Unit 1: The Cardiovascular System (Lecture) Flashcards
_______ ________ delivers blood to each organ system
systemic circulation
Oxygen and nutrient rich blood
Arterial blood
In the circulatory tree blood is delivered to the organ system in __________
parallel
Which side of the heart ejects blood into the aorta?
Left
__________ ___________ delivers blood to the lungs
Pulmonary circulation
Oxygen and nutrient poor blood
Venous blood
Where must venous blood pass through before entering into systemic circulation?
Lungs
Blood leaving the pulmonary circulation enters the…
Left atrium
Right and left pulmonary arteries pass ________ blood
venous
Right and left pulmonary veins pass __________ blood
arterial
Atrio-ventricular valves are located…
Between atria and ventricles
Semilunar valves are located…
Between the left ventricle and aorta
Between the right ventricle and pulmonary trunk
_________ muscles are specialized muscles that originate in the ventricular wall
Papillary
Papillary muscles attach to the AV valve flaps via tendon like structures known as _______ ________
Chorda tendinae
What contracts at the same time as the ventricles?
The papillary muscles
The aortic and the pulmonary semilunar valves are _________ dependent
Pressure
Cardiac output
The amount of blood pumped by the ventricles per minute
At rest, the left and right ventricles each pump about ___ liters of blood per minute.
5
Cardiac output increases to as much as ____ liters/minute during maximal exercise.
30
The muscle tissue of the heart is supplied with blood from the…
Coronary circulation
The right and left coronary arteries originate on the…
ascending aorta
The right coronary artery supplies the…
- Sinoatrial (SA) node
- Atrioventricular (AV) node
- Parts of the right atrium
- Interventricular septum
- Right ventricle
- Left ventricle
The ___________ branch originates on the right coronary and supplies the anterior portions of the right ventricle
Marginal
The ____________ ____________ branch originates on the right coronary and supplies the posterior portions of both ventricles.
Posterior interventricular
The left coronary artery supplies the…
- Sinoatrial (SA) node
- Parts of the left atrium
- Interventricular septum
- Ventricles
The __________ branch supplies the left atrium and posterior regions of the left ventricle.
Circumflex
The __________ __________ branch originates from the left coronary and anterior portions of both ventricles.
Anterior interventricular
________ _______ vein drains the anterior heart
Great cardiac
The ________ _________ vein drains the posterior heart.
Middle cardiac
The great and middle cardiac veins drain into the _________ ________
Coronary sinus
The coronary sinus drains into the ________ _________
Right atrium
The left semilunar valve can’t open until it reaches what pressure level (average adult human)?
100 mmHg
The right semilunar valve can’t open until it reaches what pressure (average adult human)?
35 mmHg
What does pressure dependent mean?
Valves that take a certain amount of pressure to open
What are the other names for the left atrio-ventricular (AV) valve?
Biscuspid or mitral
What is the other name for the right atrio-ventricular (AV) valve?
Tricuspid
Heart filling, open valves
Diastole
Contracted, close valves
Systole
Striated fibers
actin and myosin packaged in myofibrils
The sarcomere contains…
Z discs, A bands and I bands
In cardiac muscle there is typically one centrally located _________
nucleus
There is one ________ per sarcomere
T-tubule
Desmosomes
Physical coupling of adjacent cells
Gap junctions
Electrical coupling
Intercalated discs
structures that connect adjacent cardiac muscle cells
The myocardium is considered a…
functional syncytium
Syncytium
A syncytium is a single cell that contains multiple nuclei.
A network of cardiac muscle cells connected by gap junctions that allows coordinate contraction of the ventricles
Gap junctions
intercellular connections that directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells
What allows for electrical impulses to pass quickly from one cell to the next and throughout heart muscle?
Gap junctions
Cardiac pacemaker
Sino atrial (SA) node, mass of cells in the right of the atrial wall
In the heart, what spontaneously discharges action potentials?
Pacemaker cells in the sino atrial (SA) node and the atrio-ventricular (AV) nodes
The atria and ventricles must contract in a…
coordinated fashion
What is the first even in the sequence of cardiac muscle excitation?
Depolarization of the sino-atrial (SA) node
After depolarization of the SA node, action potentials then…
travel down and across both atria, causing atrial muscle fiber contraction.
At the AV border there is a band of…
poorly-conducting tissues (small fibers, few gap junctions)
What is the effect of the delay at the AV border?
Provides the atria enough time to empty before muscle contraction.
Pacemaker cells discharge action potentials spontaneously at the rate of…
100-120 per minute
Our resting heart rate is controlled by the…
Autonomic/Parasympathetic nervous system
Our resting heart rate is controlled by the…
Autonomic/Parasympathetic nervous system
Plateau
Decline in K perm, increase in CA perm
In physiology, refractory refers to…
The period of time when a muscle or nerve cell is unresponsive to stimulation
The absolute refractory period refers to the time when…
the cell will not response regardless of the strength of stimulus
How long does the refractory period in the heart muscle last?
