Circulatory System Flashcards
Perfusion
Flow of blood through a tissue
Ischemia
Inadequate blood flow
Hypoxia
Adequate circulation but oxygen supply reduced
Arteries
Carry blood away from the heart at HIGH pressure
Veins
Carry blood to the heart at LOW pressure
Arterioles
As arteries get further from the heart, pressure decreases and the arteries branch into arterioles
Arteries branch into arterioles which then branch into
Capillaries
Arterioles have ____ which can control the amount of blood entering the capillaries
Capillaries are
Smooth muscle that can restrict or increase blood going to capillaries which are very small vessels (often only wide enough for one blood cell to pass) that allow exchange of material from the blood and tissues
After blood passes through arteries branch into arterioles which then branch into capillaries, the blood enters:
Small veins called Venules which takes the blood to the veins for return to the heart
Endothelial cells make up
Endothelial cells and the capillaries
Inner linings of all blood vessels
Capillaries are a single layer of endothelial cells
Endothelial cells role in vascular function (4)
Vasodilation and vasoconstriction
Inflammation
Angiogenesis (forming new blood vessels)
Thrombosis (blood clotting)
Angiogenesis
Forming new blood vessels
Right side of the heart pumps blood to
Lungs
Left side of the heart pumps blood to
Rest of body (other than the lungs)
Pulmonary Circulation
Flow of blood from the heart to the lungs and back to the heart (right side)
Systemic circulation
Flow of blood from the heart to the rest of the body and back again (left side)
Most blood flows through only one set of capillaries before returning through the heart
EXCEPT
Portal systems in which blood goes through multiple system’s capillaries
Direct transport systems to connect two areas without passing through the whole body
Right ventricle and left ventricle
Deoxygenated or oxygenated blood?
R: deoxy
L: oxy
Atria
“Waiting rooms” where blood can collect from the veins before getting pumps to the ventricles
Ventricles
Pump blood out of the heart at high pressures into arteries
Right atrium receives ____ from the ___ and pumps ____
Deoxygenated blood from the systemic circulation (S&I Vena Cava) and pumps to right ventricle
From the right ventricle, blood passes through the
Pulmonary arteries and through the lungs to get oxygenated
Oxygenated blood from the lungs arrives back into the heart at the ____ via the _____
Left atrium
Pulmonary arteries
When oxygenated blood arrives through the left atrium, it is
Pumped into the left ventricle before being pumped out of the heart in a single large artery, the AORTA to systemic circulation
Do all arteries carry oxygenated blood?
No the pulmonary arteries carry deoxygenated blood to the lungs
Antroventricular valve is necessary to prevent
Backflow from the ventricles to the arteries due to the high ventricular pressure and low atrial pressure
AV valve between the left atrium and left ventricle is called the ____ valve
Mitral/bicuspid
Must withstand enormous pressures
AV valve between the right atrium and ventricle is called the ____ valve
Tricuspid
Semilunar valves include which valves (2)?
Separate what?
- Pulmonary valves
- Aortic semilunar valves
Between the ventricles and the arteries they pump blood into
Function of valves throughout the circulatory system / body
To create a driving force for blood to get back to the heart
Cardiac cycle consists of two parts:
Diastole and systole
Diastole
Ventricles relax and blood flows into them from the atria
Atria actually contract during this stage to put blood into the ventricles
Systole
Begins when ventricles start to contact, pressure buildup causes AV node to shut and eventually causes the semilunar valve to open and blood to shoot into the aorta and pulmonary artery
End: ventricles nearly empty and done contracting, back flow begins to occur but the semilunar valves slam when the pressure in the ventricle is less than the pressure in the arteries
Which is shorter: systole or diastole?
Systole is shorter (occupies space between Lub and dub while Diastole occupies space between Lub-dub and another Lub-dub)
Heart rate/pulse
Number of times the S/D cycle occurs in one minute
Normal HR / pulse
Around 1beat/second (45-80 is normal range)
Stroke volume
Amount of blood pumped with each systole
Why is 45 bpm or 80 bpm normal?
