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3 years ago

What is the layer of stem cells that constantly divide to renew the epidermis?

Biology

1 answer:

Mnenie [13.5K]3 years ago

6 0

Answer: I think, I may be wrong, but I think the answer is stratum basale. i <em>found this online</em>

Explanation: The topmost layer is dead and sheds continuously. It is progressively replaced by stem cells that divide in the basal layer (stratum basale). The dermis connects the epidermis to the hypodermis and provides strength and elasticity due to the presence of collagen and elastin fibers.

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What is a primary reason an increase in glaciers on land would cause sea level to fall? g?

LiRa [457]

The amount of water on the planet is fixed; it neither increases or decreases. Glaciers are sheets of moving ice. This water to form these extensive sheets must come from somewhere. The water comes from the most extensive store on the planet; the oceans. Ice Ages always corresponds to periods of low sea level because much of the ocean water is is land locked as glaciers.

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3 years ago

According to the principal of dominance, if a recessive gene for tallness is paired with another recessive gene for tallness, th

AfilCa [17]

According to this principal, if a recessive gene for tallness is paired with another recessive gene for tallness, the organism is categorized as a homozygous recessive in terms of its genotype.

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3 years ago

Read 2 more answers

Which mutation is an example of an insertion mutation?

Burka [1]

Answer:

d. AAU CCG CAU UGG A

Explanation:

A mutation is any change or alteration to the sequence of a gene. There are, however, different types of mutation depending on how it occurs in the gene. One of these types is INSERTION MUTATION as mentioned in this question. Insertion mutation is a type of mutation in which one or more nucleotide base is added to the sequence, hence, changing the reading frame of the original sequence.

In this question, the original mRNA sequence is given as: AAU CCG CAU GGA.

An insertion mutation will cause nucleotide base(s) to be added to this sequence, which will be noticed by an increase in number of bases in the sequence.

The correct answer is: AAU CCG CAU UGG A. In this mutated sequence, nucleotide "U" has been added to the sequence.

8 0

3 years ago

The EMG is a recording of: The action potential of the motor nerves supplying the muscle fibers. The contraction forces of the i

Lelechka [254]

Answer:

The correct answer is option B. The contraction forces of the innervated muscle fibers.

Explanation:

Electromyography or EMG is the study of muscle activity with the help of analyzing electric signals that are burst or generated by the contraction of the muscle fibers. In other words, it is the electrical activity of the skeletal muscles in response to a nerve's stimulation of the muscle.

EMG uses the myoelectric signals to analyze muscle that is generated during the contraction forces of the inverted muscle fibers of the skeletal muscle.

Thus, the correct answer is option B. The contraction forces of the innervated muscle fibers.

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3 years ago

Some of the nerve endings in the skin are sensitive to changes in temperature. They are part of a negative feedback mechanism re

Gemiola [76]

Answer:

Answer is option A (receptor).

These nerve endings represent a receptor in the negative feedback mechanism.

Explanation:

Homeostasis in the human body is the tendency of the body to maintain its internal environment suitable for normal and optimal functioning by adjusting the changes occurring in internal variables such as body temperature, blood pressure, etc using feedback mechanisms. The two feedback mechanisms involved in homeostasis are positive feedback (the output of the system stimulates the system to increase the output further) and negative feedback mechanisms (the output of the system stimulates the system to decrease the output).

The various components in the feedback loop include;

stimulus - an initiation event that causes changes in a variable.

variable - a physiological factor that is kept at a normal range.

receptors - monitor the variable, detect changes in the variable value and report to control center.

control center - it compares the variable value to the normal range and if any deviation is found, the effectors are activated.

effectors - return the value to the normal range by making adjustments in the same direction (positive feedback) or opposite direction (negative feedback) of the stimulus.

In the body’s thermoregulation mechanism, a negative feedback loop is used in which the variable is body temperature. The nerve endings in the skin that are sensitive to changes in temperature are called heat-sensitive thermoreceptors. They detect changes in body temperature and produce nerve impulses that signal the hypothalamus in the brain. The hypothalamus is the control center that compares the body temperature with the normal range and activates and controls different effectors such as muscles, blood vessels, adrenal glands, sweat glands, etc. These effectors controlled by the hypothalamus perform certain physiological activities that can return the body temperature to normal range.

When body temperature drops, the hypothalamus activates and control the effectors such as blood vessels to constrict in order to decrease the flow of heat to the skin, muscles to shiver in order to increase the production of heat, adrenal glands to secrete hormones (norepinephrine and epinephrine) in order to increase metabolic rates and heat production. All these effects cause the body temperature to increase and return to normal.

When body temperature rises, the hypothalamus activates and controls the effectors such as blood vessels to dilate in order to increase the flow of heat to the skin, sweat glands to release sweat, which on evaporation cools the skin. All these effects cause the body temperature to decrease and return to normal.

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3 years ago