250 ms
Blood enters the right ventricle via…
The right atrium and tricuspid valve
The SA node discharges the action potentials spontaneously at the rate of…
100-120 times/minute
In a healthy young adult, the resting heart rate is…
70 beats/min
The blood entering the right atrium is…
Mixed venous blood
________ is the period of ventricular relaxation and filling
Diastole
________ is the period of ventricular contraction and blood ejection
systole
Atrial diastole
The atria fill passively.
In diastole, both AV valves are open and blood flows into the ventricles.
Ventricular diastole
Starts with ventricular muscle repolarization, and with a drop in the ventricular pressure that results in passive filling of the ventricle
Atrial systole
Brief synchronous contraction of the atria; active filling of the ventricles
Ventricular systole
When the AV valves close and the pressure within the ventricles begins to rise as the cardiac muscle fibers are depolarized and then contract
Preload
End-diastolic volume
Afterload
Aortic or pulmonary pressure
Contractility
Force with which the ventricles contract
Principle determinants of stroke volume
- Preload
- Afterload
- Contractability
Factors of EDV
- Driving pressure
- Muscle pump
- Respiratory pump
Driving pressure
Filling of the heart chambers when there is a pressure differential
Respiratory pump
Breathing affects venous return through changes in right atrial pressure
Muscle pump
Venous return, when body muscles are relaxed the blood valves are closed. When we contract our muscles, their valves open.
Passive contractility
Changes in contractility due to changes in the length of cardiac muscle fibers
Active contractility
Change in heart muscle contractility due to stimulation of the heart by nervous system input
During active contractility, sympathetic neurons release ________
Norepinephrine
Chronotropy
Increased heart rate
Inotropy
increase force of cardiac muscle contraction
Norepinephrine increase permeability of the cardiac muscle fibers to…
Ca
The release of norepinephrine causes an increase in…
- heart rate
- force of cardiac muscle contractility
- number of actin/myosin cross bridge interactions
- strength of cardiac contraction
Each cardiac cycle has a duration of
0.8 seconds
Cardiovascular control centers are located in the…
caudal medulla
Cardio-accelatory (fight or flight)
Sympathetic NS
Cardio-inhibitory (rest and digest)
Parasympathetic NS
Effects on the heart rate are called…
Chronotropic effects
Circulating hormones
Epinephrine
Thyroxine
SNS preganglionic neurons release ______ onto postganglionic neurons
Acetylcholine (ACh)
SNS postganglionic neurons release __________ onto target cells
Norepinephrine (NE)
NE activates ________ receptors which have a wide-spread effect on cardiac nervous and muscle tissue
beta-1 receptors
What in the cardio-accelatory center synapse upon preganglionic neurons in the thoracic spinal cord?
Sympathetic neurons
Which neurons synapse onto postganglionic neurons located in the sympathetic chain ganglia?
Preganglionic SNS neurons
Which neurons send axons to the SA and AV nodes, and cardiac muscle?
Postganglionic SNS neurons
Which neurons send axons to the heart in the vagus nerves?
Parasympathetic NS
Which nerves synapse directly on the SA and SA nodes, and on the atrial muscle?
Vagus nerves
Which nerves release ACh onto the postsynaptic cells and slow heart rate?
Vagus nerves
What causes an increased rate of depolarization in the SA and AV nodes?
Increase in inward NA current
Heart rate is modified by:
- emotions
- cortical input
- circulating hormones
Hypocalcemia
Reduced ionic calcium depresses contractility
Hypercalcemia
Dramatically increases heart rate irritability and leads to spastic contractions
Hypernatremia
Excess Na blocks heart contraction by inhibiting ionic calcium transport
Hyperkalemia
Excess of potassium leads to heart block and cardiac arrest
How do oxygen and nutrients exit the blood?
Capillaries
When nutrients exit a capillary, what do they enter?
Interstitial fluid
Do carbon dioxide and metabolic waste move in the same or opposite direction as nutrients?
Opposite
A network of capillaries where exchange of materials with the tissue cells can take place
Capillary bed
Every tissue cell is within ____ cell diameters of a capillary
2-3
The average capillary length is…
1 mm
The capillary lumen diameter is about…
0.8 micrometers
Blood flow velocity in a capillary is about…
0.1-0.3 cm/sec
Capillary density in a given tissue is proportional to that tissue’s…
metabolic activity
What passes the capillary wall via intercellular clefts?
water and water-soluble “solutes”
What can cross a capillary wall through endothelial cell membranes?
Small molecules and gases
What can cross a capillary wall through fenestrations?
