Bio 220 Ch 45

Local regulators

Molecules that act over short distances, reach their target cells solely by diffusion and act on their target cell

Paracrine signaling and autocrine signaling

Paracrine signaling

Target cells lie near secreting cells

Autocrine signaling

Secreting cells themselves are the target cells

Prostaglandins

Local regulators that are either pro or anti inflammatory

Nitric acid

Gas released when blood oxygen levels fall causing vasodilation

Neurotransmitters

Molecules secreted by neurons that diffuse a very short distance and bind to the receptors in the target cell

Neurohormones

Hormones that diffuse from nerve cell endings into the blood stream

Pheromones

Chemicals that are released into the external environment

Polypeptide, steroid, amine

3 major classes of hormones

Steroids

Lipid soluble class of hormone

Polypeptide, amine

Water soluble class of hormones

Cytosol

Location of receptor for lipid-soluble hormone

Cytosol

Location of receptor for lipid-soluble hormone

Thyroxine, vitamin D

Non-steroid lipid soluble membranes

Have receptors in nucleus

Endocrine glands

Endocrine cells grouped in ductless organs

Exocrine gland

Glands that have ducts that carry secreted substance onto body surface or into body cavities

(Ex: saliva, sweat)

Simple endocrine pathway

Endocrine cells respond directly to an internal/environmental stimulus by secreting a particular hormone

Hormone travels in the bloodstream to target cells and interacts with receptor

Signal transduction pathway brings physiological response

Simple neuroendocrine pathway

Stimulus received by a sensory neuron

Sensory neuron stimulates a neurosecretory cell which secretes neurohormone

Neurohormone diffuses into blood stream and travels to target cell

Ecdysteroid

Steroid produced by prothoracic gland in invertebrates

Causes the insect to molt

Juvenile hormone

Hormone in insects that determine the results of the molt

Suppresses metamorphosis at high levels

Hypothalamus

Brain region that receives information from nerves and initiates neuroendocrine signaling

Pituitary gland

Gland located at the base of hypothalamus

Posterior and anterior

Posterior pituitary

Gland that secretes ADH and oxytocin

Anterior pituitary

Gland that synthesizes and secretes hormones in response to hormones in the hypothalamus

Tropic hormones

Hormones that regulate other endocrine glands to produce another hormone

TSH, LH, FSH, ACTH

4 strictly tropic hormones from the anterior pituitary gland

TSH - thyroid stimulating hormone

Tropic hormone from anterior pituitary gland

Acts on thyroid to make thyroxine

LH - Luteinizing hormone

Tropic hormone from anterior pituitary gland

Stimulates gonads for ovulation and testes for testosterone

FSH - follicle-stimulating hormone

Tropic hormone from anterior pituitary gland

Stimulates gonads for estrogen development

ACTH - adrenocorticotropic hormone

Tropic hormone from anterior pituitary gland

Stimulates adrenal cortex to release more hormones

Prolactin, MSH

Non-tropic hormones from the anterior pituitary gland

Prolactin

Non-tropic hormone from anterior pituitary gland

Acts on mammary gland to secrete milk

MSH - melanocyte stimulating hormone

Non-tropic hormone from anterior pituitary gland

Produces melanin

Growth hormone

Tropic and non-tropic hormone from anterior pituitary gland

Acts on growth plate to allow them to increase in size

T3, T4, calcitonin

Hormones made from the thyroid

Thyroid regulation

Hypothalamus secretes TRH causing anterior pituitary gland to secrete TSH which causes thyroid to produce thyroxine

Hypothyroidism

Too little thyroid hormone

High levels of TSH because hypothalamus detects a deficiency in thyroid hormone but thyroid hormone isn’t being properly produced

Hyperthyroidism

Too much thyroid hormone

Antibodies mimic TSH telling thyroid to produce more thyroid hormone

Hashimoto thyroiditis

Disease where immune system attacks the thyroid

Goiter

Iodine deficiency so thyroid hormone cannot be produced which enlarges the thyroid

