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Lecture 7: Blood Lecture 8: Cardiac Muscle
Plasma
55% portion of the blood. Plasma is made up of Water, ions, organic molecules, trace elements, and gases
Hematocrit
The percentage by volume of red cells in your blood.
normal: 45%
anemia: 30%
polycythemia: 70%
dehydration: 70%
Hematocrit of 30% indicates…
Anemia
Hematocrit of 70% indicates…
polycythemia or dehydration
Universal Donor
To be a universal donor means that your blood lacks A & B antigens, so all blood types that contain A and B antibodies will not agglutinate.
Type O is the universal donor
Dissolved gases
including oxygen (O2), carbon dioxide (CO2), and nitrogen (N2), dissolved in the fluid fraction of blood
Buffy Coat
makes up <1% of the blood. consists of the platelets and white blood cells
Universal Recipient
Can receive all blood types. (type AB)
contains all antigens and no antibodies
Large Plasma Proteins
Albumins, Globulins, Fibrilinogen
Anemia
low red blood cell count from a low amount of iron in the body( usually indicated by a hematocrit of 30%)
low iron = low hemoglobin = low red blood cells = anemia
Chylomicron
Chylomicrons are large triglyceride-rich lipoproteins produced in enterocytes from dietary lipids
a droplet of fat present in the blood or lymph after absorption from the small intestine. Responsible for the transport of cholesterol and lipids from intestine (dietary) to liver via blood.
Small/Soluble blood components ie antibodies
Lymphocytes, Monocytes, Neutrophils, Eosinophils, Basophils
Polycythemia
a blood disorder occurring when there are too many red blood cells
is usually indicated by a hematocrit of 70%
LDL- low density lipoprotein
Low Density Lipoproteins transport cholesterol and lipids from liver to tissues throughout the body. (Too much is bad, because if you build up cholesterol and lipids in tissues, I.e. in arteries, this leads to plaque build-up and arteriosclerosis.)
Formed elements, AKA cellular elements in the blood
Red blood cells, white blood cells, platelets ( anything in the blood that isnt plasma)
Erythropoietin (EPO)
a glycoprotein hormone that is made in the kidney, that is responsible for stimulating red blood cells production.
HDL- high density lipoprotein
High density lipoprotein is known as the good cholesterol.
responsible for transporting excess cholesterol from tissues and delivers it to liver. (HDL = Healthy, excess cholesterol from tissues is properly disposed of or stored in the liver for future use.
RBC's (erythrocytes)
Red blood Cells. Their main function is to carry oxygen from the lungs and deliver it throughout our bodies. Hemoglobin protein is what allows for them to carry oxygen
Hemoglobin (Hb)
Protein found in red blood cells that allows for the carrying of oxygen. around 280 million Hb molecules in a rbc
One molecule of oxygen can bind to the iron atom of a heme group, giving each hemoglobin the maximum capacity to transport four oxygen molecules.
Platelets (thrombocytes)
Platelets, or thrombocytes, are small, colorless cell fragments in our blood that form clots and stop or prevent bleeding
Heme
an iron-containing compound of the porphyrin class which forms the nonprotein part of hemoglobin. there is 4 heme groups in one hemoglobin molecule.
WBC's (white blood cells/ leucocytes)
They circulate in the blood and mount inflammatory and cellular responses to injury or pathogens
Agglutinate/Agglutination
Agglutination, which refers to the clumping of particles together, is an antigen-antibody reaction that occurs when an antigen is mixed with its corresponding antibody at a suitable pH and temperature.
What does ESR stand for?
erythrocyte sedimentation rate (ESR)
what is an ESR used for?
measures how quickly red blood cells settle to the bottom of a test tube. a blood test that that can show if you have inflammation in your body. Inflammation is your immune system's response to injury, infection, and many types of conditions, including immune system disorders, certain cancers, and blood disorders. Erythrocytes are red blood cells.
Problems associated with iron deficiency anemia
not enough iron in the body to manufacture RBC’s
Problems associated with iron aplastic anemia
failure of bone marrow to produce RBC’s correctly
Problems associated with iron sickle cell anemia
a genetic defect that causes Hb in the cells during low oxygen conditions (such as in the capillaries when exercising) to bind together, forming crystalline spikes which rupture the cell membrane.
