A10-Blood Pressure and Heartbeat Flashcards
A complete heartbeat is called a…
cardiac cycle
-This involves a full contraction and relaxation of each chamber of the heart
The cardiac cycle is usually divided into two basic phases
diastole and systole phase
disastole phase
when the heart is relaxed and filling with blood
systole phase
when the heart contracts and is emptying
The cardiac cycle: Diastole begins when…
Relaxed atria fill with blood
-As it fills, pressure pushes the atrioventricular valves open abd blood begins to fill relaxed ventricle
-Atria folls and musculars wall of atria contact and ventricles completely fill with blood they contract
The cqardiac cycle: This ________ of ventricles marks the start of systole phase
Contraction
- Increasing pressure forces the atrioventriclular valves shut, pushing blood through the semilunar valves and into arteries
- Valves relac and volume in ventricles increases
-Pressure in ventricles decreases
-Blood is prevented from re-entering ventricles by closing of semilunar valve
-
“lubb-DUBB” of the heartbeat is actually caused by the…
opening and closing of heart valves
The “lubb” occurs when….
the atrioventricular valves close and the ventricles begin to contract
The “DUBB” occurs when…
ventricles relax and the semilunar valves snap shut
Instrument used to listent to heart
stethoscope
If the heartbeat sounds are not normal this may be a sign of a
leaking valve, known as a heart murmur
What heart muscle has the ability to contract and relax on its own without stimulation of nerves?
myogenic muscle
-This is why someone with a damaged nervous system may still have a beating heart
The contraction that initiates the heartbeat is from a cluster/group of cells in the right atrium called the….
sinoatrial (SA) node
What does the SA nodes do speficially?
cells sends an electrical signal which causes the atria to contract
SA Node acts as a…
pacemaker
- its signals are responsible for setting a normal rhythm of the heartbeat
The electrical signal then propagates (i.e. “spreads”) to a group of cells in the between the right atrium and ventricle called the
atrioventricular (AV) node
What does AV node do spefically?
This cluster of cells sends an electrical signal through special conductive fibers called purkinje fibers
This signal is passed down the septum and causes the ventricles to contract
The control of heart rythm steps:
- Artriole systole begins
- Artrial contractions forces blood into ventricles
- P-wave
2.Ventricular systole (first phase)
-Ventricular contractions pushes AV valves closed
- QRS Complex
- Ventricular systole (2nd phase)
-semilunar valves open and blood is ejected
- T-wave
4.Ventricular diastole (early)
-semilunar valves closed and blood flows into atria
- Ventricular disastole (late)
-Chambers relax and blood fills ventricles passively
The heart is ____ stimulated
Electrically
The heart can be observed by the….
measuring length and strength of electrical signals
The tool used to obsrve the heart is called…
electrocardiograph (EGC)
-If there is an abnormality in the heart, an ECG can provide doctors with information
Blood is always….
under pressure in the blood vessels because of the contractions from your heart
When does pressure in the heart increase?
Pressure increases when your heart is contracting and decreases when your heart relaxes
The pressure your blood exerts on the ____ of the circulatory system is what we call blood pressure
walls
If the amount of blood increases, so does the….
force on the walls of the blood vessels and therefore so does the pressure
-Too much pressure on the vessels can lead to serious health risks
Blood pressure is measured using a….
sphygmomanometer
The unit of measurement for blood pressure is millimetres of mercury (mm Hg)
What are the 2 things the sphygmomanometer measure?
-systolic pressure ( when your heart is contracting)
- diastolic pressure (when your heart is relaxed)
normal blood pressure of a healthy young adult should read around
120/80
Systolic pressure of 120 mm Hg
Diastolic pressure of 80 mm Hg
ECG Pattern for normal heartbeat:
- Starts with an electrical sitmulis from the SA node
- Stimuls spreads and causes contractions of atria creating P wave on ECG
- Signals travel to AV node,w hich causes delqy in transmissipn signal
- QRS complex follows, while electrical stimulus moves via puninke fibers to the tip of the ventricle
-Contraction of ventricles starts the the top of the heart and spreads supwards, rpodcuing squeezing action that forces blood out into aorta and pulmonary arteries
-Slight delay after QURS complex because ventricles recover and prepare for next contraction. This porduces T wave
Low blood pressure
Systolic: less than 90
Diastolic: less then 60
High blood pressure (stage 1)
Systolic: 159
Diastolic: 99
prehypertension
Systolic: 139
Diastolic: 99
High blood pressure stage 2
Systolic: 160+
Diastolic: 100+
Crisis blood pressure
Systolic: 180+
Diastolic: 110+
Systole is the highest….
Blood pressure level.
-Conteatcs to force blood through arteries
Diastolic is the…
lowest pressure
Elastic fibers help with…
factors that affect blood pressure along blood vessels to be elastic
Factors that affect blood pressure
-Blood thickness
-High salt diet: salt promotes waster retention and high blood pressure
-Stress: releases hormone which increases resistance
