Lecture 14: Autonomic and Endocrine Systems Flashcards
What does the PNS consist of?
all nervous tissue outside of CNS
Cranial nerves - 12 pairs
Spinal nerves - 31 pairs - radiate out from the spinal cord
Ganglia - mass of nervous tissue (cell bodies) switching stations
Peripheral Nerves into peripheral tissues
What does the CNS consist of?
Brain and Spinal Cord (which are connected by the Foramen Magnum)
What does the CNS process?
CNS processes many kinds of sensory info and is the source of -thoughts, emotions and memories
What are sensory neurons?
Afferent neurons
autonomic/somatic receptors detect stimuli and collect information
respond to information inside and outside our body
via Cranial and Spinal Nerves
What are Motor neurons?
Efferent neurons
Not under voluntary conscious control
Somatic (voluntary) –> skeletal muscle
Autonomic(involuntary) –> sympathetic or parasympathetic –> cardiac muscle, smooth muscle, glands
What is the role of nerves?
Hardwired mechanism which coordinate our actions and bodily functions through collecting information and sending signals out
What do autonomic motor neurons control?
Involuntary muscle
e.g.: Cardiac muscle, Smooth muscle, Glands
What is the role of axons?
transmits APs along the neuron
very long as they need to take information a really long distance before they terminate the information
What is the role of the myelin sheath?
insulating layer
What is the role of dendrites?
To radiate out of the cell body/nucleus and receive APs
What are the 5 steps to nerve impulse transmission?
Occurs rapidly in course of milliseconds
- Nerve impulses travel down presynaptic neuron
- Opens voltage gated Ca2+ channels, which changes its structure(proteins in axon terminal cell wall) due to voltage change
- Influx of Ca2+ promotes vesicles (containing neurotransmitters) to empty into the synaptic cleft by fusing with the membrane and releasing neurotransmitters
- Neurotransmitter binds to ligand gated SODIUM channels/receptor on post synaptic neuron- causing influx of Na2+
- Voltage changes and Conducts a nerve impulse down post synaptic neuron (dendrites–>cell body–>axon)
What do unmyelinated nerves look like?
They have Schwann cells associated with it but not wrapped insulation around them
What are nerve impulses?
Electrochemical signals
Rapid moving voltage
What is the Autonomic Nervous system?
Self governing system
How has a the sympathetic system evolved?
Evolved to help respond to particularly dangerous or threatening situations
What is the sympathetic division?
Responses associated with Exercise, Emotion and Excitement
What response in included in the sympathetic division?
The alarm response
“fight , fright or flight response”
In what areas of the body does the autonomic NS affect?
Heart Eyes Mouth Lungs Skin Gut
What change occurs in the Heart during the Alarm response?
Increased rate
Increased force of contraction
so blood can move through up to 5 times faster with more force
What change occurs in the Eyes during the Alarm response?
Pupils are dilated
- more (sensory) aware of your surroundings
- get information more quickly and easily
What change occurs in the Mouth during the Alarm Response?
Decrease in saliva
-aids digestion which is not required so energy is used elsewhere
What change occurs in the Lungs during the Alarm response?
Dilated Bronchi
allow more O2 into the body
What change occurs in the Skin during the Alarm Response?
Constrict Peripheral Blood vessels - pushes blood to muscles and key areas - lighter skin colour
Contract erector pili muscles - hairs stand on end/look threatening
Increased sweet secretion - more evaporation-heat removed/cool surfaces
What changes occur in the Gut during the Alarm Response?
Decrease Digestion
-digestion is an energetic long term process so it would be wasteful
What additional changes occurs to the blood during the Alarm Response?
Increased Blood Sugar- needed for respiration(muscles to move to fight or flee) from liver
Increase BP and Increased Water Retention - transport is fast by the water retention - release a loss of blood in potential damage in fight
What response in included in the parasympathetic division?
The relaxation response
What is the parasympathetic division?
Responses associated with - Repletion, Rest and Relaxation
What changes occur in the Heart during the Relaxation Response?
Decrease rate
Decrease force of contraction
What changes occur in the Eyes during the Relaxation Response?
Pupils contract
What changes occur in the Mouth during the Relaxation Response?
Increased Saliva
-regeneration activities such as - digestion and -repair
What changes occur in the Lungs during the Relaxation Response?
