Notes, summaries, assignments, exams, and exercises for Biology for Other courses

The Human Circulatory System

The circulatory system is a complex network of organs that facilitates the movement of blood throughout the body to distribute nutrients and oxygen.

Anatomy of the Heart

The heart is a muscular organ located in the thorax between the lungs. It is roughly the size and shape of a fist and consists of three layers:

• Pericardium: The outer protective sac.
• Myocardium: The muscular middle layer.
• Endocardium: The inner lining.

The system also includes blood vessels: arteries, veins, and capillaries.

Internal Heart Structure

The heart is divided into four chambers:

• Atria (Top): Two chambers that act as receptors.
• Ventricles (Bottom): Two chambers that act as propulsion pumps.

Atrioventricular valves regulate blood flow, ensuring it...

Medical Vocabulary

• Slide: Muestra de cristal / Portaobjetos
• Pipette: Pipeta
• Vein: Vena
• Syringe: Jeringa / Jeringuilla
• Drop: Gota
• Pump: Bombear
• Test tube: Tubo de ensayo
• Leaves: Dejar / Salir
• Microscope: Microscopio
• Valve: Válvula
• Enters: Entrar
• Artery: Arteria
• Flows: Fluir
• Atrium: Atrio
• Fills: Rellenar / Llenar
• Aorta: Aorta
• Opens: Abrir
• Closing: Cerrar
• Beat: Palpitar / Latido
• Bodily fluids: Fluidos corporales
• Cells: Célula
• Clot: Coágulo
• Drip: Goteo o gotear
• Forensic Analysis: Análisis forense

Grammar Exercises: Conditionals

1. If you explain, she will tell you what to do.
2. When you have an anaesthetic, it stops you feeling pain.
3. If I have time, I will help you with your homework.
4. You have a fever if your temperature is over 37.5.
5. If a person's brain doesn't get oxygen,

Biodiversity of Costa Rica (CR)

Biodiversity includes all living organisms in a geographic area and all the relationships between them. Biodiversity is characterized by the abundance and multiplicity of species in a given region. It is the variety of living beings that inhabit the Earth.

Why is Costa Rica so diverse?

Why is CR so diverse? Costa Rica (CR) displays exceptionally high biodiversity. Several determinants explain this diversity:

Determinants of biodiversity

• Location (Neotropics)

  Costa Rica is located in the Neotropics; for this reason it receives more solar energy year-round, which promotes the abundance and richness of species.

• Geological history and soils

  The geological history of the country has involved many processes such as volcanism

Proteins: Structure, Composition, and Function

Amino Acids and Basic Composition

• Atomic Composition: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N).
• Sub-molecular Unit: Amino acid.
• There are 20 amino acids, 8 of which are essential.
• Amino acids bind via the Peptide Bond, resulting in the loss of a water molecule.

Amino Acid Polarity and Characteristics

• Hydrophobic Amino Acids: Water repellent (non-polar).
• Polar Amino Acids: Can form hydrogen bonds with water molecules.

Protein Sources

Meat, eggs, vegetables, and milk.

Amino Acid Color Coding (Visualization)

In certain models, amino acids are color-coded based on their properties:

• Brown: Hydrophobic Amino Acids (water repellent).
• Green: Polar Amino Acids (can form hydrogen bonds with water molecules).

Protists

Protists are eukaryotic organisms. They include protozoa and algae, most of which are unicellular. As eukaryotes, protists possess a membrane-bound nucleus (karyotheca) and membranous organelles.

Protozoa

Protozoa are eukaryotic, unicellular heterotrophs. Protozoa are classified by the organelles they use for locomotion:

• Rhizopods: move by means of pseudopodia. Example: Amoeba.
• Ciliates: move by means of cilia. Example: Paramecium.
• Sporozoans: have no locomotor structures, and parasitic protozoa lack organelles for movement. Examples: Plasmodium (malaria) and Toxoplasma gondii.
• Flagellates: move by means of flagella. Example: Trypanosoma cruzi (Chagas disease).

Algae

Algae are eukaryotic, unicellular autotrophs. They are found in various environments,...

Arthropods

Arthropods: abundant, well-known species (flies, crabs) and representatives in virtually all habitats.

Body plan

The arthropod body plan is based on several key features:

• Body segmented: segments are grouped into regions, such as head and abdomen.
• Exoskeleton: strong and flexible due to chitin; arthropods molt to grow — they emerge from the old exoskeleton and secrete a new one.
• Jointed appendages: some appendages are walking legs, others serve sensory or feeding functions.

Major groups

Characteristics of the major groups of arthropods:

• Arachnids (spiders, scorpions)
• Crustaceans (crabs, shrimp)
• Insects (flies, beetles, butterflies)
• Myriapods (centipedes, millipedes)

Echinoderms

Echinoderms: sea animals such as starfish and sea urchins. They...

Topic: Sebaceous Glands and Hair Follicles

Sebaceous glands, associated with hair follicles, secrete sebum (oil). These glands are shaped like lobes, constituted by many cells that discharge their secretion. Sebum secretion mixes with perspiration, forming the epicutaneous emulsion. They are surrounded by a basal epidermal membrane and separated from the lobes by connective tissues. They are not supplied by ducts but are surrounded by many blood vessels.

Factors Influencing Sebum Secretion:

• Abundance: High in the middle region of the face, scalp, and upper back.
• Age: Production starts at puberty and increases with age until about 50 years, when it begins to decrease.
• Sex: Males produce more sebum.

Gladulas Sweat (Sweat Glands)

Sweat glands are localized...

Historical Theories of Biological Evolution

As the old theories explain the evolution of species, Fixism is a theory that proposes that species do not change, but rather remain essentially unchanged over time since their creation. This materialized in the 18th century with the work of Linnaeus.

Catastrophism is a theory that proposes that each geological cataclysm destroys existing species, so that subsequently, a creation of new species is produced. In the 18th century, it showed a very fragile state due to new input against it by Leclerc and other scientists.

Lamarck's Evolutionary Hypothesis

Lamarck's evolutionary hypothesis is called Transformism and assumed that species evolve to be gradually transformed into one another. It is based on two...

Structure and Function of Cell Organelles

Membrane Components

Plasma Membrane

The plasma membrane is a thin envelope surrounding all known cells. It is a lipid-protein structure. The plasma membrane is fluid; molecules move within it to some degree. The fluidity depends on the type of lipid composing it. In animal cells, the membrane's fluidity is controlled by cholesterol molecules. Tissue cells bind through the extracellular matrix.

Cell Wall

The cell wall is found in plant cells. It is an extracellular matrix formed by cellulose fibers, providing rigidity and maintaining cell shape. Walls accumulate substances like lignin, causing them to stiffen.

Internal Cellular Environment

Cytoplasm

The cytoplasm is the space between the cell nucleus and the...

Cytoskeleton

The cytoskeleton is located between the karyota and the membrane. It provides intercellular support, aids in movement, participates in cell division, and is rich in protein. There are three types of eukaryotic cytoskeleton filaments:

• Actin microfilaments: Composed of actin proteins, approximately 3.7 nm in diameter.
• Intermediate filaments: Fibrous proteins, 10 nm in diameter, located in the cytoplasm.
• Microtubules: 25 nm in diameter, originating from the microtubule-organizing center, composed of alpha and beta tubulin proteins.

Cellular Functions and Processes

Cerumen

Cleans, lubricates, and protects against fungi, insects, and bacteria.

Protein Denaturation

The alteration of the secondary, tertiary, and quaternary structure of a protein...