Lecture 1: Endocrine Background Flashcards
Nervous System vs Endocrine System
The nervous system produces short-term, very specific responses
The endocrine system: many times it produces long-term, general responses
Role of endocrine system
The role of theendocrine systemis to maintain the body in balance through the release ofhormones(chemical signals) directly into the bloodstream.
Role of Hormone
Hormones transfer information and instructions from one set of cells to another.
What are hormones? Process of hormones
Hormones are chemical substances that affect the activity of another part of the body (target site).
Hormones serve as messengers, controlling and coordinating activities throughout the body.
Upon reaching a target site, a hormone binds to a receptor, much like a key fits into a lock.
Once the hormone locks into its receptor, it transmits a message that causes the target site to take a specific action.
Hormone receptors may be within the nucleus or on the surface of the cell.
Major Endocrine Gland Examples
Pituitary gland Hypothalamus Thyroid gland Thymus gland Suprarenal glands Pineal gland Parathyroid glands Pancreas Reproductive glands
Examples of functional hormones
Endocrine Hormones – Travel through the blood to act at a site distant from the secreting cell or gland
Paracrine Hormones – Act on cells near the secreting cell
Autocrine Hormones – Act on the secreting cell
Neurocrine Hormones – Secreted by neural cells
neurotransmitters
neurohormones
Types of chemical hormones
Protein and polypeptide
Amine
Steroid
Tropic vs non-tropic
Non-tropic hormonesare hormones that directly stimulate target cells to induce effects.
For example, aldosterone acts directly on the kidney (non-endocrine gland) to promote reabsorption of sodium, which causes an increase in blood pressure.
Tropic hormones, which act on other endocrine glands to stimulate (or inhibit) release of a second hormone.
For example, thyroid-stimulating hormone is responsible for stimulating the release for thyroid hormone by acting on the thyroid gland.
Describe the overall process of functional hormones
- endocrine gland releases hormone into blood
- Travels in blood to target cells (cells with the appropriate receptor)
- Hormones binds and promotes a response in the target cell
neurotransmitter vs neurohormone
neurohormone: are chemicals released by neurons into the bloodstream to travel to the target cell
Neurotransmitter:
chemicals released by neurons that diffuse across a small gap to the target cell
Chemical Hormones grouped on..
What are the 2 groups and features
Grouped according to chemical structure.
Steroid hormones are fat-soluble molecules made from cholesterol.
Non- steroidal
Protein and Amino acid derivatives, such as epinephrine, are water-soluble molecules
Water vs fat soluable hormones
Water soluable
Like the amino acid derivatives and peptides, can travel freely in the blood because they “like” water.
However, they are repelled by lipid or fatty structures such as the membranes that surround the cell and nucleus. Because of this, these hormones generally bind to receptor sites on the outside of the cell and signal from there.
Fat soluable
Like the sex hormone steroids estrogens and androgens, are fat soluble and water repellent.
That is, they “like” lipid or fatty structures such as those surrounding cells but are generally repelled by watery areas.
Steroids generally travel to their target cells attached to a special carrier protein that “likes” water
The hormones detach before passing into the cell where they bind to receptors.
Chemical Hormones:
Protein and polypeptide Hormones:
Characteristics
Synthesis and Secretion pathways
- Products of translation
- vary considerably in size
- synthesized as prohormones, then proteolytically clipped to generate their mature form.
secreted by one of two pathways:
Regulated secretion:The cell stores hormone in secretory granules and releases them in “bursts” when stimulated. This is the most commonly used pathway and allows cells to secrete a large amount of hormone over a short period of time.
Constitutive secretion:The cell does not store hormone but secretes it from secretory vesicles as it is synthesized.
Protein hormone action digram and labelled
- lipid soluable hormone enters the cell membrane to the cytoplasma
- Binds to cytoplasm receptor forming a hormone-receptor complex
- This complex enters the nucleus and prompts geen transcription
- The transcribed mRNA is taken to the cytoplasm and undergoes translation to form an active protein that alters cell activity.
Chemical Hormones:
Amine Hormones synthesised from what?
What are the tyrosine derivatives and where are they located and function.
Amine hormones are synthesised from the amino acids tryptophan (derivative makes melatonin) or tyrosine.
Tyrosine derivatives include the metabolism-regulating thyroid hormones, as well as the catecholamines, such as epinephrine, norepinephrine, and dopamine.
Epinephrine and norepinephrine are secreted by the adrenal medulla and play a role in the fight-or-flight response
Dopamine is secreted by the hypothalamus and inhibits the release of certain anterior pituitary hormones.