Constrict Bronchi
-dont take in as much oxygen into the body as we are relaxing
What changes occur in the Skin during the Relaxation Response?
Dilate Peripheral blood vessels
-allows more blood into tissues and cellular areas
What changes occur in the Gut during the Relaxation response?
Increased digestion
What sort of action is the parasympathetic system?
Deactivating action as it moves into a rest and relaxation response
What sort of systems are the somatic and autonomic nervous systems?
Inducible’s systems
They can be turned on and off when needed to be
What does the Somatic Nervous system consist of?
Sensory input: Special senses and somatic senses
Control of Output: Voluntary from Cerebral cortex
Effectors: Skeletal Muscle
Motor Neuron Pathway: One neuron Pathway
Neurotransmitter: ACh (acetylcholine) - directly innervates synapse with muscle
What does the Autonomic system consist of?
Sensory input: Mainly interoceptors - internal sensing
Control of Output: Involuntary from limbic system, hypothalamus, brain stem and spinal cord
Effectors: Smooth muscle (contraction or relaxation), Cardiac Muscle (increase or decreased rate and force of contraction), Glands (increased or decreased secretions)
Motor Neuron Pathway: Two neuron pathway
Neurotransmitters: 3x combinations, using ACh or NE
What are the Neurotransmitters for the ANS?
Cholinergic ACh + aclinergic NE = sympathetic division = innervation to most effector tissues but sweat glands
Cholinergic ACh + Cholinergic ACh = Sympathetic division= innervation to most sweat glands
Cholinergic ACh + Cholinergic ACh = Parasympathetic division= always ACh
What does the Somatic Nervous Pathway consist of?
Spinal cord –> cell body/axon –> Somatic Myelinated Motor Neuron –> Effector Skeletal Muscle
What does the Autonomic Nervous system consist of?
Spinal cord –> cellbody/axon –> PREganglionic Myelinated Neuron –> Post Ganglionic Autonomin Unmyelinated Motor Neuron –> Effector Muscle
What is the Endocrine System?
System which secretes hormones or responds
What is the role of the Hypothalamus?
Controls internal organs via the Autonomic System and Pituitary gland (endocrine/hormonal system effects on pituitary) in order for us to stay alive
Which 5 things does the Hypothalamus Regulate?
- Behavioural patterns
- Circadian rhythms
- Sleep/wake cycles
- Controls body temperature
- Eating and drinking behaviour
Which 3 things form the HPA?
"Hypothalamus - Pituitary - Adrenal Axis" Pituitary Gland Adrenal Gland Hypothalamus controls most of the endocrine system
What is the role of the Testes and Ovaries?
Gonads
Which can secrete Reproductive hormones
What are hormones?
small molecules which are produced by a cell, travels through blood stream and which affect the function of an organ/cell in a distal site
Signal molecules produced in one place, affecting some place else
What are the 2 types of hormones?
Circulating Hormones
Local Hormones
Where are Circulating Hormone receptors located?
Receptor distal to the endocrine cell
Where are Local Hormone receptors located?
Receptor cell in close proximity to the Paracrine cell
Hormones acts back on its own cell - autocrine cell and target cell is the same
What is the Target cell also?
Autocrine cell
What is the control of hormone release?
Inducible System (1. Synthesis-> Storage-> Release(hormone producing cell)) ---release and circulation--> 2. Blood ----> 3. Desired response (target cell with receptors for specific hormones (only affects tissues with receptors)) -----> 4. Hormone Disposal (concentration diminished due to breakdown and excretion by enzymes in tissue/bloodstream) ----> 5. Feedback signal (usually negative) ---> 1.
How do Lipid Soluble Hormone systems function?
Produced with carrier/transport protein which allows it to get through/be carried through the blood stream in a soluble form
1. Lipid soluble hormone diffuses into the cell (through lipid bilayer of target tissue)
2. Diffuses into nucleus, Activated receptor-hormone complex alters gene expression
(turns specific genes of nucleus DNA on/off, via transcript making mRNA)
3. Newly formed mRNA directs synthesis of specific proteins on ribosomes
4. New proteins alter cells activity = new/altered cell activity/function
How do Water soluble Hormone systems function?
