ANS Lectures 1&2 Flashcards
1
Q
What two communicating systems are involved in the ANS?
A
Nervous system and Endocrine system
2
Q
What are three functions of the ANS?
A
- Maintain homeostasis
- Response to stress
- Regulates day to day functions in the body
3
Q
Fill in the table comparing the ANS and the SNS:
Autonomic NS vs Somatic NS
A
4
Q
In the ANS, the efferent path is a _______ link:
- The first neuron is called the _________ and has it’s cell body in the _____. It’s axon terminates in the _______ (cluster of neuronal cell bodies outside of the CNS). The axon is ________.
- The second neuron is called the _______ and it’s cell body is found in the _____. It’s axon is ______ and terminates on the target tissue
A
In the ANS, the efferent path is a two-neuron link:
- The first neuron is called the pre-ganglionic neuron and has it’s cell body in the CNS. It’s axon terminates in the Ganglion (cluster of neuronal cell bodies outside of the CNS). The axon is myelinated.
- The second neuron is called the Post-ganglionic neuron and it’s cell body is found in the ganglion. It’s axon is unmyelinated and terminates on the target tissue
5
Q
Where are the cell bodies of preganglionic fibres located?
Sympathetic
A
Sympathetic division:
- cell bodies are located in the thoracic and lumbar regions of the spinal cord
- Specifically: thoracic levels 1-12 and lumbar regions 1 and 2
Parasympathetic:
- cell bodies are located in the brainstem and sacral regions of the spinal cord
- Cranial nerves 3, 7, 9, and 10 carry parasympathetic fibres
- In the sacral region, cell bodies arise from regions S2-S4
6
Q
Where are the cell bodies of the preganglionic neurons of the ANS?
Parasympathetic
- CN?
- Sacral nerves?
A
Parasympathetic:
- cell bodies are located in the brainstem and sacral regions of the spinal cord
- Cranial nerves 3, 7, 9, and 10 carry parasympathetic fibres
- In the sacral region, cell bodies arise from regions S2-S4
Sympathetic division:
- cell bodies are located in the thoracic and lumbar regions of the spinal cord
- Specifically: thoracic levels 1-12 and lumbar regions 1 and 2
7
Q
What forms the spinal nerve?
A
The joining of the dorsal and ventral roots from the spinal cord
8
Q
In the somatic system, where are cell bodies of somatic motor neurons found?
A
Ventral horn of the grey matter
9
Q
Where are the cell bodies of the preganglionic fibre of the parasympathetic division?
Where do their axons leave the spinal cord?
A
In the lateral region (lateral horn) of the grey matter.
Axons pass through the ventral roots, join the spinal nerve and then branch off to a ganglion
10
Q
Where are ganglia of the parasympathetic system located?
What are they called?
A
Close to (or within) the target organs and are called terminal ganglia
11
Q
The parasympathetic division has a ____ preganglionic fiber and a _______ postganglionic fibre
A
The parasympathetic division has a long preganglionic fiber and a short postganglionic fibre
12
Q
What is it called when one preganglionic fibre connects with several postganglionic fibres?
A
Divergence
13
Q
What is it called when several preganglionic fibres converge into a single post-ganglionic fibre?
A
Convergence
14
Q
What is a ganglion?
A
collection (cluster) of neuronal cell bodies outside of the CNS
15
Q
Preganglionic sympathetic fibres have their cell body in the ________
And leaves the spinal cord via the ______
A
Preganglionic sympathetic fibres have their cell body in the lateral region of the grey matter
And leaves the spinal cord via the ventral roots
16
Q
What are the 3 pathways that a sympathetic preganglionic fibre can take when it leaves the spinal cord?
A
- Synapse immediately with a postganglionic neuron in sympathetic ganglion at the same level
- travel up or down the chain and synapse in ganglia at other levels
- Pass through chain without synapsing , continue to collateral ganglion as splanchnic nerve
17
Q
What are communicating Rami?
