Transcript Cardiovascular System Powerpoint

Basic Definitions
•
•
•
•
•
Arteries carry blood away from the heart
Veins carry blood back to the heart
Arterioles = small arteries
Venules = small veins
Capillaries: smallest vessels where nutrient,
waste and gas exchange take place. So narrow
that blood cells proceed through single file.
Walls are a single layer of epithelium.
Summary Concepts
• The human heart has four chambers
left and right atria, left and right ventricles
• The human heart has four valves
two atrioventricular valves
(tricuspid and mitral)
two semilunar valves
(aortic semilunar and pulmonary semilunar)
• Pulmonary circulation: starts as blood leaves the right ventricle
and enters the pulmonary trunk -> lungs -> pulmonary veins -> left
atrium
• Systemic circulation: starts as blood leaves the left
ventricles -> aorta -> head, arms, legs, body -> vena cava -> right
atrium
Coronary circulation: provides blood to the heart muscle
(myocardium). Aorta -> coronary arteries -> heart muscle -> cardiac
veins -> vena cava.
The Heart and the
Pulmonary Circulation
Subclavian artery
Superior vena cava
Left carotid artery
Brachiocephalic artery
Aortic arch
Pulmonary trunk
Pulmonary arteries
Pulmonary veins
left atrium
Right Atrium
Coronary arteries
Cardiac veins
Left Ventricle
Right ventricle
Inferior vena cava
Valves and Conduction Fibers
of the Heart
Atria: receive blood from principle
veins and assist in filling the ventricles
Ventricles: pump blood under high
pressure into pulmonary trunk and
the aorta.
Left Atrium
Aortic
Semilunar
Right Atrium
Pulmonary
Semilunar
Bicuspid
(mitral)
Left Ventricle
Tricuspid
Right Ventricle
Tissues of the Heart
•
•
•
•
•
Pericardium: serous membrane sack surrounding the heart
Epicardium: serous membrane on outer surface of the heart
Myocardium: muscle of the heart
Endocardium: membrane lining the interior of the heart
Chordae tendonae: “heart strings” that guide the
atrioventricular valves.
• Papillary muscle: small muscles that anchor the chordae
tendonae to the ventricular walls.
Heart Valves are passive and move
According to pressure gradients
(like a loose screen door in a breeze)
Atrioventricular
Semilunar
Aorta
Superior
Vena Cava
7
8
Pulmonary
trunk
Pulmonary
Vein
4
3
5
1
6
2
video
Inferior
Vena Cava
The Cardiac Cycle
Diastole: period of relaxation
And ventricular filling
Atrial Systole: atria contract
force additional blood into
the ventricles.
Ventricular Systole: ventricles
contract and force blood into
pulmonary trunk and aorta.
Purkinje Fibers
Conduction System Video
Electrical Recovery of Myocardium
R
P
T
Q S
Electrocardiogram
Cardiac Output
Stroke Volume (mL/beat) X Heart Rate (beats/min) = Cardiac Output (mL/min)
75 mL/beat X 72 beats/min. = 5400 mL/min.
Questions
1. Do athletes have greater or lesser demands for oxygen than non-athletes?
2. Do athletes have greater or lesser resting heart rates than non-athletes?
3. How do you reconcile this observation?
Affects of Athletic Training
- Stroke volume increases, heart rate decreases
95 mL/beat X 60 beats/min. = 5700 mL/min.
Even though the athlete has a lower resting heart rate, s/he has a greater
Cardiac Output than the untrained person.
Cardiac Center in the
Medulla
Controls two nerves that lead to the heart
1. accelerator nerve (sympathetic)
*acts on the sinoatrial node and ventricles
*increases heart rate using norepinephrine
2. vagus nerve (parasympathetic)
*acts on the sinoatrial node
*decreases heart rate using acetylcholine
Regulation of Heart Rate
Cardiac Center
(medulla)
Vagus nerve
Accelerator
nerve
Sensory
nerves
Proprioceptors
Baroreceptors and
Chemoreceptors in
the carotid and aortic
arteries
Sensory Inputs
1. Proprioceptors
(Am I moving more?)
2. Baroreceptors
(Is my blood pressure low?)
3. Chemoreceptors
(Is my CO2 high or O2 low?)
Motor Output
1. Accelerator nerve
(sympathetic)
(releases norpepinephrine)
increase rate and force
2. Vagus nerve
(parasympathetic)
decrease rate
Arteries = elastic elements
Veins = capacitance elements
compliant
valves
skeletal muscles
= Resistance Vessels
Large arteries are elastic
absorb kinetic energy
store potential energy
Arterioles and pre-capillary
Sphincters are muscular
constrict  add resistance
dilate  reduce resistance
Each organ has its own set of
Arterioles, and capillary beds
Which may be dilated or constricted
The microcirculation
1. Capillary exchange by diffusion
nutrients
Vitamins
CO2
O2
wastes
2. Capillary exchange by bulk flow
Starling hypothesis
- capillaries have low permeability to protein (osmotic effect)
- hydrostatic pressure decreases as blood passes through
Net outward pressure = 11 mmHg
Net inward pressure = -9 mmHg
Formation of Lymph
• Edema
• Alcoholism
• Elephantiasis