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

Human Digestive System Processes

Digestion involves two main types of processes:

• Mechanical Digestion: Food is ground, cut, and mixed with juices.
• Chemical Digestion: Food is broken down by hydrolytic enzymes.

1. Digestion in the Mouth

Mastication

This is the mechanical process involving the teeth and tongue. Food is torn and ground into small pieces.

Insalivation

Food is mixed with saliva. Pieces of food are moistened to form a bolus. Saliva is produced by the salivary glands and contains:

• Salivary Amylase: Responsible for the digestion of starch.
• Mucin: Gives viscosity to the saliva.
• Lysozyme: Attacks bacteria.

2. Deglutition (Swallowing)

The food bolus moves from the mouth towards the pharynx and passes the epiglottis. The bolus then enters the oesophagus,... Continue reading "Human Digestive System: Stages and Processes" »

1. An example of an organic compound would be: CH4.

2. Which of the following would not be an organic molecule? WATER

3. The measurement of the concentration of hydrogen ions compared to the concentration of hydroxide ions in a solution is called: pH.

4. The waste products of cellular respiration include: WATER AND CARBON DIOXIDE.

5. Matter is anything that: HAS MASS AND TAKES UP SPACE.

6. When an overwhelming body of observations and measurements supports a scientific hypothesis or group of related hypotheses, it becomes a: SCIENTIFIC THEORY.

7. Which of the following statements is a correct distinction between autotrophs and heterotrophs? ONLY AUTOTROPHS CAN LIVE ON NUTRIENTS THAT ARE ENTIRELY INORGANIC.

8. What happens to all the energy you expend?... Continue reading "Understanding Organic Compounds and Cellular Processes" »

Components of the Respiratory Tract

These are the nasal cavities, pharynx, larynx, trachea, bronchi, and bronchioles. Inside the larynx, there are two ring-shaped folds (vocal cords). They create sound when the passage of air makes them vibrate.

Lungs: Site of Gas Exchange

This is where the gas exchange between blood and air takes place.

Respiratory Tract Function

When air reaches the lungs, it needs to be clean, humid, and warm. This preparation process takes place in the respiratory tract.

Nasal Cavity: Air Entry Point

This is the place where air enters the body. In the first section, the internal wall has several capillaries which warm up the air because they carry blood. Mucus purifies and humidifies the air.

Pharynx: Shared Passageway

This area... Continue reading "How Breathing Works: Organs and Processes" »

Key Concepts in Health and Medicine

Fundamental Definitions

• Medicine: The social institution responsible for treating disease and restoring or improving the health of a population.
• Health: A state of complete physical, mental, and social well-being.
• Disease: Usually defined as a structural or physiological dysfunction.
• Illness: The social and cultural response to a disease.

Vital Signs: Indicators of Health

Physiological parameters that inform us of our state of health or the evolution of a disease:

• Body Temperature: The balance between the heat produced by our body from metabolism and the heat it loses.
• Heart Rate: The number of heartbeats in one minute.
• Breathing Rate: The number of breathing cycles (inhale-exhale) in one minute.
• Blood Pressure: The

The Endocrine System

Hypothalamus: Produces releasing hormones, which control the activity of the pituitary gland.

Pineal Gland: Controls the daily sleep-wake cycle and produces melatonin.

Pituitary Gland: Directs the activity of other endocrine glands with a variety of hormones.

• Gonadotropic Hormones: Act on the sex organs.
• Oxytocin: Stimulates uterine contractions during childbirth.
• Growth Hormones: Control the elongation of bones.

Thyroid Gland: Regulates the body's overall metabolism with thyroxine. Produces calcitonin, which increases blood calcium levels.

Adrenal Glands: Regulate metabolism with cortisol, regulate kidney function with aldosterone, and prepare the organism for high-stress situations with adrenaline.

Pancreatic Islets: Control blood... Continue reading "The Endocrine and Nervous Systems: A Comprehensive Overview" »

Essential Nutrients for Adolescents

Fruit and Vegetables

These are essential every day. Fruit juice, for example, rich in vitamin C, contributes to preventing reduced defenses at a time of change like adolescence.

Dairy

Daily consumption of dairy products promotes growth and provides the calcium you need to properly feed your skeleton.

Fish and Seafood

Oily fish (Tuna, sardines, salmon, and mackerel) is especially recommended because it provides high concentrations of vitamins A and D, much needed during periods of growth. Squid, cuttlefish, and mussels are also high in RD.

Proteins

Are vital for building strong muscles and also for proper brain function. If you do not eat enough protein, your intellectual ability will be diminished. Do not forget... Continue reading "Essential Nutrients for Adolescents: A Comprehensive Guide" »

Human Reproduction Process

Sexual Reproduction Fundamentals

Human reproduction is a form of sexual reproduction. This process involves two gametes (reproductive cells) from different sexes joining together to produce a zygote, which then develops into a new individual.

Gametes, Gonads, and Biological Sex

Gametes are formed in the reproductive organs, known as gonads, which are part of the reproductive system.

• Male Gonads (Testes): Produce spermatozoa (sperm).
• Female Gonads (Ovaries): Produce ova (eggs).

Sex refers to the biological condition determined by an individual's gonads.

Defining Sex and Sexuality

Sexuality is a broader concept that includes biological sex, as well as emotions, feelings, and sex-related experiences. These aspects are not always... Continue reading "Human Reproduction: Development and Male System" »

Ecosystem Components and Definitions

An ecosystem is a system formed by different organisms (biocenosis), the environment, its physical and chemical characteristics (biotope), and the interactions that are established between them.

Environmental Factors and Biocenosis

Environmental factors are all the components of the ecosystem that have an impact on the biocenosis. They determine the distribution and composition of the biocenosis, the number of organisms present, and the adaptation of the organisms.

Abiotic Factors and Climatic Conditions

Abiotic factors include physical and chemical components such as temperature, water, and light. Climatic conditions form the large terrestrial ecosystems or biomes.

Biodiversity and Organism Adaptations

Organisms... Continue reading "Ecosystem Dynamics and Species Interactions" »

Impulse Transmission in the Nervous System

Impulse / nervous system: The stimulus is received and a depolarization takes place in the neuron membrane. The impulse travels along the axon; many axons are insulated by a substance called myelin. When the impulse arrives at the end of the axon it has to cross a gap called the synaptic cleft. Synaptic vesicles fuse with the membrane and release neurotransmitters, which pass to the dendrite of the next neuron. The message then goes to the nervous system and finally to the effectors.

Protection of the Central Nervous System

Protection of the CNS: The brain and the spinal cord are surrounded by three membranes called the meninges and by a liquid called the cerebrospinal fluid (líquido encefalorraquídeo)... Continue reading "Nervous System Function, Neuron Structure & Sense Organs" »