A
Branches, or connections, between the spinal nerve and the ganglia
18
Q
What is the white ramus communicans?
Why does it appear white?
A
the branch that leads into the ganglion from the spinal nerve
- white because it is carrying a myelinated preganglionic fibre
19
Q
What is the grey ramus communicans?
A
Branch that goes back into the spinal nerve
- Grey because it is carrying unmyelinated postganglionic fibre
20
Q
What are the two main types of ganglia and their locations?
A
- Sympathetic chain ganglia (or sympathetic trunk)
- also called paravertebral ganglia as they are next to or parallel to the vertebral column
- Collateral ganglia
- aka prevertebral ganglia as they are found in the front of the vertebrae column, roughly in the midline of the body
21
Q
With both types of sympathetic ganglia, the sympathetic preganglionic fibres are ____ and the postganglionic fibres are _____
A
With both types of sympathetic ganglia, the sympathetic preganglionic fibres are short and the postganglionic fibres are long
22
Q
What is a varicosity
A
Chains of swellings along the branches of postganglionic fiber; contain synaptic vesicles which release NT’s
23
Q
Where is a varicosity found?
A
Both sympathetic and parasympathetic postganglionic fibres
*Not preganglionic fibres*
24
Q
What is the purpose of varicosities?
A
Varicosities on postganglionic nerve terminals are spread along the surface of the target tissue/organ, allowing a chemical messenger to spread rapidly.
25
What is the sympathoadrenal system?
a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli.
26
What are the two regions of the adrenal glands?
Outside adrenal cortex and inside adrenal medulla
27
The adrenal medulla is innervated by \_\_\_\_\_\_\_\_\_\_
sympathetic preganglionic fibres
(No parasympathetic innervation)
28
The adrenal medulla acts as a modified \_\_\_\_\_\_\_\_\_\_\_
The adrenal medulla acts as a modified _sympathetic postganglionic fibre_
29
What cells in the adrenal medulla produce, store and release hormones?
Chromaffin Cells
30
What hormones does Chromaffin produce, store and release?
Chromaffin cells from the adrenal medulla produce, store and release the hormones:
* epinephrine
* norepinephrine
* (Considered hormones because they are released into the blood and carried about the body through the circulatory system,)
31
Which transmitters of the ANS are released from the preganglionic fibres in both sympathetic and parasympathetic systems?
* ACh (Acetylcholine)
32
What is ACh?
* released from which ganglia?
* acts on?
* Transmitter at all autonomic ganglia
* released from preganglionic fibres in both sympathetic and parasympathetic systems at the ganglia
* Acts on **postganglionic** fibre
* Released from postganglionic parasympathetic fibres and acts on target tissue
33
Parasympathetic: ACh released from _________ fibres acts on \_\_\_\_\_\_
Parasympathetic: ACh released from _postganglionic parasympathetic_ fibres acts on _target tissue (smooth muscle, cardiac muscle, glands)_
34
Which transmitters/hormones are released from postganglionic fibres?
* ACh (released from both pre and postganglionic fibres in both sympathetic and parasympathetic pathways)
* Norepinephrine (NE): released from postganglionic *sympathetic* fibres
35
Sympathetic: NE released from _________ acts on most target tissues
Sympathetic: NE released from _postganglionic sympathetic fibres_ acts on most target tissues (smooth muscle, cardiac muscle, glands)
36
Adrenal medulla is innervated by _________ which release ACh which causes ________ cells to release \_\_\_\_\_, ______ into the blood which acts as hormones
Adrenal medulla is innervated by _sympathetic preganglionic fibres_ which release ACh which causes _chromaffin_ cells to release _epinephrine_, _norepinephrine_ into the blood which acts as hormones
37
A receptor that is able to bine ACh is called a \_\_\_\_\_\_
Cholinergic recepter
38
Cholinergic refers to which transmitter?
