Absorption Cont.

Question 1

Bulk flow

Answer 1

Substances are transported in the body along with the movement of air in the respiratory system during breathing and the movements of blood, lymph or urine

Question 2

Bulk flow

Answer 2

Substances are transported in the body along with the movements of air in the respiratory system during breathing and the movements of blood, lymph, or urine

Question 3

Filtration

Answer 3

Due to osmotic pressure water flows in bulk through pores in the endothelium

Question 4

Types of absorption

Answer 4

1. Pulmonary
2. Percutaneous
3. GIT
4. Other routes : IV,IM,SC,IP

Question 5

Effectiveness of route of exposure

Answer 5

IV > inhalation > IP > IM > ingestion > topical

Question 6

Effectiveness of route exposure

Answer 6

IV > inhalation > IP > IM > ingestion > topical

Question 7

Volume of distribution

Answer 7

D/Co*K

Where D : amount of substance in the body at a given time
Co: concentration in blood, plasma /serum at that time
K: body weight

Question 8

Vd of < 1 kg body weight

Answer 8

Indicates preferential distribution in the blood

Question 9

Vd > 1 kg body weight

Answer 9

Indicates a preference for peripheral tissues such as adipose tissue for fat soluble substances

Question 10

Factors determining the rate of distribution of chemicals in the body

Answer 10

1. Accumulation: build up of a substance in a tissue or organ to higher levels than in blood and plasma
2. Physiological barriers: the blood vessels in the brain , testes and placenta have special anatomical features that inhibit passage of large molecules like protein
3. Plasma concentration: substances may be bound to RBC or plasma components or occur unbound in blood
4. Protein binding : chemicals highly bound to proteins have small Vd
5. Affinity of chemicals to certain tissues: concentration of a chemical in certain tissues after a single may persist even when plasma concentration is reduced eg: lead concentrate in bone tissue

Question 11

Elimination half-life

Answer 11

The time required for the concentration of the drug to reach 1/2 of its original value

T1/2 = ln 2/Ke

Question 12

Elimination half-life

Answer 12

The time required for the a drug to reach 1/2 of its original value

T1/2= ln 2/Ke

Question 13

The effectiveness of any drug depends on

Answer 13

Its half life

Question 14

Elimination rate constant (Ke)

Answer 14

The rate at which a drug is removed from the body

Ke= ln2/ t1/2

Ke = CL/Vd

Question 15

Clearance

Answer 15

The vol of blood per unit time completely cleared of a substance

Question 16

Intrinsic clearance

Answer 16

The capacity of metabolites to transform a substance

Question 17

Concentration time curve

Answer 17

Curve of concentration in blood vrs time

Question 18

Routes of excretion

Answer 18

1. Urinary excretion
2. Exhalation
3. Biliary excretion via faecal excretion
4. Milk
5. Saliva
6. Sweat

Question 19

Why would a body try to form metabolites of a substance which accidentally enters the body?

Answer 19

For elimination
To reduce toxicity of a substance

Question 20

Target organs

Answer 20

Greater susceptibility of the target organ

Higher concentration of active compound

Question 21

Metabolism

Answer 21

Process by which the administered chemical are modified by the organisms by enzymatic reactions

Question 22

Primary objectives of metabolism

Answer 22

Make chemical agents more water soluble and easy to excrete

Decrease lipid solubility thus decreasing the amount at target sites

Increase ionization this increasing excretion rate this decreasing toxicity

Question 23

Mechanism of toxicity

Answer 23

1. Delivery
2. Reaction of the ultimate toxicant with the target molecules
3. Cellular dysfunction and resultant toxicity
4. Repair / disrepair

Question 24

Forms of cell death

Answer 24

Apoptosis
Necrosis

Question 25

Unprogrammed death ( necrosis)

Answer 25

Passive form of cell death induced by accidental damage of tissue and doesn’t involve activation of any cellular program

Question 26

Characteristics of necrosis

Answer 26

Early loss of plasma membrane integrity and swelling of the cell body followed by bursting of cell

Mitochondria and various cellular processes contain substances that can be damaging to the surrounding cells and are released upon bursting and cause inflammation

Cells necrotize in response to tissue damage

Question 27

Programmed cell death (apoptosis)

Answer 27

Active form of cell death enabling individual cells to commit suicide

Casepase dependent

Question 28

Characteristics of apoptosis

Answer 28

Dying cells shrink and condense then fragment to release macrophages

Intracellular constituents not released may have adverse effects on neighboring cells

Cell blebbing: presence of spherical bubbles distorting the shape of the cell

Question 29

Characteristics of apoptosis

Answer 29

Dying cells shrink then condense then fragment releasing macrophages

Intracellular constituents which are not released might have adverse effect on neighboring cells

Presence of cell blebbing : spherical bubbles distorting the cell’s shape

Question 30

Phenotypes of apoptosis

Answer 30

Overall shrinkage in volume on its nucleus

Loss of adhesion to neighboring cells

Formation of blebs on the cell surface

DNA fragmentation

Rapid engulfment if dying cells by phagocytosis

Question 31

Factors that induce apoptosis

Answer 31

Internal stimuli: abnormalities in DNA
External stimuli: removal of growth factors, addition of cytokines

Question 32

Signal transduction pathways leading to apoptosis

Answer 32

Intrinsic pathway: mitochondria dependent
Extrinsic pathway : mitochondria independent

Question 33

Primary metabolic disorders jeopardizing cell survival

Answer 33

ATP depletion
Sustained rise in Intracellular Ca
Overproduction of reactive oxygen species and reactive nitrogen species