Module C Flashcards
what is the structure of the cardiovascular system?
Right atrium - Returns of blood form the venous circulations (venous return)
Right ventricle- Pumping of venous blood into the pulmonary circulation
Left atrium - Reservoir for blood coming, from pulmonary circulation, primes the left ventricle
Left ventricle - Pumping of (oxygenated) into the systemic circulation
what is the function of cardiovascular system (cardiac output) ?
(CO) is a measurement of the amount of blood pumped by each ventricle in one minute.
describe the cardiac action
The cardiac action potential is a brief change in voltage (membrane potential) across the cell membrane of heart cells.
This action potential passes along the cell membrane causing the cell to contract,
the structure of arteries
Each artery is a muscular tube lined by smooth tissue and has three layers:
1) The intima,
2) the inner layer lined by a smooth tissue called endothelium.
3) The media, a layer of muscle that lets arteries handle the high pressures from the heart.
the function of arteries
Arteries transport blood away from the heart.
- arteries Have thick muscular and elastic walls to pump and accommodate blood
the structure of veins
consists of three main layers.
- The outer layer is connective tissue, called tunica adventitia or tunica extern
- The middle layer of smooth muscle called the tunica media,
- The inner layer lined with endothelial cells called the tunica intima.
the function of veins
Veins return blood back toward the heart.
- veins Have thin walls - have less muscular tissue than arteries
the structure of capillaries
Capillaries are very thin, and are composed of only two layers of cells—an inner layer of endothelial cells and an outer layer of epithelial cells.
- They are so small that red blood cells need to flow through them single file.
the function of capillaries
Capillaries surround body cells and tissues to deliver and absorb oxygen, nutrients, and other substances.
what is the function of blood vessels
Blood vessels flow blood throughout the body.
what is the cardiac conduction system
A network of specialized muscle cells is found in the heart’s walls. These muscle cells send signals to the rest of the heart muscle causing a contraction. This group of muscle cells is called the cardiac conduction system
what is cardiac valves
The valves prevent the backward flow of blood. These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one-way inlets of blood on one side of a ventricle and one-way outlets of blood on the other side of a ventricle.
the function of cardiac valves
- The atrioventricular valves (tricuspid & mitral) permit fillining of the ventricles and prevent backflow from ventricles to the atria during ventricular contraction
- The A-V valves are anchored by the papillary muscles
- The aortic and pulmonary artery valves typically have smaller opening and withstand higher back pressures
what is Cardiac Action potentials
Cardiac Action potentials in the heart differ considerably from action potentials found in neural and skeletal muscle cells.
what is pacemaker cell
The cells that create these rhythmic impulses, setting the pace for blood pumping, are called pacemaker cells, and they directly control the heart rate
- pacemaker cells found in nodal tissue within the heart,
what is non-pacemaker cell
- positive potassium ions are leaving the cell and thereby making the membrane potential more negative inside
the difference between pacemaker and non-pacemaker cell
pacemaker cell- 3 distinct phase rapid depolarization repolarization resting potential (unstable)
non-pacemaker cells- 5 distinct phase rapid depolarization initial repolarization action potential plateau repolarization resting potential (stable)
what is coronary circulation
Coronary circulation is the circulation of blood in the blood vessels that supply the heart muscle. Coronary arteries supply oxygenated blood to the heart muscle,
what is cardiac function
Cardiac function is the ability of the heart to meet the metabolic demands of the body. The delivery of oxygenated blood and removal of cellular waste products is fundamental to life
what is the cardiac function effected by
- It is affected by the force of the ventricular contraction - the volume of blood filling the ventricle.
what are the phase of cardiac cycle
two phase=
Systole- the development of the ventricular pressure which enables sufficient pressure to open the major vaves which allow blood to flow out of that chamber.
Diastole- is when the ventricles are relaxing which it doesn’t have to be all section hearten relaxation
physiological principles that influence cardiac function
Cardiac output = blood elected from the left ventricle each minute
Stroke volume = blood ejected from the left ventricle with each cardiac cycle
what is stroke volume influenced by
Preload: End diastolic pressure when the ventricle if fillies (at end-diastolic volume) preload is the stretching your arm
Afterload: the pressure in the aorta (or resistance in the circulation) is the pressure in the aorta
what is ohm’s Law
Ohm’s law:
flow= pressure/resistance
Pressure (mean arterial pressure ) = flow (cardiac output) / resistance (peripheral resistance )
the human circulation
- 20% of blood volumes resides in the arterial system
- The function of the arteries is to transport blood under the high pressure to the tissues
- The arterials system consist of conduit and resistance vessels
control of cardiac output
Most healthy individuals can increase their cardiac output 4 to 6 fold such s during exercise
= Increase in cardiac output can be achieved through
Intrinsic cardiac regulation of output
= Changing in heart rate via autonomic nervous system control.
what is the frank-starling mechanism
The Frank–Starling law of the heart represents the relationship between stroke volume and end diastolic volume.
- The law states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles
what is arterial pressure.
arterial pressure or blood pressure refers to the pressure measured within large arteries in the systemic circulation.
key features of arterial system
- Thicker tunica media, consisting of smooth muscle cells and elastic fibers.
