Skeletal System

3.2 - Bones

Functions

• Support the body and give it shape.
• Allow movement of various body parts.
• Protect internal organs (brain, lungs, etc.).
• Serve as the main repository of minerals (calcium, potassium, etc.).
• Some bones act as organs of blood cell production.

Common Illnesses and Their Causes

Illnesses Caused by Viruses

Viruses are responsible for a variety of illnesses, some of which are highly contagious. Here are a few examples:

• The Common Cold: A highly contagious illness that causes mild discomfort, increased nasal secretions, congestion, and sneezing. It typically does not cause fever. Transmission occurs through direct contact, but the virus can also spread through the air. Frequent handwashing is crucial for prevention.
• Flu (Influenza): Often confused with the common cold due to its prevalence in winter and similar transmission methods. However, the flu generally causes greater discomfort, including joint pain, and is a more serious illness.
• AIDS (Acquired Immunodeficiency Syndrome): A serious

Cellular Functions

Cellular functions are basic units of life and conduct nutrition, relationships, and reproduction. Unicellular cells perform all these functions within a single cell, while multicellular organisms have specialized cells.

• Nutrition: Molecular intake from the external environment provides energy to renew cellular structures. This process inside the cell is known as metabolism.
• Relationships: Cells communicate with the outside environment, adapting to changes and maintaining stability.
• Reproduction: New cells are formed from existing ones. In unicellular organisms, this leads to a new being. In multicellular organisms, it replaces dying cells and increases cell numbers during growth. Cells pass their genetic material to their daughter