Problems associated with iron pernicious anemia
lack of vitamin B12
Can ESR be used to diagnose disease?
no, but it can be a good indicator of infection or inflammation
How long do mature RBC's survive?
around 120 days
How does the body replace them? What organ is responsible for this? What hormone is involved?
the hormone erythroprotein (made in the kidney) will send a signal to the stem cells that were made in the bone marrow to make more rbc
What is hemoglobin? Where is it found? How does hemoglobin help RBC's carry oxygen to tissues? What is essential for this function?
Hemoglobin is a protein found in the red blood cells, there is about 180 million hemoglobin in each rbc and within each Hb there is 4 heme groups. Within these heme groups, there is an iron unit which allows for the attachment of oxygen . By binding oxygen to this iron, it allows for the rbc to deliver oxygen from the lungs to the tissues in the body.
explain blood typing
the study of blood types and how their antigen-antibody interactions will effect one another
There are 4 main blood groups defined by the ABO system: blood group A – has A antigens on the red blood cells with anti-B antibodies in the plasma. blood group B – has B antigens with anti-A antibodies in the plasma. blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma.
How do we determine blood type?
Your blood sample is mixed with antibodies against type A and B blood. Then, the sample is checked to see whether or not the blood cells stick together.
Does the blood type refer to the antigens on the cell surfaces or the antibodies found in the plasma?
antigens on the surface of the cells! the antibodies in the plasma is what prevents other blood types from being able to mix
Why does cholesterol pose a special problem for transport in our circulation?
because cholesterol is water soluble, it needs to be wrapped in protein packages (lipoproteins) to travel in the blood from the liver
How do our bodies transport cholesterol (along with some triglycerides and phospholipids).
lipoproteins. the liver makes low density lipoproteins that can bind to any cell besides the liver. these are sent out into the circulatory system and any cells that needs come cholesterol can take it
What is the major organ responsible for synthesizing cholesterol for our bodies?
liver
What do the terms chylomicron, HDL & LDL refer to? Which is the "good" lipoprotein? Why?
chylomicron, HDL, and LDL are all lipoproteins, resposible for transporting cholesterol throughout the body.
the good guy is HDL, because it has the ability to absorb cholesterol in the blood and takes it back tot he liver, who then flushes it out.
Intercalated discs
where cardiac muscle cells are joined together. Intercalated discs form an interlocking zigzag connection between the individual cardiac muscle.
Purkinje fibers
Purkinje fibers are specialized cardiac muscle fibers that conduct electrical impulses through the ventricles, coordinating their contraction for efficient blood pumping. They are larger and more branched than regular cardiac muscle cells.
Desmosomes
a type of cell junction. Desmosomes act as binders during contraction, supporting the filaments in adjoining cardiac cells to prevent separation.
Pacemaker potential
The pacemaker potential refers to the spontaneous depolarization of specialized cells in the heart, known as pacemaker cells. These cells generate electrical impulses that initiate the heartbeat. The pacemaker potential is characterized by a gradual increase in membrane potential until it reaches the threshold for an action potential, triggering the contraction of the heart muscle.
Pilocarpine
Pilocarpine is a natural alkaloid derived from the leaves of the Pilocarpus plant. It acts as a cholinergic agonist, specifically targeting muscarinic receptors in the body. While pilocarpine primarily affects the exocrine glands, such as salivary and lacrimal glands, it also has an indirect effect on the cardiac muscles. Pilocarpine stimulates the parasympathetic nervous system, leading to increased vagal tone and subsequent bradycardia (slowing of the heart rate). However, its direct effect on cardiac muscles is minimal compared to its impact on other organs.
Gap junctions
gap junctions are the tiny channels between the adjoining cardiac cells that allow for the rapid passage of ions from one cell to the next, resulting in depolarization “/” and contraction, which causes cardiac muscle cells to contract simultaneously.
Basically, gap junctions act as a bridge that allows for a quick passage of electrical signals that is gonna allow the heart to contract and pump in unison.
Cholinergic
Cholinergic refers to the activation or stimulation of the parasympathetic nervous system, specifically the release of the neurotransmitter acetylcholine. In terms of cardiac muscle, cholinergic stimulation leads to a decrease in heart rate and contractility. Acetylcholine binds to muscarinic receptors on the cardiac muscle cells, causing hyperpolarization and slowing down the electrical conduction through the heart, ultimately resulting in a decrease in heart rate.
