Questions Flashcards
What does the cardiovascular system consist of? (3 answers)
-what
- main role:
- function
- blood (moving blood around the body)
- main role: transport substances
- the substance transported in vessels via blood
Blood roles (3 answers)
Transport: nutrients, dissolves gases, hormones, wastes
Regulation (homeostasis): pH, ions, water, temp.
Defence: It fights against fluid loss, pathogens, and toxins
What is special about blood? (3 answers)
- specialized connective tissue
- contains plasma (aqueous matrix)
- contains cells and platelets
Blood is a fluid connective tissue containing what? (3 answer)
- Cells: RBCs and WBCs (platelets)
- Extracellular matrix: plasma
- Extracellular protein: plasma protein
what is the ratio of blood? (remember!)
Red blood cells (45%)
Plasma(55% - range 46%-63%)
-> plasma protein (7%):
-> Albumins: transport and fluid balance
-> Globulins: immune and transport
-> Fibrinogen: clotting
-> Enzymes and hormones
-> Other Solutes (1%)
-> Electrolytes
-> Organic nutrients
-> Organic wastes
-> Water (92%)
What do the non-protein components of plasma do?
- constantly circulate and mix w/ other extracellular fluid
- in more tissues, h20 and small solutes can move freely from blood vessels into the interstitial fluid (ISF) between cells
Hemostasis (3 phases and notes under each)
- Vascular Phase
-> rapid change to cells in the blood cells in the blood vessel wall
- 1. contraction (vascular spasm)
- 2. Increases endothelial ‘stickiness’
-> exposes connective tissue and basement layer to the blood
-> The vascular and platelet phases are collectively (also known as ‘primary hemostasis’) - Platelet Phase
-> Platelets aggregate at the exposed endothelial surface plus the broken vessel
-> Platelets attach to the stick endothelial cells and basement membranes and become activated
-> Activated platelets change shape and release chemicals that attract other platelets & help them stick to each other - Coagulation Phase
-> A fibrin mesh network forms around platelets, producing a clot
-> The ultimate effect of coagulation (2nd hemostasis) is to create stands of insoluble fibrin
-> a protein which binds aggregated platelets (and blood cells) into clots
A positive feedback loop (related to the circulatory system)
- the accumulation and aggregation of platelets = pos feedback loo
IMPORTANT
- the only phase of blood clotting that is a pos feedback loop is the platelets phase
- the interaction between activated platelets and chemicals that attract more platelets
More about Coagulation phases (and notes) (2 steps total)
- involved a cascade of enzymes that catalyze the formation of fibrin from solvable fibrinogen
-> Coagulation is triggered by tissue damage or exposed connective tissue
-> It take at least 30 sec after bessel damage to begin and involves many enzymes - Involved many clotting factors: enzymes that are linked in a complex cascade that produces fibrin
After the vessel wall is repaired, what happens?
As the clot forms, repair of the blood vessel begins. When the wall is repaired the fibrin will be cleaves and thus the clot dissolves
Steps of Fibrinolysis (3 steps)
- tissue plasminogen activator (t-PA) is released from the repaired vessel wall
- t-PA convert plasminogen) plasma protein to plasmin
- Plasmin degrades fibrin
What produces blood cells and platelets
red bone marrow = found in the space around the spongy bone
What are the 2 main potent lineages that come from hematopoietic stem cells?
lymphoid and myeloid
what is the lifespan of a typical RBC?
What happens to the dead RBC?
- around 4 months
- is recycled into new RBCs and/ or excreted
How does blood flow through vessels?
- they flow through based on differences in pressure
- contractions of the heart create a pressure gradient that drives blood movements
- as a fluid, blood moves (flow from areas of high -> low pressure)
Blood flow direction…
heart-> arteries-> capillaries -> veins
- this is true for both systemic and pulmonary circuits
- but there is an exception: portal veins (sends blood to liver rather than veins)
Are the pulmonary and systemic circuits connected?
they are not directly connected, except through the heart
what is the function of smooth muscle in the vessel walls?
- they allow arteries and veins to change their diameter, altering blood flow
- they respond to the ANS and to different hormones
How does the blood flow in the circulatory system
-systemic veins empty into…
- pulmonary veins empty into…
- blood flow from each atrium into the corresponding ventricles, and from ventricles into arteries
- systemic veins empty into the right atrium
- pulmonary veins empty into the left atrium
- when the ventricle contracts, blood only flows into the arteries, NOT back into the atria
What is the function of the heart tissue?
Who is its supplier?
Supplier:
- is supplied w/ blood through a separate (coronary) blood supply
- has high metabolic demands, thus requires it own arteries and veins (not blood sitting inside its chambers)
What must happen in order for the heart to contract?
- cardiac myocytes must be (electrically) excited in order to contract
what do cardiac muscle cells lack?