Calcitonin

Hormone secreted when blood calcium levels are too high

Inhibits bone breakdown and enhances calcium excretion

Parathyroid hormone

Antagonistic hormone of calcitonin

Calcitonin

Antagonistic hormone of parathyroid hormone

Gigantism

Caused from hypersecretion of growth hormone

Pituitary dwarfism

Caused from hyposecretion of growth hormone

Acromegaly

Certain growth plates are acted on in a way that causes some extremities to be too long

Parathyroid hormone PTH

Hormone that raises blood calcium levels

Stimulates calcium release from bones and causes kidneys to absorb calcium

Adrenal gland

Gland on top of kidney

Adrenal medulla

Inner portion of adrenal gland

Short-term stress response

Epinephrine, norepinephrine

Hormones released by adrenal medulla

GPCR receptor

Catecholamines

Increase glycogen breakdown and release glucose to be used as fuel

Increase heart rate, blood supply to brain, heart, muscle and more

Catecholamines

Class of amine hormones

Epinephrine and norepinephrine

(GPCR receptor, water soluble)

Adrenal cortex

Outer portion of adrenal gland

Long-term stress response

Glucocorticoids, mineralocorticoids

Hormone from adrenal cortex

Increases blood glucose levels, suppresses the immune system, increases blood pressure

(Ex: cortisol)

Gonads

Principal source for sex hormones

Androgens, estrogens, progesterone

Three major types of steroid sex hormones

Testosterone

Main androgen

First functions in male embryo to produce reproductive system

Responsible for development of secondary sex characteristics

Estrogen

Hormone responsible for maintenance of female reproductive system and development of secondary sex characteristics

Progesterone

Hormone involved in preparing and maintaining uterus for embryo

Melatonin

Modified amino acid that regulates functions related to light and seasons

Produced by pineal gland in the brain

Pancreas

Gland that produces insulin and glucagon

Only organ with both endocrine and exocrine portion

Endocrine cells called islet of langerhans

Insulin

Hormone function to lower blood sugar levels by increasing glucose uptake of cells

Binds to TKR receptor which makes GLU-T which allows cells to accept glucose

Type 1 diabetes

Insulin is not made so it is given as an injection

Type 2 diabetes

Insulin can still be made but cells have a resistance and cannot make GLU-T

Alpha pancreas cells

Cells that produce glucagon

Beta pancreas cells

Cells that produce insulin

Glucagon

Antagonistic hormone to insulin that increases blood sugar levels

G protein-coupled receptor (GPCR)

Transmembrane receptor that uses a G protein

GPCR Steps

G protein binds to receptor and becomes active with GTP

Activated G protein disassociates from receptor and binds to enzyme

Enzyme changes shape and triggers next steps

G protein hydrolyzes its bound GTP to GDP and P, detaches from enzyme

Reception, signal transduction, response

3 steps for hormone response

Nuclear receptor

Receptor for lipid soluble signals found in cytoplasm

Tyrosine-Kinase Receptor (TKR)

Transmembrane receptor

Binding of molecule causes two receptor monomers to dimerize forming a homodimer

Dimerization causes tyrosine kinase to add a P from an ATP molecule to each tyrosine

Relay protein in cell binds to tyrosine causing transduction pathway

Ion channel receptor

Ligand-gated channels that open (or close) upon binding of a signaling molecules to allow ions to flow through

Protein kinase C

Activated from G protein

In turn activates another protein kinase which activates another

Adenyl Cyclase

Activated from G protein

Causes ATP to become AMP which leads to cAMP

cAMP

A secondary messenger

Phosphodiester needed to convert back to AMP

Phospholipase

Activated from G protein

Acts on phospholipids, breaking down phospholipid into diacyl glycerol and IP3

IP3 can activate calcium channels

Phosphorylation cascade

Phosphorylation of successive kinases from phosphate from ATP

After kinase accepts phosphate it takes an ATP to pass onto the next then loses the phosphate due to dephosphorylation

cAMP, Ca2+, IP3

Three secondary messengers

MAP kinase pathway

Ras activating pathway

Ligand binds to receptor, receptor binds to Ras, Ras goes into nucleus

Ras activates MAP kinase kinase kinase which activates MAP KK which activates MAP K which activates MAP which results in gene transcription

JAK-STAT pathway

Pathway involved in repairing DNA and cell death