Notes, abstracts, papers, exams and problems of Biology

Which Nerve Slows the Heart Down?

The Vagus Nerve

Function of Heart Valves

Heart valves ensure one-way blood flow.

Atrioventricular Valves

• Tricuspid valve (3 cusps): Located between the right atrium and right ventricle.
• Bicuspid (mitral) valve (2 cusps): Located between the left atrium and left ventricle.
• Chordae Tendineae: Also known as 'heart strings'.

Semilunar Valves

• Pulmonary semilunar valve: Directs blood from the right ventricle to the pulmonary trunk.
• Aortic semilunar valve: Directs blood from the left ventricle to the aorta.

Arteries vs. Veins

Arteries carry oxygenated blood away from the heart to the body, while veins carry oxygen-poor blood back from the body to the heart.

Three Functions of Blood

Blood has three main functions:

1. Transportation:

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 ->

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

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" »

Cell Organization and Structure

Cells in Humans (Eukaryotic Cells)

Cell Membrane

The outermost membrane, a lipid bilayer, controls what enters and exits the cell. This structure is also used in vaccine production to hold mRNA.

Mitochondria (Mitochondrion)

The powerhouse of the cell, responsible for ATP (Adenosine triphosphate) production. The ATP production rate depends on the folds of cristae. Some cells, like liver cells, have multiple mitochondria. The mitochondrion contains a matrix, a thick liquid with a high concentration of enzymes that facilitate ATP production.

Lysosome

The cell's recycle bin.

Golgi Apparatus

Packages proteins for transport in and out of cells.

Rough Endoplasmic Reticulum

Creates proteins.

Smooth Endoplasmic Reticulum

Creates... Continue reading "Cell Biology: Structure, Function, and Chemical Reactions" »

Human Eye Structure and Function

Key Components:

• Conjunctiva: Thin, transparent membrane lining the front of the sclera. It's moistened by tears, produced in the tear glands, which contain lysozyme, an enzyme that kills bacteria.
• Pupil: Opening in the iris through which light passes. It controls the amount of light entering the eye and appears black due to the black pigment of the choroid.
• Lens: Clear structure that allows light into the eye. It's made of stiff jelly and can change shape to focus light.
• Iris: Colored part of the eye that responds to light.
• Cornea: Transparent, protective layer at the front of the eye.
• Suspensory Ligaments: Fibers supporting the lens. When pulled tight, the lens is thin; when loosened, the lens is thicker.
• Ciliary Muscles:

Ecology

The scientific study of how organisms interact with each other and with their non-living environment.

Ecological Niche

The manner in which an organism uses the resources in, and is influenced by the conditions of its habitat.

Habitat

The physical place, or type of place, where an organism lives.

Physical Adaptation

Genetically-inherited characteristics that enable a given organism to survive and reproduce using a given niche.

Niche Partitioning

The division of niches between species so as to cut down on competition.

Resource

A material that is used, and potentially used up.

Environmental Conditions

Background features of the habitat.

Fundamental Niche

The largest array of resources an organism can utilize.

Realized Niche

The actual set of resources... Continue reading "Ecology: The Study of Organism Interactions and Adaptations" »

Nucleus:

Converts genetic material, controls all the cell, and contains nucleolus.

Mitochondria:

Converts solar energy in food to usable compounds.

Chloroplast:

Converts solar energy to chemical energy stored in food.

Cytoskeleton:

Maintains cell shape and helps cell move.

Ribosomes:

Synthesize proteins.

Endoplasmic Reticulum:

Assembles proteins and lipids.

Vacuoles and Vesicles:

Store materials.

Centrioles:

Organize cell division.

Cell Membrane:

Regulates materials that enter and leave the cells.

Golgi Apparatus:

Packages proteins and lipids for storage or transport out of the cell.

Cell Wall:

Shapes, supports, and protects cell.

Lysosomes:

Break down and recycle macromolecules.

Cytoplasm:

Gel-like mixture, surrounded by cell membrane, contains hereditary... Continue reading "Functions of Cell Organelles" »