Introduction to Medical Terminologies

1. Introduction to Medical
Terminologies
Lecture 04
PREPARED BY
MUHAMMAD SALMAN BUTT
1SAUDI ELECTRONIC UNIVERSITY

2. Lecture: 4
oWhat is an ossification process
oWhat are the different types of cells important in bone formation
oWhat are the important physiological processes in the body to maintain homeostasis
oWhat is a feedback mechanism and different types of feedback mechanism
oWhat are the chemical reaction happening in the body
oHow the chemical compounds formed and what are the different types of chemical compounds
oWhat are the organic compounds and how they are different from the inorganic compounds.
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3. Chapter 10: The Ossification
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4. The Ossification
The process of bone formation is known as ossification.
Types of ossification:
According to embryological origin, there are 2 types of ossification.
1. Intramembranous Ossification: In this type of bone formation, the embryonic mesenchyme
directly differentiates into bony tissue. This process usually occurs in case of those bones
which are urgently required for support or protection. e.g. Bone of skull, face and clavicle.
2. Intra-cartilagenous or endo-chondral ossification. In this type of ossification, first of all a
cartilaginous model of bone is formed which is later on replaced by bony tissue. It is
altogether more leisurely phenomenon. e.g. All long bones except clavicle, short bones.
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5. Cells participating in ossification.
Four types of cells are involved in ostenogenesis. It should be kept in mind that the cytological
aspects are the same in intramembranous as well as intracartilagenous ossification.
1. Osteogenic Cells: These are elongated, irregular cells. The cytoplasm and nuclei are pale
staining. They can be identified by following features.
A. Location: They are seen at 2 places:-
a) In the region of mesenchyme where bone formation is occurring.
b) In the areas near the surface of growing bones.
B. They are seen in association with osteoblasts.
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6. Cells participating in ossification.
2. Osteoblasts (Bone-Building Cells): They are generally larger than Osteogenic cells. These cells
are responsible for secretion of organic components of bone matrix. e.g. collagen fibres and
osseoproteins.
3. Osteocytes (Bone Preserving Cells): These are almond shaped cells present in spaces of
matrix called Lacunae. The osteocytes are derived from osteoblasts by modulation. These cells
maintain the constituents of matrix at normal level.
4. Osteoclasts (Bone-destroying cells): These are multinucleated gain cells found in depressions
called “Howships’s Lacunae”. These cells reabsorption of bone by releasing proteolytic enzymes
contained in the lysosomes.
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7. Chapter 11: Introduction to Human Physiology
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8. Introduction
Physiology is the science of body functions, that is, how the body parts work.
The Internal Environment: About 60 per cent of the adult human body is fluid, mainly a water
solution of ions and other substances. Although most of this fluid is inside the cells and is called
intracellular fluid, about one third is in the spaces outside the cells and is called extracellular fluid.
The extracellular fluid is also called the internal environment of the body.
Metabolism is the sum of all the chemical processes that occur in the body. It includes the
breakdown of large, complex molecules into smaller, simpler ones and the building up of complex
molecules from smaller, simpler ones. For example, proteins in food are split into amino acids. The
amino acids are the building blocks that can then be used to build new proteins that make up
muscles and bones.
Responsiveness is the body’s ability to detect and respond to changes in its internal (inside the
body) or external (outside the body) environment.
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9. Introduction
1) A disorder is any abnormality of structure and/or function.
2) Disease is a more specific term for an illness characterized by a recognizable set of symptoms and signs.
3) Symptoms are subjective changes in body functions that are not apparent to an observer for example,
headache or nausea.
4) Signs are objective changes that a clinician can observe and measure, such as bleeding, swelling,
vomiting, diarrhea, fever, a rash, or paralysis.
5) Diffusion: Movement of ions from higher concentration to lower concentration.
6) Osmosis: Osmosis is a passive process in which there is a net movement of water through a selectively
permeable membrane. Water moves by osmosis from an area of higher water concentration to an area of
lower water concentration (or from an area of lower solute concentration to an area of higher solute
concentration).
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10. HOMEOSTASIS
The trillions of cells of the human body need relatively stable conditions to function effectively
and contribute to the survival of the body as a whole. The maintenance of relatively stable
conditions is called homeostasis. Homeostasis ensures that the body’s internal environment
remains constant despite changes inside and outside the body.
Control of Homeostasis: Feedback Systems: The homeostatic mechanisms of the body are
mainly under the control of two systems, the nervous system and the endocrine system.
1- Nervous System: The nervous system detects changes from the balanced state and sends
messages in the form of nerve impulses to organs that can counteract the change.
2- Endocrine System: The endocrine system corrects changes by secreting molecules called
hormones into the blood. Hormones affect specific body cells, where they cause responses that
restore homeostasis
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11. Control of Homeostasis: Feedback Systems
Homeostasis is maintained by means of many feedback systems. A feedback system or feedback
loop is a cycle of events in which a condition in the body is continually monitored, evaluated,
changed, re-monitored, reevaluated, and so on.
Three basic components make up a feedback system: a receptor, a control center, and an
effector.
1- A receptor is a body structure that monitors changes in a controlled condition and sends
information called the input to a control center. Input is in the form of nerve impulses or
chemical signals. Nerve endings in the skin that sense temperature are one of the hundreds of
different kinds of receptors in the body.
2- A control center in the body, for example, the brain, sets the range of values within which a
controlled condition should be maintained, evaluates the input it receives from receptors, and
generates output commands when they are needed. Output is information, in the form of nerve
impulses or chemical signals, that is relayed from the control center to an effector.
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12. Control of Homeostasis: Feedback Systems
3- An effector is a body structure that receives output
from the control center and produces a response that
changes the controlled condition. Nearly every organ or
tissue in the body can behave as an effector. For
example, when your body temperature drops sharply,
your brain (control center) sends nerve impulses to your
skeletal muscles (effectors) that cause you to shiver,
which generates heat and raises your temperature.
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13. Types of Feedback
1- Negative Feedback Systems : It reverses a change in a controlled condition. Example: After
eating the level of glucose increases in the body. Pancreas detect the increase in blood glucose and
release the Insulin hormone. Insulin is taken up by the body cells and lower the blood glucose level.
2- Positive Feedback System: It strengthens a change in a controlled condition. Normal positive
feedback systems tend to reinforce conditions that don’t happen very often, such as childbirth,
ovulation, and blood clotting. Because a positive feedback system continually reinforces a change in
a controlled condition, it must be shut off by some event outside the system. If the action of a
positive feedback system isn’t stopped, it can “run away” and produce life-threatening changes in
the body.
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14. Chapter 11: Introduction to Chemistry
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15. Introduction
1) Chemistry: It is the science of the structure and interactions of matter.
2) Matter: It is anything that occupies space and has mass.
3) Mass: Mass is the amount of matter in any living organism or nonliving thing.
4) Chemical elements: All forms of matter are made up of a limited number of building blocks called
chemical elements, substances that cannot be broken down into a simpler form by ordinary
chemical means.
5) Chemical bonds hold the atoms of a molecule together. Electrons in the valence shell (outermost
shell) are the parts of an atom that participate in chemical reactions (are involved in forming and
breaking bonds).
6) A free radical is a destructive ion or molecule that has an unpaired electron in its outermost shell.
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16. Atom
Atom: Each element is made up of atoms, the
smallest units of matter that retain the
properties and characteristics of the element.
An atom consists of two basic parts:
1. The centrally located nucleus contains
positively charged protons ( p) and
uncharged (neutral) neutrons (n0).
2. The electrons (e) are tiny, negatively
charged particles that move about in a
large space surrounding the nucleus
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17. Ions, Molecules, and Compounds
1) A molecule consists of two or more atoms
sharing electrons
2) A molecular formula indicates the number
and type of atoms that make up a molecule
3) A compound is a substance containing atoms
of two or more different elements
4) A free radical is an ion or molecule that has
an unpaired electron in its outermost shell
5) Energy is the capacity to do work.
6) Potential energy is energy stored by matter
due to its position.
7) Kinetic energy is the energy of matter in
motion.
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Formation of Ions
Sodium Atom Sodium ion + 1 electron
Chlorine + 1 electron Chlorine ion
Formation of Molecule
Sodium ion + Chlorine ion Sodium Chloride
(Salt)