ACh
39
What two things combine to form ACh
Acetyl CoA and choline
40
What are the 5 events at the Cholinergic nerve terminal?
1. _\_\_\_\_\_\__ is brought into the nerve terminal by a protein acting as a choline-carrier
2. _\_\_\_\__ is packaged into vesicles and stored in the terminal until a stimulus causes its release
3. Stimulus for release of ACh from vesicles: _\_\_\__arrives, opens \_\_\_\_\_\_\__._ _\_\_\_\_\__rushes in causing the vesicles containing _\_\_\_\_\__ to move to the membrane and fuse, releasing _\_\_\__ into the synapse
4. ACh acts on _\_\_\_\_\_\_\__on the membrane of the _\_\_\_\_\_\_\__ fibre
5. Once released from the receptor, ACh is broken down by _\_\_\_\_\_\_\_\__ into choline and acetate
What are the 5 events at the Cholinergic nerve terminal?
1. _Choline_ is brought into the nerve terminal by a protein acting as a choline-carrier
2. _ACh_ is packaged into vesicles and stored in the terminal until a stimulus causes its release
3. Stimulus for release of ACh from vesicles: _AP_ arrives, opens _voltage-gated Calcium channels._ _Ca_ rushes in causing the vesicles containing _ACh_ to move to the membrane and fuse, releasing _ACh_ into the synapse
4. ACh acts on _cholinergic receptors_ on the membrane of the _postganglionic_ fibre
5. Once released from the receptor, ACh is broken down by _acetylcholinesterase_ into choline and acetate
41
If norepinephrine is released, what division of the nervous system does the postganglionic fibre belong?
Sympathetic
42
What are the events at a (Nor)Adrenergic Varicosity?
1. Norepinephrine is synthesized from the amino acid ______ which is taken up into the terminal.
2. Tyrosine converted to _____ and then to _____ which is taken up into the vesicle and converted to NE
3. Release of NE occurs when an _____ comes down the ________ and causes the opening of \_\_\_\_\_
4. _____ moves into the cell and the increase in its concentration causes the vesicles to move to and fuse with the outer membrane
5. NE is released via \_\_\_\_\_
6. NE binds to ________ receptors on the target tissue membrane
What are the events at a (Nor)Adrenergic Varicosity?
1. Norepinephrine is synthesized from the amino acid _tyrosine_ which is taken up into the terminal.
2. Tyrosine converted to _DOPA_ and then to _dopamine_ which is taken up into the vesicle and converted to NE
3. Release of NE occurs when an _AP_ comes down the _sympathetic postganglionic fibre_ and causes the opening of _Ca channels_
4. _Calcium_ moves into the cell and the increase in its concentration causes the vesicles to move to and fuse with the outer membrane
5. NE is released via _exocytosis_
6. NE binds to _andrenergic_ receptors on the target tissue membrane
43
How is the action of norepinephrine terminated?
Reuptake into the nerve terminal
NE is removed from the synaptic space by a special transport system which takes NE back into the varicosity
\*NE is NOT broken down but the whole molecule is taken up
NE is repacked into vesicles to be used again
44
What are the transmitters of the ANS other that acetylcholine and noradrenaline?
Non-adrenergic, non-cholinergic (NANC) transmission
* peptides, amines, amino acids, gases
45
ACh is released from:
(3)
1. Autonomic ganglia (parasympathetic and sympathetic)
2. Parasympathetic postganglionic endings
3. A few sympathetic postganglionic endings (thermoregulatory sweat glands, blood vessels in skeletal muscle)
46
Norepinephrine is released from:
* Most sympathetic postganglionic endings
* adrenal medulla (also epinephrine; hormones)
47
What type of receptors does Acetylcholine bind to?
Acetylcholine binds to Cholinergic Receptors
Two types:
* Nicotinic
* Muscarinic
48
What are the two types of Cholinergic receptors and their subtypes?
