Chapter 20 Flashcards
(36 cards)
What are the 3 type of blood vessels?
Arteries:
- Carry blood AWAY from heart
Veins:
- carry blood TO heart
Capillaries:
- networks BETWEEN arteries and veins
exchange vessels - both oxygenated and deoxygenated
Capillaries
- Also called exchange vessels
- Exchange materials between blood and tissues
- Dissolved gases, nutrients, wastes
Anatomy of the Heart
- Great veins and arteries at the base
- pointed tip is apex
what are the 3 layers of the heart wall?
Epicardium:
- outer layer
Myocardium
- middle layer
Endocardium:
- inner layer
The Vena Cava
Delivers systemic circulation to right atrium
- Superior vena cava: RECEIVES blood from head, neck, upper limb, and chest
- Inferior vena cava: RECEIVES blood from trunk, and viscera, lower limbs
Coronary Sinus
Cardiac veins RETURN blood to coronary sinus
- Coronary sunus open into right atrium
Foramen Ovale
- before birth, is an opening through interatrial spectrum
- connects the 2 atria
- seals off at birth, forming fossa ovalis
The Heart valves
one-way valves prevent backflow during contraction
Regurgitation
Failure of Valves
- causes backflow of blood into atria
Coronary circulation
Coronary arteries and cardiac veins
- supplies blood to muscle tissue of heart
Right Coronary Artery
supplies blood to;
-right atrium
-portions of both ventricles
-cells of sinoatrial (SA) and atrioventricular nodes
-marginal arteries (surface of right ventricle)
Left Coronary Artery
Supplies blood to:
- left ventricle
- left atrium
- interventricular septum
The Conducting System
A system of specialized cardiac muscle cells:
- initiates and distributes electrical impulses that stimulate contraction
automaticity ( doesn’t need nerves from the brain to make heart beat)
- cardiac muscle tissue contracts automatically
Structures of conducting system
Sinoatrial (SA) node
- atrioventricular (AV) node
- conducting cells
Conducting Cells
- interconnect SA and AV nodes
- Distribute stimulus through myocardium
- in the atrium:
internodal pathways - in the ventricles:
AV bundles and bundle branches
The conducting system
Starts
1. sinoatrial (SA) nodes
2. Internodal pathways
3. Atrioventricular (AV) node
4. AV bundle
5. Bundle branches
6. Purkinje fiber (smallest)
Heart Rate
SA nodes generate 80-100 potentials per minute
- parasympathetic stimulation slows heart rate
- AV nodes generates 40-60 action potentials per minute
Abnormal Pacemaker Function
Bradycardia:
- abnormally slow heart rate
Tachycardia:
- abnormally fast heart rate
The cardiac cycle
- the period between the start of 1 heartbeat and the beginning of the next
- includes contraction and relaxation
2 Phases of the cardiac cycle
within any 1 chamber:
- systole (contraction)
- diastole (relaxation)
Blood Pressure
In any chamber:
- rises during systole
- falls during diastole
Blood flows from high to low pressure:
- controlled by timing of contractions
- directed by one-way valves
4 phases of the cardiac cycle
- Atrial systole
- Atrial diastole
- Ventricular systole
- Ventricular diastole
4 Heart sounds
s1:
- loud sounds
- produced by AV valves
s2:
- loud sounds
- produced by semilunar valves
s3:
- soft sounds
- blood flow into ventricles and atrial contraction
Cardiac Output
- Cardiac output (CO) ml/min =
- Heart rate (HR) beats/min
- Stroke volume (SV) ml/beat