BI 375: endocrine system

Coordinating ____ systems needs ___ signaline

biological, cell

Which 2 systems help in coordinating biological systems

nervous & endocrine

What is the key difference between the nervous and endocrine systems

• nervous- cluster of muscles, targeted

• endocrine- widespread message, anyone with receptor

What are the main cell signaling paths?

endocrine, paracrine, autocrine, synaptic, neuroendocrine, neuromodulate, neuropeptide, parahormone, prohormone

How does endocrine cell signaling work?

release of hormones into circulation fluid

How does paracrine cell signaling work?

immediate contact with surrounding cells

How does autocrine cell signaling work?

self signaling, binds to own receptor

How does synaptic signaling work?

neurotransmitters released over synaptic cleft

How does neuroendocrine cell signaling work?

neurotransmitters/neurohormones, synapse on blood vessel, brain to blood

How does neuromodulate cell signaling work?

synapse makes hormone more/less likely to fire

How does neuropeptide cell signaling work?

peptide hormones

How does neurosteroid cell signaling work?

steroid hormones

How does parahormone signaling work?

hormone -like chemical is released by other cells, not endocrine glands

ex- prostaglandins

How does prohormone signaling work?

precursor to other hormones, can be hormones

ex- testosterone → estradiol, DHT

What are features of the endocrine system?

• glands are ductless

• have a rich blood supply

• hormones are secreted into bloodstream

• hormones travel in the blood to every cell in body

• hormone receptors are specific binding sites, embedded in cell membrane/inside cell

• receptors interact with an individual/class of hormones

What are the major endocrine structures?

hypothalamus, pineal gland, pituitary gland, thyroid, adrenal glands, pancreas, gut, gonads

Hypothalamus

control of hormone secretions

Pineal gland

reproductive maturation, body rhythms

Anterior pituitary

hormone secretion by thyroid, adrenal cortex & gonads, growth

Posterior pituitary

water balance, salt balance

Thyroid

growth & development, metabolic rate

Adrenal cortex

salt & carb metabolism, inflammatory reactions

Adrenal medulla

emotional arousal

Pancreas

islets of Langerhans, sugar metabolism

Gut

digestion & appetite control

Gonads

body development, maintenance of reproductive organs in adults

What distinguishes the 2 types of hormones?

peptide hormones are hydrophilic/polypeptides, steroid hormones are hydrophoci

What are amines?

amino acids as hormones, can be peptide or steroid

What is the significance of peptide hormones, & why?

largest group, longvity related to size, larger = last longer, variable length of amino acids

How are peptide hormones stored & released?

stored in vesicles, released by exocytosis

How are peptide hormones removed?

through degradation or excretion

T or F: peptide hormones aren’t blood soluble.

False, peptide hormones are soluble in blood

Where do peptide hormones act?

act on cell surface receptors

What do protein/peptide hormones vary in?

length & amino acid sequence

Amino acid sequences for protein hormones can be ____ specific.

species

What are monoamines?

made from single amino acids, include catecholamines & indoleamines, thyroid hormones

What are catecholamines?

epinephrine, norepinephrine, dopamine, T3, T4

What are indoleamines?

serotonin, melatonin both derived from tryptophan

What are steroid hormones?

made from cholesterol, include androgens, estrogens, corticoids

How are steroid hormones released?

made & immediately released, pass through membrane & attach to carrier proteins in blood, bind to intracellular receptors

How are steroid hormones identified?

3 6 carbon rings & 5 carbon rings, identified by # of carbons

How are steroid hormones produced

cholesterol (C27) → progestins (C21)→ corticoids(C21), androgens (C19)→ estrogens (C18)

Which hormones are C21 steroid hormones?

progestins & corticoids: progesterone, corticosterone, cortisol

Which hormones are C19 steroid hormones?

androgens: testosterone

Which steroid hormones are C18?

estrogens: estradiol

T or F: steroid hormones are sex hormones.

false, produced by both sexes, differ in concentration

What hormones are derived from testosterone?

DHT, estradiol

Which receptors are protein hormone receptors?

G protein-coupled receptors, Ligand-gated ion channels, receptor tyrosine kinases

G protein-coupled receptors

release second messengers, use G proteins for cellular cascade

Ligand-gated ion channels

open ion channels in response to hormone/neurotransmitter binding

Receptor tyrosine kinases

receptor is an enzyme that phosphorylates kinases, starts cellular cascade

What kind of receptors do steroid hormones use?

intracellular receptors, bind to hormone, move to nucleus & act as transcription factors

HPE system

hypothalamus, pituitary gland, tropic hormones

Hypothalamus

receives info from nervous system, secretes ‘releasing hormones’/neurohormones

Pituitary gland

receives neurohormones, secretes tropic hormones

Tropic hormones

trigger hormone secretion in gonads, thyroid, or adrenal glands

Which hormones does the hypothalamus release?

• gonadotropin releasing hormone (GnRH)

• thyrotropin releasing hormone (TRH)

• corticotropin releasing hormone (CRH)

• growth hormone releasing hormone (GHRH)

Which hormones does the pituitary gland release?

• Luteinizing hormone (LH)

• Follicle stimulating hormone (FSH)

• Thyroid stimulating hormone/thyrotropin (TSH)

• Adrenocorticotropin hormone (ACTH) Growth hormone (GH)

Which hormones are tropic?

• estradiol (E2)

• progesterone (P)

• testosterone (T)

• triiodothyronine (T3)

• tetraiodothyroxine/thyroxine (T4)

• corticosterone

• cortisol

Which hormones does the posterior pituitary gland release, & where do they go?

ADH/vasopressin to kidney tubules, oxytocin to mammary glands/uterine muscles

Which hormones does the anterior pituitary gland release, & where do they go?

• FSH/LH → testes/ovaries

• TSH → thyroid

• ACTH → adrenal cortex

• prolactin → mammary glands

• MSH → melanocytes

• GH → liver< bones → tissues

Which hormones only have tropic effects?

FSH, LH, TSH, ACTH

Which hormone has tropic & non-tropic effects?

growth hormone

Which hormones only have non-tropic effects?

prolactin, MSH