Stronger heart pumps more blood in one contraction (athletes) and weaker heart pumps less blood in one contraction (elderly/babies)
Cardiac output
Amount of blood pumped per minute
Cardiac output =
CO = HR x SV
Frank-Starling mechanism to increase cardiac output
If venous return(return of blood to the heart) is increased, the heart fills more, stretching it more, contracting it more forcefully
Increases SV significantly
Functional Syncytium
In cardiac muscle cells, the gap junctions through which different cells can communicate is found in intercalated disks, connections between cardiac muscle cells
AP can be communicated directly through the cytoplasm to the neighboring cardiac muscle cells
I.E. electrical synapse, no chemical
Intercalated disks
connections between cardiac muscle cells
Cardiac conduction system
AP fired in the heart is transmitted from the atrial syncytium to the ventricles
Fast vs slow sodium channels involvement in cardiac muscle action potentials
Fast are important like in neurons but:
Slow stay open longer causing depolarization to last longer in cardiac muscles than in neurons producing a plateau phase
Contraction lasts longer, so more force expels the blood
T tubules
Maximize amount of Ca2+ entering the cell by running the length of the cell to allow depolarization and activation of the sarcoplasmic reticulum to release calcium
Makes a combo of intracellular and extracellular calcium
Combo of intracellular and extracellular calcium around the cell causes
Contraction of actin-myosin fibers
SA Node
Initiates AP in the heart (pacemaker of the heart)
SA Node AP phases
0, 3 and 4 (NO 1 and 2 LIKE OTHER CARDIAC MYOCYTES)
SA Node is unique because it has an unstable resting potential which is:
Phase 3 (automatic slow depolarization) caused by sodium leak channels which brings the cell potential to threshold for VG Ca2+ channels
When VG Ca2+ channels open, ___ begins:
Phase 0
Drives membrane potential of the SA node toward positive Ca2+ equilibrium potential GRADUALLY because the channels operate more slowly than Na+ in other AP
Phase 3 of SA Node AP
Repolarization
Caused by the closure of the Ca2+ channels and opening of K+ channels leading to K+ exiting the cell to drive membrane potential toward the negative K+
Phase 0,3,4 occurs
Once per heart beat
The SA node has the most ____ which means it _____ and therefore sets the rate of contraction for the heart
Na+ leak channels
Depolarizes first
When the SA node is injured,
The AV node or Purkinje fibers will take over but the heart will be set at a slower rate
Cardiac muscle cells of the heart have an action potential that differs from the SA node and other conduction systems:
Threshold is -90 mV
AP have a longer duration
Phases 0-4
Phase 0 Phase 1 Phase 2 Phase 3 Phase 4
0: Depolarization due to influx Na+
1: Initial repolarization Na+ close and K+ open
2: Plateau because Ca2+ channels open and influx balances K+ efflux
3: Depolarization when Ca2+ close and K+ still open/leave
4: Resting membrane potential dictated by action of the Na+/K+ ATPase (pump) and K+ leak channels
Internodal tract
Connects the SA and AV node to transmit AP rapidly without contracting
Impulse travels to the AV node ___ than it does to the atria
At the AV node the impulse is ___ before traveling to the ___
This part of the conduction pathway is known as the ___
Faster
Delayed
Ventricles via the conduction pathway
AV bundle
AV bundle divides into the ___ and then the ___
Right and left bundle branches Purkinje fibers (allow impulse to spread over both ventricles)
Where do the purkinje fibers spread on the ventricles and why?
Purkinje fibers spread over the bottom portion of the ventricles because contraction here pushes blood up toward the arteries and valves
Intrinsic firing of the SA node is 120bpm but the heart rate is approx. 60
Why?
Because the parasympathetic nervous system constantly inhibits the heart from contracting
What inhibits the SA node?
The vagus nerve releases ACh to inhibit depolarization by binging to cell receptors on the SA node
Vagal tone
Constant inhibition by the vagus nerve
Sympathetic nervous system excites the heart in fight or flight: how?
Epinephrine
Peripheral resistance equation
Change in pressure = cardiac output x resistance
Precapillary sphincters
Primary determinant of resistance
Degree of constriction of arteriolar smooth muscle
Adrenergic tone
Constant sympathetic nervous system input to innervate the precapillary spinchters
Systemic arterial pressure
Blood pressure
BP=120/80
What do the two numbers mean?
