INTRODUCTION TO HUMAN PHYSIOLOGY

Dr. Matwa C. OBSc (Hons); MBChB

OVERVIEW

Concept of normalcy Descriptive terms Units of expression

HUMAN PHYSIOLOGY

• Physiology: • Biological science• Dealing with the normal life phenomena

exhibited by all living organisms.• Human physiology:

• Basic science• Dealing with normal life phenomena of

the human body. • Goal of physiology:

• explain the physical and chemical factors that are responsible for the origin, development and progression of life.

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HUMAN PHYSIOLOGY Physiology:

GreekThe study of nature, the involvement of

Physics and Chemistry. The basis for

PathophysiologyPharmacology Immunology Biochemistry Microbiology

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WHY DO WE STUDY PHYSIOLOGY?

Understand the physiological principle that underlies the normal function in order to cure the impairment

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Organization of the human body

CellsTissues

Organs

Organ systems

Organisms(Human body)

Different Level of Physiological Research

HUMAN BODY

Comprises a variety of systems that function in synchrony: Gastro-intestinal Respiratory Urinary Cardiovascular Reproductive Nervous Endocrine Musculo-skeletal etc

NORMALCY

Being within certain limits that define the range of normal functioning

Oxford Illustrated Dictionary, 1962: normal is what corresponds to the standard, regular, usual, typical

Medical and sociological concepts Littre and Robin, 1873: normal is what is in

line with a rule/norm Laland, 1938: normal is what we see in most

specimens of the same species or what represents an average or a unit of measure

CONT’D

A philosopher discussing a problem of mutual interest with a physician flatly states, "The normal is simply the most usual and I have an inclination to use it that way."

A psychologist states, in his textbook, that the term normal always refers to the middle of the distribution and that the idiot is about as abnormal as the genius.

An educator and a neurologist use the word in a similar manner.

CONT’D

Concept of normality branches into several source concepts: Biological normality Physiological normality Anthropological normality Socio-psychological normality Legal normatility

OFFER AND SABSHIN

In 1991, they developed a framework to decipher normalcyI. Normality as health:

Equivalent to absence of disease

II. Normality as utopia Optimal functioning

III. Normality as average Average of measured variables that are measured

severally over a period of time

IV. Normatology Scientific study of normality over a life cycle

PHYSIOLOGICAL CONCEPT OF NORMALCY

To cure means to restore a function or an organism to a healthy state

concept of complete health = ideal type Where the physician takes the norm from?

From his/her own knowledge of physiology From his/her own perception of organ functions From a norm currently of general value

We perceive the life and health of an individual (and of society) in a way that we see first the mistakes, irregularities and violations, and only afterwards do we see regularities

PHYSIOLOGICAL APPROACHES

Two approaches Claude Bernard's idea of the internal

environment "The stability of the internal environment [the milieu

intérieur] is the condition for the free and independent life.“

Muller’s and Ludwig’s theoryunderstanding of functioning of internal and

external environment (biological and socio-ecological) and man’s constitution

HOW TO DETERMINE THE BORDERLINE BETWEEN NORMAL AND PATHOLOGICAL?

Pathological positive or negative quantitative deviation from

physiological Pathological is opposite to normal

marked by hyper and hypo Concept of biological reserve

ADOLPHE QUETELET

1835, presented anthropometric theory measurements of human trait are grouped

according to the normal curve This normal variation helped to provide proof

that a population produces enough variation for artificial or natural selection to operate

Quetelet's established a simple measure for classifying people's weight relative to an ideal weight for their height. His proposal, the body mass index (or Quetelet index), has endured with minor variations to the present day

CONT’D

Biometrical measurements of population: data on temperature, basal blood and tissue

metabolism development of comparative physiology, anatomy,

pathology – tabulae biologicae

comparison of individual variables and their associations with climate and race

CONT’D

Normalization process of restoring organs, organisms,

individuals or community to a normal state –establishment of biological and physiological processes for normal functioning of an organism

Theory of normalization theoretical and therapeutic contrast to theory of

labeling Normalization

different meaning within ethnic groups

DESCRIPTIVE TERMS Homeostasis

Maintainance of relatively constant physical/ chemical conditions of the internal environment