Large molecules
Capillary:
- least permeable
- tight junctions between endothelial cells
- intercellular clefts allow the passage of small molecules
Continuous capillaries
Location of continuous capillaries
- lungs
- skeletal muscle
- connective tissue
Capillary:
- Pores/fenestrations
Fenestrated capillaries
Location of fenestrated capillaries
- Kidney
- Endocrine glands
- Small intestine
Capillary:
- Large fenestrations
- Few tight junctions
- Wide intercellular clefts allow for the exchange of large molecules
(Discontinuous) Sinusoidal capillaries
Location of sinusoidal capillaries
- Liver
- Spleen
- Bone marrow
- Pituitary gland
Movement of molecules or ions from a region of higher concentration to one of lower concentration until equilibrium is reached
Diffusion
Diffusion is a ______ process
passive
Refers to the movement of a fluid from a region of higher pressure to one of lower pressure
Bulk flow
Bulk flow is a ______ process
passive
Substances enter pinocytotic vesicles, move to endothelial cells via endocytosis, and exit on the opposite side via exocytosis
Transcytosis
Transcytosis is a _______ process
active
Forces favoring movement of fluid out of the capillary into the interstitial fluid
Blood hydrostatic pressure
Interstitial fluid osmotic pressure
Blood hydrostatic pressure
pushed fluid out through the capillary pores
Interstitial fluid osmotic pressure
pulls fluid out of the capillary via osmosis
compared to BHP this pressure is very small
Blood colloid osmotic pressure
Differences in protein concentration between plasma and ISF.
Tends to pull water from the ISF into the capillary.
Interstitial fluid hydrostatic pressure
pressure exerted by interstitial fluid, but typically is very small
Refers to the net movement of fluid determined by the difference between the inward and outward pressure
Net filtration pressure
The main determiners of fluid movement across the capillary wall
Blood hydrostatic pressure
Blood colloid osmotic pressure
____ results in a constant flow of fluid that washes over the tissue cells at the arterial end of the capillary, carrying nutrients and oxygen with it
filtration
_____ results in a return of fluid to the capillary at the venous end, thereby depositing wastes into the venous system
reabsorption
Under normal conditions, slightly more fluid leaves than is returned by…
capillaries
Hemodynamics
the study of fluid flow in the vascular system
If blood pressure was equal throughout the CV system…
blood would not flow
The pressure difference between regions is termed…
driving pressure
BP in large elastic arteries near the heart is…
pulsatile
BP peaks during…
systole
BP falls during…
diastole
Arterial BP reflects…
two features of arteries near to the heart
Which vessel is elastic and compliant?
Large arteries
Arterial compliance
stretch
Elasticity
Recoil
Alternating waves of expansion and recoil result in a pressure wave called…
pulse pressure
Stiff arteries are less…
compliant
To eject the same volume into the circulation, pressure must…
increase
Hypertension results when arteries become…
stiffer
Pressure in the pulmonary circuit are much ____ than those in the systemic circuit
lower
Pulmonary circulation is highly…
compliant
The mean pressure in the pulmonary artery at rest is about…
14 mmHg
The mean left atrial pressure is about…
5 mmHg
Blood flow is proportional to the…
driving pressure
Blood flow is inversely proportional to…
the resistance to flow
Blood flow =
driving pressure / resistance
Resistance is the sum of all forces that…
retard flow
Resistance to fluid flow is caused by…
friction between the molecules in the fluid and with the walls of the tubes
Frictional resistance…
reduces flow
Resistance =
viscosity * vessel length / radius^4
Mean arterial pressure =
Diastolic BP + 1/3 (Systolic BP - Diastolic BP)
Pulse pressure =
Systolic BP - Diastolic BP
Refers to changes in vessel diameter due to circulating hormones
Humoral regulation
Regulation of blood vessel diameter by substances released by tissue cells and which is a function of the level of tissue metabolic activity
Metabolic or “local” regulation
Increase HR and contractility
sympathetic vasomotor neurons
Parasympathetic neurons decrease…
HR
Regulate blood vessel diameter
sympathetic vasomotor neurons
What synapse onto arteriolar smooth muscle to regulate vasoconstriction?
Sympathetic nerves
Cardiovascular neurons receive peripheral afferent input from…
- baroreceptors
- chemoreceptors
- proprioceptors
Baroreceptors
Blood pressure
Chemoreceptors
Chemical composition
Proprioceptors
body position and location of space
What are “more important” receptors in cardiovascular regulation?
