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Unit 3 Physiology
Terms in this set (69)
What makes up the cardiovascular system
Heart, blood, blood vessels
What makes up blood
Red blood cells, white blood cells, platelets and plasma containing dissolved molecules, ions and proteins.
Blood plasma is the liquid portion of the blood making up 55% of blood volume. It is the liquid part left after centrifuging a blood sample and contains ions, proteins, and other fine, dissolved substances. The larger blood cells move to the bottom as a pellet, while the plasma remains at the top (supernatant)
Percent of the blood volume occupied by Red Blood Cells
Functions of blood
Transport Oxygen from lungs to cells and CO2 from cells to lungs for exhalation
Regulates pH (through blood buffers), temperature, and osmotic potential of cells
Protection - clotting, WBCs and antibodies function in immune system
Anemia is the term for a lower than normal number of normal, healthy red blood cells (and only indirectly indicates oxygen carrying capacity of the blood)
Where blood cells are formed
Red Bone Marrow
How blood cells are formed
They are formed from pluripotent stem cells in the marrow. These stem cells are only a very small percentage of all cells present in the bone marrow. These stem cells can differentiate into different types of blood cells (red blood cells, white blood cells, and platelets). If not carefully monitored, radiation can kill these stem cells which may result in the need for a bone marrow transplant
Hemoglobin and some properties of hemoglobin
Hemoglobin is a protein carried by red blood cells. It binds Oxygen tightly and is responsible for carrying Oxygen to cells for cellular respiration, and for carrying carbon dioxide away from the cells to be exhaled. There are 4 heme molecules per hemoglobin which are responsible for the oxygen binding properties of hemoglobin. Each of these contains iron at its core which is why iron is important for proper utilization of oxygen.
Red Blood Cell nucleus
No nucleus in RBCs. The nucleus is lost following production to leave more space for oxygen transport (more hemoglobin). For this reason, they can't repair themselves and have an average lifespan of ~120 days
Function of White Blood Cells
They can live months or years and are involved in immune responses. When sick, the number of WBC's may increase substantially
White Blood Cells different vs. Red Blood Cells
WBCs (leukocytes) have a nucleus and no hemoglobin.
Fragments of larger precursor cells and therefore do not have a nucleus- aid in blood clotting by forming a plug.
Understand which blood type is the universal donor and which blood type is the universal acceptor. Know which blood type can be accepted by a person with a different blood type.
-Type 'A' blood has a protein sticking out of it called the A antigen (an antigen is something the immune system recognizes and attacks - if you are blood type 'A', your body will see that antigen as friendly and not attack it)
-Type 'B' blood has the B antigen
-Type 'AB' blood as both
-Type 'O' blood has neither
(If you have A blood, your body wouldn't recognize the B antigen and would attack it. Same for B blood with the A antigen. O blood would attack both A and B (and AB) blood)
-Rh is an antigen that is either there (Rh+) or isn't there (Rh-). "A+ blood" means the blood cell contains the 'A' antigen and the Rh antigen.
Why Rh factor is important in a mother with Rh- blood.
Rh is an antigen so a blood cell with the Rh antigen (Rh positive) would be recognized and attacked by the immune system of an Rh negative recipient. If blood from Rh+ fetus contacts Rh-mother during birth, anti-Rh antibodies are then made by the mother. The effect is on the second Rh+ baby.
Vasoconstriction and vasodilation
Only arteries, arterioles and veins have smooth muscle to control vessel diameter to regulate overall blood pressure. Capillaries and venules have no smooth muscle tissue so they are not capable of vaso-dilation/constriction. Arterioles control blood flow into the capillaries which can control fluid buildup in the extracellular space (edema or swelling)
Gas exchange both inside (cells) and outside (lungs)
Capillaries. Capillaries have the thinnest cell walls and the lowest blood flow rate of all vessel types.
Receives blood from the body via 3 veins (superior vena cava, inferior vena cava, coronary sinus)
-it is deoxygenated
-goes through Tricuspid Valve to the Right Ventricle
most of the front (anterior) surface of the heart - Pumps blood to the lungs
-it is deoxygenated
-goes through the Pulmonary Arteries to the Lungs
Oxygenation in pulmonary capillaries
-it is oxygenated
-goes through the Pulmonary Vein to the Left Atrium
Receives blood from the lungs through 4 pulmonary veins
-it is oxygenated
-goes through the Bicuspid Valve to the Left Ventricle
Sends blood throughout the body - workhorse - larger, more powerful
Blood flows through the Aortic Valve to the Aorta
-it is oxygenated
Which chambers send blood where
The human heart has 4 chambers
-2 atria - top (superior) of the heart - send blood to their respective ventricles.
