Download Transcripts/4_10 10-12 (pt.1) (Benvensee)

Cardio: 10:00 - 10:30 (Part A)
Scribe: Teresa Kilborn
Friday, April 10, 2009
Proof: Chaz Capra
Dr. McNicholas
Autonomics
Page 1 of 3
ANS-Autonomic Nervous System, CV- cardiovascular system, Ach- Acetylcholine, NE- Norepinephrine, Eepinephrine, SA- sinoatrial, AV- atrioventricular
I.
II.
III.
IV.
V.
VI.
Autonomics[S1]:
a. This will be an introduction of the electrical physiology of the heart
b. This part is a basic review of the ANS as it relates to the CV system
c. She will give us a handout like last time that describes the slides- no need for a textbook for her material
Autonomic Nervous System [S2]:
a. Known as the visceral nervous system
b. It is the involuntary nervous system, in general we have no conscious control of the ANS
c. It regulates the activity of the heart and also the smooth muscle of the blood vessels
d. The ANS maintains homeostasis within the body and modulates the intrinsic rhythm and tone of smooth muscle
e. In the heart and in some smooth muscle there is intrinsic rhythm in that muscle
f. The ANS presents a balance of activity. Depending on which branch of the ANS is activated you will have a
modulation, either an up regulation or a down regulation of each of those processes
ANS Subdivisions [S3]
a. Subdivisions are the sympathetic and parasympathetic
i. Sympathetic is involved in the flight and fight reflex. It defends the body against adverse conditions. It is
activated in times of stressful conditions, if you are in pain, if you are frightened, or if you are angry. It is
involved mostly in the expenditure of energy.
b. Parasympathetic nervous system is the rest and digest subdivision of the ANS. It provides the relaxation type of
activity. It helps in the restoration and conservation of energy
Picture [S4]
a. This figure shows the areas of the brain and brain stem that are involved in the ANS.
b. The hypothalamus and some of the higher cortical areas of the brain are involved in regulation of the
parasympathetic nervous system
c. Areas of the brain stem are involved in activities of the heart and vascular system. It is involved, for example, in
cardiac acceleration and vasoconstriction
d. The cortex and hypothalamus are in contact which each other through neurons to the medulla where the
Nucleus Tractus solitaries (NTS) will either activate the vagal system or it is involved in regulation of the
sympathetic nervous system.
e. You have distal receptor afferents, from baroreceptors and chemoreceptors
f. Chemoreceptors detect composition of blood and they send messages to the medulla that then tells the
parasympathetic nervous system or the sympathetic nervous system to modulate activity of its effecter organ
g. In the somatic nervous there is 1 neuron that goes to the effecter organ. In contrast, 2 neurons involved in ANS:
a pre-ganglionic and postganglionic neuron
h. The neurotransmitter between the pre and post-ganglionic neuron in the ANS is Ach, but it is not always the NT
when you reach the target organ, it can be Ach or NE
Diagram [S5]
a. Somatic Nervous system- a single axon that originates in the CNS and goes to the effecter organ
b. Parasympathetic Nervous system- the neuron that connects with the synapse is a longer neuron than you find in
the sympathetic nervous system. At the synapse the NT is Ach. The receptors at the effecter are cholinergic
subtypes.
c. Sympathetic Nervous system- Ach is the NT at the synapse. There are shorter pre-ganglionic and longer post
synaptic fibers that then direct electrical impulses to the effecter organ such as smooth muscle and cardiac
muscle. The smooth muscle in this case is in the blood vessels. When you reach the effecter organ there are
alpha and beta receptors and it depends on the tissue type that those receptors are present on.
d. The second effecter of the sympathetic nervous system is on the adrenal medulla. Synaptic transmission of Ach
has an effect on the adrenal medulla to release E and NE.
e. How do the E and NE reach the target organ from the adrenal medulla? The blood stream so that is a hormonal
regulation rather than a neuronal regulation. They both act together to effect the effecter organ.
