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" »

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" »

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" »

Infectious Disease

is caused by agents that have invaded the body

Pathogen

any agent that causes disease

Koch Postulates

rules for determining the cause of a disease

Mucous Membrane

epithelial tissue that protects the inferior surface of the body that might be exposed to pathogens

Inflammatory Response

events that suppress infection and speed recovery

Histamine

substance that increases the permeability of surrounding capillaries

Phagocytes

type of white blood cell that pass through capillary walls, ingest and destroy foreign matter

Neutrophil

type of phagocyte that squeeze through capillary walls

Macrophage

type of phagocyte that engulfs pathogens and cellular debris

Natural Killer Cells

large white blood cells that attack pathogen-infected cells

Complement System

proteins... Continue reading "Understanding Infectious Diseases and the Immune System" »

Understanding Inheritance and Continuous Variation

This type of inheritance refers to continuous characteristics regulated by genes that are inherited independently.

Sometimes, continuous variation does not only depend on one quantitative inheritance but also on the influence environmental factors have on the genotype. The height and weight of a population are classic examples of continuous characteristics that are affected by environmental factors.

Mendel's Laws of Inheritance

Mendel's First Law: Law of Uniformity

When two pure-bred individuals are crossed, all offspring of the first filial generation (F1) have the same genotype and phenotype.

Mendel's Second Law: Law of Segregation

When two individuals from the first filial generation are crossed,... Continue reading "Understanding Inheritance, Cell Theory, and the Origin of Life" »

Ovaries:

• Composed of ovarian follicles (sac-like structures)

Gametes

produced by gonads

Uterus:

• Located between the urinary bladder and rectum
• 3 layers: 1. Endometrium 2. Myometrium 3. Perimetrium
• Functions of the uterus:
  • Receives / retains a fertilized egg
  • Nourishes the fertilized egg

Penis:

• Delivers sperm into the female reproductive tract
• Regions:
  • Shaft
  • Glans penis (enlarged tip)
  • Prepuce (foreskin)
• Internally 3 areas of spongy erectile tissue around the urethra

Ovulation:

when the egg is mature the follicle ruptures

Haploid:

1N

Oocyte:

The oocyte is viable for 12 to 24 hours after ovulation

Sperm:

are viable for 12 to 48 hours after ejaculation

• Sperm cells must make their way to the uterine tube for fertilization to be possible

Fertilization:

When sperm nucleus... Continue reading "Female Reproductive System and Endocrine Glands" »

Traits are characteristics present in an organism that can be inherited by its offspring.

Homozygotes and Heterozygotes

• Two identical alleles (AA or aa): Homozygous
• Two different alleles (Aa): Heterozygous

A: Dominant allele

a: Recessive allele

Genotype is an organism's set of genes.

Phenotype is the way in which... Continue reading "Understanding Traits, Genes, and Mutations" »