NMJs; instead, excitation is myotonic
Anatomy of the heart (2 points)
- the right ventricle has a thinner wall than the left
- the greater vessels of the systemic circuit are larger and thicker than those of the pulmonary circuit
What happens at a resting heart rate?
- full diastole
- both sets of chambers being relaxed
- lasts for about half the duration of each cardiac cycle
- pressure changes in heart chambers and arteries carry predictably across a single cardiac cycle
What is the difference between cardiac and skeletal muscle cells? (3 points)
- Cardiomyocytes usually only have a single central nucleus, and branched structures, and are about 0.2 mm long
- they have the same organelles but they may be indifferent locations (ex: nucleus)
- there is no NMJ in cardiac myocytes
What is the difference between myofibres and cardiac myocytes?
- ## cardiac myocytes have reduced T-tubules and sarcoplasmic reticulum and lack specialized neuromuscular junction
which action potential is faster skeletal myofibres or cardiac myocytes?
- cardiac myocytes (prolonged plateau of depolarization) are slower and last about 200x longer than skeletal myofibres APs
what does the contraction cycle in cardiac myocytes involve? (2 points)
- steps for calcium-induced calcium release (2 points)
- interactions between sliding filaments, similar to myofibres
- once Ca+2 is present, the interaction cycle in cardiac myocytes closely resembles what occurs in a skeletal myofibre (involves calcium-induced calcium release)
Steps
1. some calcium ions enter the cytoplasm from the ECF
2. the elevated (CA+2) triggers the release of more calcium from cellular stores (the SR)
what is the difference between skeletal muscle cells and cardiac muscle cells (in regards to EC coupling)
(6 points total -> 3 each)
Skeletal muscle cell: Mechanical coupling
- no ion flow through DHPR (dihydropyridine receptor)
- DHPR pulls open the RyR (Ryanodine receptor)
Cardiac muscle cells: biochemical coupling
- calcium floes through DHPR into the cytosol
- concentration of calcium increases = opens the RyR
What happens from depolarization from SA node (2 points)
- spreads through the atrial myocardium and the conduction pathway
- SA node cells are electrically coupled to cardiac myocytes, and to the conducting cells of the intermodal fibres, = depolarization to rapidly spread across both atria
what are the conduction pathways cells specialized for?
- for rapid electrical conduction; they can conduct APs up to several meters per sec
When is depolarization faster, conduction system or cardiac myocytes?
conduction system
How in the Purkinje fibres involved in depolarization?
- the depolarization travels rapidly through the interventricular bundle to the Purkinje fibres, then back up the ventricle wall
- the Purkinje fibres will be excited (and contracted) before the base
- this allows for efficient emptying into the arteries
What does the cardiac cycle describe?
- the sequences of contraction and relaxation of the heart chambers
- a cardiac cycle is one heartbeat and its relaxation period
What is the resting heart rate (Hr) of the entire cardiac cycle?
800ms -> represented by about 75 beats per min (bpm)
Heart and valves, what pressure makes the heart?
Relaxation=
Contraction=
Relaxation= low pressure (valves closed)
Contraction= high pressure (valve open)
think of a pipe with a lid at the end
What does the cardiac cycle generate and what does that lead to?
The cardiac cycle generates pressure to produce cardiac output (blood flow into and through the blood vessels)
What does the pressure in the heart drive out and into what?
It drives blood out of the heart and into the systemic and pulmonary circuits
What is the cardiac output (CO) formula?
- include units for each element
CO = SV x HR = mL/min
SV = stroke volume (mL/beat)
HR= heart rate (bpm)
Where does the cardiac cycle end (and begins)?
What else happens during this time?
- The ventricular and atrial diastole, when the passive filling of the ventricles occurring
- During this time, blood returning form the veins can flow through the atria and into the ventricles
What happens during End Diastolic Volume (EDV) (2 points)
- atrial systole completes the filling of the ventricles, which reach their End Diastolic Volume (EDV)
- during this time, blood is squeezed from the atria to the ventricles and the ventricles achieve their maximum volume (End Diastolic Volume)
What is the End Diastolic Volume (EDV) affected by
venous return and by ventricular filling time
What initiates afterload?
is directly affected by resistance (pressure) in the blood vessel
When do semilunar valves open?
they ONLY open when the ventricular pressure exceeds the pressure in its artery (pulmonary or aorta)
If arterial pressure increases what happens to afterload?
the afterload of that side of the heart increases
What happens if valve opening is delayed?
the time for ventricular ejection is reduced
What happens when less blood is released at SV?
thus more remains as ESV
What does NE or E signalling use?
they use receptors created by biochem signals that enhance multiple parts of cardiac excitation-contraction coupling, increasing the tension produced for each excitation (AP)
What happens to cardiac output during exercise?
