Mairead - ANS Integration, Reflexes and Tone Flashcards
What happens if an organ is innervated by both the sympathetic and parasympathetic division?
(2)
The divisions might have opposing effects e.g. in the heart
Or they might have complementary effects e.g. in reproduction
Which autonomic division are the arteries and veins innervated by?
Most are innervated by the sympathetic division
What is autonomic tone?
The resting level of spontaneous activity shown by the ANS neurons in the absence of stimuli
Write a note on the ANS and the heart
(4)
Has both sympathetic and parasympathetic innervation
The sympathetic increases heart function (HR and SV)
The parasympathetic decreases heart function (mostly just HR)
At rest both are active but parasympathetic is dominant
Write a note on the blood vessels and the ANS
(2)
Blood vessels are mainly innervated by sympathetic nerves
Control of blood flow and blood pressure by increasing/decreasing sympathetic tone
What is integration?
Sensory receptors, sensory nerves, nervous interpretation, motor nerves and an effector all in a circuit called a reflex
In the somatic NS, what does reflex speed depend on?
Giving examples (3)
The length of the circuit
Spinal reflexes are short and quick and have few synapses
Brain reflexes are long and slower and usually have many sensory inputs
List the steps to a reflex arc
(5)
- Arrival of stimulus and activation of receptor
- Activation of a sensory neuron
- Information processing in CNS
- Activation of a motor neuron
- Response by effector
Where can integration/information processing take place in the ANS?
In the ganglia
In the CNS
Give a specific type of ganglia where information processing can take place
Parasympathetic ganglia
Give some locations in the CNS where integration can take place.
Also give the type of integration that occurs.
(3)
In the spinal cord (subconscious)
In the brainstem (subconscious)
In the hypothalamus (both conscious and subconscious elements)
What is the blood pressure reflex called?
Baroreceptor reflex
What happens to the Baroreceptor reflex when the SNS activity increases and the PSNS activity decreases?
There is an increase in cardiac output and vasoconstriction which increases blood pressure
What happens to the Baroreceptor reflex when the PSNS activity increases and the SNS activity decreases?
There is a decrease in cardiac output and vasodilation which reduces blood pressure
Define negative feedback
(2)
A corrective mechanism that opposes or negates a variation from normal limits
A stimulus triggers a response, then the response reduces the strength of the stimulus
What is the main role of the hypothalamus?
It’s responsible for the maintenance of body internal environment -> maintenance of homeostasis by regulation of the ANS, the somatic NS and the endocrine system
What balances does the hypothalamus control?
(5)
Body temperature
Blood pH
Electrolyte balance (Na+, K+, Ca++, PO4, etc)
Blood sugar
Blood gases
Write a note on the sensory control of the hypothalamus
(2)
It has the integrative function of the spinal cord and the brainstem reflexes
It receives sensory information from many different systems
Give five examples of places the hypothalamus receives sensory information from
The thalamus (all senses except smell synapse here)
The limbic system (thoughts)
The cerebral cortex
The blood flowing through the hypothalamus
CSF
What three systems does the hypothalamus motor control involve?
ANS
Somatic NS
Endocrine System
How does the hypothalamus react to decrease in body temperature?
(3)
ANS decreases blood flow to the skin
Somatic NS stimulates shivering, hair on skin rises
Endocrine system stimulates the release of thyroid hormone to increase metabolism
Write a note on ANS reflexes
Reflexes are visceral and cranial or they include higher centres
There are some intra organ reflexes where there is no CNS involvement (fast and automatic)
Write a note on the visceral and cranial nerve reflexes
They provide automatic responses that can be modified, facilitated or inhibited by higher centres e.g. eye reflexes that are activated by light or dark may also be triggered by some emotional states
Give an example of an intra organ reflex
Control of movement of chyme from the stomach into the duodenum
List the four higher centres
Cerebral cortex
Thalamus
Limbus
Hypothalamus
List some of the reflex centres of the brainstem
(3)
Vasomotor centre
Respiratory centre
Cardiac centre
What are the reflex centres of the brainstem modified by?
The higher centres
Where are the sensory receptors responsible for blood pressure control?
They are found in the Baroreceptors of the large arteries e.g Aorta and Carotid
Where does integration for blood pressure control take place?
(3)
The medulla oblongata of the brainstem in the:
Vasomotor centre
Cardiac accelerator
Cardiac inhibitory centres
What are the effectors for blood pressure control?
The smooth muscle of the blood vessels, the SA node, the AV node and the cardiac muscle
How does the blood pressure reflex respond to decreased blood pressure?
(3)
Increased sympathetic to heart and blood vessels
Decrease parasympathetic activation
Increases cardiac output and vascular resistance => increasing blood pressure
How does the blood pressure reflex respond to increased blood pressure?
(3)
Barroreceptors stretched and sensory nerve alerts the medulla oblongata
Increased parasympathetic to the heart, decreases sympathetic to heart and arterioles
Decreases cardiac output, vasodilate => decrease blood pressure
What are chemoreceptors?
Measure gas of the aortic blood and in medulla oblongata
