Flashcards in Endocrine and Nervous System Deck (35):
What processes does the endocrine system influence?
Metabolism, growth and reproduction
What mediators does the endocrine system release?
What is a Hormone?
Chemical messenger released by endocrine glands to regulate activity of cells in other parts of body
What do circulating hormones do?
Secreted by endocrine cells into bloodstream, travel through bloodstream to target cells
Exert effect via receptors expressed on target cells
What organ inactivates circulating hormones?
What organ excretes circulating hormones?
What do local hormones do?
Secreted by one cell type into extracellular fluid to affect surrounding cells
Exert effect via receptors expressed on surrounding cells
Examples of local hormones
Paracrine hormones e.g. Histamine
Autocrine hormones- e.g. Interleukin 2 (IL-2)
local hormones that act of the same cell that secreted them
What are the two types of ways hormone can be transported around the body?
Water soluble hormones
Lipid soluble hormones
What are water soluble hormones?
Hormones that circulate freely within the blood
What are lipid soluble hormones?
Hormones that are bound to proteins, which are temporarily water soluble
Are hormones specific or non-specific?
Specific- can only affect specific target cells
Only target cells for a specific hormone will express receptors for that hormone
Where are hormone receptors located?
Within the target cell or on the target cell membrane
What happens after the lipid soluble hormones bind to receptors within target cells?
Activated-receptor hormone complex alters gene expression
mRNA directs synthesis of a new protein (enzyme) which alters cell's activity
Where do water soluble hormones bind?
Receptors on cell membrane
What happens when the water soluble hormones bind to the receptors?
Hormone-receptor complex activates a G-protein
What happens after the G-protein is activated by the water soluble hormone?
Activates a cascade of events which amplify the reaction
Cellular proteins are activated or inhibited, and a physiological response is produced
What feedback loop does the endocrine system take?
Negative feedback loop
What is the nervous system?
A regulatory system composed brain, spinal cord and nerves
What does the Central Nervous System control?
Controls movement, intellectual and physiological function, detects and processes sensory information
What mediators do the Nervous System release?
What is a neurotransmitter?
Chemical messengers released by neurones to regulate activity of other neurones, glands and muscles
What releases neurotransmitters?
Neurone releases it into a synapse
What is a synapse?
Region where communication occurs between a neurone and an effector cell (muscle or gland) or another neurone
What happens after a Neurotransmitters (NTs) released into chemical synapse?
NTs diffuse through synaptic cleft and bind to specific receptors on target cell
NT binding to receptor activates one of many pathways
Like hormones , can activate a G-protein cascade which produces a physiological response
How do electrical synapses release neurotransmitters?
Ions flow directly between adjacent cells through a gap
Gap junction connects cytosol of two cells together
Where are gap junctions found?
Smooth muscle, cardiac muscle and developing embryo
What neuropeptides are released from nerves in hypothalamus?
What do the endocrine and nervous system have in common?
Both associated with the brain
Same molecules can be both neurotransmitters and hormones
Two systems work simultaneously to regulate critical body processes
What are the differences between the nervous and endocrine systems?
Endocrine secretes hormones that are transported in the bloodstream
Nervous system secretes neurotransmitters released directly onto target cells
Nervous system- activates targets quickly not long lasting
Endocrine system- longer lasting effects
What are hormones physiological functions?
What is paracrine signalling?
What is synaptic signalling?
Between cells with a synapse in between
What is autocrine signalling?
Cell secretes hormone/messenger