-2 ventricles - bottom (inferior) of heart - The left ventricle pumps blood to the body. The right ventricle pumps blood to the lungs.
New blood vessel development
The difference between Arteries and Veins
Arteries take blood away from the heart. Veins return blood to the heart
What causes the rhythmic beating of the heart?
The 4 pacemakers in the heart and in what order are they recruited
1st Pacemaker - 100Xs /min
Sinoatrial (SA) node - located in the right atrial node
Spontaneously depolarizes by leaking ions (like Sodium). When it reaches threshold, it triggers an action potential which travels along the atria toward the AV node
2nd Pacemaker - 40-60/min
Atrioventricular node (AV node) Located between the two atria
3rd Pacemaker -
Bundle of His - A.P conducts from the Atria to the Ventricles
4th Pacemaker - Purkinje Fibers
Conducts from the Apex of the heart throughout the Ventricles
Recording of the electrical signals generated by the heart
Waveforms on an electrocardiogram
P-wave is a small upward deflection - represents atrial depolarization
(Spreads from SA node throughout the atria)
QRS Complex - Large, upright, triangular wave flanked by two smaller downward waves - represents rapid ventricular depolarization - Atrial repolarization occurs here too but it is masked by the larger depolarization signal of the ventricles.
T-wave - small, wider upward deflection - represents ventricular repolarization
The role of calcium in cardiac muscle cells and the effect of calcium on contraction?
Voltage gated Calcium channels on the cell membrane open during an action potential which allows extracellular calcium into the cells. This offsets the repolarizing effect of potassium and keeps the cell in a depolarized state for a longer period of time. This has the effect of lengthening the refractory period which prevents the cell from depolarizing too quickly following the previous depolarization event
Atrial and Ventricular systole and diastole
Relationship of the cardiac cycle to the waveforms generated by an electrocardiogram
Atrial Systole - follows depolarization of the SA node
(Conduction slows at the AV node giving the atria time to contract)
Atrial diastole follows atrial repolarization
Ventricular Systole - begins shortly after QRS appears and continues through S-T segment
Ventricular diastole - begins shortly after the T-Wave begins
Sounds that can be heard with a stethoscope
The sounds that are heard with a stethoscope are caused by blood turbuluance associated with opening and closing of valves. Unobstructed blood flow does not make a sound
Lub - sound 1 - caused by blood turbulence associated with closure of the bicuspid and tricuspid (AV) valves
Dub - Sound 2 - caused by blood turbulence associated with closure of the semilunar valves
Cardiac Output is the volume of blood ejected from the left or right ventricles into the aorta or pulmonary trunk each minute (pulse X stroke volume)
Volume of blood ejected by the ventricle during each contraction
Maximum cardiac output minus cardiac output at rest (how much more blood your heart is capable of pumping compared to when it is at rest). It may change with the health of the heart. Severe heart disease patients have little or no reserve... their heart is working as hard as it can.
Control of heart rate
-Hormones - Epinephrine and Norepinephrine speed it up (sympathetic). Acetycholine slows it down (parasympathetic)
-Cations - elevated K+ and Na+ increases heart rate
Tachycardia and bradycardia
-Tachycardia - elevated resting heart rate
-Bradycardia - low resting heart rate
Pulse is strongest in the arteries, weaker in arterioles
-More highly branched vessels have lower blood flow volumes
-Flow in capillaries is <0.1 cm/second
-Flow in the aorta is 40 cm/second
The instrument used to measure blood pressure
Systolic and diastolic
-Systole - contraction phase of the cardiac cycle
-Diastole - relaxation phase of the cardiac cycle
How does squeezing the arm tell us anything about blood pressure? What are we looking at/for?
The pressure generated at systole causes the arteries to expand slightly. The amount of pressure required to block this expansion is determined by the amount of pressure being generated by the heart during systole. Applying the same pressure as systole will block blood flow and thereby the pulse beyond that point.
