Answer:
Option A, Hormones are controlled by a feedback loop; information about a system is sent back to the controller of the system to improve its function.
Explanation:
Negative feedback loop controls the hormone production and release. This is done by eliciting the release of substances till a certain level after which the stop signal is activated thereby preventing further release. By this method, concentration of hormones in blood is maintained within the narrow range.
For example – Thyroid hormones is released when the anterior pituitary signals the thyroid. This continues till the hormones in the blood reach the threshold level. Once the threshold level is reached, hypothalamus receives a feedback and then signals anterior pituitary to inhibit further signaling to the thyroid
Hence, option A is correct
This shows that the so called hot spots on the tectonic plates are moving along with the actual tectonic plate. Because volcanoes form on hot spots, the most chain of active and non active volcanoes proves that if the hot spots are moving, so are the tectonic plates.
Answer: exocrine glands
Explanation: Exocrine gland secrete substances to an epithelial surface through a channel.
The sebaceous and sweat glands associated with the skin also secrete substance to skin surfaces via ducts/ channels and are classified as endocrine gland. There are two glands in the human body Exocrine gland and Endocrine gland.
Endocrine gland secrete substance into the bloodstream directly. Examples of exocrine glands are sweat, salivary, mammary, sebaceous, and mucous.
liver and pancreas are both exocrine and endocrine glands simultaneously.
As exocrine gland, the liver secrete bile and the pancrease secrete pancreatic juice into the gastrointestinal tract through channels. While as endocrine gland they secrete other substances directly into the bloodstream.
