Neurotransmitters and Hormones Types

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Questions and Answers

What is the primary function of neurotransmitters?

Secreted by cells into the extracellular fluid

Released by glands into the circulating blood

Released by axon terminals into the synaptic junctions (correct)

Carried by the circulatory system to cells throughout the body

What is the main difference between endocrine hormones and neuroendocrine hormones?

Endocrine hormones are carried by the circulatory system, while neuroendocrine hormones are not

Endocrine hormones are secreted by glands, while neuroendocrine hormones are secreted by neurons (correct)

Endocrine hormones affect target cells locally, while neuroendocrine hormones affect target cells at a distance

Endocrine hormones are secreted into the extracellular fluid, while neuroendocrine hormones are secreted into the bloodstream

Which of the following is an example of a paracrine?

Insulin secreted by the pancreas

Growth hormone secreted by the pituitary gland

Cytokines secreted by cells into the extracellular compartment (correct)

Thyroxine secreted by the thyroid gland

What is the primary function of cytokines?

To function as autocrines, paracrines, or endocrine hormones Signup and view all the answers

Which hormone affects many different types of cells in the body?

Growth hormone Signup and view all the answers

What is the primary function of the placenta in the endocrine system?

To produce hormones such as estrogen and progesterone Signup and view all the answers

Which of the following is an example of a steroid hormone?

Cortisol Signup and view all the answers

What is the primary mode of transportation for endocrine hormones?

Through the circulatory system Signup and view all the answers

What are the derivatives of the amino acid tyrosine?

All of the above Signup and view all the answers

What is the characteristic of polypeptides and proteins that make them water soluble?

They are made up of amino acids Signup and view all the answers

What is the minimum number of amino acids required to be classified as a protein?

100 Signup and view all the answers

Where are protein and polypeptide hormones synthesized?

Endoplasmic reticulum Signup and view all the answers

What is the characteristic of steroid hormones in terms of storage?

There is little storage of steroid hormones in steroid-producing endocrine cells Signup and view all the answers

What is the source of cholesterol esters in cytoplasmic vacuoles?

Rapid mobilization for steroid synthesis after a stimulus Signup and view all the answers

What is the process by which proteins hormones are secreted?

Exocytosis Signup and view all the answers

What is the chemical structure of steroid hormones similar to?

Cholesterol Signup and view all the answers

Study Notes

Types of Hormones

Neurotransmitters: released by axon terminals of neurons into synaptic junctions
Endocrine hormones: released by glands or specialized cells into the circulating blood
Neuroendocrine hormones: secreted by neurons into the circulating blood and influence target cells at another location
Paracrines: secreted by cells into extracellular fluid and affect neighboring cells of a different type
Autocrines: secreted by cells into extracellular fluid and affect the function of the same cells that produced them
Cytokines: peptides secreted by cells into extracellular compartment and can function as autocrines, paracrines, or endocrine hormones

Endocrine Hormones

Carried by the circulatory system to cells throughout the body, where they bind with receptors and initiate many reactions
Affect many different types of cells, or specific target tissues, depending on the presence of receptors
Examples: growth hormone, thyroxine, adrenocorticotropic hormone (ACTH), and ovarian hormones

Hormone Structure

Classes of hormones: proteins and polypeptides, steroids, and amines
No known polysaccharides or nucleic acid hormones
Stored in secretory vesicles until needed

Proteins and Polypeptides

Most hormones in the body are polypeptides and proteins
Size range: from small peptides with as few as 3 amino acids to proteins with almost 200 amino acids
Polypeptides with 100 or more amino acids are called proteins
Those with fewer than 100 amino acids are referred to as peptides
Synthesized on the rough end of the endoplasmic reticulum of different endocrine cells
Water soluble, allowing them to enter the circulatory system easily

Synthesis of Protein Polypeptide Hormones

Synthesis: usually synthesized first as larger proteins that are not biologically active (preprohormones)
Cleavage occurs to form smaller prohormones in the endoplasmic reticulum
Packaging into secretory vesicles occurs in the Golgi apparatus
Enzymes in the vesicles cleave the prohormones to produce smaller, biologically active hormones and inactive fragments
Vesicles are stored within the cytoplasm, and many are bound to the cell membrane until their secretion is needed
Secreted by exocytosis caused by increased cytosolic calcium concentration

Steroid Hormones

Chemical structure is similar to that of cholesterol, and in most instances they are synthesized from cholesterol itself
Lipid soluble
Usually very little hormone storage in steroid-producing endocrine cells
Large stores of cholesterol esters in cytoplasm vacuoles can be rapidly mobilized for steroid synthesis after a stimulus

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Description

This quiz covers the four main types of chemical messengers: neurotransmitters, endocrine hormones, neuroendocrine hormones, and paracrines and autocrines.