Signaling Types
What type of signaling involves communication between nearby cells without entering the bloodstream?
Paracrine signaling
What class of hormone includes insulin and is made of amino acids?
Polypeptide (peptide) hormones
What type of hormone is typically transported in the blood bound to carrier proteins?
Lipid-soluble hormones
What type of feedback loop increases the original stimulus, such as in oxytocin release during childbirth?
Positive feedback
What gland releases epinephrine during stress responses?
Adrenal medulla
What type of signaling uses neurons to release neurotransmitters across a synapse?
Synaptic signaling
What hormone released from the adrenal medulla is responsible for “fight-or-flight” responses?
Epinephrine
Where do lipid-soluble hormones typically bind inside a target cell?
Cytoplasm or nucleus
What hormone is released when acidic chyme enters the duodenum and triggers bicarbonate secretion?
Secretin
What endocrine structure includes the anterior and posterior divisions and connects to the hypothalamus?
Pituitary gland
What is the term for local signaling molecules like nitric oxide that diffuse short distances?
Local regulators (paracrine/autocrine signaling molecules)
What hormone from the adrenal cortex helps regulate glucose metabolism and immune responses?
Cortisol
Why do water-soluble hormones require membrane receptors instead of entering the cell directly?
Because they cannot cross the lipid bilayer of the cell membrane
What type of feedback mechanism is used to maintain blood calcium levels within a narrow range?
Negative feedback
What gland is responsible for producing thyroid hormones like thyroxine?
Thyroid gland
What type of signaling occurs when hormones travel through the bloodstream to distant target cells?
Endocrine signaling
What class of hormones includes cortisol and aldosterone?
Steroid hormones (corticosteroids)
What happens after a lipid-soluble hormone binds to a receptor inside the nucleus?
The hormone-receptor complex alters gene transcription, leading to protein production
In which endocrine pathway does the hypothalamus stimulate the pituitary, which then signals another gland to respond?
Hypothalamic-pituitary axis (endocrine signaling pathway)
What adrenal gland region produces catecholamines like epinephrine?
Adrenal medulla
How do prostaglandins function differently from hormones that travel through the bloodstream?
They act as local regulators, affecting nearby or the same cells (paracrine/autocrine signaling) rather than traveling long distances in blood
Why are steroid hormones able to directly influence gene expression?
Because they are lipid-soluble, they diffuse into cells and bind intracellular receptors that regulate transcription
The endocrine and secretin pathway is what type of feedback?
Negative
Compare Autocrine to paracrine signaling
Autocrine signaling occurs when a cell secretes a signal that binds to its own receptors, essentially "talking to itself" to regulate its own functions. Paracrine signaling involves a cell sending signals to nearby neighbors, allowing for quick, local communication between different cells in the same area.
How does the adrenal cortex respond to long-term stress in contrast to the adrenal medulla?
It releases steroid hormones (cortisol, aldosterone) for long-term regulation, unlike the medulla which handles immediate stress responses