Total body water fluid enclosed by the integument

Intracellular fluid (ICF) Fluid within cells Aka cytosol

CONT’D

Extracellular fluid (ECF) All body fluid outside cells Aka internal environment, divided into:

Interstitial fluid: Fluid that bathes and surrounds cells Aka tissue fluid• Blood Plasma: pale-yellow fluid component of blood that normally

holds the blood cells in whole blood in suspension• Lymph fluid: Fluid that circulates through lymphatic system• Trans-cellular fluid:• Fluid that is found within epithelial lined spaces

CONT’D

Buffer: A substance that has the ability to bind or

release H⁺ in solution Electrolytes:

Molecules that dissolve in water to their anions and cations

Hyper -.. Greater

Iso-.. Same

Hypo-.. lesser

CONT’D

Amphipathic molecules contain both a polar and a non-polar region.

The membrane potential difference is defined as the potential inside the cell minus

the potential outside the cell. The difference is transiently reversed during an Action potential.

CONT’D Diffusion

is a net transport of atoms or molecules caused by their random thermal motion in an attempt to equalise concentration differences (DC).

Flux ( J ) is the amount of a substance transported along a

pressure gradient through an area unit (A is measured in m2) of a membrane in moles per second (s). Convective flux is the net amount of molecules transported through A per time unit (mol s-1 m-2), caused by a pressure gradient and fluid (liquid or air) volume transport. Influx Efflux

CONT’D An ideal semi-permeable membrane

is permeable to water only, but impermeable to all solutes. Most real semi-permeable membranes are permeable to water and to low molecular substances (crystalloids), but not to macromolecular substances (colloids such as proteins)

A permeable membrane allows the passage of all dissolved substances

and the solvent (mainly water). A selectively permeable membrane

is permeable to a particular compound (sucrose, Na+, Ca2+, anions only or to cations only).

UNITS OF EXPRESSION Pressure (P )

is measured as force per area unit - that is in Newton per square m or Pascal.

Osmosis is transport of solvent molecules (mainly water) through

a semi-permeable membrane. Osmotic pressure (p) is the hydrostatic pressure, that must be applied to the side of a rigid ideal semi-permeable membrane with higher solute concentration in order to stop the water flux, so that the net water flux is zero.

Volume (V ) in liters (L). Standard temperature, pressure, dry (STPD) is an

abbreviation for a volume at standard temperature of 273 K, standard pressure of 101.3 kPa or 760 mmHg, and dry air

UNITS OF EXPRESSION

Concentration: Mass or mole of a substance per unit of fluid volume [K⁺] for potassium 4.3mmol/L

Mole (mol) Gram-molecular weight of a substance Amount of the substance that contains Avogadro’s number 6.022

x 1023 molecules per mol 1 mole of CaCO3 = 40g + 12g + (8*3)24g =76g

Molecular weight The ratio of the mass of one molecule of a substance to 1/12 of

the mass of an atom of C-12 Dalton (Da) [atomic mass unit]

A unit of mass equal to 1/12 the mass of an atom of C-12

CONT’D

Equivalence (eq) Electrical eq:

1eq is 1mol of an ionized substance divided by its valence

1eq of Ca2+ = 40g/2 = 20g Chemical eq:

A gram eq is the weight of a substance that’s chemically equivalent to 8g of oxygen

Normality of a solution (N) Number of gram equivalents in 1L Number of equivalents per liter (eqL-1)

CONT’D

Molarity (M) Number of moles of a substance totally dissolved

per liter of solution mol/L

Molality Number of moles of a substance totally dissolved

per kilogram (kg) of solvent

CONT’D

Osmoles (Osm): One Osm equals gram-molecular weight of a

substance divided by the number of freely moving particles that each molecule liberates in solution

NaCl liberates 2 Osm Osmolarity

Number of osmotically active particles (Osm) dissolved in a liter of solution

Osm/L Osmolality

Measure of osmotically active particles in 1kg of solvent

Solvent mostly water (plasma fluid) Osm/kgH2O

CONT’D

1milli-.. 1/1000 (10-3) of a measure 1milligram = 0.001g m

1micro-.. 1/1,000,000 (10-6) of a measure 1microgram = 0.000001g μ

1kilo-.. 1000 (103) of a measure 1kilogram = 1000g kg

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