33. Human Biology

8/13/2019 33. Human Biology

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HUMAN

BIOLOGY

Prepared by:

Alerna Irene Cal, RRT


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RAD.BIOLOGY is the studyof effects of ionizingradiation on biological

tissue.


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RADIATION HORMESISsuggest that low levels of

radiation, less than

approximately 5 rad (50mGy)provide a protective effect by

stimulating molecular repairmechanisms in the human

body.


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HUMAN RESPONCE TOIONIZING RADIATION

The effects of x-rays on humansare the result of interactions atatomic levels

When an atom is ionized, itschemical binding propertieschange. If the atom is aconstituent of large molecules,

the ionization may result inbreakage of the molecule orrelocation of the atom within the

molecule.


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HUMAN RESPONCE TO IONIZINGRADIATION

The abnormal molecule may intime function improperly or ceaseto function which can result in

series impairment or death of thecell

This process is reversible. At each

stage of radiation damage it ispossible to recover. Ionized atomscan become neutral again by

attracting a free electron.


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EARLY EFFECT/ IMMEDIATEif the radiation response occurs

within minutes or days after theradiation exposures it isclassified as an immediate/early

effect.

LATE EFFECT/ DELAYED if thehuman injury is not observablefor many months/years it istermed a delayed/late effect of

radiation.


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LATE EFFECTS OF RADIATION ONHUMANS

1. LEUKEMIA2. OTHER MALIGNANT DISEASE

a. Bone cancer

b. Lung cancer

c. Breast cancer

3. LOCAL TISSUE DAMAGE

a. Skin

b. Gonadsc. Eyes

4. LIFE SPAN SHORTENING

5. GENETICALLY SIGNIFICANT DOSE


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EFFECTS OF FETAL

IRRADIATION

1. Prenatal death

2. Neonatal death

3. Congenital malformation

4. Childhood malignancy

5. Diminished growth anddevelopment


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CELL THEORY1665, ROBERT HOOKE the Englishschool master, first named the cell as thebuilding block

1973, ANTON VAN LEEUWENHOEKaccurately described a living cell based onhis microscopic observations

1838, SCHNEIDER AND SCHWANNshowed conclusively that all plants andanimals contains cell as their basicfunctional units. This is the beginning ofthe cell theory

1953, WATSON AND CRICK describethe molecular structure of DNA which isthe genetic substance of the cell.


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COMPOSITION OF THE BODY

The atomic composition of thebody determines the characterand degree of the radiation, andthe molecular and tissue

composition defines the nature ofthe radiation injury.

Radiation interaction at the

atomic level results in molecularchange and molecular change canproduce a cell abnormal in

growth and metabolism.


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ATOMIC COMPOSITION OF THE

BODY


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MOLECULAR COMPOSITION

MACROMOLECULES is a very largemolecule which sometimes consist ofhundreds of thousands of atoms

MOLECULAR COMPOSITION OF THE BODY


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1. WATER

80%

The most abundant molecularconstituent of the body

It is consist of 2 atoms ofhydrogen and 1 atom of oxygen(h2O)

Humans are basically astructured aqueous suspension.

The water molecules exist both

in the free and bound states.


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HOMEOSTASIS the constancyof the internal environment of the

human body

METABOLISM

a. CATABOLISM

breaking downinto smaller units

Water and carbon dioxide

are end products in catabolisma. ANABOLISM the production

of large molecules from small.


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2. PROTEINS

15%Proteins are long chain

macromolecules that consist of

a linear sequence of amino acidconnected by peptide bonds

There are 22 amino acids usedin proteins production, or

protein synthesis


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Generalized formula of

protein:Cn= 50% carbon

Hn= 7% hydrogenOn= 20% oxygen

Nn= 17% nitrogenTn= 6% other elements

n# of atoms of each element in themolecule


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Proteins have a variety of

uses in the body. Theyprovide structure and

support.

Proteins also function as

enzymes, hormones and

antibodies.


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a. ENZYMES

are molecules that arenecessary in small

quantities to allow a

biochemical reaction to

continue but they do not

directly enter into thereaction


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b. Hormones

are molecules thatexercise regulatory control

over some functions such as

growth and developments

Endocrine gland (pituitary

gland, thyroid, parathyroid,pancreas and gonads)


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c. ANTIBODIES

constitute a primary defencemechanism of the body against

infections and diseases.

The molecular configuration ofan antibody may be precise for

attacking a particular type ofinvasive or infectious agent, the

antigen.


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3. LIPIDS

2%

Lipids are organicmacromolecules composed

solely of carbon, hydrogen andoxygen

They have the general

formulation CnHnOnNnThis structure distinguishesthem from carbohydrates.


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In general, lipids are composedof 2 kinds of smaller molecules,

glycerol and fatty acid.Each lipid molecule iscomposed of one molecule ofglycerol and 3 molecules of fattyacid

Lipids are present in all tissuesof the body and are thestructural components of cell

membranes.


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Lipids often are concentratedjust under the skin and serve as

a thermal insulator from theenvironment.

Lipids also serves as fuel forthe body by providing energystores

It is more difficult, however toextract energy from lipids thanfrom the other major fuel

source, carbohydrates.


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4. CARBOHYDRATES

1%

Carbohydrates, like lipids arecomposed solely of carbon,

hydrogen and oxygen but theirstructure is different

The ratio of number of

hydrogen atoms to oxygenatoms in a carbohydratesmolecules is 2:1, as in water


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Carbohydrates are considered

to be watered or hydcarbo-

hydrate. Hence, their name

carbohydrates

Also called saccharrides.Monosaccharides and

disaccharides are sugars

C6H12O6 chemical formula

for glucose (simple sugar)


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(C6H10O5)n chemical formulafor polysaccharides

n is the number of simplesugar molecules in themacromolecules

Polysaccharidesare largeand include plant starches and

animal glycogenThe chief function ofcarbohydrates in the body is to

provide fuel for cell metabolism


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The human polysaccharides,

glycogen is stored in the

tissues of the body and used

as fuel only when the simple

sugar, glucose is not presentin adequate quantities.

