Biology 165 Exam 3

Circulatory System in Endocrine Regulation

It transports a signal (hormone) to a cell

Hormone Composition

Can be a protein (string of amino acids)

Can be a molecule based on cholesterol

Can be a modified amino acid

Hormone signaling can be like….

a switch

some are on/off, some are dimmers, etc.

switch acts as a kind of pathway

Reception

detects the signal in the first place

Transduction

Send the signal along the relay

Cellular Response

Whatever happens

Types of signaling

Direct (cell to cell it’s touching)

Paracrine (cell to nearby cell)

Autocrine (cell back to itself)

Endocrine (cell to far away cell - goes through circulatory cell)

Neuroendocrine (cells of nervous system gets signal and releases a hormone)

Direct Signaling

Cell sending a signal to another cell that it’s physically touching

Paracrine Signaling

Cell signal goes to a nearby cell

Autocrine Signaling

Cell sends a signal back to itself

“note to self”

can be signal telling itself to grow, etc

Endocrine Signaling

Cell sending a long distance signal that ahs to go through circulatory system

Neuroendocrine Signaling

A cell within the nervous system receives signal and releases a hormone

Two parts of the pituitary

Anterior (front)

Posterior (back)

Thalamus

Relay center for sensory info

Hypothalamus

below the thalamus and sends signals to pituitary

controls the endocrine system

determines whether a human has enough energy to grow (enough sleep, food, etc)

Somatostatin

Hormone that blocks the release of growth hormone that is made by anterior pituitary

“growth hormone inhibiting hormone”

negative feedback loop

Fenestrated

Has windows/holes

Capillaries in capillary bed are fenestrated (it lets hormones out)

Circulatory system pathway

Hypothalamus receives signal → neurosecretory cells secrete hormone → enters ap blood vessel → hormone binds to receptor in ap cells → ap cells release a different hormone into capillaries

Growth hormone pathway

Anterior pituitary receives information (day/night, energy) → nerve cells release a paracrine signal that acts on cells in anterior pituitary → anterior pituitary makes different hormone that release into blood stream

Growth Hormone Releasing Hormone

A hormone that is a endocrine signal that stimulates growth hormone release from anterior pituitary

made by neurosecretory cells

Sensor for GHRH

Cells in hypothalamus

Stimulus for GHRH

Sleep cycle, nutrient reserves, exercise, years of age

What does GH stimulate in the liver

It stimulates the liver to release another hormone: IGF-1 (Insulin-like growth factor)

Liver is an …. organ

endocrine

because it releases IGF-1 when stimulated by GH

What does IGF-1 do?

It signals the hypothalamus to release somatostatin