Atropine
Atropine is a medication. It belongs to a class of drugs called anticholinergics. Atropine works by blocking the action of a acetylcholine in the body. It has various medical uses, including treating certain heart conditions, dilating the pupils during eye exams, and reducing secretions in the respiratory tract. Atropine can also be used as an antidote for certain types of poisoning.
Atropine has an overall effect on the heart by increasing the heart rate. It achieves this by blocking the inhibitory effects of the vagus nerve on the heart, leading to an increase in heart rate and cardiac output.
Syncitium
The syncytium of the heart refers to the coordinated contraction of cardiac muscle cells. It allows the heart to function as a single unit, pumping blood efficiently throughout the body. The cells in the heart are connected by gap junctions, allowing electrical signals to pass freely between them. This synchronization ensures that the chambers of the heart contract in a coordinated manner, enabling effective blood circulation.
Adrenergic
Adrenergic refers to the activation or stimulation of the sympathetic nervous system, which is responsible for the release of adrenaline (epinephrine) and noradrenaline (norepinephrine). Adrenergic receptors are found in various tissues and organs throughout the body and play a role in regulating functions such as heart rate, blood pressure, and smooth muscle contraction. Activation of adrenergic receptors can have a wide range of physiological effects, including increased heart rate, dilation of airways, and constriction of blood vessels.
HCN (hyperpolarization-activated cyclic-nucleotide channels)
Hyperpolarization-activated cyclic-nucleotide (HCN) channels are specialized proteins found in cell membranes, particularly in neurons and cardiac cells. These channels play a crucial role in regulating the electrical activity of cells. HCN channels are unique because they open in response to hyperpolarization, which is a shift in the cell's membrane potential towards a more negative value. When these channels open, they allow the flow of positively charged ions, such as potassium and sodium, into the cell, leading to depolarization and the generation of electrical signals. This process is important for various physiological functions, including the control of heart rate and the transmission of signals in the nervous system.
Myogenic
Myogenic refers to the ability of certain cells or tissues to generate their own electrical impulses within the muscle without external stimulation from the nerves
Agonist
An agonist is a drug that binds to the receptor, producing a similar response to the intended chemical and receptor
Norepinephrine (NE)
Norepinephrine (NE) is a neurotransmitter and hormone that plays a crucial role in the body's stress response and regulation of blood pressure. It is produced by the adrenal glands and certain neurons in the brain. It plays an important role in your body's “fight-or-flight” response. As a medication, norepinephrine is used to increase and maintain blood pressure in limited, short-term serious health situations. functions by binding to adrenergic receptors, which are found throughout the body, and can have various effects depending on the specific receptor subtype activated. It is involved in increasing heart rate, constricting blood vessels, and mobilizing energy resources in times of stress or danger. In the brain, norepinephrine is involved in mood regulation, attention, and arousal.
SA node
The SA node, also known as the sinoatrial node, is a small cluster of specialized cells located in the right atrium of the heart. It acts as the natural pacemaker of the heart, initiating and regulating the electrical impulses that coordinate the heart's contractions.
Overall, the SA node plays a crucial role in maintaining the regular rhythm and proper functioning of the heart.
Antagonist
antagonist is a drug that binds to the receptor either on the primary site, or on another site, which all together stops the receptor from producing a response.
Acetylcholine (ACh)
Acetylcholine (ACh) is a neurotransmitter that plays a crucial role in the nervous system. It is involved in transmitting signals between nerve cells and muscle cells, including cardiac muscles. In the context of cardiac muscles, ACh acts to slow down the heart rate by binding to specific receptors called muscarinic receptors. This binding leads to a decrease in the electrical activity of the heart, resulting in a decrease in heart rate.
Sinus venosus
The sinus venosus is a small chamber in the hearts of certain animals like fish and amphibians. It is positioned near the heart's entrance and functions as a collection area for oxygen-depleted blood coming back from the body.
In fish, the sinus venosus receives blood from the veins and sends it to the atrium.
In amphibians, it acts as a pacemaker, starting the heart's contraction.
Autorhythmicity
Contractions of the heart (heartbeats) are controlled by specialized cardiac muscle cells called pacemaker cells that directly control heart rate. This property is known as autorhythmicity.
Internodal fibers/pathway
Internodal fibers/pathway refer to specialized cardiac muscle fibers that conduct electrical impulses between the atria and the ventricles of the heart. They help in coordinating the contraction and relaxation of the heart chambers, ensuring efficient blood pumping.
