Quiz 3 Lecture

Question 1

Equation for volume ejected by a ventricle in 1 minute:

Answer 1

CO = HR x SV

Question 2

Equation for resting CO:

Answer 2

CO = 75bpm x 70 ml/beat = 5,250 ml/min, usually about 4 to 6 L/min

Question 3

Equation for vigorous exercise CO:

Answer 3

CO to 21 L/min for fit person. Up to 35 or 40 L/min for a world class athlete

Question 4

Cardiac reserve:

Answer 4

difference between maximum and resting CO

Question 5

What happens when ventricular output differs on the right and left?

Answer 5

Congestive heart failure: fluid accumulation in either circuit. (Build up of pressure & fluid in one of the circuits.)

Question 6

5 facts about heart rate:

Answer 6

• Measured frompulse
• Infants have HR of 120 beats per minute or more
• Young adult females avg. 72 - 80bpm
• Young adult males avg. 64 - 72bpm
• HR rises again in the elderly

Question 7

What is Tachycardia? Name 5 causes.

Answer 7

persistent, resting adult HR > 100

- stress, anxiety, drugs, heart disease or increased body temp

Question 8

What is Bradycardia?

Answer 8

persistent, resting adult HR < 60

- common in sleep and endurance trained athletes (increased Stroke volume)

Question 9

Chronotropic agents?

Answer 9

Positive chronotropic agents raise HR

Negative chronotropic agents lower HR

Question 10

The cardiac center of the medulla oblongata is an autonomic control center with 2 neuronal pools:

Answer 10

• Cardioacceleratory center (sympathetic)

- Cardioinhibitory center (parasympathetic)

Question 11

Sympathetic Nervous System, what is the cardioacceleratory center? Name 3 things about it.

Answer 11

• Sympathetic cardiac accelerator nerves through cardiac plexus to SA node, AV node and mycardium
• these nerves secrete norepinephrine, which binds to B-adrenergic receptors in the heart
• Increases HR, blood flow through coronary circulation, and contractility

Question 12

Parasympathetic Nervous System, what is the cardioinhibotory center of medulla?

Answer 12

-Stimulates vagus nerves
*Right vagus neve - cardiac plexus, then
postganglionic fibers in cardiac nerves to SA
node
*left vagus nerve- to cardiac plexus, then
post ganglionic fibers in cardiac nerves to
AV node
-secrete Ach
*binds to muscarinic receptors
*opens K+ channels in nodal cells, which
become hyperpolarized, fire less frequently,
HR slows down
- Vagal tone and parasympathetic withdrawal

Question 13

Name the inputs to the cardiac center, and what do they respond to?

Answer 13

Higher brain centers: cerbral cortex, limbic system, hypothalamus

• respond to sensory and emotional stimuli
• conscious control limited

Question 14

Reflexes:

Answer 14

proprioceptors

baroreceptors

Question 15

What are chronotropic chemicals:

Answer 15

• Neurotransmitters
• Drugs
• Hormones
• Electrolytes (K+ has greatest chronotropic effects)

Question 16

Give all examples of each type of chronotropic chemical

Answer 16

• Neurotransmitters:
  *norepinephrine and epinephrine
  (catecholamines)
  *Ach
• Drugs
  *caffeine inhibits cAMP breakdown
  *nicotine stimulates catecholamine secretion
• Hormones
  *TH increases adrenergic receptors in heart,
  increases sensitivity to sympathetic
  stimulation, increases HR
• Electrolytes (K+ has greatest chronotropic effects)
  *Hypercalcemia: high Ca++ decreases HR
  *Hypocalcemia: low Ca++ increases HR

Question 17

What is stroke volume governed by?

Answer 17

• Preload - end diastolic volume
• contractility - force at a give EDV
• afterload = blood pressure

Question 18

what stroke volume governing factors have a positive relationship and increase blood ejected? what lessons blood ejected?

Answer 18

Positive relationship: Preload & contractility

Afterload: blood pressure

Question 19

Contractility

Answer 19

.