Lecture 6 - Introduction to Endocrinology

What are the three components of a reflex pathway?

1. Input

2. Integration

3. Output

Hormones are secreted by what cells?

Epithelial

What produces and stores hormones?

Specialized gland tissues or cells

Do hormones exert effects at low or high concentrations?

very low

Do hormones have a long or short half life?

usually short

What are the small proteins primarily released by immune cells?

Cytokines

Cytokines bind to specific cell surface receptors and trigger ________________

intracellular signal cascades

Are cytokines stored or produced on demand?

produced on demand

hormones are degraded in the __________ and by _________ in the liver and kidneys

bloodstream; and by enzymes in the liver and kidneys

What are the three main hormone categories?

1. peptide

2. steroid

3. amine

What is the most common type of hormone?

Peptide

Do peptides need a transport protein in the bloodstream?

no, they are water soluble

How long is the half life of peptides?

short, only minutes

Where are preprohormone peptides produced?

produced in endoplasmic reticulum

Preprohormone are modified into prohormone by the:

endoplasmic reticulum

______ signaling induces exocytosis of peptides

Ca²+

Steroid hormones are derived from

cholesterol

Are steroids lipophobic or lipophilic?

lipophilic

steroid hormone solubility in plasma is:

low

Carrier protein protects from:

degradation

Cellular mechanism of action of steroid hormones:

1. _____ or ______ stimulate genomic effects

2. ___________ receptors stimulate nongenomic responses

1. cytoplasmic or nuclear receptors

2. cell membrane receptors

Most hydrophobic steroids are bound to _________________.

plasma protein carriers

Steroid hormone receptors are in the:

cytoplasm or nucleus

The steroid hormone receptor complex binds to ______ and activates or represses one or more genes.

DNA

Most amine hormones are made from ___________.

tyrosine

Amine hormones are produced by:

neurons and thyroid glands

Catecholamines are produced by what two things?

Neurons in the brain and adrenal medulla (glands)

What do catecholamines bind to?

membrane receptors

What are epinephrine, dopamine, norepinephrine?

Catecholamines

Neurohormones are secreted by _________ into the blood.

Neurons

Thyroid hormones bind to:

Intracellular receptors

Tyrosines and iodine atoms make ______ ________.

Thyroid hormones

The __________ cell is the sensor in simple endocrine pathways.

endocrine

What shuts off the parathyroid hormone reflex pathway?

Increased plasma Ca²+ levels

In the parathyroid hormone reflex pathway, what stimulates endocrine cells?

Low plasma calcium levels

In the parathyroid hormone reflex pathway, elevated calcium levels that suppress parathyroid hormone secretion are examples of ________ feedback.

negative

How is parathyroid (PTH) reflex pathway classified?

simple endocrine reflex pathway

What are the two endocrine structures in the brain?

Pineal and Pituitary glands

Catecholamines are produced by:

adrenal medulla

Hypothalamic neurohormones are secreted from:

posterior pituitary

Hypothalamic neurohormones controls release from:

anterior pituitary

Anterior pituitary gland is considered the:

true endocrine gland

Posterior pituitary gland is considered the:

extension of the brain

What does the posterior pituitary do?

Secreted neurohormones produced by the hypothalamus

_____________ regulates lactation, uterus contraction, and some social interaction

oxytocin

________ is an antidiuretic hormone that regulates water balance by acting on kidneys

vasopressin

_____________ controls growth, metabolism, and reproduction

the anterior pituitary

How do neurohormones travel to target cells in the pituitary?

through the portal system (capillaries)

the portal system consists of _______ sets of capillaries

two

Pituitary hormones control secretion of other hormones, making them:

tropic hormones

What is the Growth Hormone reflex pathway considered?

A complex neuroendocrine reflex pathway

In complex neuroendocrine pathways, the hormones act as:

negative feedback signals

Short-loop negative feedback occurs with:

prolactin, growth hormone, and ACTH

What is synergism?

When the combined effects of hormones exceed the sum of the individual effects

What is it called when the full effect of a hormone depends on the presence of another hormone?

Permissiveness

What is it called when hormones have opposing physiological actions and may reduce the effect of one another?

Antagonism

__________ exaggerates a hormone’s affect

Hypersecretion

Hypersecretion is often caused by:

tumors or exogenous iatrogenic treatment (physician-caused)

In hypersecretion, negative feedback may lead to:

atropy of glands

ACTH stands for:

adrenocorticotropin

CRH stands for:

corticotropin-releasing hormone