19. Synthesis of a molecule
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20. Decomposition of a molecule
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21. Chemical Compounds.
Inorganic Compound: Inorganic compounds usually lack carbon, are structurally simple, and are
held together by ionic or covalent bonds. They include water, many salts, acids, and bases.
Types of Inorganic Compounds:
1. Water: The chemical composition of water is 2 atom of Hydrogen combine with one atom of
oxygen. H-O-H or H2O.
2. Base: base, by contrast, usually dissociates into one or more hydroxide ions (OH) when it
dissolves in water
3. Acid: It is a substance that breaks apart or dissociates into one or more hydrogen ions (H) when
it dissolves in water
4. Salt: A salt, when dissolved in water, dissociates into cations (- ions) and anions (+ ions), neither
of which is H or OH
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22. PH Scale
1. A solution’s acidity or alkalinity is expressed on the pH scale, which extends from 0 to 14.
2. This scale is based on the number of hydrogen ions in a solution.
3. The midpoint of the pH scale is 7, where the numbers of H and OH are equal. A solution with a pH
of 7, such as pure water, is neutral—neither acidic nor alkaline.
4. A solution that has more H than OH is acidic and has a pH below 7.
5. A solution that has more OH than H is basic (alkaline) and has a pH above 7.
Maintaining pH: Buffer Systems
1. Buffers are chemical compounds that act quickly to temporarily bind H, removing the highly
reactive, excess H from solution but not from the body.
2. Buffers prevent rapid, drastic changes in the pH of a body fluid by converting strong acids and
bases into weak acids and bases.
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23. Organic Compounds
Organic compound: Organic compounds, by contrast, always contain carbon, usually contain
hydrogen, and always have covalent bonds. Examples include carbohydrates, lipids, proteins,
nucleic acids, and adenosine triphosphate (ATP).
1. Carbohydrates are organic compounds and include sugars, glycogen, starches, and cellulose.
The elements present in carbohydrates are carbon, hydrogen, and oxygen. The ratio of carbon to
hydrogen to oxygen atoms is usually 1:2:1. For example, the molecular formula for the small
carbohydrate glucose is C6H12O6.
Carbohydrates are divided into three major groups based on their size: monosaccharides,
disaccharides, and polysaccharides. Monosaccharides and disaccharides are termed simple
sugars, and polysaccharides are also known as complex carbohydrates.
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24. Organic Compounds
2. Lipids: Lipids contain carbon, hydrogen, and oxygen. Unlike carbohydrates, they do not have a
2:1 ratio of hydrogen to oxygen. The proportion of oxygen atoms in lipids is usually smaller than
in carbohydrates.
The diverse lipid family includes triglycerides (fats and oils), phospholipids (lipids that contain
phosphorus), steroids, fatty acids, and fat-soluble vitamins (vitamins A, D, E, and K).
3. Protein: Proteins are large molecules that contain carbon, hydrogen, oxygen, and nitrogen;
some proteins also contain sulfur.
Amino acids are the building blocks of proteins. All amino acids have an amino group (—NH2) at
one end and a carboxyl group (—COOH) at the other end. Each of the 20 different amino acids
has a different side chain (R group).
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25. SAUDI ELECTRONIC UNIVERSITY 25
Amino Acid

