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

Human Skeletal System: Key Structures and Functions

Types of Synovial Joints

• Plane Joints

  Characterized by flat surfaces on one bone meeting with flat surfaces of another, allowing for slipping and gliding movement with no axial rotation. Common examples include the carpal bones of the wrist.

• Hinge Joints

  A cylindrical projection of one bone fits into a trough-shaped surface of another bone. These joints permit flexion and extension, like the elbow joint (specifically, the olecranon process of the ulna).

• Pivot Joints

  A rounded projection of one bone fits into a rounded depression or sleeve of another bone, often held together by ligaments. They allow for uniaxial movement, such as the rotation of the odontoid process of C2 (axis) within the anterior

Characteristics of Sexual Reproduction

Human reproduction is sexual. This means that it's necessary for two individuals of different sexes to take part.

1. Each sex produces a different type of sex cell or gamete.
2. Fertilization is internal; it takes place inside the female reproductive system.
3. We are viviparous; the fetus grows in the mother's womb.
4. We are sexually dimorphic. This means that males and females have physical differences. This happens in many species.

Process of Reproduction

1. Gametogenesis: formation of the gametes.
2. Fertilization: joining of the male and female gametes.
3. Embryo Development: cell division and differentiation.
4. Childbirth: birth of the baby.
5. Development: cells increase and mature.

Changes in Adolescence

Adolescence begins with puberty,... Continue reading "Human Reproduction: Characteristics, Process, and Systems" »

Main Reasons Why Cell Divides

• Larger cell demands more place for the DNA.
• Larger cells result in less moving nutrients and waste materials across the cell membrane.

Information Overload

Cell grows, information is used to build the molecules needed for cell growth. DNA doesn't increase.

Exchanging Materials

Food, oxygen, water enter by the cell membrane, waste products also go out like that.

Division of the Cell

Forms 2 daughter cells. Cell division: process in which a cell divides into 2 daughter cells.

Asexual Reproduction

1 parent, cell divides by fission, little chances of genetic variation, found in bacteria, 2 offspring.

Sexual Reproduction

2 parents, cell divides by meiosis, genetic variation, found in mammals, 1 offspring.

Both

Forms of reproduction,... Continue reading "Cell Division, Chromosomes, and Cell Differentiation" »

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" »

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" »