Chapter 12 Cardiovascular System, Vessels Part 3 Flashcards
A patient visits a physician for a second opinion about a diagnosed heart murmur affecting the right AV valve. Heart murmurs are caused by valve prolapse (the valve turn inside out). Which of the following symptoms could the physician check to confirm the heart murmur?
A. A missing QRS complex on an EKG
B. A weak second heart sound
C. A missing T wave on an EKG
D. A weak first heart sound
D. A weak first heart sound
What do are blood vessels?
- Blood vessels provide a network of transport throughout the body
- Think of the heart as the starting point
- Arteries (red) AWAY from the heart
- Veins (blue) towards the heart
- Capillaries location of exchange
What is the circulatory route of blood flow?
- Normal flow of blood:
- Heart artery arteriole capillary
- At the capillary bed exchange of materials occur
- Capillary venule vein back to heart
What do the vessels consist of?
- All vessels, except capillaries, have three layers of tissue
- Tunica intima, tunica media (muscle/collagen), tunica externa
- Muscle and collagen in tunica media helps with accommodating pressure so the vessel does not rupture
- Variations between arteries and veins pressure
- Arteries are under more pressure (closer to heart)
- The Artery has more muscle
What is the perfusion of capillary beds?
- Capillary beds are the site of exchange of materials
- Relies of diffusion
- Ex. Higher oxygen in blood than tissue, oxygen diffuses to tissues
- Flow of blood to controlled by precapillary sphincters
- Only about ¼ of body’s capillary are “open” at any given time
What is the general information about the Vein?
- Vessels that carry blood BACK to heart
- Typically carry deoxygenated blood
- Veins have thin walls, with less muscle and elastic
- Under low pressure compared to arteries
- Contain valves that prevent backflow
- Uses our skeletal muscle contraction as a “pump
What is blood pressure and what are the pressures?
- The force that the blood exerts against an artery wall
- Systolic pressure
- Peak pressure during ventricle contraction
- Diastolic pressure
- Peak pressure during ventricle relaxation
- Mean arterial pressure (MAP)
- Pressure at organ level
- ESTIMATION:
MAP = diastolic pressure + (systolic pressure-diastolic pressure)/3
Age 20-30 120/75, MAP= ~93
Hypertension 140/90, MAP= ~106
MAP of at least 60mmHg will sustain organs
What affects Blood Pressure?
- Cardiac output
- Amount of blood the heart pumps per minute
- Higher output higher pressure (SYMPATHETIC)
- Lower output lower pressure (PARASYMPATHETIC)
- Resistance of blood flow in vessels
- Combined effect of blood composition, vessel diameter, and vessel length
- Vessel diameter can change (vasomotion)
- Vasoconstriction smaller vessels, higher blood pressure SYMPATHETIC ACTION
- Vasodilation larger vessels, smaller blood pressure
- PARASYMPATHETIC ACTION
- Blood volume
- Total volume of blood in the vessels
- Mainly controlled by the kidneys and hormones
What are Cardiovascualr Centers?
- Homeostasis of blood pressure
- Combine action of cardiac centers and vasomotor center in the medulla oblongata (CNS)
- Cardiac centers controls heart rate (and cardiac output)
- Motor neurons of sympathetic or parasympathetic system
- Action potentials increase or decrease heart rate alters cardiac output
- Vasomotor center controls vessel diameter
- Action potentials alters diameter of vessels alters MAP
What is the afferent input to cardiovascualar center?
- VISCERAL SENSORY information to the CNS
- Cardiac centers input and Vasomotor center
- Chemoreceptors are represented by green circles, baroreceptors as red circles. Red arrow indicate afferent path to CNS
What cardiac center input and vasomotor center input include?
- Cardiac centers input includes:
- Proprioceptors
- Baroreceptors (Blood pressure)
- Chemoreceptors (waste)
- Vasomotor center input includes:
- Baroreceptors (blood pressure)
- Chemoreceptors (waste)
What are Baroreceptors?
- Free neuron dendrite (Type 1) embedded in artery walls
- Mechanoreceptors on the plasma membrane of neuron sense stretching of artery due to changes in blood pressure4
- Alters rate of action potentials of neurons (more stretch, more action potentials)
- Communicate with CNS (medulla oblongaata) via nerves (carotid sinus and vagus nerve in picture. You don’t need to know these names.)
What are two other characteristics about afferent input to cardiovascular center?
- Short-term homeostasis
- Immediately corrects pressure too high or pressure too low
- Baroreceptors are indicated by yellow dots
What is the Efferent to vasomotor center?
- Ex. When blood pressure gets too high:
- Increase of action potentials from baroreceptor to medulla oblongata
- Cause the cells of the vasomotor and cardiac centers to increase parasympathetic action
- Visceral motor neurons to
- Vasodilation, decreased heart rate
What is the main “wrap up” of the cardiac and vasomotors?
- Cardiac centers and vasomotor center work together to maintain blood pressure homeostasis
- Balance between sympathetic action (increase heart rate and vasoconstriction) and parasympathetic action (decrease heart rate and vasodilation)
- Blood volume also plays a role, controlled by kidneys
Describe an example of sympathetic and parasympathetic pathways of the cardiovascular centers?
- Ex. When blood pressure gets too high:
- Increase of action potentials from baroreceptor to medulla oblongata (afferent)
- Cause the cells of the vasomotor and cardiac centers to increase parasympathetic action (interneuron)
- Visceral motor neurons to vasodilate major vessels, decrease heart rate