- skeletal muscle uses more oxygen and nutrients from systemic blood circulations
- skeletal muscles produce more waste products (and heat)
- thermal homeostasis needs to be maintained by radiating heat away at the dermis
What happens when contractility is enhanced?
= a higher stroke volume is produced for the same EDV
- proportional to the intensity of the exercise
What happens to the sympathetic activity and epinephrine section during exercise?
they both increase
- epinephrine secretion is from the adrenal medulla
What affects stroke volume?
muscle activity, vessel blood flow patterns, sympathetic activity and hormones
As Hr (heart rate) increases what happens to diastole?
- what could also be affected due to Hr increase
the % of time spent in diastole drops
- the loss of filling time only slightly reduced EDV, bc/ most passive filling happens very early in diastole
What can aerobic training lead to in regard to your health? (3 points)
- increase stroke volume due to both physiological and structural changes
- can elevate cardiac output regularly for prolonged periods of time
- induces hypertrophy of cardiac myocytes, adding sarcomeres in a way that increases the volume of the ventricles
List the type of blood vessel walls and their difference (10 points)
- 3 options
Categories: - Lumen Diameter:
- Smooth Muscle Layer:
- Endothelial Layer:
- Tunics (tissue layer):
- Arteries
- Lumen Diameter: intermediate
- Smooth Muscle Layer: thick
- Endothelial Layer: tight
- Tunics (tissue layer): 3 - Capillaries
- Lumen Diameter: Smallest
- Smooth Muscle Layer: Absent
- Endothelial Layer: Leaky (gaps)
- Tunics (tissue layer): 1 - Veins
- Lumen Diameter: Largest
- Smooth Muscle Layer: Thin
- Endothelial Layer: Tight
- Tunics (tissue layer): 3
Larger pressure gradient =?
more force
what slows down the velocity of liquid and thus volume flow rate?
resistance (caused friction between the walls of the tube and the fluid)
The longer the vessel =?
more surface that is in contact w/ the blood -> thus more friction that blood will encounter
Vessel luminal diameter is inversely and proportional to?
- inversely to resistance
- proportional, more of the blood inside a small diameter vessel will be in contact w/ or near the vessel wall (source of most friction)
What will happen in the change in vessel diameter and explain why?
will always produce a larger change in resistance than an equivalent change in length this is bc/ the resistance associated w/ diameter is proportional to the radius
When the liquid is more viscous =?
its molecules (and materials suspended within it) interact w/ each other, causing internal friction which slows down the overall flow
how is Venule involved with the connection of…?
- what do they lack?
venules connect capillary beds to veins
- they lack tunica media
What do arterioles have but also lack?
have tunica media but lack a true tunica externa
When is arterial pressure highest and lowest?
highest during and just after ventricular systole
- lowest during diastole
Blood pressure is reported as?
Systolic Pressure/ Diastolic Pressure
The pressure drop-off is largest through?
arterioles= that these vessels provide the highest total resistance to volume flow
Blood pressure reduces each time when?
blood flow must overcome resistance from a vessel
- therefore, the more vessels are from the ventricles (the source of the pressure gradient), the lower the average pressure w/ in them
Where is the cross-sectional area of all blood vessels highest in? and lowest in?
highest in capillaries and lowest in elastic arteries
Factors affecting blood flow through circuits and factors affecting cardiac output are interrelated. There are 4
- Cardiac output affects pressure
- Pressures affect blood flow
- Blood flow affects venous return
- Venous return affects cardiac output
The relationship between arteries, veins and gravity
Arteries
- supply blood to the head must generate enough pressure to push blood directly against the force of gravity, as well as against vascular resistance
- supply blood to regions below the heart get an assist from the force of gravity
Veins
- the limbs contain valves to help prevent backflow of blood due to gravity
How does skeletal muscle work w/ valves?
- they work together to provide a secondary pump that helps propel blood toward the heart
- muscles contracting around the vein compress the vein, providing extra pressure which helps squeeze blood upward toward the heart, countering the force of gravity
Capillary Exchange
- definition
- 3 components
- it’s the bidirectional movements of substance into or out of the blood from body tissues
3 components to capillary exchange
1. Diffusion
2. Filtration
3. Osmosis
Near an arteriole there is…
- pos NFP, favouring filtration
- BCOP is a constant value; related to the concentration of colloidal (large suspended) particles in plasma
- CHP is initially (relatively) high in the proximal part of the capillary, as blood enters from the arteriole
- CHP > BCOP = +ve NFP, meaning a pressure gradient that favours fluid movement into the ISF
Filtration step
- occurs along a capillary, CHP will decreased but BCOP will not change
- near the middle of the capillary bed, the 2 forces are balanced
- CHP = BCOP = 0 NFP
- no more fluid moves into the ISF ( through solute diffusion does still occur)
- CHP is reduced if filtration has already occurred bc/ of resistance, and also bc/ there is less fluid removing inside the capillary
- BCOP remains the same (all the larger particles are still present in plasma)
Near a venule
- there is a neg NFP, favouring reabsorption
- CHP decreasing further (still slowed by resistance)
- CHP < BCOP = -ve NFP
- meaning a pressure gradient that favours fluid movement from ISF back to plasma
What are the blood pressure (effectors for short-term alterations)?
