14 Flashcards
structure of veins
low pressure blood
thinner walls
larger interior diameters
blood flow increased by skeletal muscle activity
Capillaries structure and function
-walls one cell layer thick
-blood pressure drops as blood passes into capillaries
- gas, nutrients, and waste exchange
Arterioles has _____ _____ that allow
-muscle fibres
- contraction to decrease blood fliw
Aorta receives blood from ______ has _____ ______ in its wall allowing it to:
heart, elastic fibres, allows it to expand when blood enters it under high pressure and propel blood forward through elastic recoil
how is blood flow to specific tissues regulated by signals from the NS
NS sends signal for muscle fibres in arteriole to contract or relax
difference between the structure of artery and vein
artery has elastic tissues
thin flaps of tissue in larger veins that prevent backflow of blood are called
one way valves
skeletal muscle contraction and negative thoracic pressure assists in:
venous returns
interstitial fluid builds up because of two forces
- an outward directed hydrostatic force in capillaries, created by the pressure generated by the heart
- an inward directed osmotic force in capillaries, created by the higher conc of solutes in blood.
the mechanism to drain excess fluid is carried out by the _____ ______
lymphatic system
the lymphatic system is composed of
thin walled branching tubules called lymphatic ducts.
interstitial fluid that enters the lymphatic ducts is called
lymph
lymphatic fluid is returned to the general circulation via the:
left and right subclavian veins
the ___ recieves blood returning from circulation
atria
the _______ generate force to propel the blood out of the heart and through the circulatory system.
ventricles
atria are separated from ventricles by
atrioventricular valves
A ______ ________ carries blood to the lungs, and _________ _______ carries oxygenated blood to the heart
pulmonary artery, pulmonary veins
ciculation is split into two circuits:
- pulmonary circuit
- systemic circuit
thr pulmonary circuit take blood to the
lungs
the systemic circuit takes blood to the:
body
two separate circuits allow for a
high pressure systemic circuit and a low pressure systemic circuit
the human. circulatory system returns blood low in oxygen to the right atrium through the:
inferior and superior venae cavae
steps in pulmonary circulation
- blood enters right atrium
- blood enters right ventricle
3 blood is pumped to lungs
steps in systemic circulation
- blood returns to left atrium from lungs through pulmonary vein
- left atrium contracts and pushes the blood into the left ventricles
- the muscle of left ventricle contracts and sends oxygenated blood at high pressure through the aorta and into the arteries of the systemic circulation.
heart murmur is caused by
damage to the heart valves
two pumps that assist in moving blood back to heart
skeletal muscle contraction
respiratory pumps
cardiac muscle makes up -1- and is responsible for -2-
the walls of the heart
pumping blood throughout the body
cardiac muscle cell structure
- intercalated discs
- striated
- branched, intercalated discs form direct cytoplasmic connections between cells
- contains sarcomeres
- involuntary, motor neuron is not required
_____ in intercalated discs connect cytoskeletons together
desmosomes
____ _____ in intercalated discs act as channels between cardiac muscle cells
gap junctions
electrical signals are rapidly conducted between _______ in cardiac muscle through ____ _____
cardiomyocytes, gap junctions
why is the action potentials of cardiomyocytes more prolonged than those of skeletal muscle
cardiomyocytes have an extended plateau phase mediated by calcium influx
the cells in the heart that initiate contraction are called
pacemaker cells
pacemaker cells are located in a region in the ____ ______ called ______ _____
right atrium, sinoatrial node (SA)
electrical impulses are directed through the heart on pathways composed of _____ _______
modified cardiomyocytes
characteristics of modified cardiomyocytes
-elongated
-do not contract
-spread action potentials rapidly throughout myocardium
-undergoes depolarization
electrical activation of the heart can be recorded with an
electrocardiogram(ECG)
How is ECG generated?
by amplifying the overall electrical signal conducted from the heart to the chest wall through the tissues of the body.
P wave shows
atrial depolarization
QRS complex
shows ventricular depolarization
T wave
shows ventricular repolarization
steps in heart electrical activity
- signal originates in the sinoatrial node,
- SA signal spreads and atrial muscles contract pushing blood into ventricles.
- signal reaches the AV node and is delayed before spreading along conducting fibres in the ventricular walls
- signal from AV spreads along conducting fibres to bottom and then to top of ventricles after all blood has pooled into the ventricles
- ventricles relax
At rest, ______ neurons slows down heart rate
parasympathetic
parasympathetic neurons secrete _____ to slow down heart rate
acetylcholine
_______ slows the rate of depolarization of cardiac cells
acetylcholine
_______ neurons speed up heart rate and increase force of cardiac muscle contraction
sympathetic
sympathetic neurons release ______ and ________ to speed up heart rate
epinephrine, norepinephrine
the contraction phase of the atria and ventricles is called
systole
the the relaxation phase of the atria and atrium is called
diastole
a complete cardiac cycle consists of
one complete systole and diastole
blood pressure measured in the systemic arterial circulation at the peak of ventricular ejection into the aorta is called
systolic blood pressure
blood pressure measured just before ventricular ejection is called
diastolic blood pressure
blood pressure sensed by ______ are found in major arteries
baroreceptors
when baroreceptors detect changes in blood pressure, they trigger _______ or _______ signals that change the heart’s output
parasympathetic, sympathetic
cardiac output can be changed by adjusting both ____ _____ and _____ _____ ______
heart rate, force of contraction
another name for heart attack
myocardial infarction
