BIOL1040 Module 6 L1: principles of endocrine systems

What is homeostasis?

The maintenance of a stable internal environment despite external changes.

What are the two main ways animals manage their internal environment?

By regulating internal conditions (regulators) or conforming to external conditions (conformers).

What is the main function of the endocrine system?

To regulate internal processes through chemical signaling via hormones.

What is endocrine signaling?

Hormones are secreted into the bloodstream and act on target cells throughout the body.

What is synaptic signaling?

Neurotransmitters are released across synapses to target nearby cells.

What is neuroendocrine signaling?

Neurohormones released by neurosecretory cells enter the bloodstream and act on distant targets.

What is paracrine signaling?

Local regulators act on neighboring cells in the extracellular fluid.

What is autocrine signaling?

Local regulators act on the same cell that secreted them.

How can hormones released into the bloodstream have specific effects?

Only target cells with specific receptors for that hormone can respond.

What determines the location of a hormone receptor?

The chemical nature of the hormone (water-soluble or lipid-soluble).

Where are receptors for water-soluble hormones found?

On the plasma membrane of target cells (GPCR).

Where are receptors for lipid-soluble hormones found?

Inside the target cell, often in the cytoplasm or nucleus. (insulin and steroid)

Give an example of a water-soluble hormone.

Adrenaline (epinephrine).

Give an example of a lipid-soluble hormone.

Oestradiol (a type of estrogen).

What are polypeptide hormones?

Non-steroid, water-soluble hormones that bind to membrane receptors.

What are steroid hormones?

Lipid-soluble hormones derived from cholesterol that bind to intracellular receptors.

How can one hormone have multiple effects?

It can bind to different receptors on different cell types, leading to varied responses.

What are thyroid hormones responsible for?

Regulating homeostasis and development.

What type of feedback mainly regulates endocrine responses?

Negative feedback.

What is the main interaction between the endocrine and nervous systems?

The hypothalamus and pituitary act as control centers linking neural and hormonal responses.

What does the hypothalamus do in endocrine regulation?

t secretes releasing and inhibiting hormones that control pituitary function.

What is the pituitary gland’s role?

It releases hormones that regulate other endocrine glands and body functions.

How do hormones mediate stress responses?

By triggering short-term (adrenaline-mediated) and long-term (cortisol-mediated) physiological changes.