Systemic and pulmonary circuits

Figure 22.2

Figure 22.2

Position of the heart in the body

Figure 22.3

The heart walls and membranes that surround the heart

Figure 22.6

Figure 22.5

Figure 22.5 continued

Figure 22.7 Fibrous Skeleton:--composed of dense collagenous CT-- anchors and supports valves--electrically isolates (insulates) the atria from ventricles--anchor/attachment for cardiac muscle

Figure 22.10

Myocardial Cells (myocytes, cell that contract):-Short-Branched-Uninucleate-Many, many mitochondria-Connect end-on-end to other myocytes-contain SR that releases calcium--has mild t-tubules--alternating, and overlapping myosin and actin filaments for contraction

CARDIAC MUSCLE CELLS

• Branched• joined by intercalated discs

– desmosomes: tightly bind cells & transfer of tension– gap junction: electrical synapses that directly transfer electrical

activity/AP from one cell to the next

• Contractile/myocardial Cells (myocytes) => contract and conduct AP’s• Conductile/autorhythmic cells => produce and conduct action potentials

Conceptual Overview: Electrical Stimulus originating at SA node is distributed to heart leading to contraction. --Blood is pumped out of the heart during contraction --Blood fills the heart during relaxation

Fig. pf 20.13

Intrinsic/natural pacemaker

Electrical connection

between atria and ventricles

Figure 22.11

Nervous System regulation of heart

• Heart is regulated by medulla oblongata (cardiac control center)

• Medulla receives sensory input through vagus nerve (CN X) and

glossopharyngeal nerve (CN IX).

– Baroreceptors in aorta (aortic sinus) and common carrotid artery (carotid

sinus)

• Some receptors in heart

• Medulla sends motor output through the:

– Vagus nerve—parasympathetic division of ANS

– Sympathetic nerves (cardiac plexus)—sympathetic division of ANS

Sensory input and motor output of cardiac control centers in medulla

Glossopharyngeal nerveVagus nerve

Figure 22.12 Motor output to heart (from medulla)

PD

Figure 22.13

Figure 22.13 continued

Figure 22.14

Figure 22.14

Figure 22.8

Figure 22.9

Coronary vessels:

•Significant anastomoses•Flow during diastole•Directly to R. A.

Table 22.1

Table 22.2

Table 22.3