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

Digestive System: Definition and Function

Definition: Set of organs that are responsible for carrying out digestion; this is for transforming food into simple substances that pass into the blood and eliminate undigested remains. Function: Provide nutrients to cells by digesting food.

Stomach

Muscular organ 'J'-shaped, located in the abdominal cavity beneath the diaphragm. It dilates when filled with food. On its internal wall there are gastric glands which secrete gastric acid and mucus. The mucus stops the gastric acid from attacking the stomach's own walls.

Pancreas: Exocrine and Endocrine

Exocrine: It secretes pancreatic juice into the small intestine (duodenum) through the ampulla of Vater. It contains enzymes capable of digesting molecules... Continue reading "Digestive and Cardiac System Functions: Stomach, Liver, Heart" »

1. Human Beings and Health

The World Health Organization (WHO) defines health as 'the complete physical, mental and social well-being, not only the absence of disease'.

The Environment

Healthy surroundings should be free of biological, physical or chemical elements that are harmful to your health.

Personal Characteristics

Genetic factors, age and gender predispose people to suffer from certain types of illnesses.

Lifestyle

Healthy habits and lifestyles are very important for staying healthy.

Healthcare

It is essential to have an efficient healthcare system to guarantee public health.

Vital Signs

Vital signs are physiological parameters that inform us of our state of health or the evolution.

Cause -> Organic Alteration -> Symptoms and Signs ->

Nutrients and Life Stages

The quantity of nutrients that our body needs depends on the stage of life we are in.

• Breastfeeding (0–6 months): Requires breast milk.
• Childhood: Diet gradually becomes similar to an adult diet. Children generally require more calories for growth.
• Adolescence: Nutritional needs are similar to adults.

Nutritional Needs During Adulthood

Specific needs apply, especially during pregnancy. Pregnant women require approximately 300 kcal more per day, increased proteins, specific vitamins (e.g., folic acid), minerals (e.g., calcium), water, and fiber.

Nutritional Needs in Old Age

Older adults generally require similar nutrients to adults, but fewer calories overall.

Macronutrient Distribution and Calories

Recommended Daily Allowance... Continue reading "Essential Health Metrics: Nutrition, Diagnosis, and Disease Facts" »

Origin of Life and Biological Evolution

Theories on Spontaneous Generation

Early experiments tested the concept of spontaneous generation:

• Francesco Redi: Rejected spontaneous generation.
• John Needham: Supported spontaneous generation (later refuted).
• Louis Pasteur: Rejected spontaneous generation using swan-neck flasks.
• Lazzaro Spallanzani: Rejected spontaneous generation.

Darwin's Observations

Species vary globally, locally, and over time.

Biological Evolution

Evolution is characterized by descent from a common ancestor and adaptation to the environment.

Hierarchy of Life Organization

1. Species
2. Population
3. Community
4. Ecosystem
5. Biome
6. Biosphere

Essential Biomolecules

Biomolecules are the fundamental building components of life.

• Carbohydrates (Carbs)

  Primary source

Continental Drift

Pangaea

Plankton

Holoplankton

Zooplankton

Meroplankton

Shark Anatomy and Physiology

Spiracles

Swim Bladder

Lateral Line

Cartilage

Operculum

Marine Reptiles

Crocodile Mothering

Marine Reptile Features

Role of the Mucous Membrane in the Respiratory Tract

Describe the role of the mucous membrane in the respiratory tract:

• Mucociliary escalator:

  The mucus layer is moved by cilia to trap microorganisms and transport them to the throat to be expelled.

• Goblet cells:

  Goblet cells in the mucous membrane produce mucus. They are scattered throughout the membrane and resemble a goblet or wine glass.

• Protection:

  Protects the lower respiratory tract.

Why We Cannot Cure the Common Cold

Why cant we treat the common cold? (Two questions: why is it not possible to find a cure? And why can it not be treated with antibiotics?)

• Viruses cannot be treated with antibiotics.

• Vaccine development challenges: It is difficult to make a broadly effective vaccine because there

1. Interaction and Coordination

The basic path of a nerve impulse from stimulus to response is:

1. A stimulus occurs.
2. Sensory receptors detect the stimulus.
3. Sensory neurons receive the information and transmit it to the central nervous system (CNS).
4. The CNS receives the information and a response is decided.
5. Motor neurons transmit the response to the effectors.
6. Effectors carry out the response. An effector can be a muscle or a gland.
7. The response is given. There are two types: motor responses, which are carried out by muscles, and secretory responses, which are carried out by glands.

Coordination Systems

• Nervous system: Receives and transmits information rapidly via electrical impulses through sensory neurons and processes them in the CNS. Responses are

Non-specific defenses

act against any type of microorganism or foreign particle. This action is carried out by phagocytes: white blood cells that trap and eliminate pathogenic microorganisms. This process is called phagocytosis.

INFLAMMATORY RESPONSE

is a non-specific defense mechanism. When pathogens get through the external barriers, the blood cells dilate to increase the blood flow. The result is pus.

Specific defenses

act against specific microorganisms or foreign molecules. Other types of leukocytes, called lymphocytes, produce proteins called antibodies. Antibodies are specific for each microorganism and destroy or inactivate the invading agents.

INCUBATION - this is the time between the moment the pathogenic agents invade organisms and the... Continue reading "Understanding Body Defenses and Diseases: A Comprehensive Guide" »

Classification of Living Organisms into Three Domains

Living organisms were originally divided into five kingdoms based on the presence of certain structural features. In 1978, this system was refined to account for clear biochemical differences between living organisms, specifically differences in rRNA sequences. According to the three-domain classification scheme, there are three distinct types of cellular organisms to which all living things belong:

• Eukarya: Contain a membrane-bound nucleus (includes plants, animals, protists, and fungi).
• Eubacteria: Lack a nucleus and consist of the traditional or 'true' bacteria (e.g., most pathogenic forms, E. coli, S. aureus, etc.).
• Archaea: Lack a nucleus and consist of the extremophiles or 'ancient' bacteria