Lecture 2 Flashcards
What is cardiac output?
Heart rate x stroke volume
What are some points of regulation to change blood pressure?
HR, SV, total peripheral resistance.
If someone weighs 70kg, what would their stroke volume be?
70 ml
Where is the cardiovascular control centre located?
Predominantly the medulla oblongata, some in pons. These are in the brainstem.
The sympathetic centre of the medulla oblongata has what distinct regions?
Augmenter and accelerator.
What are the distinct regions of the parasympathetic centre?
Nucleus vagus and the nucleus ambiguous.
What are some higher brain centres that input into the brainstem cardiovascular control centre?
The hypothalamus, thalamus and cerebral cortex.
What are some stimulus that come to the brainstem from higher centres of the brain?
Anxiety, excitement, exercise and emotion
Other than the higher brain centres, what other inputs does the brainstem receive?
From receptors and reflexes
Is the sympathetic pre-ganglionic fibre long or short?
Short
Where is the ganglion for the sympathetic nervous system and what is it called?
Stellate ganglion at level C6 and C7.
Where do fibres from the right stellate ganglion go?
The the nodal tissue in the heart to control rate
Where do fibres from the left stellate ganglion go to?
Ventricular tissue for contractility
What neurotransmitter controls the heart in the sympathetic nervous system?
NE on beta 1 receptors
What is a positive chronotropic effect?
Increases heart rate
What is a positive ionotropic response?
Increases contractility.
What is increased lustrophy?
Increased relaxation rate
What is dromotropy?
Conduction through the heart
Describe the fibres in the parasympathetic nervous system
Long preganglionic fibres. short postganglionic fibre
Where is the parasympathetic autonomic ganglion for the heart?
On the heart
What neurotransmitters act on the heart in the parasympathetic nervous system?
Ach on muscarinic receptors on SA and AV node
What is the effect of the parasympathetic nervous system on the heart?
Negative chronotropic effect by prolonging delay at the AV node.
What is the fat on the heart called?
Epicardial fat
What are the ganglionic plexuses?
Autonomic ganglia on the epicardial fat of the heart.
What drug blocks the parasympathetic nervous system?
Atropine
What blocks the sympathetic nervous system?
Propranolol
Which system is predominant control of heart rate at rest?
Parasympathetic
Why are transplanted heart rates faster than normal?
No vagal tone to the heart
