communication, integration, and homeostasis-chp6 Flashcards
what is responsible for most communication within the body?
chemical signals
what are some types of physiological signals?
electrical signals and chemical signals
electrical signals
changes in the membrane potential of a cell
chemical signals
neurotransmitters/hormones
they are secreted into the ECF
responsible for most communication within the body
what responds to signals?
target cells or targets
what do Gap Junctions do?
they form direct cytoplasmic connections between adjacent cells.
they are super prevalent in the heart.
autocrine signals
act on the same cell that secreted them.
Paracrine signals
are secreted by one cell and diffuse to adjacent cells.
Hormones are secreted by ______ glands or cells into the blood. only____ cells with ____ receptors for the hormone respond to the signal.
Hormones are secreted by endocrine glands or cells into the blood. Only target cells with receptors for the hormone respond to the signal.
what are neurocrines?
chemical signals secreted by neurons like:
neurotransmitters
neuromodulators
neurohormones
neurotransmitters:
chemicals secreted by neurons that diffuse across a small gao to the target cell.
Neurohormones
chemicals released by neurons into the blood for action at distant targets.
Ex:hypothalamus to pituitary
These are the ones that will only bind to target cells that have the receptors for them
what are the five steps of signal pathways?
1-signal molecule 2-binds to membrane receptor protein 3-activates intracellular signal molecules 4-alter target proteins 5-create response
what are the different types of membrane receptors?
Receptors channel (chemically gated)
receptor-enzyme
G-protein-coupled receptor
integrin receptor
Receptor Channel (chemically gated)
ligand binding opens or closes the channel
Receptor-enzyme
ligand binding to a receptor-enzyme activates an intracellular enzyme
G-protein coupled receptor
ligand binding to a G protein couples receptor opens an ion channel or alters enzyme activity. there are more of these than any other in the body. It doesn’t have a pore, nothing goes across.
Integrin Receptor
ligand binding to integrin receptors alters the cytoskeleton
tyrosine kinase receptor
transfers a phosphate group from ATP to a tyrosine (an AA) of a protein
What do G proteins do when they are activated?
open ion channels in the membrane
alter enzyme activity on the cytoplasmic side of the membrane.
what are the different second messengers?
cAMP cGMP IP3 DAG Ca2+
cAMP
made from ATP
activates protein kinases, especially PKA.
binds to ion channels
phosphorylates proteins. Alters channel opening,
cGMP
made from GTP.
activated protein kinases especially PKG
binds to ion channels
it phosphorylates proteins and alters chennel opening
IP3
made from membrane phospholipids
releases Ca from intracellular stores
same effects as Ca
DAG
made from phospholipids
activates protein kinase C
it phosphorylates proteins
Ca2+
binds to calmodulin and other proteins alters enzyme activity exocytosis muscle contraction cytoskeleton movement channel opening
what are the steps of the GPCR adenylyl transduction signal transduction and amplification?
a signal molecule binds to g protein coupled receptor which activated G protein
G protein then activates adenyl cyclase which is an amplifier enzyme which then concerts ATP to cAMP . cAMP activated protein kinase A which phosphorylates other proteins leading to a cellular response.
describe the g coupled protein receptor (GPCR) phospholipase C signal transduction
a signal molecule activates the receptor which activated the G protein
G protein then activated phospholipase C (PLC) which is an amplifier enzyme. PLC then concerts membrane phospholipid into DAG (which stays an in the membrane) and IP3 which diffuses into the cytoplasm.
DAG activates protein kinase C (PKC) which phosphorylates proteins and IP3 causes Ca2+ release from organelles which creates a Ca signal
signal transduction using ion channels
receptor channels open or close in response to signal molecule binding.
some channels are directly linked to G proteins that when GPCR are activated the channels open.
then there are some channels that open as a response to intracellular second messengers.
how does Ca induce a response?
Ca is generally pretty low in cells so when it does increase we know that there is an important message.
How is Nitric oxide produced and where does it go?
NO is produced by endothelial cells (and neurons) and can just diffuse through membranes into smooth muscle and causes vasodilation
how is Nitric Oxide (NO) synthesized?
by the action of nitric oxide synthase (NOS)
What does NO activate?
it activates guanylyl cyclase (which takes guanine from GTP) and forms cGMP.
What does NO act as?
A neurotransmitter an neuro modulator in the brain
Carbon Monoxide (CO)
Also activates guanylyl cyclase and form cGMP.
it targets smooth muscle and neural tissue
Leukotrienes
play a role in asthma and anaphylaxis
what are some prostanoids
prostaglandins
thromboxanes
sphingolipids
prostaglandins
sleep, inflammation, pain, fever
nonsteroidal anti-inflammatory drugs (NSAIDs) help prevent inflammation by inhibiting cyclooxygenase
sphingolipids
help regulate inflammation, call adgesion and migration, and cell growth and death.
down-regulation
decrease in receptor number
up-regulation
inserts more receptors in cell membrane
what are different uses of the word receptor?
cell membrane or intracellulsr receptor proteins
sensors which are specialized cells that concert various stimuli into electrical signals
