lecture 23

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Questions and Answers

Which type of hormone is capable of crossing cell membranes?

Hydrophobic hormones (correct)

Hydrophilic hormones

Amine hormones

Peptide hormones

What is the primary function of the Releasing Hormone from the hypothalamus?

To respond to sensory input from the nervous system

To regulate the release of hormones from the thyroid gland

To control the level of calcium in the blood

To signal the anterior or posterior pituitary to release hormones (correct)

What is the primary function of the corpora allata in insects?

Producing neurotransmitters to stimulate muscle contraction

Coordinating sensory input from the environment

Maintaining homeostasis through the release of hormones

Regulating molting and metamorphosis through hormone secretion (correct)

What is the primary function of hormones in the human body?

To regulate a large number of bodily processes Signup and view all the answers

Which of the following hormones is NOT released by the anterior pituitary gland?

Oxytocin Signup and view all the answers

What triggers the release of sex hormones in animals approaching adulthood?

Mate presence Signup and view all the answers

What is the term for the process by which hormones trigger a cascade of enzyme activations, leading to a amplified response?

Hormone amplification Signup and view all the answers

What is the primary function of Tropic Hormones?

To cause the release of other hormones Signup and view all the answers

What is the primary function of the pituitary gland in humans?

Regulating growth and development through hormone secretion Signup and view all the answers

Which type of hormone receptor is typically found on the surface of cells?

Transmembrane receptor Signup and view all the answers

Which gland forms from epithelial cells in the roof of the mouth?

Anterior pituitary gland Signup and view all the answers

What is the term for hormones that stimulate the secretion of other hormones?

Tropic hormones Signup and view all the answers

What is the purpose of a hormonal pathway?

To stimulate hormone production Signup and view all the answers

What is the function of the hormone released by the posterior pituitary gland that helps regulate water balance in the body?

Antidiuretic Hormone (ADH) Signup and view all the answers

What is the role of the endocrine system in regulating environmental responses?

Coordinating sensory input from the nervous system Signup and view all the answers

What is the term for chemical signals that act on the same cell that secreted them?

Autocrine Signup and view all the answers

What is the term for the process of insects shedding their exoskeletons to accommodate growth?

Molting Signup and view all the answers

What is the term for the process by which hormones regulate blood sugar levels?

Blood sugar regulation Signup and view all the answers

Study Notes

Hormone Regulation

Hormones regulate various bodily processes, including circadian rhythms, metabolism, "fight, flight, freeze" responses, and blood sugar regulation.
The pancreas, an endocrine organ, regulates blood sugar levels via negative feedback loops.

Hormone Characteristics

Hormones target specific cells that have a receptor for the hormone.
Hormone receptors can be on the cell surface or inside a cell, depending on the molecular makeup of the hormone.
Hydrophilic hormones (e.g., peptides and amines) cannot cross cell membranes, while hydrophobic hormones (e.g., steroids) can.

Hormone Types

Amines and peptide hormones are more abundant and diverse, working in minutes to hours and typically initiating signal cascades that activate or repress enzymes.
Hormone amplification occurs along a hormonal pathway, where one gland releases a hormone that triggers a second gland to release a hormone, amplifying the signal until the final impact on the target cell.

Evolutionary Conservation of Hormones

Vertebrates and invertebrates share a number of hormones, although their functions differ between the groups.
Some hormones also function as neurotransmitters.

Vertebrate Endocrine System

The hypothalamus responds to sensory input from the nervous system by secreting releasing hormones, which signal the anterior or posterior pituitary.
The pituitary gland, formed from epithelial cells in the roof of the mouth and neural tissue at the base of the brain, releases hormones to regulate the rest of the endocrine system.

Pituitary Gland

Hormones released by the anterior pituitary act on other glands to cause the release of other hormones (tropic hormones).
Hormones released by the anterior pituitary include TSH, FSH, LH, and ACTH.
Hormones released by the posterior pituitary gland include oxytocin and antidiuretic hormone (ADH).

Other Body Glands

The parathyroid gland controls the level of calcium in the blood by signaling bone to be built or broken down.
The pineal gland controls circadian rhythms by secreting melatonin.
The adrenal medulla secretes epinephrine and norepinephrine, regulating fight, flight, freeze responses.

Local Chemical Communication

Paracrines are chemical signals that act on nearby cells.
Autocrine signals are chemical signals that act on the cell that secreted them.
Histamines are paracrines released when a cell is damaged, causing inflammation and dilating blood vessels.

Endocrine System

The endocrine system regulates responses to the environment, growth and development, homeostasis, and reproduction.
The system is often triggered by sensory input from the nervous system.

Growth Regulation

Sex hormones are released to trigger the development of secondary sex characteristics as an animal approaches adulthood.
Molting and metamorphosis in insects are triggered by the release of hormones in tissues in the head.
In humans, growth regulation is primarily controlled by the pituitary gland, which produces Human Growth Hormone (hGH or somatotropin).