Cell Biology Fundamentals: Structure, Function, Types

Cell Theory Explained

Cell theory states:

  • The cell is the fundamental structural and anatomical unit of all living organisms. All organisms are formed by one or more cells.
  • The cell is the basic physiological or functional unit. Every cell is capable of maintaining life independently.
  • Cells are the unit of genetic origin. Every cell derives from a pre-existing cell.

Common Characteristics of All Cells

All cells share these common characteristics:

  • A cell membrane
  • A set of structures called organelles
  • Genetic
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Human Circulatory System: Function and Blood Flow Q&A

Understanding the Human Circulatory System

1. Are red blood cells and platelets true cells?

Red blood cells are specialized cells (lacking a nucleus in mammals). Platelets, however, are not true cells; they are fragments of larger cells (megakaryocytes).

2. Explain the link between low hemoglobin and fatigue in anemia.

Anemia often involves low hemoglobin, the protein in red blood cells that carries oxygen. Insufficient hemoglobin leads to reduced oxygen delivery to tissues, causing symptoms like fatigue

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Key Concepts in Biology and Ecology

Adaptations

Features which enable organisms to survive are called adaptations. Adaptations can be classified as anatomical, physiological, or behavioural.

Types of Adaptations

  • Anatomical adaptations are the structures of an organism that are modified to perform an adapted function.
  • Physiological adaptations are features of the processes inside an organism’s body that increase its chance of survival or reproduction.
  • Behavioural adaptations are any actions by organisms which help them to survive or reproduce.
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Maxillary Premolar and Molar Root Canal Anatomy

Maxillary Second Premolar Anatomy

This tooth typically has one root (88%) or two roots (12%). Root canal configurations within a single root can vary:

  • Type I (One canal): 53%
  • Type II (Two canals merging into one): 22%
  • Type III (Two separate canals): 12%

One, two, or three canals can occur within a single root, although the incidence of three canals is low (1%). The majority of teeth have a single canal extending to the apex.

Buccal View (Recently Calcified)

A view of a recently calcified second premolar

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Human Digestive and Respiratory Systems

Digestive System

The function of the digestive system is to transform food into simple compounds called nutrients.

Nutrition vs. Digestion

The difference between nutrition and digestion is that:

  • Nutrition: Involves all the processes by which the body takes in, digests, absorbs, and uses food.
  • Digestion: Is the process of breaking down food into the smallest particles that can be absorbed by the blood.

It is made up of the digestive tract (mouth, pharynx, esophagus, stomach, small intestine, and large

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Understanding Infection and Immunity

Infection and Immunity

What is Infection?

Infection is the clinical term for the colonization of a host organism by external species. In clinical use, infection implies that the colonization is harmful, making the organism a pathogen.

What is Immunity?

Immunity describes having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity has both specific and nonspecific components. Nonspecific components act as barriers or eliminate pathogens before

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