The pressure at diastole, or the relaxation phase, is the point at which the cuff is putting no additional pressure on the artery beyond its 'at-rest' pressure. Since no additional pressure is being applied, no turbulent blood flow is being caused and therefore no pulse sound can be heard.
Function of the lymphatic system
The lymph system scavenges extracelluar fluid and subsequently returns it to circulation. The lymph travels through a series of lymph nodes where lymphocyte white blood cells can identify any pathogens or other white blood cells that have had interactions with pathogens. Once pathogens are cleared, the lymph passes back to the blood circulation through the subclavian vein.
How fluid is moved through the lymph vessels
After fluid moves into the lymph vessels it is transported using one-way valves powered by the squeezing action of muscles surrounding the vessels and other body movements (one reason why being sedentary can cause edema).
What makes up the respiratory system structurally and functionally
-Upper respiratory system
----Nose, pharynx, (larynx)
-Lower respiratory system
----Trachea (larynx), bronchi and lungs
-Conducting zone - conducts air to lungs
----Nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles
-Respiratory zone - main site of gas exchange
----Respiratory bronchioles, alveoli
-Hypoxia is a deficiency of O2 at the tissue level
-Anemic hypoxia - too little hemoglobin
-Ischemic hypoxia - blood flow is obstructed
Pulmonary Ventilation, External Respiration, and Internal Respiration
-Pulmonary ventilation = breathing= mechanical flow of air into and out of the lungs
-External Respiration = Exchange of gasses between air spaces in lungs and pulmonary capillaries CO2 O2 O2 CO2
-Internal Respiration = Exchange of gasses between blood in capillaries and tissues throughout the body
*Inhalation is an active process caused by contraction (or flattening) of the diaphragm muscle. The lungs are only passively involved since they do not contain any muscle tissue. Exhalation is caused by recoil of the lungs, which are elastic. Forced exhalation is caused by abdominal and intercostal (rib) muscles.
Tidal Volume is the volume of air in each inhalation/exhalation event during at-rest breathing
Inspiratory and Expiratory Reserve Volume
Also understand the relationships between vital capacity, total lung volumes with tidal volume, residual volume, inspiratory and expiratory reserve volume
-Inspiratory Reserve Volume is the volume of air we are capable of inhaling beyond the tidal volume (a deep breath).
-Expiratory reserve volume is the volume of air we are capable of exhaling beyond the tidal volume (blowing out the excess air in our lungs).
How Oxygen (O2) and Carbon Dioxide (CO2) are transported in blood
-Oxygen is carried primarily on hemoglobin in red blood cells.
-Carbon Dioxide is carried:
----primarily as Bicarbonate anion (HCO3-) - 70%
----also may be bound to hemoglobin - 23%
----as well as some dissolved in the plasma - 7%
Some properties of hemoglobin
Hemoglobin is made of 4 protein subunits. Each of these subunits contains a single heme group. At the center of the heme group is an iron atom. It is on the iron atom that oxygen binds. Therefore, 4 oxygen molecules can bind to each hemoglobin molecule
How pH affects the affinity of hemoglobin for oxygen
At low pH, oxygen binds less tightly (lower affinity) than at higher pH. This allows Oxygen to be released near cells where pH is slightly lower (acidic), and to be collected in the alveoli where pH is not lower
Fetal hemoglobin and the mother's hemoglobin
Fetal hemoglobin has higher affinity for oxygen, which makes it bind oxygen more aggressively than oxygen binding to the mother's hemoglobin. This assures the fetus has sufficient oxygen.
Ventilation (breathing) effect on blood pH
The blood buffer is Carbonic acid (H2CO3) and Bicarbonate (HCO3-)
We can see, based on the following chemical equation:
CO2 + H2O H2CO3 HCO3- + H+
A buildup of CO2 will drive the equation to the right thereby producing more free Hydrogen (lower pH = acidosis)
A decrease in CO2 will force the equation to the left thereby decreasing free Hydrogen (higher pH = alkalosis)
Hyperventilation - allows the inhalation of more O2 and the exhalation of more CO2 which has an affect on blood pH as described above
Control of ventilation
Pons and Medulla in the brain stem
What are the functions of the kidneys
-Regulate blood ionic composition
-Regulate blood pH
-Regulate blood Volume
-Regulate Blood Pressure
-Solute and water content keeps blood osmolality constant
Functional unit of the kidney
Glomerular filtration rate
Positive pressure from the bloodstream pushes blood through glomerular capillaries and into the nephron usually increasing or decreasing in response to blood pressure. Decreasing the glomerular filtration rate keeps blood in the bloodstream which keeps blood pressure higher. Releasing more blood into the kidney through the Bowman's capsule (increasing GFR) relieves the vessels of the pressure and leads to more urine production.