- Tunica intima that consists of an internal elastic membrane
- “Wavy” endothelial layer due to residual contraction of smooth muscle.
the function of arterial system
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, with the exception of blood in the pulmonary artery. Arteries typically have a thicker tunica media than veins, containing more smooth muscle cells and elastic tissue.
control of blood flow
- the local blood flow is regulated via vasodilation and vasoconstriction within each region responses to changes on
- local metabolism (02,C02, metabolites)
shear stress
temperature
blood flow controlled via
endothelial-derived factors
humoral mechanisms
nervous system control
what is coronary circulation
is the circulation of blood in the blood vessels that supply the heart muscles (myocardium)
what is the coronary arteries
supply oxygenated blood to the heart muscle, and cardiac veins drain away the blood once it has been deoxygenated.
what is the function of Coronary circulation
part of the systemic circulatory system that supplies blood to and provides drainage from the tissues of the heart.
what is coronary metabolism
is a highly concerted plethora of chemical reactions leading to the conversion of substrates for energy production in the form of ATP to sustain cell function and allow contraction and also for the synthesis of building blocks to allow for growth, repair, and regeneration.
coronary metabolism
- myocardial ATP production is 95% from aerobic metabolism
- resting myocardial energy demand is approximately 20-fold that of skeletal muscle.
- To maintain O2 supply, O2 extraction in cardiac tissue is 75%
- As a result, O2 demand during exercise is mediated primarily by increased coronary blood flow.
coronary blood flow
- Opposite pattern - flow occurs in diastole rather than systole.
- Primarily due to compression of epicedial arteries during ventricular contraction
control of coronary blood flow
regulated in proportion to O2 demand
during periods of high demand, coronary blood flows is matched to demand via
= Release of vasodilator substances (adenine nucleotides , prostaglandins, nitric oxide) appear to increase local coronary flow.
what is the Capillary structure
- Diameter 5-10
- Single endothelial layer, surrounded by basement membrane.
- capillaries permits the passage of water, metabolic products, O2, CO2 and more
- Capillary flows dedicated by demand (not continuous)
capillary blood flow
Intermittent flow , known as vasomotion , caused by intermittent contraction of arterioles and precapillary sphincters.
- Flow through capillary bed is determined by average of all flow through capillaries supplying that bed.
- controlled in proportion to metabolic demand and the release of vasoactive substances in tissue bed.
the difference between artery and veins
artery
- tunica externa - tunica media - tunica intima
- smooth muscles
- internal elastic membrane
- vasa vasorum
- external elastic membrane
- endothelium
- elastic fiber
vein
- tunica externa - tunica media - tunica intima
- vasa vasorum
- smooth muscle
- endothelium
what is the function of venous system
- The venous system is large blood reservoir
- Cardiac output is controlled by venous system
diffusion through capillary membrane
Exchange of water, gases, nutrients and other substances predominantly via diffusion.
- Lipid- soluble substances (O2, CO2) can be diffuse directly through the cell membrane of capillary.
- water -soluble (non-lipid-soluble) substances (water , glucose, sodium) diffuse through intercellular clefts located between endothelial cells.
fluid filtration across capillaries
Determined “starling” forces
- Capillary hydrostatic pressure & interstitial fluid pressure
- Plasma colloid osmotic pressure & interstitial colloid osmotic pressure
- Elevated capillary pressure at ventral and results in a net outward force
what is nervous system
The nervous system controls everything you do, including breathing, walking, thinking, and feeling. This system is made up of your brain, spinal cord, and all the nerves of your body.
anatomic nervous system
Sympathetic innervation of blood vessels (most notably resistances vessels and veins)
= Increase resistance to flow
= Local blood control and pressure control
Sympathetic innervation of the heart
= Increase HR and contraciticaly
= Parasympathetic controls of HR
Neurological regulation of blood pressure
flow depends on the cardiovascular centers located in the medulla oblongata. This cluster of neurons responds to changes in blood pressure as well as blood concentrations of oxygen, carbon dioxide, and other factors such as pH.
Sympathetic vasoconstriction
Efferent sympathetic nerve activity increases concomitantly and constricts blood vessels in nonactive tissue to direct blood toward exercising muscle,
vasoconstriction balances the robust local vasodilatation to prevent a profound decrease in peripheral vascular resistance
Autonomic control of cardiac activity
- Primarily occur through changes in HR
- Sympathetic nerve fibers directly innervate the myocardium
= increase d SA noodle disarchage
= Increased conduction velocity
= Increased contractility
important features of autonomic nervous system (ANS) control
- The action of adrenaline and norepinephrine is largely dependent on the type of receptors present in the tissue
- It is influenced by feed-forward and feed-back control
- it ‘s action is rapid.
what is Baroreceptors reflex
is one of the body’s homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels.
Baroreceptors reflex
- are stretch receptors located in carotid sinus and aortic arch
-Increased baroreceptors stretch (via increased pressure) increase nerve firing
= pressure= HR and vasodilation
= pressure = increase HR and vasoconstrict
low term blood pressure
low -pressure arterial and pulmonary artery receptors
= act s in parallel with baroreflex
The kidney & long term blood pressure control
Long term control of arterial pressure is closely intertwined with homeostasis of fluid volume.
- Pressure diuresis refers to renal output of water in responds to increasing pressure
- Pressure natriuresis refers to salt output from, in response to increasing pressure
