Endocrine LEcture

What is the second major controlling system of the body?

Endocrine System

What is the main purpose of the endocrine System?

to maintain delicate balance of homeostasis

What signals does the Endocrine system use?

chemicals = hormones

What pathways do the E.S use?

blood transport or Extracellular fluid

What is the speed the info travels in the E.S?

slow

Is the duration of effects in the Endocrine System short or long?

they can be short or long lasting

What are the targets of the Endocrine system?

many cells throughout the body

What must be present in order for hormones to bind to a target cell?

specific hormone recpetors

What is the mechanism of communication Endo System uses?

signal transduction

How does signal transduction work?

stimulus is needed and then a trigger of chain reactions within the cell occurs

What kind of feedback does the Endocrine System have?

positive and negative feedback

T or F: one hormone produce different reactions in different cells

true

Negative feedback

ends the reaction/process that is occuring

positive feedback

keeps going and amplifies reaction/process

hormones

signaling molecules that are carried by bldstream, they bind to receptors on cells to elicit a response

target organs

organ that responds to a hormone

endocrine gland

• ductless

• release product right into bldstream

exocrine glands

• haves ducts

• releases product into a specific location

• ex: salivary

hyposecretion

production at a slow rate/insufficient quantites

hypersecretion

production at an excessive rate overly large amount

tropic hormones

hormones which stimulate the release of other hormones

5 Endocrine Glands

• pituitary

• thyroid

• parathyroid

• adrenal

• pineal

What kind of organ is the hypothalamus?

neuroendocrine organ

3 organs that have exocrine and endocrine fucntions

• pancreas

• gonads

• placenta

Examples of other tissues/organs that produce hormones

adipose cells, thymus, cells in walls of small intestine, stomach, kidneys, and hearts

3 chemical groups of hormones

• peptide

• steroid

• amine

T or F: peptide hormones aren’t the majority type of hormone

false

What are petides made up of?

chains of amino acids

Peptides are ___soluble therefore easily transported in blood plasma

water

Where are the hormone receptors for peptides located?

on the cell surface

2 examples of Peptide hormones

insulin and growth hormone

What are steroid hormones synthesized from?

cholestrol

Steroids are ____ soluble so they easily diffuse through cell membrane

lipid

Where are the receptors for steroid hormones located?

on nucleus or in cytoplasm

Steroid hormones can also activate …..

gene transcription

examples of steroid hormones

estrogen, testosterone, cortisol

What are amine hormones syntehsized from?

from amino acid tyrosine (single amino acid)

T or F: amine hormones can either be water or lipid soluble

true

examples of amine hormones

epinephrine, thyroxine

three types of signaling (distance)

• endocrine

• autocrine

• paracrine

How far do autocrine signaling goes?

most local, acts on the same cell that secretes it

How far does paracrine signaling go?

• only influences nearby cells

• diffuses locally in ecf

• degrades quickly

how is histamine release an example of paracrine signaling?

release of histamine caues smooth muscle in nearby bld vessel to relax which brings in more bld

Can water soluble hormones pass through the cell membrane?

no

Can lipid soluble hormones diffuse through the cell membrane?

yes

Where are the receptors for lipid soluble hormones located?

in the nucleus or cytoplasm

how hormones work (3 steps)

1. endocrine (secreting) cell sends the signal

2. hormone receptor

3. cell responds

3 types of hormone receptors

• cell surface receptors

• intracellular (cytoplasm) receptors

• nuclear

What types of hormones bind to nuclear receptors

steroid amine

what types of hormones bind to intracellular receptors?

steroid amine

What types of hormones bind to cell surface receptors?

proteins, peptides, amines

amino acid-based hromones exert their effects through _____ systems

second messenger

two types of second messenger systems

• cyclic AMP

• PIP2-Calcium

5 steps of Cyclic AMP signaling mechanism

1. hormone binds to receptor

2. receptor activate G protein

3. gprotein activated/inhibits effector enzyme adenylate cyclase

4. adenylate cyclase converts ATP to cAMP

5. cAMP activats protein kinases that phosphorylate other proteins

What happens to the phosporylated proteins during Cyclic AMP signlaing?

they can either be activated or inactivated

in order to stop cAMP signaling, cAMP has to be degraded. Which enzyme degrades it?

phosphodiesterase

5 steps of direct gene activation

1. steroid hormone diffuses through ECF and binds to intracellular receptor

2. receptor hormone complex enters nucleus

3. receptor hormone complex binds a specific DNA regio

4. binding start transcription of the gene to mRNA

5. mRNA directs protein systhesis

What two things are needed to create a receptor hormone complex?

steroid hormone and receptor protein

3 types of endocrine gland stimuli

1. humoral

2. neural

3. hormonal

What is a humoral stimuli?

changes in blood level of ions and nutrients which directly stimulate secretion of hormones

Example of humoral stimuli

decline blood calcium concentration stimulates parathyroid glands to secrete parathyroid hormone

What is a nueral stimuli?

nerve fibers that stimulate hormone release

example of nerual stimuli

sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines

WHat is a hormonal stimuli?

when hormoes stimulate other endocine organs to release their hormones

Hypothalamic hormones stimulate the release of most ____ hormones

anterior pituitary

Anterior pitutary hormones then sitmulate ____ to secrete more hormones

targets

What is the endocrine organ feedback loop?

hyptohalmaic- pitutitary-target

T or F: hormones from final target organs inhibit release of anterior pituitary hormones

true

T or F: nervous system can make adjustments to hormone levels when needed

true

nervous system can also ___ normal endocrine glands

override

3 factors of target cell activation

1. blood levels of hormone

2. relative number of receptors on/in target cell

3. strength of binding between receptors and hormone

can the amount of hormones influence number of receptors for that hormone?

yes

up-regulation

target cells form more receptors in response to low hormone levels

down-regulation

target cell lose receptors in response to high hormone levels

hormones can circulate the blood in two ways

free or bound

what hormones travel the blood binded to plasma proteins?

steroidsn and thyroid hormones