26. Organic Compounds
4. Enzymes: Enzymes are the living cell’s
solution to this problem, because they speed
up chemical reactions by increasing the
frequency of collisions and by properly
orienting the colliding molecules.
Substances such as enzymes that can speed up
chemical reactions without themselves being
altered are called catalysts.
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An enzyme speeds up a chemical reaction without
being altered or consumed

27. Nucleic Acids: Deoxyribonucleic Acid (DNA)
and Ribonucleic Acid (RNA)
Nucleic acids so named because they were first discovered in the nuclei of cells, are huge organic
molecules that contain carbon, hydrogen, oxygen, nitrogen, and phosphorus.
A nucleic acid molecule is composed of repeating building blocks called nucleotides.
Types of Nucleic Acid
The two kinds of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
1. Deoxyribonucleic Acid (DNA): Each nucleotide of DNA consists of three parts;
a. One of four different nitrogenous bases, ring-shaped molecules that contain atoms of C, H, O, and N.
In DNA, the four bases are Adenine (A), Thymine (T), Cytosine (C) and Guanine.
b. A five-carbon monosaccharide called deoxyribose.
c. A phosphate group (PO43).
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28. Structure of DNA
1. The molecule consists of two strands, with
crossbars. The strands twist about each
other in the form of a double helix so that
the shape resembles a twisted rope ladder.
2. The uprights (strands) of the DNA ladder
consist of alternating phosphate groups
and the deoxyribose portions of the
nucleotides.
3. The rungs of the ladder contain paired
nitrogenous bases, which are held together
by hydrogen bonds. Adenine always pairs
with thymine, and cytosine always pairs
with guanine.
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The paired nitrogenous bases project toward the center of the double
helix. The structure is stabilized by hydrogen bonds (dotted lines)
between each base pair. There are two hydrogen bonds between
adenine and thymine and three between cytosine and guanine.

29. Adenosine Triphosphate
Adenosine triphosphate (ATP) is the “energy currency” of living organisms.
ATP transfers energy from energy releasing reactions to energy-requiring reactions that maintain
cellular activities. Among these cellular activities are contraction of muscles, movement of
chromosomes during cell division, movement of structures within cells, transport of substances
across cell membranes, and synthesis of larger molecules from smaller ones.
Structure of ATP
Structurally, ATP consists of three phosphate groups attached to adenosine, which is composed
of adenine and ribose.
Energy Reaction
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