Vagus nerve
The vagus nerve, also known as the vagal nerves, are the main nerves of your parasympathetic nervous system. This system controls specific body functions such as your digestion, heart rate and immune system. These functions are involuntary, meaning you can't consciously control them.
PVC (Pre-Ventricular Contraction)
are extra heartbeats that begin in one of the heart's two lower pumping chambers (ventricles). These extra beats disrupt the regular heart rhythm, sometimes causing a sensation of a fluttering or a skipped beat in the chest.
AV node
atrialventricular node. similar in function to the SA node in terms of automatically generating impulses, located between the atria and ventricles
Plateau phase
Phase 2, a plateau phase, is the longest phase. It is unique among excitable cells and marks the phase of calcium entry into the cell.
Bundle of His
The Bundle of His, also known as the atrioventricular bundle, is a specialized group of cardiac muscle fibers located in the heart. It plays a crucial role in the conduction system of the heart. The Bundle of His transmits electrical impulses from the atria to the ventricles, coordinating the contraction and relaxation of the heart chambers. This ensures an efficient pumping of blood throughout the body.
Epinephrine (EPI)
Epinephrine (EPI), also known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands. It plays a crucial role in the body's response to stress and emergency situations. Epinephrine acts on various receptors in the body, including alpha and beta adrenergic receptors, to increase heart rate, constrict blood vessels, dilate airways, and mobilize energy stores. It is commonly used in medical settings to treat severe allergic reactions (anaphylaxis), cardiac arrest, and asthma attacks.
What is similar/different between skeletal muscle and cardiac muscle?
While skeletal muscle consists of parallel linear fibers, the cardiac muscle cells (cardiomyocytes) are arranged in fibers exhibiting cross-striations formed by alternating segments of thick and thin protein filaments
What are the functions of the desmosomes and gap junctions?
desmosomes help prevent separation between muscle cells and gap junctions are the little channels alone the meeting points of the muscle cells that allow for the quick passage of ions through one another.
What in general is the profile and time frame of: cardiac pacemaker cells, cardiac contracting cells?
Cardiac pacemaker cells are special cells in the heart that create electrical signals to start the heartbeat. They can spontaneously generate action potentials because they have automaticity. These cells depolarize at a slower rate compared to other heart cells.
On the other hand, cardiac contracting cells are responsible for the heart's mechanical contraction. They can generate force and pump blood because they have contractility. These cells depolarize at a faster rate compared to pacemaker cells.
Pacemaker cells set the pace for the heart's electrical activity over a longer time frame. Contracting cells, on the other hand, contract and relax to pump blood throughout the body over a shorter time frame.
What is a pacemaker potential? What causes a pacemaker potential?
A pacemaker potential is the spontaneous depolarization of specialized cells, such as those in the sinoatrial (SA) node of the heart. It is responsible for initiating the electrical impulses that regulate the heart's rhythm. The pacemaker potential is caused by a combination of slow influx of sodium ions (Na+) and efflux of potassium ions (K+), as well as the activity of funny channels (HCN channels) that allow the influx of sodium and potassium ions. This unique combination of ion movements leads to the gradual depolarization of the cell, eventually reaching the threshold for an action potential and initiating the heartbeat.
Why can't cardiac myocytes summate?
Cardiac myocytes cannot summate because they have a long refractory period. This refractory period prevents the myocytes from being stimulated again until they have fully repolarized. As a result, the individual contractions of cardiac myocytes cannot be added together to produce a summation of force like in skeletal muscle. This is important for the coordinated and rhythmic contraction of the heart to ensure efficient pumping of blood.
What is the ANS? How many divisions are there and what are they? What do they mediate (type of response)?
ANS is the Autonomic Nervous System and it is divided into two things: The sympathetic nervous system and the Parasympathetic nervous system. Sympathetic - “Fight or Flight” NT = NE, EPI Speeds up heart
Parasympathetic -“Rest/Relaxation” Vagus, Cranial Nerve X. NT = ACh… Slows heart
Briefly describe the ANS anatomically.
Sympathetic is located in the greater splanchnic nerves (T1-L2). Superior mesenteric ganglion, The entire sympathetic system can be activated simultaneously because of the sympathetic chain ganglion which goes all the way down the entire sympathetic nerve system
whereas the parasympathetic is located primarily in the midbrain/hindbrain (Cranial nerves) and S2-S4 (pelvic nerves). Inferior mesenteric ganglion
What neurotransmitters (NT) are used by the ANS?
