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

Endocrine System

The endocrine system coordinates body processes using chemical messengers called hormones.

Functions of Hormones:

• Control cell metabolism
• Maintain the body's internal stability (homeostasis)
• Regulate growth, sexual development, and reproduction

Endocrine Glands

Endocrine glands produce and release hormones, which the bloodstream distributes throughout the body to all cells.

Hormone Regulation

The endocrine glands and circulatory system work together to regulate hormones. For example, the pancreas secretes insulin when it detects excess glucose in the blood. Insulin causes muscle cells and liver cells to absorb glucose from the bloodstream.

Nervous System Coordination

The nervous system coordinates the activity of endocrine glands through... Continue reading "Endocrine System and Hormone Regulation: A Comprehensive Guide" »

Nature of Science

Science attempts to study and gain information about nature. Science poses hypotheses (usually based on observations) and attempts to explain these hypotheses by observations, inferences, and experimentation.

Hypothesis vs. Theory

A theory is the basis of facts and how they work together. A hypothesis is a question or an educated guess.

Properties of Water

Water is polar. Water is most dense at 4 degrees Celsius.

Cell Organelles and Their Functions

Chromosomes

• Usually in the form of chromatin
• Contains genetic information
• Composed of DNA
• Thicken for cellular division
• Set number per species (e.g., 23 pairs for humans)

Nuclear Membrane

• Surrounds nucleus
• Composed of two layers
• Numerous openings for nuclear traffic

Nucleolus

• Spherical shape
• Visible

The Electron Transport Chain: ATP Production

Inside the inner membrane of the mitochondria, there is a chain of electron carriers known as the electron transport chain (ETC). Electrons generated from oxidative reactions in earlier stages of cellular respiration pass along this chain.

NADH donates two electrons to the first carrier. As these electrons pass along the chain, they release energy from one carrier to the next. At three specific locations along the chain, sufficient energy is released to synthesize ATP via ATP synthase, an enzyme also located in the inner mitochondrial membrane.

FADH₂ also donates electrons, but at a later stage than NADH. Electrons from FADH₂ release enough energy at only two locations along the chain. This ATP production,... Continue reading "Electron Transport Chain: ATP Synthesis & Oxygen's Role" »

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" »