* Autonomic nervous system * Intrinsic conduction system, or the nodal system
2
New cards
Intrinsic conduction system, or the nodal system does
* Sets the heart rhythm * Composed of special nervous tissue * Ensures heart muscle depolarization in one direction only (atria to ventricles) * Enforces a heart rate of 75 beats per minute
3
New cards
Sinoatrial( SA) node
* Located in the right atrium * Serves as the heart’s pacemaker
4
New cards
Atrioventricular (AV) node is…
* at the junction of the atria and ventricles
5
New cards
Atrioventricular (AV) bundle (bundle of His) and bundle branches
* are in the interventricular septum
6
New cards
Purkinje fibers spread
* within the ventricle wall muscles
7
New cards
The sinoatrial node (SA node)
* starts each heartbeat
8
New cards
Impulse spreads
through the atria to the AV node
9
New cards
Atria
* contract
10
New cards
At the AV node,
 the impulse is delayed briefly
11
New cards
Impulse travels
* through the AV bundle, bundle branches, and Purkinje fibers
12
New cards
Ventricles contract;
* blood is ejected from the heart
13
New cards
Tachycardia
rapid heart rate, over 100 beats per minute
14
New cards
Bradycardia
* low heart rate, less than 60 beats per minutes
15
New cards
The *cardiac cycle* refers to
* one complete heartbeat, in which both atria and ventricles contract and then relax * Systole = contraction * Diastole = relaxation
16
New cards
Average heart rate
* approximately 75 beats per minute
17
New cards
Cardiac cycle length
* normally 0.8 second
18
New cards
Blood vessels form
* a closed vascular system that transports blood to the tissues and back to the heart
19
New cards
Vessels that carry blood away from the heart
* Arteries and arterioles
20
New cards
Vessels that play a role in exchanges between tissues and blood
* Capillary beds
21
New cards
Vessels that return blood toward the heart
\
* Venules and veins
22
New cards
Three layers (tunics)
* in blood vessels (except the capillaries)
23
New cards
Tunica intima forms a friction-reducing lining
Endothelium
24
New cards
Tunica media
* Smooth muscle and elastic tissue * Controlled by sympathetic nervous system
25
New cards
Tunica externa forms protective outermost covering
* Mostly fibrous connective tissue * Supports and protects the vessel
26
New cards
Arteries have
a heavier, stronger, stretchier tunica media than veins to withstand changes in pressure
27
New cards
Veins have
* a thinner tunica media than arteries and operate under low pressure * Veins also have valves to prevent backflow of blood * Lumen of veins is larger than that of arteries * Skeletal muscle “milks” blood in veins toward the heart
28
New cards
Capillaries
* Only one cell layer thick (tunica intima) * Allow for exchanges between blood and tissue
29
New cards
Form networks called *capillary* *beds* that consist of: