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Chapter 1

HLTB21H3 Chapter Notes - Chapter 1: Cell Theory, Neuroglia, Ob River


Department
Health Studies
Course Code
HLTB21H3
Professor
Suzanne Sicchia
Chapter
1

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Human Biology and Health
Overview
Discipline of science dates back to about 2,500 years to ancient Greece
Derived from Greek episteme-distinguishes science as knowing not only that something
is so, act of experience, but also why it is so
Metaphysics- An act of the ‘knowledge of first causes’ as stated by Aristotle
Introduction
Biology is science of life (bios meaning life and logos meaning reasoned account)
Study of living organism, what they are made of and how they function and how they
interact with each other and the environment
Broad academic fields including zoology, botany and physiology—(aims to unravel
how the body functions, for ex mechanisms by which a person feels pain, pumps blood
round the body, breathes in and out, absorbs food
Science divided into basic and applied:
Basic or pure science is description and understanding of phenomena and can be
applied to many areas
Applied is application of scientific principles to meet a specific, recognized need. For
ex biomedical sciences may apply scientific principles and methods to human illness in
the hope of treating a disease
The Contributions of biology to heath
Biology: Scientific discipline that contributes to our understanding of the bodily
processes and functions that keep us alive in various states of health
Studies how a body functions; it is not of itself clinical
Informs medicine but has separate identity
Investigates what living organisms are made of, the chemicals and structures, as well as
what they do
Cell Theory
Cells: Smallest functioning unit within which life can be carried out; little chemical
factories
Organisms composed of one microscopic cell are called unicellular and those that have
billions of cells are multicellular like humans
Tissues: Groups of structurally and functionally similar cells; can be solid such as skin,
or liquid such as blood
Categorized into four types:
Nervous tissue: Cells that conduct electrical potentials (neurons) and support cells glia

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Muscle tissue: Consists of the skeletal, voluntary muscle that we use in locomotion,
smooth, involuntary muscle that moves our internal organs such as the waves of
contraction (peristalsis) that move food through gastrointestinal tract, and cardiac muscle
that pumps liquid blood into blood vessels for transport around bodies
Connective tissue: Comprises many cells types including: bone, cartilage and tendons,
as part of skeleton, blood cells and liquid plasma, fibroblasts and their secretions such as
collagen, elastin, and adipose fat tissue as well as dermal layer
Epithelial tissue: Comprising epidermis and endodermis, lining outer surfaces such as
skin and inner surfaces such as blood vessels and kidney tubules
Organs: Specialized structures composed of tissues that carry out certain functions. For
ex the heart is an organ that pumps blood, whereas stomach breaks down food
Cloning: Transferring nuclei into eggs is a form of cloning. Two types of nuclear cloning
are therapeutic and reproductive (both rely on the transfer of a nucleus from a somatic
cell into a recipient cell- somatic cell nuclear transfer (SCNT)
Therapeutic cloning into an egg cell may yield embryonic stem cells whereas
reproductive cloning aims to make a fully developed replica of the organism being cloned
by implanting altered egg cell into uterus and allowing it to grow into an independent
organism
Embryonic stem cells: Stem cells produce all the types of cells of the body during early
development (ESC)
Somatic stem cells (SSC): Replace and maintain cell numbers in the adult
Differentiation: How one type of cell, the stem cell, can make many types of functional
end cells such as red blood cells, kidney cells and pancreatic cells
Homeostasis
Keeping balance and maintain a stable internal environment is known as homeostasis
Cells must maintain themselves within very strict and quite narrow ranges; humans have
cells that function only within a temp range around 37oC and strict oxygen/carbon
dioxide limits
Other cells, such as those of aquatic organisms or plants, have diff ranges, but still need
to be kept within their optimal limits for the cell to survive and flourish
Claude Bernard first observed that it is the constancy of the internal environment which
is the condition of free and independent life. All vital mechanisms varied they may be,
have only one object, that of preserving constant the conditions of life in the internal
environ
Cells are bathed by interstitial fluid, which is their internal environ; this helps provide
nutrients and oxygen to sustain the life of each cell
Waste products from the cell’s metabolism are added to the internal environment before
being removed to the blood and then disposed of in various ways
Genes and Genetics
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