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Chap 20 bio 202
Test 2
37
Anatomy
Undergraduate 2
03/13/2012

Additional Anatomy Flashcards

 


 

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Term
cardiac muscle tissue
Definition
shorter than skeletal muscle with centrally located nucleus. The ends of neighboring cardiac fibers connect by intercoralated disk. The intercoralated disk contain gap junctions, which allow action potentials to conduct to neighboring fibers. This structure coordinates atrial and ventricular contraction. Many more mitochondria in cardiac muscle than skeletal muscle
Term
autorythmic fibers
Definition
self excitable fibers that repeatedly generate action potentials that trigger heart contractions. They do not need the brain to send a signal. About 1% of cardiac muscle fibers become autorythmic fibers. 2 main functions: 1. Act as a pace maker (setting the rhythm of heart contractions)  2. Form a conductions system(coordinate chamber contractions
Term
cardiac condition system
Definition

·      sequence that occurs for a heart beat

 

sinotrial (SA) node

Atrioventricular (AV) node

Purkinje fibers

 

Sa node is known as the natural pace maker of the heart. starting the contraction action potential

Term
Sinotrial (SA) node
Definition

o   located in the wall of the right atrium and it initiates cardiac contraction when depolarized. The SA node send it’s action potential through each atria causing coordinated contraction

Term
Atrioventricular (AV) node
Definition
the action potential from the sa noted reaches the AV node in the inter atrial septum. Which sends and action potential to the atrioventricular bundle which branches and travels down the interventricular septum to the heart
Term
purkinje fibers
Definition
they conduct the action potential upward from the apex to the rest of the myocardium of the ventricles causing contraction and pushing blood out of the heart.
Term
action potential and contraction of contractile fibers
Definition

Action potentials produced by the sa nodes spread to contractile fibers of the heart

  1. depolarization
  2. plateau
  3. repolarization

contraction occurs the same as skeletal muscle with regulatory proteins binding to troponin and activating actin and mysoin. cardiac muscle relies almost entriely on arobic cellular resporation for atp production

 

Term
depolarization
Definition
contractile fibers resting membrane potential is -90mv. When brought to threshold sodium channels are open and contraction occurs.
Term
plateau
Definition

                              1.     the period of maintained depolarization due to the opening of calcium channels and potassium channels.

Term
replarization
Definition
 recovery to the resting membrane potential. Closure of calcium channels more opening of potassium channels. 
Term
electrocardiogram (EKG) (ECG)
Definition

·      records action potential during each heart beat for 4 reasons

                              1.     It determines whether the conduction pathway is normal or abnormal

                              2.     Determines if The heart is enlarged

                              3.     Determine if the heart is damaged

                              4.     Determines the cause of chest pain

Term
cardiac cycle
Definition

all events associated with one heart beats. It consist of systole and diastole of both atrias and ventricles.

  1. atrial systole
  2. ventricular systole
  3. pause
  4. relaxation

 

Term
systole
Definition
phase of contraction
Term
diastole
Definition
phase of relaxation
Term
pressure and volume changes in cardiac cycle
Definition
 the atrius and ventricles alternate contractions forcing blood from high concentration to a low concentration.
Term
atrial systole
Definition
It last about 0.1 seconds and is the time that the atrias are contracting and ventricles are relaxed. Typically at rest 25ml goes to the atria to the ventricles.
Term
ventricular systole
Definition
last about 0.3 seconds. And is the time that the ventricles are contracting and the atria are relaxed. Typically about 70 ml of blood are injected from the ventricles.
Term
pause
Definition

o   There is a 0.5 second pause between atrial systole and ventricular sytole

Term
relaxation
Definition

o   last about 0.4 seconds where the atrias and ventricles are relaxed. When your heart has to beat faster the relaxation period gets shortened.

Term
heart sounds
Definition

·      technically 4 sounds but only the 1st 2 can be heard because smooth blood flowing through the artery is silent.

Term
auscultation
Definition

o   act of listening to the sounds in the body, usually done with a stethoscope.

Term
s1
Definition
first heart sound and its called lub. It is louder and longer than the 2nd sound. The sound is paused by closer of the av valves after ventricular systole.
Term
s2
Definition

o   second heart sound called dub. Shorter and softer sound. Caused by closure of semi lunar valves at ventricular diastole(when ventricles relax)

Term
s3 and s4
Definition
not heard
Term
cardiac output (Co)
Definition

volume of blood injected from the left ventricle into the aorta each minute.

Term
Stroke volume (SV)
Definition
volume of blood injected by the ventricle
Term
heart rate (HR)
Definition
number of beats per min
Term
regulation of heart rate (2)
Definition
  1. autonomic regulation
  2. chemical regulation
Term
autonomic regulation
Definition
controlled by the cardiovascular center of the medulla oblongata this area regulates heart rate by receiving input from various sensory receptors. It regulates by either increasing or decreasing autonomic stimulation and increasing is done by sympathetic autonomic nervous system specifically the cardiac accelerator nerves. Decreasing heart rate is done by parasympathetic autonomic system specifically vagus nerve.
Term
proprioceptors
Definition
receptors that monitor limb position and muscle nerve impulses.  When these receptors are stimulated they increase their signal to the cardiovascular center.
Term
chemoreceptors
Definition
receptors that monitor chemical changes in the blood, such as oxygen levels, ph, and cations.
Term
baroreceptors
Definition

§  monitor the stretching of arteries and veins due to pressure from the blood flowing through them. their rule is to regulate blood pressure. They are found in the aorta and carotid artery.

Term
chemical regulations
Definition
  1. hormones
  2. cations
Term
hormones
Definition
epinephrine and norepinephrine enhance the hearts pumping by increasing heart rate and contractions. Thyroid hormone increases cardiac contraction and heart rate, hyperthyroidism symptom is a racing heart.
Term
cations
Definition
potassium, calcium, and sodium effect heart function.
Term
aerobics
Definition
any activity that works large muscles for at least 20 minutes Elevating cardiac output
Term
exercise and heart rate
Definition

§  Exercise increases oxygen demand this requires the heart to increase its rate of oxygen delivery to the tissues. Stroke volume increases while heart rate decreases when you are a trained athlete

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