Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

Nutrition: The digestive system (introduces food and transforms it), respiratory system (obtains O₂ and eliminates CO₂), circulatory system (transports nutrients and oxygen), and excretory system (releases waste substances outside the organism). Digestive System The gastrointestinal tract (about 8 meters long, starts in our mouth and ends at our anus) consists of the following parts: oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine. The mucus, produced by an inner cell called the mucous membrane, creates a lubricant substance called mucus. Accessory glands include salivary glands, the liver, and the pancreas. Digestion: This is the process by which foods are transformed into nutrients. Mechanical processes (like...

The Digestive System

Liver

The liver, the largest internal organ, contains ducts called hepatocytes. These hepatocytes collect bile secreted by liver cells. The liver plays a crucial role in the metabolism of carbohydrates, lipids, and proteins.

Gallbladder

The gallbladder is a pear-shaped structure located under the liver. Its primary function is to store bile.

Pancreas

The pancreas is a long, narrow gland with two ducts, located on the left side of the abdomen.

Small Intestine

The small intestine starts at the pylorus and ends at the ileocaecal valve, where it joins the large intestine. It has two main parts:

• Duodenum: Secretes bile and pancreatic juice into this section.
• Jejunum and Ileum: Form the rest of the intestine. The small intestine is covered

Cell Organelles

Mitochondria: Oval-shaped organelles with two membranes. Through cellular respiration, mitochondria produce energy for the cell.

Vesicles: Small, rounded organelles that store, transport, or digest cellular substances. Lysosomes are rounded vesicles produced by the Golgi body.

Endoplasmic Reticulum: A network of interconnected membranous sacs and channels. There are two types:

• Rough ER: Connected with the nuclear envelope and ribosomes.
• Smooth ER: This type has no attached ribosomes.

Golgi Body: Flat, membranous sacs arranged in layers. Secretory vesicles transport substances out of the cell.

Centrosome: Consists of two centrioles: perpendicular cylindrical structures composed of microtubules. They are surrounded by other microtubules...

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

Human Body Organization

The human body is structured in a hierarchical manner, from the smallest components to the entire organism and its interactions within an ecosystem.

1. Subatomic Level

Consists of subatomic particles, i.e., protons, electrons, and neutrons (and sub-particles like quarks and leptons).

2. Atomic Level

Formed by atoms, the bioelements found in living beings. These include:

• Primary Bioelements: Essential for forming organic biomolecules (C, H, O, N, P, S), constituting 96% of dry living matter.
• Secondary Bioelements: Constitute 3% of dry living matter.
• Trace Elements: Present in small amounts but crucial for health (e.g., iron, iodine).

3. Molecular Level

Molecules are formed by grouping two or more atoms. Biomolecules in living beings...

Organs and Organ Systems

Organs

Organs are complex structures composed of various types of tissue. They perform single or similar functions.

Organ Transplant

Organ transplant is the replacement of a damaged organ or tissue. A common problem is rejection.

Organ Systems

• Nutrition:
  • Digestive system: Digests food and absorbs nutrients.
  • Respiratory system: Exchanges O2 and CO2.
  • Circulatory system: Transports substances throughout the body.
  • Excretory system: Removes metabolic waste, such as urine.
• Interaction:
  • Nervous system: Receives stimuli and sends instructions.
  • Endocrine system: Produces hormones.
  • Locomotive system: Enables movement and provides protection.
• Reproduction:
  • Reproductive system: Creates new life.

Health and Illness

Concept of Health

Health is a state...

Fertilization

Fertilization occurs when a sperm and an ovum unite, forming a zygote. This process requires both ovulation and sexual intercourse. It's only possible during a 24-48 hour window after ovulation, although sperm can survive up to 5 days inside the female reproductive tract. The sperm penetrates the ovum's covering, and a fertilizing membrane forms, preventing other sperm from entering. The nuclei of the sperm and ovum join. After fertilization, the zygote travels to the uterus. The corpus luteum continues to release progesterone, maintaining the thick endometrium walls and preventing menstruation. During its journey, the zygote divides, becoming a ball of cells called a morula (around day 4) and then a blastocyst (around day 5)....

Understanding Heredity

Traits

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

Genes and Alleles

A gene is a section of DNA containing information about a specific trait and controlling that trait. Alleles are the different alternatives that a gene controlling a particular trait can have.

Homozygous and Heterozygous

• Homozygous: If the two alleles of a specific gene are identical (e.g., AA or aa), the individual is homozygous or pure for that trait.
• Heterozygous: If the two alleles of a specific gene are different (e.g., Aa), the individual is heterozygous or hybrid for that trait. (A is the dominant allele and a is the recessive allele).

Genotype and Phenotype

• Genotype: An organism's set of genes.
• Phenotype: The

• The outer ear: it is formed by the pinna and the auditory canal.
• The middle ear: a cavity in the eardrum that reaches the oval window and the round window.
• The inner ear: formed by the membranous labyrinth.
• Sweat gland: this secretes sweat, cooling the body surface when it is necessary and removing certain waste substances.
• Sebaceous gland: these secretes substances that lubricate the skin and hair.
• Taste buds: are located inside the mouth especially on the tongue.
• Long bones: these are long and contain spongy bone tissue at either end, as well as compact bone.
• Short bones: these are rounded and mostly made up of spongy bone tissue.
• Flat bones: these are plate-shaped. Formed by an inner layer of bone tissue surrounded by two layers of compact bone

SPERMATOZOA