Baroreceptors and chemoreceptors
High pressure baroreceptors are located in the…
carotid sinus and aortic arch
Input from the high pressure baroreceptors is carried to the CV center via…
Cranial nerve IX
Cranial nerve X
Low pressure baroreceptors are located in…
the right atrium and vena cavae
Input from low pressure baroreceptors is carried to the CV center via…
Cranial nerve X
Chemoreceptors in the carotid sinus reach the CV center in the medulla via…
cranial nerve IX - glossopharyngeal
Chemoreceptors in the aortic arch reach the CV center in the medulla via…
cranial nerve X - vagus
Chemoreceptors respond to increased…
Hydrogen ion content
CO2
Chemoreceptors respond to reduced…
O2 (hypoxia)
Chemoreceptor stimulation activates the SNS and results in increased…
HR, SV, and vasoconstriction
(NE and E) circulate and bind directly to receptors on cardiac muscle fibers and on smooth muscle cells of blood vessels
Catecholamines
Increase HR and SV, and constriction of veins and arterioles
Catecholamines
Which vessels are not subject to vasoconstriction by SNS or catecholamines?
Arteries supplying the brain and heart
Arteries supplying the brain and heart…
autoregulate
Produced in the hypothalamus with increases in Na concentration blood
Antidiuretic hormone
Causes widespread vasoconstriction in case of extremely low BP
Antidiuretic hormone
Causes water retention by kidneys
Antidiuretic hormone
Causes intense vasoconstriction when renal perfusion is inadequate
Angiotensin II
Causes water retention and increase blood volume
Aldosterone
Release of renin by the kidney causes…
lowered blood pressure
What converts renin into angiotensin I?
Angiotensinogen
Where is angiotension converting enzyme located?
Endothelial cells of the lung
What is one of the most powerful vasoconstrictor substances?
Angiotensin II
What regulates secretion of aldosterone?
Angiotensin
Elevated angiotensin II levels cause…
aldosterone secretion by the adrenal cortex
What promotes salt and water re-absorption by the kidneys?
Aldosterone
Substances that lower blood pressure?
Histamines
Released by mast cells cause vasodilation by relaxing blood vessel smooth muscle
Histamine
Wastes move in the ______ direction
reverse
Clear, straw colored watery liquid that consists of 91.5% of H2O and 8.5% solutes
Plasma
Cells and cell fragments
formed elements
Where are plasma proteins created?
liver
Albumin
maintains blood osmotic pressure
immunoglobins
antibodies that bind antigens
Fibrinogen is for…
clottin
Normal female hematocrit range
38-46%
Normal male hematocrit level
40-54%
Anemina
Insufficient erythrocytes or not enough hemoglobin
Polycythemia
Too many erythrocytes (greater than 65%)
Causes of polycythemia
Dehydration
Tissue hypoxia
Blood doping
The binocave shape of erythrocytes (RBCs) increases the surface area available for…
oxygen binding
The protein that carries oxygen
hemoglobin
Each hemoglobin molecule can carry __ O2 molecules
4
Oxygen is loaded onto hemoglobin in…
lung capillaries
Blood concentration of Hb in women
14 g / 100 ml
Blood concentration of Hb in men
16 g / 100 ml
Erythropoiesis
Formation of erythrocytes (RBCs)
Where does erythropoiesis occur?
red bone marrow
After birth, RBCs are formed from…
stem cells
During erythropoiesis, stem cells differentiate into…
proerythroblasts
Proerythroblasts become…
reticulocytes
During erythropoiesis, at maturity reticulocytes…
eject the nucleus then form Hb
Regulates differentiation and proliferation of blood cells
erythropoietin
Worn out cells removed by…
fixed macrophages in spleen and liver
RBCs only live…
80-120 days
How is globin broken down into amino acids?
By macrophages in the liver or spleen
What is heme broken down into?
Fe and biliverdin
How is iron transported in the blood?
the protein transferrin
Where is iron stored?
liver, muscle, or spleen
When iron is stored, what is it attached to?
Ferritin or hemosiderin protein
Biliverdin is converted into…
bilirubin
Bilirubin is secreted by…
liver into bile
Bile is excreted via…
kidneys and intestine
Cell fragments that circulate for 5-9 days before they die
Thrombocytes
What percent of mature platelets circulate?
2/3
What percent of thrombocytes reside in the spleen?
1/3
Clot formation
Thrombosis
Thrombus
clot
A circulating clot is referred to as an…
embolus
TPO is released from the…
liver
EPO is released from the…
kidney
Severe uncontrolled bleeding
hemorrhage
Series of reactions designed to stop bleeding
Hemostasis
3 phases of hemostasis
- Vascular spasm (vasoconstriction)
- Platelet plug formation
- Coagulation (blood clotting)
Two main functions of thrombin
- Convert fibrinogen into fibrin mesh
- Activates factor XIII which stabilizes fibrin network
Where are clotting factors synthesized?
Liver
Which vitamin is necessary for clotting factors?
Vitamin K
Individuals lacking factor VIII
hemophiliacs
Dissolution of a clot
Fibrinolysis
What digests fibrin strands to break down a clot?
Plasmin
