Endocrine System: Hormones

What are the two major types of hormones?

1. membrane-bound receptor hormones
2. intracellular receptor hormones

What is membrane-bound hormone?

The hormone cannot pass through the cells and needs a gated channel (non-steriods)

What is an intracellular receptor hormone?

The hormone that can pass easily through cells. (Steroids)

in _____ change occurs rapidly

membrane bound receptors (reheating a frozen meal analogy)

What are the 2 mechanisms of membrane-bound receptors?

G proteins and other membrane-bound receptors

What does G proteins do?

Trigger response from intracellular mediators which will cause cellular change

What does Other Membrane Bound Receptors do?

Trigger a direct change to the cell

What are the first 3 steps of G protein function?

1. Hormone binds to receptor causing receptor to change shape

2. Receptor binds to a subunit of the G protein inside the cell

3. Subunit releases GDP then binds with and it is actived by GTP

(check image)

What is the 4th and last step of G protein function?

4. Subunit combines with other proteins to either:
1. Open ion channels when Ca2+ acts as an intracellular mediator
Example: in smooth muscle

OR

2. Activate cAMP (adenylate cyclase converts ATP to cAMP) whcih activates enzymes through phosphorylation (attachment of phosphates) to increase or decrease their activity
Example: Glucagon increases release of glucose in liver

What is Intracellular Receptors?

They can pass through cells but interact with DNA to produce a new one. Takes several hours as they are creating a new one. (Ex:Steroid hormone)

What are the two types of modulated systems in our body? (modulated system = hormones that determine strength of signals)

Amplitude Modulated and Frequency Modulated

What does Amplitude modulated mean?

The concentration of the hormone determines the strength of the signal.

Lower hormone = weaker strength.

Example: Endocrine System

What is frequency modulated system?

How often the signal is sent determines the strength of singal.

Low amount of hits per second = less strength

Example: Nervous system

What are the 3 types of Control Secretion Rates (aka how much hormone Brain need to release)

Extracellular concentration Control, Neural control and Hormonal concentration

What does Extracellular concentration Control mean?

Produces Hormones based on the concentration of non hormonal substances.

Example: concentration of glucose determines how much insulin is released

What is Neural Control?

Endocrine glands produce Neurotransmitters as hormones to affect the brain.

Example: Epinephrine from the adrenal glands makes your heart beat fast.

What is Hormonal Control?

Release of hormone to target a particular tissue

Example: Thyroid-stimulating Hormone (TSH) from the pituitary gland causes hormone release from the thyroid.

What are the two types of feedback loops?

Positive Feedback and Negative Feedback loops

What is positive feedback loop?

Signal continues to increase and stimulate the secretion of more of the hormone

Example: Baby's birth releases oxytocin for uterine contraction

What is a negative feedback loop?

Signal decreases the secretion of hormones

Example: Blood sugar regulation

What are the 3 types of hormone regulations (aka how stable are hormones)?

Chronic Hormone, Acute Hormone, and Cyclic Hormone.

What is Chronic Hormone Regulation?

Relatively constant concentrations are maintained for long periods of time, Ex: GH or Thyroid

What is Acute Hormone Regulation?

Hormone rapidly increases in response to stimulus. Example: Epinephrine

Cyclic Hormone Regulation

Increases and decreases in the concentration occur at roughly the same time and in the same amount. Example: Estrogen and Progesterone (period cycles)