Anatomy module 4.1 Flashcards
Systole
phase of contraction–Depolarize
Diastole
phase of relaxation–repolarize
Atrial and ventricular Diastole (late diastole)
Both atria and ventricles are relaxed
Blood is flowing from the veins into Right Atrium and into the Left Atrium
The AV valves are open and the SL Valves are closed
Atrial Systole
Initiated by depolarization
Preceded by the “P” wave of EKG
Atria contract
Blood flows from AV Valves to the Ventricles
Most Ventricular filling occurs before atrial systole
What is the advantage of atrial systole?
Forces last amount of blood out of the atrium into the ventricle.
Ventricular Systole (and atrial diastole)
Action potential has now traveled along the
Bundle of HIS to the ventricles.
It is preceded by the QRS wave of the EKG
The ventricles contract
The _____ventricular pressure causes the ______to ____ and a moment later the SL valve to _____. The ____ of ____valves cause the _____heart sound
(still a part of Ventricular Systole ( and atrial systole)
Increased AV Valves Close Open Closing AV valves first
The stage called _______occurse when the ______close but before the _____valves open.
Isovolumetric contraction
AV valves
SL Valves
Muscle contraction stays same length
Isovolumetric contraction
The stage called ______begings when _____valves _____.
Ventricular ejection
SL
Open
Ventricular diastole
Ventricles relax
Preceded by the T wave of EKG
Ventricular Diastole cont’d.
The _____ventricular pressure causes the SL valves to ____and a moment later the AV valves to____.
decreased
close
open
The closure of the ____ valves causes the ____ heart sound
SL
Second
The stage called ______occurs when the ____valves close but before the _____valves open
isovolumetric relaxation
SL
AV
Ventricular filling actually begins when the ____valves open
AV
Another cycle begins when the____fires another electrical signal
SA NODE
The volume of blood ejected from each ventricle per minute
Cardiac output
The number of contractions per minute
heart rate
Volume of blood ejected by a ventricle per beat
Stroke Volume
equation for CO, HR and SV
CO=SV*HR
Frank Sterling Law
The more the heart muscle is stretched during diastole, the greater the force of contraction during systole
Volume of blood returning to the right ventricle.
Venous Return
Degree of stretch on the heart before it contracts
Pre-Load
increases stroke volume
Forcefulness of contraction of individual ventricular muscle fibers
Contractility
increases stroke volume
Pressure that must exceed before ejection of blood from the ventricles can occur. “downstream”
After-Load
Decreases stroke volume
Substances that either increase or decrease contractility
Inotropic effect
Measurement of the % of blood leaving your heart each time in contracts
Ejection Fraction
EF=SV/EDV * 100
Cardiac Control centers are located….
Medulla oblongata
Originate in the cardioinhibitory center post-ganglionic axons release the neurotransmitter acetylcholine decrease rate of firing of SA node Responsible for vagal tone vagus nerve cause decrease in cardiac output
Parasympathetic signals
Originate in the cardioacceleratory center
post-ganglionic axons release the neurotransmitter norepinephrine
increase rate of firing SA Node
Increase contractility of cardiac muscle fibers
positive inotropic effect
Sympathetic signals
3 layers of blood vessel walls
Tunica Intima (Interna) SIMPLE SQUAMOUS Tunica Media VASCULAR Tunica externa (adventitia) FIBROUS CONNECTIVE
Only layer of capillary walls Innermost layer in direct contact with lumen consists of simple squamous epithelium smooth layer; facilitates flow of blood also known as endothelium
Tunica Interna
Contains smooth muscle
contains elastic connective tissue
middle layer
Tunica Media
Consists of fibrous connective tissue
outermost layer
Tunica externa (adventitia)
Sequence of flow of 3 major types of blood vessels
1) ARTERIES—2) CAPILLARIES—3) VEINS—Back to the heart
Carries blood away from heart
Arteries
Allows exchange of substances between blood and body tissues
Capillaries
Carries blood back to the heart
Veins
Wall contains intercellular CLEFTS
Wall consists of only simple squamous epithelial cells
Site of exchange between plasma and interstitial fluid
Capillaries
Smallest artery
contains greatest proportion of smooth muscle in its wall
Capable of most significant vasoconstriction and vasodilation
Major “resistance vessels”
Arterioles
Contains greatest proportion of elastic tissue in its wall
High elasticity stretch and recoil of vessel wall maintains blood pressure; “Pressure Reservoir”
Vessel with highest pressure
Transports blood away from heart
thickest-walled vessels
Artery
Contains valves
thin walls are easily distended; “volume reservoir” for blood
vessel with lowest pressure
transports blood toward heart
Veins
Smallest vein
Venule
Volume of blood the flows through any tissue in a given time period
Blood flow
Hydrostatic pressure exerted by blood on walls of a blood vessel
Blood pressure
Driving force of blood flow that is generated by heart contraction. this is maintained by the stretch and recoil of the _____walls
pressure gradient
Artery
If blood pressure increases, blood flow_____
increases
Vessel type with the highest pressure is _____and the lowest pressure is _____
Artery
Vein
Blood vessels in order of highest to lowest blood pressure
Aorta Artery Arterioles Capillaries Venules Veins Vena Cavae
Blood flow is driven by the blood pressure gradient, but is opposed by ______.
