Lymphatic System

Chapter 14 Lymphatic System
Lymph
Lymphatic capillaries,veins, lymph nodes

MAP (Mean arterial pressure)
Mean arterial pressure is completely determined by:
1. heart rate
2. stroke volume
3. total peripheral resistance
Regulation of MAP
• MAP is a regulated variable that is regulated by negative feedback control
• The sensors for monitoring MAP are arterial baroreceptors
• Arterial baroreceptors are found in 2 locations:
1. aortic arch
2. carotid sinuses of carotid arteries

• When arterial pressure rises and stretches the walls of the arteries and the sensory   endings of the baroreceptors, this induces depolarization.
• Depolarizarion triggers action potentials then conducted to the CNS by baroreceptors axons.
• Greater stretch induces increased action potential frequency.
• Baroreceptor input to the nervous system also triggers changes in the secretion of several hormones that target the heart and blood vessels.
• Neural control of MAP is orchestrated by the medulla oblongata- cardiovascular control center.
• The cardiovascular control center receives input from the hypothalamus (fight or flight) and the the cerebral cortex (pain, emotional states, rise in BP)
• Autonomic innervations of cardiovascular system:
1. sympathetic and parasympathetic nerves to SA nerves
2. sympathetic nerves to ventricular myocardium
3. sympathetic nerves to arterioles and other resistance vessels
4. sympathetic nerves to veins
Baroreceptor reflex
The fall of arterial pressure is detected by arterial baroreceptors, triggereing an increase in sympathetic activity and decrease in parasympathetic, which increases heart rate, myocardial contractility and vascular resistance

Hormonal Control of MAP
• Low arterial pressure   stimulates epinephrine secretion.
• Epinephrine at SA node increases action potential frequency of pacemaker cells inc HR
• Epinephrine increases cardiac contractility increasing stroke volume
• Epinephrine causes vasoconstriction in...