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

Fundamentals of Nutrition and Metabolism

Defining Key Biological Concepts

Nutrition: The set of processes by which living things incorporate foreign substances to obtain matter and energy.

Food (Alimentos): Substances consumed by living beings.

Feeding (Alimentación): The process of taking food. Food is composed of substances called nutrients.

Types of Nutrition

Nutrition is classified based on how organisms obtain organic matter:

• Autotrophs

  Capable of producing their own organic matter from simple inorganic substances. They require an energy source:

  • Photosynthetic: Obtain energy from sunlight (e.g., algae, plants, and photosynthetic bacteria).
  • Chemosynthetic: Use energy released by specific chemical reactions (e.g., determined bacteria).

• Heterotrophs

  Use

Acute Renal Failure (ARF)

Signs

ARF is often asymptomatic. However, some common signs include:

• Oliguria: Urine output of less than 400 ml per day
• Increased nitrogen products in the blood
• Electrolyte and acid-base abnormalities

Classification of Acute Renal Failure

1. Pre-renal ARF

This type accounts for 55% of cases. It is characterized by a deficiency in kidney perfusion, which decreases the glomerular filtration rate (GFR). There is no frank damage to the renal parenchyma initially.

Features of Pre-renal ARF:

• Often reversible
• No initial damage to the renal parenchyma
• Prolonged deficiency can lead to ischemia and acute tubular necrosis
• The renal tubules and loop of Henle are most affected by ischemia

Phases of Pre-renal ARF:

• Extension phase: Swelling occurs,

Mammals

• Females have breasts that produce milk to feed their young.
• The body is covered with hair.
• Body temperature is constant.
• Young are born alive.
• Examples: Prototherians (e.g., the platypus), marsupials (e.g., kangaroos), and eutherians (e.g., insectivores, bats, primates, cetaceans, carnivores, Perissodactyla, and Artiodactyla).
• Temperature: Mammals maintain a constant body temperature, typically between 38 and 40 degrees Celsius, regardless of whether they live in hot or cold climates.
• Reproduction: Mammals reproduce viviparously with internal fertilization. They lay eggs without nutrient reserves, which are implanted and developed in the womb. The placenta provides nourishment and oxygen to the developing fetus and facilitates the excretion

Cellular Respiration Explained

Respiration is the process in which glucose and oxygen are transformed inside the cell into water, carbon dioxide, and energy.

The goal is to transform glucose and oxygen into energy.

Gases involved are oxygen, which we use, and carbon dioxide, the result.

It happens inside the cell in the mitochondria.

Defining Metabolic Rate

Metabolic rate is an average of the amount of energy that a person needs. While sleeping, we spend energy in circulation, for development, breathing, and protection. We spend energy because the body is working constantly.

Function of the Breathing System

In breathing, gases are exchanged. Oxygen goes from the air to the blood, and carbon dioxide goes from the blood to the air.

Lining of the Respiratory

Neurons: The Basic Unit of the Nervous System

A neuron is the basic unit in the nervous system. It is a specialized conductor cell that receives and transmits electrochemical nerve impulses. A typical neuron has a cell body and long arms that conduct impulses from one body part to another.

Three Different Parts of the Neuron:

• The cell body
• Dendrites
• Axon

Types of Neurons

• Multipolar neurons have one axon and several dendrites. These are common in the brain and spinal cord.
• Bipolar neurons have one axon and one dendrite. These are seen in the retina of the eye, the inner ear, and the olfactory (smell) area.
• Unipolar neurons have one process extending from the cell body. The one process divides with one part acting as an axon and the other part functioning

Fundamentals of Biological Molecules and Bonds

Essential Elements and Molecular Formation

The primary elements that form biological molecules are often summarized by the acronym CHOMPS (Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur). Carbon (C) is highly versatile, forming the backbone of organic compounds.

Monomers, Polymers, and Reactions

• Monomers: The smallest units of organic compounds.
• Polymers: Large molecules formed by repeating monomer units (M + M = Polymer + H₂O).
• Polymerization: The process of forming polymers.
• Dehydration Synthesis: A reaction where monomers join to form a polymer, releasing a water molecule (H₂O).
• Hydrolysis: A reaction that breaks down a polymer by adding a water molecule.

Chemical Bonds and Essential Elements

Molecules... Continue reading "Essential Biomolecules: Structure, Function, and Chemical Bonds" »

Cancer Treatment Modalities

The basis of cancer treatment lies in the elimination of tumors through surgery, chemotherapy, immunotherapy, and radiotherapy.

Chemotherapy

Chemotherapy is anticarcinogenic. Certain drugs act directly on DNA, such as oxaliplatin, anthracyclines, and cyclophosphamide. Others, like taxanes and vinblastine, interact with mitotic spindle formation. Common side effects can include hair loss or effects on leukocytes.

Immunotherapy

Immunotherapy is based on the stimulation of the immune system to trigger a response against tumors. Approaches include the use of interferon alpha, which can reduce tumor growth; vaccines using antigens present in cancer cells to stimulate immune defense; and monoclonal antibodies.

Radiotherapy

Radiotherapy... Continue reading "Cancer Treatment Methods and Surgical Procedures" »

Economic Entomology

It refers to the study of all aspects of insects that are related in a way or another with human activity involving the economic, ecological and social.

Ecology of Insects

Species: A group of individuals who share common characteristics, can interbreed and produce fertile offspring under natural conditions.

Population: Group of organisms of the same species that occupy a certain space at a given time.

Community: A group of populations of several species of plants or animals that share a certain time regardless.

Ecosystem: Habitat where biotic and abiotic factors interact to exchange energy and matter in a continuous cycle.

Agroecosystem: Artificial system manipulated by man but stable in nature.

Ecological Niche: Resources that... Continue reading "Economic Entomology: Insect Ecology and Pest Management" »

Cerebral and Basilar Arteries

The carotid artery supplies 80% of the oxygen to the cerebral hemispheres. The two internal carotid arteries branch into the middle cerebral arteries, which provide 60% of the brain's oxygen supply. The anterior communicating artery connects the right and left middle cerebral arteries.

Two vertebral arteries (left and right) ascend along the spinal cord and merge at the base of the skull to form the basilar artery. This artery supplies the medulla, pons, and other brainstem structures.

Circle of Willis

1. Frontal lobes
2. Temporal lobes
3. Middle cerebral artery (right and left)
4. Anterior cerebral artery
5. Posterior cerebral artery
6. Basilar artery
7. Vertebral arteries (right and left)
8. Spinal cord
9. Internal carotid artery
10. Anterior communicating

Cytokinesis

Cytokinesis begins in anaphase and continues through telophase.

• In animals: The process involves strangling the cytoplasm. Segmentation is a linear division, resulting in the formation of a contractile ring formed by actin filaments.
• In plants: The cell wall prevents segmentation. This is done by forming a new wall inside the cell. This new wall is formed at the equator by the association of Golgi apparatus vesicles and microtubules, and it is called a phragmoplast. It extends laterally to reach the cell wall.

Types of Cell Division

1. Bipartition

   Division of the cell. Two daughter cells originate, equal in size. The process involves karyokinesis and cytokinesis, with its variant being strangulation.

2. Multiple Fission

   Divisions of the cell.