1. **Nicotinic**
1. NM (in skeletal muscle)
2. NN (In nervous tissue)
2. **Muscarinic** (In smooth muscle, cardiac muscle, and glands)
1. ****M1
2. M2
3. M3
4. M4
5. M5
49
Where are NM Receptors found and what do they bind?
NM
* Subtype of Nicotinic Cholinergic receptors
* Bind ACh released from somatic motor neuronss
* Found in skeletal muscle at the neuromuscular junction
50
NN receptors are found:
Bind to?
* Type of Nicotinic Cholinergic receptor
1. Found in nervous tissue
* at the autonomic ganglia (ie found on the cell body of the postganglionic neuron at the autonomic ganglia)
* Binds to ACh released from the preganglionic fiber
2. Found in Adrenal Medulla
* Binds ACh released from the sympathetic preganglionic fibre
51
What are Muscarinic receptors and where are they found?
Type of Cholinergic receptor
* found in target tissues (smooth muscle, cardiac muscle, glands)
* 5 subtypes: M1-5
52
What family of receptors binds norepinephrine and epinephrine?
Adrenergic receptors
53
Where are adrenergic receptors found?
Always found on the target tissues (smooth muscle, cardiac muscle and glands)
54
What are the two types of adrenergic receptors and their subtypes?
Alpha (2 subtypes types) and
beta (3 subtypes types)
55
Nicotinic receptors are ________ (form ion channel following the binding of a ligand; ligand-gated)
Nicotinic receptors are _ionotropic receptors_ (form ion channel following the binding of a ligand; ligand-gated)
56
Muscarinic and adrenergic receptors are ______ (membrane receptor that initiates the formation of second messengers following the binding of a ligand)
Muscarinic and adrenergic receptors are _metabotropic receptors_ (membrane receptor that initiates the formation of second messengers following the binding of a ligand)
57
What type of receptor forms ion channels following the binding of a ligand and are also ligand-gated ion channels?
Ionotropic receptor
58
Which receptor has a dough-nut shape with 5 subunits embedded in the plasma membrane which have a pore in the middle
Nicotinic receptor
59
Which nicotinic subunit has the binding sight for acetylcholine?
the 2 Alpha subunits
60
What happens to the nicotinic receptor when ACh binds?
Conformation change of the receptor molecule = opens up = allows ions to move through the pore
61
Which receptors have a serpentine shape made of 7 transmembrane subunits?
Muscarinic and Adrenergic Receptors
(metabotropic receptors)
62
1. ACh ALWAYS binds to _________ receptors:
* \_\_\_\_\_\_\_
* \_\_\_\_\_\_\_
2. Norepinephrine and epinephrine always bind to:
* _________ (alpha or beta)