Peripheral Resistance
Friction between walls and blood vessels and the blood
Opposition to blood flow through blood vessels
Peripheral Resistance
Highest pressure attained in arteries during systole
Systolic Blood Pressure
Lowest arterial pressure during diastole
Diastolic blood pressure
Average blood pressure in arteries
Mean arterial blood pressure
Difference between systolic and diastolic pressure
Pulse Pressure
Arterial blood pressure is commonly measured in the _____artery
Brachial
Alternate expansion and recoil of elastic arteries after each systole of the left ventricle creates a traveling pressure wave
Pulse
Pulse is characterized of what vessel type?
Elastic Artery
Pulse is a function of what type of tissue?
Elastic connective
As ______increases, blood flow _____
Peripheral Resistance
Decreases
What two factors contribute to P.R.?
Vascular Resistance
–vessel diameter (as this increases resistance decreases)
–vessel length (as this increases, resistance increases)
Blood Viscosity
Which factor of P.R. is involved in the homeostatic regulation
Vessel Lumen (Diameter) Arterioles most significant
The widening of vessel diameter due to smooth muscle relaxation is known as:
Vasodilation
The narrowing of vessel diameter due to contraction of smooth muscle in its wall is called:
Vasoconstriction
EPINEPHERINE IS A
VASOCONSTRICTOR
Changes in arteriole diameter are important for 2 reasons:
Systemic Changes
(ANS–Sympathetic, Endocrine system)
Autoregulation
What specific division of the nervous system is primarily involved in regulation of arteriole diameter
Sympathetic Nervous System
Constant discharge by the Sympathetic Nervous System keeps arterioles slightly constricted under normal conditions. This is called:
Vasomotor Tone
Increased signals in the sympathetic NS lead to
Vasoconstriction
Decreased signals in the sympathetic NS lead to
Vasodilation
What are the hormones that influence arteriole diameter?
Epinepherine and Norepinephrine
ADH
Angiotnsion II
Atrial Natriuretic Peptide (ANP)
What structural features of capillaries promote exchange between plasma and interstitial fluid?
Thin cell walls
Intercellular cleft
Fenstrations
What blood components cannot normally exit capillaries?
Red Blood Cells
Plasma Proteins
Movement of dissolved molecules in response to a concentration gradient
Diffusion
Many substances enter and leave capillaries by diffusion
Movement via pinocytotic vescicles is called
Transocystosis
Important for Large, lipid-insoluble molecules that can’t cross capillary walls in any other way
Movement of water and small solutes in response to a pressure gradient is called
Bulk Flow (Important for regulation of relative volumes of blood and interstitial fluid.)
Pressure driven movement of fluid and solutes FROM blood capillaries INTO interstitial fluid
Filtration
Pressure driven movement from interstitial fluid INTO BLOOD capillaries
Reabsorption
_______pressure within capillary favors flow____the capillary
Blood Hydrostatic
Out of
_____(due to plasma proteins) within the capillary favors flow____the capillary
BCOP
Into
How is the slight excess flow of fluid out of the capillary returned to circulation?
Via lymph system
Volume of fluid and solutes reabsorbed normally is almost as large as the volume filtered. “near equilibrium”
Starlilng’s Law of the Capillaries
What would happen if….
Lower than normal concentration of normal plasma proteins, due perhaps to liver dysfunction
Lower blood osmotic pressure (BCOP)
What would happen if…
Increased capillary pressure due to poor venous return
Increased blood pressure
Causes more fluid to be filtered out of capillaries
What would happen if….
Blockage of lymphatic circulation
Lymphadema
Abnormal increase in interstitial fluid volume. Lack of proteins
Edema
What structures prevent backflow of blood within most veins?
Valves
Formula for relationship between mean arterial pressure, cardiac output, and peripheral resistance
CO=MAP/R; MAP=CO x R
If peripheral resistance and/or CO_____blood pressure will increase
INCREASE
Arterial blood pressure can be homeostatically regulated by regulating either _____or ______
CO
Resistance
Homeostatic regulation of arterial pressure is accomplished through the ______ reflex
Barorecptor
short term regulation
Receptors for Baroreceptor reflex are located in the walls of the _____and _____ and detect _______. When blood pressure increases, the receptors are______and send____impulses
Arch of aorta Coratid sinus pressure changes stretched/stimulated more
The integration center for the baroreceptor reflex is the_____in the _____
Cardiovascular
Medulla
The efferent pathway for the baroreceptor reflex is along_____and ______neurons
Parasympathetic
Sympathetic
The effectors for the baraorecceptor reflex are the _____and ______
Myocardium
smooth muscle
Detects changes in blood level of O2, CO2 and H+
Chemoreceptors
Regulates blood pressure
Baroreceptors
All arteries of systemic circulation are branches of the ____.
Aorta
All veins of systemic circulation are tributaries of the _____or the ____
Superior Vena Cava
Coronary Sinus