Glucose is the ultimatemolecule that fuels the body.


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Lipids can becatabolised into glucosefor energy but only great

difficulty

Polysaccharides aremuch more readily

transformed into glucose


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5. NUCLEIC ACIDS

2 principal nucleic acid in

human metabolism

a. DNA (deoxyribonucleicacid)

b. RNA (ribonucleic acid)


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a. DNA

Contains all thehereditary informationrepresenting a cell and ofcourse if the cell is a germcell, all the hereditary

information of the wholeindividual

Control center for life


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DNA


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b. RNAIs found in the nucleus and

outside the nucleus in thecytoplasm

2 types:

a. Messenger RNA (mRNA)b. Transfer RNA (tRNA)

These molecules are involved in

the growth and development ofthe cell through a number ofbiochemical pathways, notablyproteinsynthesis.


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RNA


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DNA consists of a backbonecomposed of alternating

segments of deoxyribose (asugar) and phosphate

Attached to each deoxyribosemolecules is one of 4 differentnitrogen- containing ornitrogenous organic bases

Adenine & guanine purinesThymine & cytosinepyrimidines


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The base-sugar-phosphatecombination is called a

nucleotideHuman DNA, exist as two ofthese long chains attachedtogether in ladder fashion

The side rails of the ladder are

the alternating sugar-phosphatemolecules and the rungs of theladder consists of bases joined

together by hydrogen bonds


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The ladder is twisted

about an imaginary axislike a spring- double helix

configuration

Adenine-thymines

Cytosines- guanines


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RNA resemble DNA

structurally

The sugar component is

riboserather than

deoxyribose

Uracil replaces thymineas a base component

RNA forms a single spiral,

not a double helix


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Human cell

2 major segments of the

cell

a. Nucleus

b. Cytoplasm


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a. Nucleus

The principal molecular

component of the nucleus is

DNA, which is the genetic

material of the cell

The nucleus also contains some

RNA, protein and water

Most RNA is contained in arounded structure, the nucleolus


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b. Cytoplasm

Makes up the bulk ofthe cell and contains

all the molecularcomponents in great

quantity, except DNA


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Found in the cytoplasm

are a number of

intracellular structures:

1. Endoplasmic reticulumis a channel or series of

channel that allows the

nucleus to communicatewith the cytoplasm


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2. Mitochondria largebean shaped structuresPowerhouse

Workhorses of the cellDigest macromolecules


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3. Ribosomessmall

dotlike structures

Site of protein synthesis

and therefore are essential

to normal cellular function


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4. Lysosomes small pealikesacs

Contain enzymes capable of

digesting cellular fragments and

in some situations, the cell itselfSuicide bag

Lysosomes are helpful in thecontrol of the intracellular

contaminants.


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Cell membranes

These membranes consistprincipally of lipid-protein

complexes that selectively allow

small molecules and water todiffuse from one side to the

other.

Also provide structure and

form for cell and its

components.


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1 Mrad (10kGy) is required

to produce a measurable

change in any physical

characteristic of the molecules


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Cell function

Each cell to some extent performs

the function of absorbing throughthe cell membrane all molecularnutrients.

These nutrients are used in theproduction of energy andmolecular synthesis. If the

molecular synthesis is damaged byradiation exposure, the cell maymalfunction and die.


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Protein synthesis is a good

example of most important and

critical cellular function

necessary for survival.

DNA, located in the nucleus,

contains a molecular code that

identifies what proteins that cell

will make.


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Codon a series of three

base pairs that identifies

one of the 22 humanamino acids available for

protein synthesis.


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Cell proliferation

Is the act of a single cell orgroup of cells reproducing and

multiplying in number.

This increase in number of cellsby reproduction is a result of

the process of cell division, amechanism that results in twice

the number of cells.


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2 general types of cells:

a. Somatic cell

all cells in thebody except the genetic cells

Mitosis (cell division/

proliferation)

b. Genetic cells the geneticcells are the oogoniumof the

female and the

spermatotogoniumof the male

Meiosis


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1. Interphase thechromosomes are not visible,

however during mitosis, the

DNA becomes more prominent

and begins to take structuralform

2. Prophase the nucleusswells and the DNA becomesmore prominent and begins to

take structural form

h h h


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3. Metaphase the chromosomesappear and are lined up along the

equator of the nucleus.It is during metaphase that

mitosis can be stopped and

chromosomes studied carefully

under the microscope.

Radiation-induced chromosome

damage is analyzed during

metaphase

4 Anaphase is characterized by


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4. Anaphase is characterized byeach chromosomes splitting at thecentromere so that a centromereand two chromatids are connectedby a fiber to a poles of thenucleus.

This pole are called spindles, andthe fibers are called spindle fibers

The number of chromatids per

centromere has been reduced byhalf, and these newly formedchromosomes has been migrateslowly toward the nuclear spindle

5 T l h i h i d b


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5. Telophase is characterized by

the disappearance of the structural

chromosomes into a mass of DNAand the closing off the nuclear

membrane like a dumbbell into two

nuclei.

At the same time the cytoplasm

is divided into two equal parts,

each accompanying one of the

two nuclei.

b


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b. Meiosis

Changes in genetic material

can occur during the division

process of genetic cellsReduction division


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R t R di ti i


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Response to Radiation is

related to Cell Type

The relative radiosensitivity of tissues and


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The relative radiosensitivity of tissues and

organs based on clinical radiotherapy

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33. Human Biology

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