3. How can we have multiple responses in different tissues to the binding of the transmitters?
1. ACh ALWAYS binds to _cholinergic_ receptors:
* _Nicotinic (doughnut)_
* _Muscarinic (serpentine)_
2. Norepinephrine and epinephrine always bind to:
* _Adrenergic - All serpentine_ (alpha or beta)
3. Because there are multiple subtypes of all receptors
63
_Nicotinic Receptor At the Autonomic Ganglia:_
1. an ap arrives in the ________ fibre. This opens voltage-gated _____ channels and ____ enters the aforementioned fibre
2. The increased Ca2+ causes vesicles containing _____ to fuse to the membrane of the preganglionic fibre and release it into the synapse
3. ACH moves across the synapse to the _______ fibre and binds to a _______ (\_\_\_) receptor (this receptor is a ligand-gated ion channel)
4. Binding of ACh to its binding sites on the ______ receptor opens an ion channel in the receptor. ___ enters the *postganglionic* fibre
5. Movement of ____ into the postganglionic fibre brings in a positive charge but not enough to cause an action potential in the postganglionic fibre and instead, an _____ is generated
6. This _____ causes the opening of voltage-gated ____ channels present in the membrane of the _______ cell, allowing a larger influx of ___ into the _______ fibre
7. Threshold is reached and an Action Potential is generated in the _______ fibre
_Nicotinic Receptor At the Autonomic Ganglia:_
1. an ap arrives in the _preganglionic_ fibre. This opens voltage-gated _Ca2+_ channels and _Ca2+_ enters the aforementioned fibre
2. The increased Ca2+ causes vesicles containing _ACh_ to fuse to the membrane of the preganglionic fibre and release it into the synapse
3. ACH moves across the synapse to the _Postganglionic_ fibre and binds to a _nicotinic_ (NN) receptor (this receptor is a ligand-gated ion channel)
4. Binding of ACh to its binding sites on the _nicotinic_ receptor opens an ion channel in the receptor. _Na+_ enters the *postganglionic* fibre
5. Movement of _Na+_ into the postganglionic fibre brings in a positive charge but not enough to cause an action potential in the postganglionic fibre and instead, an _EPSP_ is generated
6. This _EPSP_ causes the opening of voltage-gated _Na+_ channels present in the membrane of the _postganglionic_ cell, allowing a larger influx of _Na+_ into the _postganglionic_ fibre
7. Threshold is reached and an Action Potential is generated in the _postganglionic_ fibre
64
Binding of ACh to a muscarinic receptor or binding of NE/E to adrenergic receptors produces a response through a \_\_\_\_\_\_\_\_\_
Binding of ACh to a muscarinic receptor or binding of NE/E to adrenergic receptors produces a response through a _G-Protein coupled mechanism_
65
Neutrotransmitter (NE/E or ACh) binds to receptor on target tissue (ACh- ______ receptor and NE/E - \_\_\_\_\_) causing a _________ in the receptor.
1. This causes a change in conformation of the _______ which is present nearby at the cytosolic surface of the plasma membrane
2. When the G-protein is inactive, it is bound to \_\_\_\_\_\_. When the G-Protein undergoes conformational change, its affinity for _____ is decreased and its affinity for _____ is increased
3. The GProtein releases the GDP and then _____ binds. This give the G-protein energy
4. The _____ subunit of the GTP-bound G-protein then dissociates from the _____ and _____ subunits and moves in the membrane to an enzyme
5. The GP will then cause a change in the activity of the ____ (increase or decrease activity)
6. The active-state enzyme causes some precursor molecule in the cell to be converted into a molecule called a \_\_\_\_\_\_\_
7. Which activates a cytosolic protein ____ which *phosphorylates* proteins in the cell, producing a response
Neutrotransmitter (NE/E or ACh) binds to receptor on target tissue (ACh- _muscarinic_ receptor and NE/E - _adrenergic_) causing a _conformation change_ in the receptor.
1. This causes a change in conformation of the _G-protein_ which is present nearby at the cytosolic surface of the plasma membrane
2. When the G-protein is inactive, it is bound to _GDP_. When the G-Protein undergoes conformational change, its affinity for _GDP_ is decreased and its affinity for _GTP_ is increased
3. The GProtein releases the GDP and then _GTP_ binds. This give the G-protein energy
4. The _alpha_ subunit of the GTP-bound G-protein then dissociates from the _gamma_ and _beta_ subunits and moves in the membrane to an enzyme
5. The GPrtn will then cause a change in the activity of the _enzyme_ (increase or decrease activity)
6. The active-state enzyme causes some precursor molecule in the cell to be converted into a molecule called a _second messenger_
7. Which activates a cytosolic protein _kinase_ which *phosphorylates* proteins in the cell, producing a response
66
What do protein kinases do?
Phosphorylates proteins producing a response
67
The chemical messengers found outside of the cell in signal transduction are:
Transmitters/hormones
68
What does it mean when we say G-proteins are translucent?
They are involved in turning an extracellular signal into an intracellular one
69
Most organs/tissues receive ______ (innervation from both ______ and _______ divisions)
Most organs/tissues receive _dual_ (innervation from both _sympathetic_ and _parasympathetic_ divisions)
70
What are some exceptions to dual innervation?
