Chemical Signaling

Hormone

chemical messengers or signaling chemicals that bind to receptors on target cell

What are two roles of hormones?

• help regulate metabolic processes

• control rate of chemical reactions

Which parts of the body are hormones involved in? What do they target?

• involves every part of the body

• however, specific hormones only targets specific target cells that have receptors for that hormone

What is the primary purpose of the endocrine system?

secrete hormones directly into the bloodstream

What type of molecule are receptors?

Proteins

Receptors

binding sites for specific signaling chemicals

What are some locations that receptors can be located in?

cell membrane, cytoplasm, or on nucleus membrane

Ligand

any molecule that binds to a receptor

What happens when the ligand binds to the receptor?

It causes a cell response

What are four types of cell response?

• gene expression (making protein from using DNA gene)

• change in metabolic activity

• shape or structure changes

• some type of movement or transport occurs

Quorum sensing

a process of cell-to-cell communication that allows bacteria to sense their population density and coordinate their behavior

The more the bacteria, the more ____ are produced

Autoinducers

How does bacteria sense its population with quorum sensing?

based on the amount of autoinducers

What occurs when the bacteria population density becomes high? Example?

Gene expression occurs which then causes a response

i.e. bioluminescence

What are two types of cell response of ligands?

Localized and distant cell responses

Describe a localized cell response with an example of a chemical

neurotransmitters move across a synapse to cause a change in the postsynaptic neuron

Describe a distant cell response with an example of a chemical

hormones produced in one part of the body travels in blood to target a distant cell/organ

What are protein hormones made of?

Made of amino acids

What are some examples of protein hormones?

insulin, ADH, glucagon

What type of substance are protein hormones?

a polar substance (not soluble in non-polar cell membrane)

What is the known name of protein hormones?

Primary messengers

What do protein hormones bind to?

binds to receptors on the plasma membrane of target cells

What are steroid hormones made of?

cholesterol processes

What type of substances are steroid hormones?

they are non-polar substances (soluble in cell’s lipid membrane)

How are steroid hormones transported?

Transported/passed from the blood directly into target cell

What do steroid hormones bind to?

binds to receptors in the cytoplasm (intracellular receptors)

Describe neurotransmitters in terms of signaling chemicals

Electrochemical signaling which is involved in the nervous system

Where are cytokines used?

Can be used in plants

Define cytokines

small proteins produced by many cells act on immune system

What are some processes that cytokines influence?

inflammation, cell growth/activation

What can cytokines be used for?

Can be involved in the nervous system; used to treat cancer

What are some two types of cytokines?

Interleukin and interferon

Interleukin

allow for communication between WBCs

Interferons

defend against intracellular microorganisms

What is the purpose of calcium as a signaling chemical?

• an indicator for movement

• allows neurotransmitters to release and influence muscle contraction

What two systems does calcium involve?

Nervous and muscle system

Give some examples of amine hormones

melatonin, thyroxin, and epinephrine

Give some examples of peptide hormones

Insulin, glucagon, ADH

Give some examples of protein hormones

Insulin and oxytocin

Give some examples of steroid hormones

oestradiol, progesterone, and testosterone

Give some examples of amine neurotransmitters

dopamine, norepinephrine

Give some examples of peptide neurotransmitters

Endorphins, oxytocin

Give some examples of protein neurotransmitters

Endorphins, oxytocin

Give some examples of steroid neurotransmitters

GABA, seratonin

Hormones and neurotransmitters are either ____ or ____

excitatory; inhibitory

What is the effect of initiating signal transduction pathways?

the binding to a receptor sets off s sequence of events in a cell/organ

List two examples of effectors

muscles and glands

Summarize the properties of transmembrane signaling receptors (Polarity, hormones that can bind, location)

• hydrophilic

• polar (protein hormones)

• cell membrane (activate G proteins)

Summarize the properties of intracellular signaling receptors (Polarity of amino acids in receptor, hormones that can bind, location)

• hydrophilic

• non-polar (steroid hormones)

• cytoplasm/nucleus

What determines the type of receptor activated?

polarity, type of hormone, and location of receptor

What is always the secondary messenger?

cAMP

What does estradial (estrogen) bind to on target cells?

binds to intracellular receptors in the hypothalamus

What does estradial/estrogen regulate?

regulates expression of gonadotropin releasing hormone (GnRH)

What does estradial stimulate?

Stimulate the release of FSH and LH

What does progesterone bind to? In which target cell?

binds to an intracellular receptor within endometrium (endometrial cell that form the uterine lining)

What does progesterone regulate?

regulates the expression of a growth factor

What does progesterone promote based of growth factor?

promotes cell proliferation

What does the cell proliferation from progesterone lead to?

Leads to the thickening of endometrial lining during the menstrual cycle and pregnancy

Negative feedback

a response that is the reverse of the change; output slows down the reaction