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

The Small Intestine

The small intestine is about 6 meters long. In the duodenum, two liquids are added to continue digestion: pancreatic juice and bile. Pancreatic juice contains enzymes such as lipases, proteases, and carbohydrase (e.g., amylase).

Enzyme Breakdown

Each enzyme breaks down food in the following way:

• Protein -> protease -> amino acids
• Lipid -> lipase -> fatty acids and glycerol
• Carbohydrate -> carbohydrase -> sugar

Bile's Role in Digestion

Bile is made in the liver, stored in the gallbladder, and delivered to the small intestine via the bile duct. Bile neutralizes the acid which was added to the food in the stomach because it is alkaline. This provides the optimal pH for enzymes in the small intestine to work. Bile... Continue reading "Small and Large Intestine: Digestion and Absorption" »

Homeostasis and the Respiratory System

Homeostasis refers to the actions performed by the body to maintain a stable internal environment. The respiratory system plays a crucial role in this process.

Key Components of the Respiratory System

• Mucus: Contains water and lysozyme, an enzyme that kills bacteria.
• Trachea: A tube that carries air into the lungs, branching into bronchi and bronchioles.
• Diaphragm: A muscle that separates the chest from the abdominal cavity.
• Ribs: Protect the lungs, which have a spongy structure.

The trachea, bronchi, and bronchioles share similar anatomical characteristics. The trachea is horseshoe-shaped and located behind the liver.

Functions of the Respiratory System

• Gas exchange: The primary function, involving the intake

Arthropod Characteristics

Arthropods exhibit bilateral symmetry and a ventral nervous system. Their heart is positioned dorsally, and they have an open circulatory system. They possess an external chitinous exoskeleton, which they shed and replace with a new one during growth, a process called molting. The sensory organs of arthropods are highly developed, primarily located in the head and legs.

Chordate Features

• The alimentary canal includes glands that aid digestion, such as salivary glands, the pancreas, and the liver.
• The cerebrospinal nervous system consists of a thick dorsal nerve cord, forming the brain and spinal cord, with nerves branching out.
• Most chordates have separate sexes. Development typically occurs in eggs, although mammals and

Levels of organization refer to the different degrees of complexity in organized matter.

• Subatomic level: Particles that make up atoms (protons, neutrons, electrons).
• Atomic level: Formed by atoms; the smallest constituents of matter that retain their properties.
• Molecular level: Molecules resulting from the binding of different atoms. There are two types:
  • Inorganic: Found in non-living or dead material (water and mineral salts).
  • Organic: Found only in living matter, usually polymers, chains formed by the union of a similar type of monomer molecules.
• Cellular level: The first level with life.
• Tissue level: Groups of cells with the same function and similar structure.
• Organ level: Different tissues are grouped for a particular function.
• System level:

Mitochondria: Structure and Function

In mitochondria is where cellular respiration occurs (specifically the Krebs cycle, beta-oxidation, electron transport, and oxidative phosphorylation), whose ultimate objective is to obtain energy in the form of ATP. Mitochondria also generate precursors of the major anabolic routes.

The mitochondria are structured as follows: a double membrane formed by an external and an internal membrane, which delimits two different compartments: the intermembrane space and the mitochondrial matrix.

The Outer Mitochondrial Membrane

The outer mitochondrial membrane is in continuous contact with the cytosol. It contains numerous proteins that regulate trade in chemicals with it, including channel proteins (porins) that form... Continue reading "Mitochondrial Structure and Function in Cellular Respiration" »

Forest Ecosystems: A Comprehensive Look

Forest: A natural ground dominated by trees. Vegetation: Various species of plants with 3 strata: arboreal, shrubby, and herbaceous. Conditions: Light, heat. Virosta: Composition of residue that accumulates sun.

Plant Types

• Bryophytes (moss, liverwort)
• Pteridophytes (fern, horsetail)
• Spermatophytes (seed plants)

Gymnosperms (not enclosed seeds). Angiosperms (enclosed seeds). Vegetation Zones: Forest (arboreal), thicket (tall shrub), springs (low shrub), meadow (herbaceous).

Revolt: Perennial, deciduous. Mineral salts (active absorption via PX transport - against gradient, sometimes with gradient). Concentration: Hypotonic (-), isotonic (=), hypertonic (+).

Osmosis and Photosynthesis

Osmosis: Process of water absorption... Continue reading "Understanding Forest Ecosystems: Flora, Soil, and Life Cycles" »

Interaction

Interaction is the set of processes through which a living being obtains information from the environment, takes decisions, controls its actions, and coordinates the functioning of the body itself.

Obtaining Information

There are various mechanisms responsible for obtaining information from the exterior and the interior of the body. These mechanisms are called receptors.

Analysis of the Information and Elaboration of a Response

This process is carried out by the nervous system and the endocrine system. The elaborated response is an order that is transmitted to the organs via different procedures.

Execution of a Response

The effectors, which are the organs responsible for carrying out a response, are as varied as the possible responses... Continue reading "Interaction: Obtaining, Analyzing, and Executing Responses in Living Beings" »

Types of Illness

• Physical Diseases: Caused by injury, infection, or degenerative processes in the body. They are classified into infectious and non-infectious diseases.
• Mental Illness: Provoked by a malfunction of the brain.
• Social Ills: Caused by the existence of a social environment with serious violent, economic, or educational deprivation.

Health vs. Illness

• Health: A state of complete physical, mental, and social well-being.
• Illness: The state in which a person's health is disturbed.

Violence as a Social Disease

Violence is a terrible social disease that kills many people every year. It is a disease that is incubated in childhood.

Viruses

Viruses are not living creatures but protein capsules containing DNA or RNA that is injected into a cell.

Infectious

Sutton's Chromosome Theory of Inheritance

• Chromosomes occur in pairs.
• Chromosome pairs separate during meiosis.
• Each gamete carries one chromosome from each pair.
• Pairs of chromosomes separate independently of other pairs.
• Fertilization restores the paired condition of chromosomes in the zygote.

Mendel's Laws of Inheritance

• Factors (genes) occur in pairs.
• Factors segregate to form gametes.
• Each gamete carries a single factor.
• Pairs of factors separate independently of other pairs.
• Fertilization restores the paired condition of factors in the zygote.

Chromosomal Abnormalities

Trisomies

• Down Syndrome (Trisomy 21): Congenital mental disability, distinct facial profile, increased risk of illness, and heart defects.
• Patau Syndrome (Trisomy 13): Nerve abnormalities,

Key Definitions in Health and Disease

Agent: An animate or inanimate entity whose presence or absence can disrupt host health.

Host: Any organism capable of harboring an agent.

Environment: The complex of factors influencing a system, determining its course and way of life.

Stimulus Trigger: A factor or condition arising after a disturbance in the ecological triad's balance, initiating the disease process.

Sign: A measurable or quantifiable manifestation in an individual.

Symptom: A subjective expression of a condition reported by an individual.

Latency: A stable phase in disease evolution without subclinical manifestations, signs, or symptoms.

Causality: Conditions involving agent, host, environment, and transmissibility factors that generate a stimulus... Continue reading "Understanding Health: Agents, Hosts, and Environmental Factors" »