Sweat glands and _most_ blood vessels (receive sympathetic innervation only)
71
Activation of both divisions usually produces _____ effects in a target organ/tissue, however sometimes both divisions act together to produce similar and ______ effects
Activation of both divisions usually produces _opposite_ effects in a target organ/tissue, however sometimes both divisions act together to produce similar and _complementary_ effects
72
Which division is excitatory and which is inhibitory (parasympathetic or sympathetic)
Both divisions can produce both excitatory and inhibitory effects
-depends on the issue and receptor involved
73
What is the effect of sympathetic innervation of the **eyes**?
Dilation of pupil
Relaxation of ciliary muscle (adjustment for far vision)
74
What is the effect of sympathetic innervation on the **Cardiovascular system**?
* Increase heart rate (pacemaker)
* Increase force of contraction (myocardium)
75
What is the effect of sympathetic innervation on the **Blood Vessels**?
Constriction
76
What is the effect of sympathetic innervation on the **Exocrine glands**?
(sweat glands; salivary glands; stomach and pancreas)
* Sweat glands:
* increase for temperature regulation (muscarinic)
* local increase (stress; adrenergic)
* Salivary glands
* small volume of thick saliva
* Stomach, pancreas
* Decreased secretion
77
What is the effect of sympathetic innervation on the **Digestive Tract**?
* Decreased motility
* contraction of sphincters
78
What is the effect of sympathetic innervation on the **Lungs**?
Airway **dilation**
79
What is the effect of sympathetic innervation on the **Urinary Bladder?**
Prevent voiding
80
What is the effect of sympathetic innervation on the **Genitalia**?
* Decreased blood flow;
* contracts smooth muscle (emission/ejaculation)
81
Most blood vessels do not receive parasympathetic innervation with the exception of \_\_\_\_\_\_
Most blood vessels do not receive parasympathetic innervation with the exception of _blood vessels of the genitals_
82
What is the effect of parasympathetic innervation on the Adrenal medulla?
The adrenal medulla does not receive parasympathetic innervation
83
What is Horner's syndrome?
Disorder of the ANS
* usually effects one side of the face only (unilateral)
* Symptoms due to damage of **sympathetic nerve** innervating the face
* Constriction of pupil (*myosis)*
* Drooping of eyelid (*ptosis*)
* Lack of sweating (*anhidrosis*)
* Dilation of blood vessels (*flushing*)
84
What is the effect of parasympathetic innervation on the **eyes**?
* Constriction of pupil;
* contracts ciliary muscle (adjustment for near vision)
85
What is the effect of parasympathetic innervation on the **Cardiovascular system**?
Decrease heart rate (pacemaker)
86
What is the effect of parasympathetic innervation on the **blood vessels**?
No innervation; no effect on most blood vessels with the exception of genital blood vessels
87
What is the effect of parasympathetic innervation on the **Exocrine glands**?
(Sweat glands; salivary glands; stomach, pancreas)
* Sweat glands
* No innervation = no effect
* Salivary glands
* large volume of watery saliva
* Stomach, pancreas
* Increased secretion
88
What is the effect of parasympathetic innervation on the **Digestive tract**?
Increased motility
Relaxation of the sphincters
89
What is the effect of parasympathetic innervation on the **Lungs**?
Airway constriction
90
What is the effect of parasympathetic innervation on the **Urinary bladder**?
Voiding
91
What is the effect of parasympathetic innervation on the **Genitalia**?
* increased blood flow (erection *point)*
* No innervation of smooth muscle = no effect
92
What is the general scheme for a reflex arc?
Stimulus \> sensor \> afferent (sensory) pathway \> integrator (brain/spinal cord) \> efferent (motor) pathway \> effector (smooth muscle, cardiac muscle, glands) \> response
93
What is the efferent (motor) pathway of a reflex arc composed of?