Numerator: Systolic pressure (highest ARTERIAL pressure gets as ventricles contract: systole)
Denominator: Diastolic pressure (lowest ARTERIAL pressure gets as ventricles relax: diastole)
Local autoregulation
Tissues in need of extra blood flow are able to requisition it themselves
When a tissue is underperfused waste builds up and vasodilation occurs causing the smooth arteriolar smooth muscle to relax and increased blood flow arrives when the diameter of the artery is larger
Blood has a ___ portion and a ___ portion
Liquid portion and a cellular portion
Liquid portion of blood is called:
Cellular components of blood are called:
Plasma
Formed elements
Principle blood buffer found in plasma that keeps the blood at pH of 7.4 Is
Bicarbonate (HCO3-)
Principle sugar in the blood’s plasma is
Glucose
Constant concentration must be maintained for nutrients to be given to the organs
Proteins in the plasma in the blood:
- Albumin
- Immunoglobulins
- Fibrinogen
- Lipoproteins
- Albumin: maintains osmotic pressure in capillaries
- Immunoglobulins: immune system role
- Fibrinogen: blood clotting
- Lipoproteins: fats, cholesterol and carrier proteins
Principle metabolic waste product in the blood (2)
Urea
-Breakdown of Amino Acids
Bilirubin
-Breakdown of heme
Centrifuging blood results in the breakdown of
54% plasma
45% hematocrit (35-40 in females)
1% leukocytes
Hematocrit
Red blood cells
What does plasma contain?
Water, electrolytes, glucose, hormones, wastes, plasma proteins, lipoproteins
Erythropoeitin
Made in the kidney
Stimulates RBC production in the bone marrow
Aged RBC’s are
Eaten by phagocytes in the spleen and liver
Erythrocyte is a cell with no nucleus or organelles but it still requires ___ and it gets it from the ___
ATP
Glycolysis from ATP synthesis
Purpose of RBC is to
Hence RBC require
Transport O2 to the tissues from the lungs and CO2 from the tissues to the lungs
Large surface area for gas exchange
RBC is able to carry oxygen because it contains
hemoglobin
Blood group antigens (which determine blood type) have two major groups:
ABO blood group
Rh blood group
ABO blood group consists of 3 alleles:
Ia, Ib and i
Rh blood group consists of
RR, Rr (blood type +) and rr (blood type -)
Type IaIb or ii
IaIb is AB and ii is O
Transfusion reaction
Clumping and destruction of RBC bearing the incorrect antigen
Example: Person with A+ blood produces anti-B antibodies
If transfused with type B blood,
Antibodies will clump and destroy the donated type B cells leading to death of the recipient
Hemolytic disease of the newborn
When the mother has the FIRST child with + blood when she has -, she will become sensitized upon first exposure and her body will begin to produce the antigens
Upon SECOND baby with + blood, antibodies can cross the placental barrier to clump or destroy the baby + blood cells
Two unique types of blood types
AB+
O-
Why?
AB+ does not make antibodies to any other groups because their blood cells possess all the antigens already = “universal acceptors”
O- do not possess any of the antigens that can cause the antibody formation so = “universal donors”
White blood cells function
Fight infection and deposit debris
WBC have all the normal cell organelles present in eukaryotes
They also exhibit amoeboid mobility which is ___ and is important for
Crawling
Squeeze out of capillary intercellular junctions to roam free in the tissues, hunting for foreign particles and pathogens to rid
Chemotaxis
Movement directed by chemical stimuli which can be toxins and waste products released by pathogens or chemical signals released from other WBC
Macrophage
WBC monocyte
Phagocytose debris and microorganisms
Crawling
Chemotaxis
B cell
WBC Lymphocyte
Mature into plasma cell and produce antibodies
T cell
WBC Lymphocyte
Kill virus infected cells, tumor cells, and reject tissue grafts
Control immune response
Neutrophil
WBC Granulocytes
Phagocytose bacteria resulting in pus
Crawling
Chemotaxis
Eosinophil
WBC Granulocytes
Destroy parasites
Allergic reactions
Basophil
WBC Granulocytes
Store and release histamine
Allergic reactions
Platelets are like RBC in that they
Have no nucleus and a limited lifespan
Megakaryoctes
Bone marrow cells that five rise to platelets
Function of platelets
Aggregate at the site of damage to blood vessel wall forming a platelet plug to stop bleeding
Hemostasis
Prevents bleeding
Fibrin