- the heart and the blood vessel walls
What does the cardiac centres in the medulla oblongata dive change?
- they change the cardiac output by altering activity in ANS inputs to the SA node of the heart and the myocardium
How do vasomotor centres initiate change in blood vessel diameter (in both arteries and veins)?
by altering activity in sympathetic vasomotor fibres
What happens during increased metabolic demands?
- forms peripheral tissues can lead to changes in the overall chem composition of blood in the systemic circuit
- chem changes from globally elevated metabolic demands (or metabolic demands> current levels of Cardiac output)
- decrease PO2
- Increase PCO2
- Decrease pH
When is blood pressure (BP) homeostasis and allostasis
Homeostasis: when BP is disturbed, BP is restored to set point
Allostasis: when blood chem is disturbed, BP is moved to a new set point
what are the mechanisms we’ve seen so far not ideal for long-term regulation?
1) energy intensive
2) maintain central pressure
What need to be regulated/ changes in order to maintain BP?
- involves changes in blood volume
- to maintain oxygen delivery at normal rates, blood volume changes must involve changes to both plasma and RBC levels
- adjustment to blood volume are slow, but they can maintain BP throughout the circulatory system without constant energy input
What is the response to long-term low blood pressure? (4 p)
- is organized by 2 hormones secreted by the kidneys
Hormones:
-> renin: leads to increased plasma volume
-> erythropoietin (EPO): drives RBC production
- low BP or blood volume leads to lower levels of perfusion through kidney tissue, stimulating the release of 2 hormones
What is the long-term response to high blood pressure? (4p)
- ANP
- BNP
- is organized by 2 hormones secreted by heart muscle
- high BP ( or blood volume) leads to increased stretching in heart chamber walls, which leads to the release of natriuretic peptides (ANP and BNP)
ANP: atrial natriuretic peptide (released by the atria)
BNP: brain natriuretic peptide (released by the ventricles)
What happens during the major loss of blood? (3p)
- Blood volume changes through normal physiological mechanisms are usually slow
- but, if blood vessels (especially large ones) are damaged, causing hemorrhage, blood volume can decrease rapidly
- the body goes into survival mode
What is the short-term response to blood loss?
- involve natural reflexes and the physiological stress response
- systemic veins can hold large volumes of blood
- reducing the diameter of medium and large veins by vasoconstriction can return a large amount of blood from these ‘venous blood reservoirs’ without affecting perfusion
what can epinephrin and other hormones lead to?
can also lead to vasoconstriction or dilation
-> Whether a hormone causes vasoconstriction or vasodilation in a particular blood vessel relates to the type of intracellular biochem triggered by its receptors
What happens during active hyperemia?
(4p)
-Hyperemia: an excess of blood in the vessels supplying an organ or other part of the body.
- in skeletal muscle during exercise, intrinsic mechanisms override extrinsic regulation, leading to active hyperemia
- exercise/ active hyperemia: despite sympathetic activity increases during exercise promoting vasoconstriction (α1 receptors), blood flow is still greatly increased to skeletal muscles during exercise
- this is due to direct metabolic autoregulation
- Intrinsic regulation > Extrinsic regulation
What happens during exercise hyperemia? (4p)
- coronary arteries indirectly driven by intrinsic factors
- Adenosine (paracrine factor release when ATP is used) - a key driver of vasodilation in coronary arterioles (ex: indirect metabolic autoregulation)
- coronary blood vessels that supply heart muscle also exhibit vasodilation during exercise
What happens during skin arterioles? (4p)
- changes in constriction of skin arterioles change the proportion of blood flow through deep vs. superficial veins
- superficial veins collect blood from skin
- if there is superficial vasoconstriction, blood returns only through deep veins, maintaining core body heat (when body temp or blood volume are low)
What regulates blood flow through blood vessels in the skin
CNS to help maintain thermal homeostasis
How does blood flow help with getting rid of excess heat?
- since the skin is not metabolically active during exercise, blood flow increases to the skin to help lose excess heat generated by skeletal muscle
What happens during erectile tissue?
- it undergoes vasodilation driven by activity in sacral parasympathetic fibres which release NO
- Parasympathetic postganglionic neurons that innervate reactive tissue release NO (instead of or in addition to ACh)
- NO leads to smooth muscle relaxation, allowing the large spaces within erectile tissue to fill with blood