Able to carry through blood without transporter (can diffuse through blood) as lipid insoluble form (can’t get through lipid bilayer)
1. Binding of hormone (first messenger) to its receptor on the surface, and activates G-protein in membrane (changes structure), which activates Adenylate cyclase inside the cell (changes structure)
2. Activated adenylate cyclase converts ATP to cAMP
3. cAMP serves as a second messenger to activate protein kinases (addition of phosphate)
4. Activated protein kinases phosphorylate cellular proteins
5. Millions of phosphorylated proteins cause(catalyse) reactions that produce physiological responses
6. Phosphodiesterase inactivates cAMP. Alters Posphorylation and the way proteins work
After time period Phosphodiesterase inactivates cAMP
What are 3 examples of Lipid Soluble hormones?
Steroid Hormones - cortisol, ancligens, atclosterone
Thyroid Hormones
NO (Nitrous Oxide)
What are 3 examples of Water Soluble Hormones?
Catecholamines - epinephrine and norepinephrine
Peptides
Proteins
What is Cholera?
Chronic activation of the hormone system
What does Cholera involve?
(infection)
bacterium (cholerum bacterium) produces toxin which gets into crypts of small intestine and binds to inducible G proteins on hormone receptors irreversibly
Metabolites binds to G proteins on suface of intestinal cells
-locks G protein into activated state
system that was once inducible now becomes constituent
-high cAMP (inside intestinal cells)
-pumps chloride ions into intestines
-water flows out to lumen (trying to balance osmolarity) –> Chronic Diarrhoea
What is Rayhaud Disease?
Excessive sympathetic stimulation following emotional stress or exposure to the cold
What does Rayhaud Disease involve?
Autonomic activation
Chronic vasoconstriction (for a longer period of time/after danger)
Constricts peripheral capillaries and blood doesn’t flow
fingers and toes (extremities) become ischaemic due to lack of blood and oxygen
Fingers and toes have a White appearance and are Cold to touch
caused by exposure to cole, or having an emotions stress etc.
What do the adrenal glands do?
pump the body with adrenalin
short energy burst to respond quickly
What is the benefit of the sympathetic NS?
Allows your body to gear up and respond/be ready for danger
changes in lots of places of the body
Rapid application in response to danger, then deactivation over time
What is the function for the relaxation process?
causing to do more long term functions
sensation/rest and repletion type responses
What does Autonomic mean?
self governing
What is a major difference between somatic nerves and autonomic nerves?
Autonomic nerves aren’t a single nerve pathway
they go through switching stations called autonomic ganglions
Which Neurotransmitter is used mainly by the post ganglionic neuron when innervating other tissues?
NE
-effect in Sweat Gland innervation
Sympathetic
What are the major differences between the Somatic and Autonomic Nervous system?
Single Neuron pathway vs 2
ACH only vs ACH sympathetic to sweat + NE
autonomic= activate quickly but when you turn off, things return back to normal
Why is it important that the Autonomic NS in particular is inductive?
Because once fright, flight or fight response is activated, it needs to turn off
and therefore body needs to recalibrate to a different context
What is ischaemia?
When there is no blood circulating to an organ for a long period of time, and cells can start to die
Where is the Hypothalamus located?
In the centre of the limbic system
Where is the adrenal gland located?
just ontop of our kidneys
Adrenal = “onto of kidneys”
What is the endocrine pathway?
Hypothalamus –> Pituitary Gland
What is the location and function of the thyroid?
located around trachea
secretes growth hormones
What ist he location and function of the thymus?
located under sternum
endocrine organ
works in immune function`
What are important endocrine organs?
Pineal gland Thryoid gland Trachea Thymus Heart Lung Stomach Pancreas Kidney Small intestine
What are Paracrine cells?
Produced by a cell and acts on a cell near too it
What are Autocrine cells?
Produced by a cell and acts on the same cell
What are the 3 names of hormones?
Endocrine
Paracrine
Autocrine
What determines whether a hormone can bind to a cell?
Whether or not that cell has a receptor
No receptor = No response
What is the difference between the autonomic nervous system and the control of hormone release?
Control of hormone release time course is longer
Autonomic Nervous system = milliseconds to activate, switches off fast
Hormone Release control= seconds to activate, switch of slow as need to have feedback or need to break down the hormones to be produced
How do you reverse an inducible hormone system?
Take away the hormone
and things will revert back to the way they once were
What is the inducible part of the Water soluble Hormone Process?
G Protein
