All categories

4 years ago

Many drugs can be applied to the skin without entering the blood. how is this fact explained?

2 answers:

8 0

While the outer layer of the skin acts a physical barrier, the skin is porous. It's the same reason sweat appears on our skin when we're hot.

ra1l [238]4 years ago

7 0

*A drug administered by the cutaneous route can have one of these three actions:

Local action, superficial: ex. local anesthetic ...

Deep action: ex. anti-inflammatory action ...

Systemic or general action: ex. anti-anginal action

*The skin is a very effective barrier, which limits the number of drugs that can enter the system.

*The factor influencing the penetration of the drugs are:

- Nature and physicochemical properties of P.A: Molecular weight, hydrophilicity, lipophilicity, stability ...

- Formulation of the drug: Excipients lipophilic, hydrophilic, amphiphilic, an absorption promoter

- Nature and condition of the skin, Location, age, thickness (1 to 8 mm ...), vascularization...

*To not penetrate the skin, a drug should have to be of high molecular mass (to be unable to penetrate through the skin tissue), hydrophilic (since the skin is of a lipophilic nature).

*For example, solar creams should not enter the system so the excipients used are hydrophilic in nature.

You might be interested in

In the rat, the allele for red eye colour is dominant over the alleles for brown colour. Consider a cross between a rat that is

chubhunter [2.5K]

Answer:

1) RR x rr

2) Shown below

3) 100% Rr with red eyes

4) Punnett square shown (Rr x Rr)

5) 25% of the offspring are h0m0zygous dominant with red eyes (RR), 50% are heterozygous with red eyes (Rr), and 25% are h0m0zygous with brown eyes (rr)

Explanation:

Let's say the allele for red eyes is R and the allele for brown eyes is r.

1. A cross between a h0m0zygous dominant (two copies of the dominant allele, R) and h0m0zygous recessive (two copies of the recessive allele, r) is: RR x rr

2. R R

r Rr Rr

The F1 generation is shown in the Punnett square above.

3. The F1 generation are 100% Rr. They are heterozygous. Since red (R) is dominant, the rats all have red eyes

4. A cross between the F1 generation (Rr x Rr) gives the F2 generation

R r

R RR Rr

r Rr rr

5. 25% of the offspring are h0m0zygous dominant with red eyes (RR), 50% are heterozygous with red eyes (Rr), and 25% are h0m0zygous with brown eyes (rr)

6 0

3 years ago

PLSS HELP!! explain in detail different types of receptors

tekilochka [14]

Answer:

Chemoreceptors detect the presence of chemicals. Thermoreceptors detect changes in temperature. Mechanoreceptors detect mechanical forces. Photoreceptors detect light during vision.

I hope it's helpful!

6 0

3 years ago

How are members of the genus Homo different physically from the Australopithecus?

statuscvo [17]

Answer:

D. all of the above

Explanation:

Australopithecus (first ape-man): Australopithecus is considered as the connecting link between apes and man as they shared the characteristics of both. The fossil records shows that they appeared around 5 million years ago. Australopithecus africanus was about 1.5 meters high and had human as well as ape like features. It was with bipedal locomotion, omnivorous in their diet and had erect posture. It had human like teeth with small canines and large chewing teeth. The brain was more like an ape with the brain capacity of about 500 cc similar to that of an ape. He lived in caves, had projected brow ridges with no chin. Its believed that Australopithecus africanus gave rise to Homo habilis about 2 million years ago.

The earliest species of Homo genus is Homo habilis. They were skill full man also called as handy man or the tool maker. He had erect posture with bipedal locomotion. The teeth were like modern man. He was skilled and made tools with stones. Slowly with evolution the prognathous face changed to orthognathous in cro magnon (Homo sapiens fossilis).

6 0

3 years ago

A- Which country will have winter at about the same time as Portugal? Why?

Marina CMI [18]

Answer:

7: The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the earth's axis points towards the sun

8: Earth without a tilt would be stratified into climate bands that would get progressively colder as you moved away from the equator.

Explanation:

6 0

3 years ago

Following repolarization, the neuron may become slightly hyperpolarized before it re-establishes its resting membrane potential.

RoseWind [281]

<h2>Membrane potential </h2>

Explanation:

Membrane potential represents charge difference across the membrane, all biological cells are negative inside (cytoplasm) and positive outside (due to difference in ionic distribution)
In a typical neuron cell membrane potential of cytoplasm is negative at rest (when no stimulus is applied) hence called resting membrane potential
Resting membrane potential of excitable cells is established by Na+ and K+pump
Repolarization starts with the efflux of K+ by the opening of voltage gated K+ channels
Voltage gated K+ channels starts to open when voltage gated Na+ channels becomes inactive
Hyperpolarization occurs due to excessive efflux of K+ by voltage gated K+ channels
Additional efflux of K+ occurs due to slow inactivation of voltage gated K+ channels

3 0

4 years ago