Both divisions use ACh (acetylcholine) however, the PNS release ACh primarily called cholinergic synapses. SNS releases Norepi (noradrenaline) called adrenergic synapses
Where is EPI from?
adrenal glands
What is the function of EPI?
EPI stimulates the opening of the pacemaker HCN channels, which depolarizes the SA node faster. Increasing heart rate.
How does the ANS affect heart rate?
Symp system: releases NE and EPI, which stimulate the opening of HCN channels of the pacemakers. This ultimately leads to a faster depolarization and a higher HR.
shortens pause at AV node
increases contractility of cells, which increases strength of contraction of heart
Para system: releases Ach which promotes opening of K + channels. This exflux of K counters the influx of Na and causes depolarization to slow down
Decreases depolarization of SA node
Lengthens pause at AV node.
Decreases atrial cell contractility, but does not seem to affect ventricle contractility.
Why is it important for the ANS to regulat the HR?
Without neuronal influences, SA node will drive heart at rate of its spontaneous activity = autorhythmicity
Autonomic innervation of SA node is main controller of HR
Symp & Parasymp nerve fibers modify rate of spontaneous depolarization
Sympathetic endings in atria & ventricles also stimulate increased strength of contraction
ECG what is it? What is it not?
ECG is an Electrocardiogram and shows us the electrical signals coming from the heart. IT IS NOT AN ACTION POTENTIAL
order of the ECG reading
P-wave, QRS complex, T wave
What does the P-wave show?
atrial depolarization
what does the P-R segment show?
AV nodal delay
what does the QRS complex show?
Ventricular depolarization and atria repolarization simultaneously
What does the S-T segment show?
when ventricles are contracting and emptying (straight line)
what does the T wave show?
ventricular repolarization
T-P segment
time when ventricles are relaxing and filling
Cardiac Output (CO)
Cardiac output (CO) is the volume of blood pumped out by each ventricle per minute. DIRECTLY RELATED TO HR AND STROKE VOLUME
Isovolumetric relaxation
When the ventricular pressures drop below the diastolic aortic and pulmonary pressures (80 mmHg and 10 mmHg respectively), the aortic and pulmonary valves close producing the second heart sound.
START OF DIASTOLE
Ventricular ejection
Ventricular ejection refers to the phase of the cardiac cycle where the ventricles of the heart contract and pump blood out into the arteries. During this phase, the blood is forcefully ejected from the ventricles into the aorta (left ventricle) and pulmonary artery (right ventricle). It is an essential process for maintaining blood circulation throughout the body.
Stroke volume (SV)
the amount of blood pumped by each ventricle with each heartbeat
averaging 70ml per beat @ rest for an adult
Poiseuille's Law
describes factors effecting blood flow
blood flow (Q) = (deltaP * r^4) / (8 L n)
P is blood pressure, r is vessel radius, L is vessel length, and n is blood viscosity
Pulmonary artery
takes blood from the right ventricle to the lungs (with help of pulmonary valve)
Vascular resistance
Determines how much blood flows through a tissue or organ
– Vasodilation decreases resistance, increases blood flow
– Vasoconstriction does opposite
End systolic volume (ESV)
End systolic volume (ESV) refers to the amount of blood remaining in the ventricle at the end of systole, or the contraction phase of the cardiac cycle. It represents the lowest volume of blood in the ventricle during the cardiac cycle and is an important parameter in assessing cardiac function.
ESV is typically measured in milliliters (mL) and can be determined using various imaging techniques such as echocardiography or cardiac MRI.
Pulmonary vein
brings blood back to the heart from the lungs and into the left atrium
Mean arterial pressure (MAP)
it is the difference between the arterial and the venous pressure that drives blood through the capillary beds of our organs.
Myocardium
muscular tissue of the heart
Frank-Starling law of the heart
The Frank-Starling law of the heart states that the force of contraction of the heart is directly proportional to the initial length of the cardiac muscle fibers. In simpler terms, it means that the more the heart muscle fibers are stretched during rest, the stronger the contraction will be. This law is significant because it ensures that the heart pumps an adequate amount of blood to meet the body's demands. It allows the heart to adjust its output based on the volume of blood returning to it, ensuring efficient circulation and maintaining cardiac output.
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