Diagram [S6]
a. Illustration of the 2 branches of the ANS
b. Sympathetic on left and parasympathetic on the right
c. Circled in pink are the organs that we are concerned with: the CV system. The smooth muscle cells of the blood
vessels, the heart cells, and the adrenal medulla.
d. Only on the sympathetic side are neurons that synapse on the adrenal medulla. The sympathetic nervous
system acts directly on the adrenal medulla to release NE and E
Cardio: 10:00 - 10:30 (Part A)
Scribe: Teresa Kilborn
Friday, April 10, 2009
Proof: Chaz Capra
Dr. McNicholas
Autonomics
Page 2 of 3
e. There are branches of both the sympathetic nervous system and the parasympathetic nervous system that
effect the heart and so there is a balance of those two pathways that are involved in regulation of heart activity
f. For blood vessels, the sympathetic system affects activity of blood vessels
VII. Sympathetic Origin [S7]
a. The sympathetic origin is from the thoracolumbar outflow. The nerve fibers originate between T1 and L2. She
won’t ask a question about that kind of detail. Just to illustrate the diverse origin of the sympathetic nerves that
are involved in the ANS
b. Sympathetic nervous system affects adrenal medulla
c. It also affects the heart and a lot of other things
d. Pre-ganglionic fibers are short, NT is Ach
e. Post-ganglionic are longer and adrenergic
VIII. Parasympathetic Origin [S8]
a. Less diverse origin throughout the entire spinal cord, but this illustrates the origin of the nerves involved in the
parasympathetic nervous system
b. They have craniosacral outflow: from the cranial and sacral region of the spinal cord
IX. No Title [S9]
a. The NT involved in the ANS are NE and Ach
b. Ach are released by all preganglionic neurons to effect the post ganglionic neuron
c. NE is released by the postganglionic neuron and synapses of the adrenergic nervous system
d. Subdivision of the ANS also involves the adrenal medulla which releases NE and E
e. There is an enzyme which methylates NE to produce E. That occurs in the adrenal medulla.
f. FOR MY QUESTIONS, YOU WILL NOT NEED TO MEMORIZE THE STRUCTURES OF NE/ACH
X. Innervation of the heart by ANS subdivisions [S10]
a. Illustrates the ANS innervations of the heart.
b. Again the heart is supplied by the sympathetic and parasympathetic nervous system
c. Parasympathetic nervous system: neurons from the vagal nerve interact with the atria and the SA node
d. AV node is also supplied by nerves from the parasympathetic nervous system with Ach as the NT that affects
the activity of those cell types within the SA and AV node.
e. In contrast, in the sympathetic nervous system the nerves are much more diverse. There are more areas of the
heart innervated by those nerves
f. The parasympathetic nervous system has very little effect on the VENTRICULAR myocardium. THE PARASNS
innervated the atrial tissue...recall that ACh increases activity of IKACh channels that cause a hyperpolarization
of the atrial myocytes.
g. The nerves of the sympathetic nervous system interact with the ventricular myocytes and the cells that form the
SA node and the AV node. Those are specialized cells. They are kind of like muscle cells, but they are much
less developed in their structure and their function is very different from the gross myocardium.
XI. Adrenergic Receptor Responses to Stimulation [S11]
a. The adrenergic receptors’ responses to stimulation as they relate to the CV system.
b. The blood vessels have alpha and beta adrenergic receptors and depending on the receptor that is present
there can be constriction or dilation
c. Cardiac muscle - basic adrenergic receptors are involved in the increase in contractility
d. The receptor and interaction with intracellular signaling molecules will be discussed as how the response occurs
as far as the NT interacting with the receptor
e. FYI- as far as she is concerned we don’t need to know the subtypes of receptors, just if it is adrenergic or
cholinergic. But remember the pharmacology Prof may require this knowledge so don't dismiss it!!!
f. The AV node - has adrenergic receptor activity that increases HR
g. The SA node - receptors mediated regulation increase the activity of the heart by increasing the rate of firing of
those cells
XII. Diagram [S12]
a. The heart - there are different types of activity.
b. Chronotropy - where the rate is changed. If the sympathetic nervous system is activated, then it will increase
the firing of those cells that lead to that target and it will greatly increase the firing of those cell types. The
parasympathetic nervous system will decrease
c. The relative number of plus signs and minus signs refers to the relative intensity of increases or decreases
d. The sympathetic nervous system, it makes sense, flight or fight response that you are going to increase the rate
of firing. The parasympathetic nervous system, is the relaxation part of the ANS, it will slow the heart down and
allow it to rest.