Threadlike protein which forms a mesh holding the platelet plug together
When fibrin mesh dries,
It forms a scab
Thrombus
Scab circulating in the bloodstream
Hemophilia is caused by ____ from a mutation on the ____ and results in ___
Defects in proteins necessary for activating thrombin and fibrinogen
X chromosome
Excess bleeding
Hemoglobin
Four subunit protein each containing molecule of heme (single iron atom at its center)
Heme role
Bind O2
How many oxygen molecules can each hemoglobin carry
4 (one for each subunit with a heme molecule)
Hemoglobin subunits do not bind oxygen independently of each other
When none have oxygen bound,
When one of the subunits binds oxygen,
Thus, oxygen is said to bind ____
hemoglobin has a TENSE configuration of its subunits and does not have an affinity for oxygen
the hemoglobin relaxes when one subunit binds oxygen so the other subunits have a higher affinity for oxygen
Cooperatively
Result of hemoglobins cooperative bonding:
Oxygen is picked up in the lungs and most is released in tissues that need oxygen
Certain factors that stabilize the tense configuration of hemoglobin: (3)
Decreased pH
Increased CO2 in the blood
Increased temperature
Bohr effect
Fact that : Decreased pH Increased CO2 in the blood Increased temperature Stabilizes tense hemoglobin and reduces oxygen affinity
Certain factors that stabilize the tense configuration of hemoglobin:
Decreased pH
Increased CO2 in the blood
Increased temperature
Where are these factors optimal?
In active tissues that need oxygen
Percent saturation (% sat) =
% sat = (# O2 molecules bound) x (# of O2 binding sites) x 100%
73% of CO2 transport is accomplished by:
Conversion of CO2 to carbonic acid by catalyst carbonic anhydrase
Water soluble compounds which can be easily carried in the blood
ALSO Principal pH buffer
Some CO2 (20%) is transported by:
Stuck onto hemoglobin sites (not the oxygen ones)
Stabilizes tense Hb
CO2 is transported (7%) by:
Dissolving in the blood and being carried from tissues to the lungs
Virtually no oxygen can be dissolved
Intercellular clefts
Spaces between the single layered endothelial cells that make up the capillary wall allowing exchange between blood and tissues
There are three types of substances that must be able to pass through the intercellular clefts of capillaries:
WBC, nutrients and wastes
Do O2 and CO2 need to pass through the intercellular clefts to enter the blood cell?
No they can enter the cell via simple diffusion
Hepatic portal vein carries
AA and glucose to be absorbed in the digestive tract and carried to the liver
Connects two capillary beds (one inside intestines and other inside liver)
Fats are absorbed from the intestine and packaged into ____, which are a type of lipoprotein. The chylomicrons enter tiny lymphatic vessels in the intestinal wall called _____
Hence lipids bypass the hepatic portal vein and travel through the blood steam resulting in milky blood after eating a fatty meal (term for this is ____)
Chylomicrons
Lacteals
Lipemia
Lipemia
Lipids travel through the blood not the hepatic vein
Adipocytes
Target destination of lipoproteins
Fat cells for storage
The liver removes wastes and converts them into forms to be excreted in poop
These compounds passed through the gut are referred to as
Bile
Two of six types of WBC that can squeeze through the clefts are the ___ and ____ because they can ____
Macrophages and neutrophils
Amoeboid motility
Water has a tendency to flow out of tissues through the capillary intercellular clefts: why? (2 reasons)
Pressure created by the heart tends to squeeze water out of the capillaries
High osmolarity of the tissues tends to draw water out of the blood stream
How does the circulatory system deal with the tendency of water to flow out of the capillaries via the intercellular clefts
A high plasma osmolarity is provided by high concentrations of large plasma proteins (Albumin which is too large to pass out of the capillaries and their presence keeps water inside the cell too)
Oncotic pressure
Pressure created by the plasma proteins albumin
Cycle of capillaries life in regards to pressure and osmosis stages
- Hydrostatic pressure is high, water squeezes out
- Plasma proteins concentration increases
- Hydrostatic pressure is low, blood is concentrated so oncotic pressure is high and water flow into capillaries from tissues