Preganglionic and postganglionic fibres that innervate smooth muscle, cardiac muscle, or glands
94
Where are autonomic reflexes integrated? (3)
Autonomic reflexes are integrated in the CNS:
* Hypothalamus
* head integrating center for the ANS (*head ganglion*)
* Brainstem (*medulla*)
* Spinal cord
* regulates urination, defecation and erection
95
What are the two sphincters involved in Micturition (urination)
1. Internal urethral sphincter
* smooth muscle
* innervated by ANS
2. External urethral sphincter
* skeletal muscle
* somatic nervous system (voluntary control)
96
Which region of the CNS is the integrating centre for the micturition reflex?
Spinal cord
97
What does a low volume in the bladder stimulate?
* Low parasympathetic activity; bladder does not contract
* Tonic (prolonged and autonomic) somatic activity; external sphincter contracts
98
What does a high volume in the bladder trigger?
* High parasympathetic activity; bladder contracts
* Removal of tonic somatic activity; external sphincter relaxes and urination occurs
99
What is the role of ANS in temperature regulation?
* location of receptors?
* integrating centre?
* Ways body temperature is changed?
* Temperature receptors are found in skin and hypothalamus
* The integrating centre for temperature is the **hypothalamus**
* Change body temperature by:
* Blood flow to skin
* Amount of sweating
* Metabolism
100
What would happen if the temperature is too cold:
1. Decrease in body temperature is sensed by \_\_\_\_\_\_\_\_
2. Causes the ______ to alter ______ activity to ______ body temp
3. *increase* sympathetic activity =
* \_\_\_\_\_\_\_
* \_\_\_\_\_\_\_
* \_\_\_\_\_\_\_
4. *decrease* sympathetic activity:
* \_\_\_\_\_\_\_\_\_
What would happen if the temperature is too cold:
1. Decrease in body temperature is sensed by _thermoreceptors_
2. Causes the _hypothalamus_ to alter _sympathetic_ activity to *_increase_* body temp
3. *increase* sympathetic activity =
* *_increase_* _metabolism and increase heat production_
* _Vasoconstriction of blood vessels in skin to decrease heat loss_
* _piloerection_
4. *decrease* sympathetic activity:
* *_decrease_* _sweating and decrease heat loss_
101
What happens when the body temperature is too hot?
1. Increase in body temperature is sensed by _\_\_\_\_\_\_\__
2. causes the _\_\_\_\_\_\__to alter _\_\_\_\_\_\__ activity to decrease body temperature
3. *Increased sympathetic activity:*
* **Increase ______ and heat loss (NT _\_\_\_\__released from _\_\_\_\_\_\_\_\_\_\__ fibres)
4. *Decreased sympathetic activity:*
* ***decrease* ______ and decrease heat production
* reduce _______ of blood vessels in skin to increase heat loss
* no \_\_\_\_\_\_\_
1. Increase in body temperature is sensed by _thermoreceptors_
2. causes the _hypothalamus_ to alter _sympathetic_ activity to decrease body temperature
3. *Increased sympathetic activity:*
* **Increase sweating and heat loss (NT _ACh_ released from _sympathetic postganglionic_ fibres)
4. *Decreased sympathetic activity:*
* ***decrease* metabolism and decrease heat production
* reduce vasoconstriction of blood vessels in skin to increase heat loss
* no piloerection
102
Drugs that affect the ANS may act at multiple potential points and affect the:
(5)
1. Synthesis of the transmitter acetylcholine or norepinephrine
2. Storage of the transmitter within vesicles
3. release of the neurotransmitters
4. breakdown of the NT
5. Action of a transmitter at different receptors
103
What is an **agonist** drug?
Drug that mimics the action of the normal transmitters when they react with receptor
104
What is an **antagonist** drug?
Drug which blocks, or inhibits, the action of the physiological transmitter upon binding to a receptor
