Lecture 20 Cardiovascular system 1: Heart Flashcards Preview

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Flashcards in Lecture 20 Cardiovascular system 1: Heart Deck (25)
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1

3 components of the cardiovascular system

heart, blood, blood vessels

2

Overview of Cardio system

Heart-> arteries -> arterioles-> capillaries -> venules -> veins (-> return to heart)

3

Right heart

pumps deoxygenated blood to lungs
pulmonary circulation
lower pressure

4

Left heart

pumps oxygenated blood to entire body
systemic circulation
higher pressure

5

atria

receiving chambers

6

ventricles

pumping chambers

7

Chamber matched to correct Great Vessel

RA Pulmonary trunk (artery)
LA aorta

8

Pulmonary circulation

RV -> Pulmonary trunk -> LUNGS -> pulmonary veins -> LA

9

Systemic circulation

LV -> aorta -> BODY -> vena cavae -> RA

10

Atrioventricular valves

AV valves
prevent backflow from ventricles to atria
tricuspid valve - RA } RV
Bicuspid (mitral) valve - LA } LV

11

Role of Chordae tendineae

attached to papillary muscles prevent prolapse of AV valves

12

Semilunar valves

prevent backflow from arteries to ventricles
pulmonary valve - RV } Pulmonary trunk
aortic valve - LV } aorta

13

Autorhythmic cells

cardiac muscle cell
spontaneously initiate APs

14

Intercalated discs

allow AP to spread between cardiac muscle cells

15

SA node

Sinoatrial node
primary peacemaker

16

Excitation-Contraction Coupling in Cardiac cells

similar to skeletal muscle
AP -> T tubules -> SR -> releases Ca2+
Ca2+ -> troponin -> tropomyosin -> uncovers myosin binding sites -> uncovers myosin binding sites -> contraction

17

Roles of Ca2+
Excitation-Contraction Coupling in Cardiac cells

Ca2+ also enters from the ECF through Ca channels during contraction
Ca2+ is pumped back to SR by Ca2+ ATPase during relaxation phase
Ca2+ is also transported back out to ECF by a Na-Ca exchanger

18

Peacemaker potential in Autorhythmic cells

1. Slow depolarization toward threshold = peacemaker potential, "funny channels" permeable to NA+ and K+
2. Rapid AP depolarization - due to Ca2+ inflow
3. Repolarization

19

Autonomic NS control

sympathetic - faster depolarization -> increase heart rate
parasympathetic - slower depolarization -> decrease heart rate

20

Myocardial Action Potential in Contractile Cells

(0) initial AP depolarization - similar to other APs (voltage-gated Na+ channels)
(1) slight repolarization
(2) Plateau Phase (100-200 ms) - due to slow, inward Ca2+ flow (L-type Ca channels) results in long AP duration and long refractory period (200-300ms)
(3) repolarization - due to delayed opening of voltage-gated K channels

21

autorhythmic cells are

"peacemakers"

22

Conduction fibers

specialized to spread AP rapidly though ventricles
Sinoatrial node (SA) -> atrial depolarization -> atrioventricular (AV) node (0.1 second delay) -> AV bundle (of his) -> R & L bundle branches -> Purkinje fibers -> ventricular depolarization

23

Electrocardiogram (ECG)

P wave - atrial depolarization
QRS complex- ventricular depolarization
T wave- ventricular repolarization

24

At the plateau phase

the S-T segment
all cardiac cells are depolarized

25

The P-R segment

period of delay at AV node