EXS phys Exam 3

What are the purposes of the circulatory system?

1. Deliver adequate oxygen and nutrients 

2. Remove metabolic waste 

3. Aid in temperature regulation

What is the cardiac cycle?

Includes all the events associated with blood flow through the heart during one complete heartbeat

What is systole?

Contraction - atrial and ventricular

What is diastole?

Relaxation - atrial and ventricular

Why is systole relatively uncompromised during exercise?

The body does not want to comprise the systolic phase because IF less time was allowed for contraction, then ever little blood should be ejected from the heart

What is arterial blood pressure (BP)?

The force exerted by the blood against the arterial walls

What is systolic blood pressure (SBP)?

Pressure generated as the blood is ejected from the heart during ventricular systole

What is diastolic blood pressure (DBP)?

The pressure in the arteries between heartbeats, when the ventricles are relaxed

What is primary (essential or idiopathic) hypertension?

1. The cause of hypertensions is unknown 

2. This occurs in 90% of all cases

What is secondary hypertension?

1. The cause is known 

2. Major factor inducing hypertensions are health related diseases (kidney, thyroid, gestational, and or medication)

What is cardiac output (Q̇)?

Amount of blood pumped out of the heart per minute

What is the formula to calculate Q̇?

Q=HR x SV (stroke volume)

What is the typical Q̇ for an average adult?

5 liters

In order to change Q̇, what can you do?

1. Change your SV

2. Change your HR

What is stroke volume (SV)?

the amount of blood pumped out of the heart per beat

What is the formula for SV?

SV = EDV-ESV

What is the end diastolic volume (EDV)?

The amount of blood collected in the left ventricle during relaxation

What is end systolic volume (ESV)?

The amount of blood remaining in the left ventricle after contraction

What is the main variable influencing EDV?

1. Venous blood return. - Determines preload

What 3 factors influence preload?

1. Venoscontriction 

2. Muscle pump 

3. Respiratory pump

What is vesoconstriction?

A skeletal muscle contact, veins are compressed and blood is pushed towards the heart

What is the muscle pump?

A skeletal muscle contract veins are compressed and blood is pushed towards the heart

What is the respiratory pump?

Inspiratory pressure creates a gradient that moved blood from the abdominal towards the atrium

How does venous return (preload) affect SV?

Increase venous return → increase EDV → increase SV

Other than venous return (preload), what other factors affect SV?

1. Contracility 

2. Afterload

How does contractility affect SV?

An increase in contractility will increase SV

What is the Frank-Starling Law of the Heart?

Within physiological limits, the contraction of the heart is proportional to the degree of stretch on the L ventricle

What is law of laplace

Increase in the size of the heart will geometrically increase the energy cost of contraction

what is length-tension relationship

If the cardiac fiber stretches too much, the actin and myosin will not overlap, thereby decreasing the ability to contract

What is afterload?

The resistance by which the L ventricle must overcome to eject blood

How does afterload (resistance) affect SV?

Increase afterload (resistance) → decrease SV

What 2 systems regulate the SA node?

1. Parasympathetic nervous system 

   1. Brake pedal 

2. Sympathetic nervous system 

   1. Gas pedal

What is the main nerve stemming from the PNS?

vagus

When the vagus nerve is stimulated, what neurotransmitter does it release?

ACh

How does ACh affect HR?

Decreases HR

What is the main nerve stemming from SNS??

Accelerator

Upon stimulation, what does this nerve release?

NE / neuroepinephrine

How does NE affect HR?

increases HR and force of contraction

What does it mean when a muscle fiber has a high Myosin-ATPase (glycolytic) capacity?

High M-ATPase increases the velocity at which muscle fibers can breakdown ATP

What does it mean when a muscle fiber has a high oxidative capacity?

A: high mitochondria content

B: high capillary density

C: high myoglobin content

What are the characteristics of slow twitch (ST) fibers?

1. High capillary density 

2. High mitochondria 

3. High myoglobin 

4. Low M-ATPase

what are the other names associated with slow twitch fibers

1. Type 1 

2. Red fibers 

3. Slow Oxidative (SO) fibers

What are the characteristics of fast twitch (FT) fibers?

1. Low capillary density 

2. Low mitochondria 

3. Low myoglobin 

4. High M-ATPase

what are other names associated with fast twitch fibers

1. Type IIx

2. White fibers 

3. Fast Glycolytic fibers (FG)

What are the characteristics of intermediate fibers?

1. Have properties that are in between SO and FG fibers 

2. Type IIa 

3. Fast Oxidative Glycolytic (FOG) fibers

What is myoplasticity?

Refers to the capacity of the muscle fiber to adapt to changes

Hypertrophy:

increase diameter of the muscle fiber

Atrophy:

decrease diameter of the muscle fiber

Hyperplasia:

increase quality of muscle fibers

What is delayed onset muscle soreness (DOMS)?

1. Muscle soreness that occurs 12-48 hours after strenuous exercise 

2. Typically peaks at 36 hours

What is the purported cause of DOMS?

Ultrastructural muscle damage

What is muscle elasticity?

Muscles contain elastic structures that can be stretched absorb energy and enhance the development of force

What are the 2 main components of muscle elasticity?

1. Parallel elastic component  (PEC)

2. Series elastic component (SEC)

PEC: parallel elastic components

myofilaments, fascia, and protects muscle fibers

SEC: series elastic components

crossbridges and tendons, forces development

What is the relationship between SEC and force production?

amplifies force production during explosive movements

Why do athletes have low RHR?

because regular intense physical training changes how the heart and nervous system work