Cardio: 10:00 - 10:30 (Part A)
Scribe: Teresa Kilborn
Friday, April 10, 2009
Proof: Chaz Capra
Dr. McNicholas
Autonomics
Page 3 of 3
e. Ionotropy is related to contractility the myocardium. An increase in sympathetic origin, you will get an increase
in contractility and you will force the blood out of the ventricles more forcefully. If the parasympathetic nervous
system is activated then you can get a decrease in contractility.
f. If there is sympathetic activity then there is an increase in lusitropy or increase in relaxation of certain blood
vessels. Ex. increase in sympathetic activity will cause coronary vessels to relax and more blood to reach the
myocardium, when the sympathetic nervous system is activation you are going to send off more signals to
increase the heart rate and there has to be blood supply to the myocardium for it to perform properly
g. Dromotropy is the conduction velocity. If you increase the sympathetic activity then you will increase the
conduction velocity. If you increase the parasympathetic activity then you will decrease the conduction velocity,
so it slows the heart down, slows the rate of activation of the myocardium - the atria and the ventricles.
h. The sympathetic nervous system is involved in arterial constriction and venous constriction. The
parasympathetic system has little control over the vascular system.
XIII. Catecholamines [S13]
a. This is just to remind you that there are endogenous sympathomimetic responses to cathecholimines: NE or E,
(or adrenaline and noradrenaline) and dopamine
b. You can also have synthetic activation of the sympathetic nervous system by synthetic compounds that you can
use to increase activity exogenously as it relates to the heart
THE REMAINING SLIDES WERE TO ILLUSTRATE THE INTEGRATION OF THE ANS WITH OTHER SYSTEMS.
THESE WILL BE COVERED IN OTHER LECTURES IN MORE DETAIL. THEY MAY BE USED AS REFERENCE LATER
IN YOUR LECTURES BUT WERE NOT INTENDED AS A COMPREHENSIVE REVIEW!!!!
Diagram – Cardiac Output [S14]
a. Shows that the sympathetic and parasympathetic systems are important in the overall regulation of the CV
system, but they are not the only players
b. For ex., if you are exercising then that is going to increase the venous return
c. If you are under stress, you increase the sympathetic nervous system activity
d. Green arrows represent promotion or enhancement, red arrows represent reduction
e. If you have high blood pressure or blood volume then you’re going to decrease the sympathetic nervous system
activity. The parasympathetic nervous system will decrease the heart rate and depending on the overall activity
of the body and of the ANS, you can have an increase or decrease of cardiac output. This just illustrates that
other stresses can also affect the activity of the sympathetic nervous system
f. You can have affecters, such as baroreceptors, that detect changes and then talk to the central nervous system
and then messages are via the parasympathetic nervous system to adjust the activity of the CV system.
XV. Picture [S15]
a. This just illustrates how blood vessel constriction or relaxation can occur due to the activity of the ANS.
b. If there is frequent firing of the neurons and releasing NE into the synapse to react with the receptor on the
blood vessel, then you will increase the contraction.
c. If you decrease the number of firing events per second then you are going to decrease the amount of NE that is
released and that will allow for dilation of the blood vessel.
XVI.
Factors determine Blood Pressure [S16]
a. Illustrates that the ANS only plays one part in the regulation of the CV system
b. Other portions of the physiology of the body will have effects on the activity of the CV system and the overall
physiology of the body.
c. A decrease in blood volume is detected by baroreceptors which increase their firing rate. The change is
detected by the CNS. You will change the activity of the ANS. Which branch of the ANS that is activated? If
you have a decrease in blood volume then you will want to increase your blood pressure which is done by
vasoconstriction, so the sympathetic nervous system activates constriction of blood vessels and increase in
heart rate. The end result is an increase in blood pressure.
d. Just to show how the receptors in distal parts of the body can affect the CNS which can then affect the
sympathetic nervous system to change the activity of the heart rate or vasoconstriction that then has an effect
on blood pressure.
[End 23:10]
XIV.