Water and ion reabsorption in the nephron
-The proximal convoluted tubule is the site of most water reabsorption.
-The descending loop of Henle is the site where water reabsorption takes place but very little or no ion reabsorption takes place.
-In the ascending loop of Henle, very little or no water is reabsorbed, but ions (Na+ and Cl-) are reabsorbed.
-Based on the body's needs and hormonal control, water and ions continue to be reabsorbed in the collecting ducts to make concentrated or dilute urine.
Blood in the vasa recta flows through the renal medulla in the opposite direction as fluid in the loop of Henle and collecting duct of the nephron. The fluid in the vasa recta becomes more concentrated with salts as it flows down and takes on more water as it flows up. The fluid in the nephron tubules flows in the opposite direction shedding water on the way down and releasing salts on the way up. The counter-current flow creates a concentration gradient as it moves deeper into the kidney thereby allowing the nephron to shed both water and salts. This concentration gradient allows the collecting duct to concentrate urine by changing its permeability to water as it flows lower into the kidney. When the collecting duct is more permeable to water it allows more water to leave which makes urine more concentrated.
Diuretics slow renal reabsorption of water thereby reducing blood volume and blood pressure. It leaves more water in the urine so urine tends to be very dilute.
The hormone Vasopressin (= antidiuretic hormone (ADH)) do
Vasopressin is released by the pituitary gland (anterior) inserts water pores which allows more water to be reabsorbed by the collecting ducts. This allows more water into the blood and less in the urine. Maximal Vasopressin production decreases urine output and makes urine highly concentrated (i.e. during dehydration). As little as ½ liter per day may be produced. Diabetes Insipidus is the absence or inactivity of vasopressin. Up to 20 liters per day of urine may be produced. Can increase BP
The hormone Aldosterone
-Endocrine pathway responsible for the regulation of Sodium (Na+)
-Released from Adrenal gland (on kidney)
-Takes place in the distal tubule and first part of collecting duct.
-Higher aldosterone levels lead to increased reabsorption of Sodium (and secretion of Potassium (K+) because Sodium/Potassium pumps are pumping potassium and sodium in opposite directions)
-Release increases blood pressure
The Renin/Angiotensin/Aldosterone hormonal pathway. Be able to describe what the effect activation or deactivation of one of these hormones will be. What effect it has on blood volume (pressure). What that will do to the urine concentration (water content).
Renin, which is released by the kidney, converts inactive Angiotensinogen into Angiotensin I in the blood plasma. Angiotensin Converting Enzyme (ACE) converts Angiotensin I to Angiotensin II. Angiotensin II is the active hormone. It activates the hormone Aldosterone and Vasopressin which are also active. Angiotensin II has its effect by:
-Vasoconstriction (decreases GFR by constricting arterioles leading to the kidney)
-Increase cardiac output (stroke volume X heart rate)
-Enhances reabsorption of Sodium and Chloride and water in the proximal convoluted tubule (leading to more water in the blood and less excreted as urine)
-Stimulates the release of Aldosterone which signals the collecting ducts to reabsorb more Na+ (and Cl-).
**Together these increase blood volume thereby increasing blood pressure
Atrial Natriuretic Peptide (ANP)
-Peptide hormone produced in the atria of the heart
-Enhances Sodium and water excretion
-Released in response to increased pressure in the atria
-Inhibits renin, aldosterone and vasopressin
Why sodium intake is restricted in patients with hypertension (high blood pressure)
-To maintain constant osmotic pressure, any increase in solutes will increase the need for water to offset the high amount of solute concentration (here we're talking about sodium and chloride = table salt). Therefore, increasing salt leads to the body's need to increase water volume to offset that increase. An increase in water volume leads to an increase in blood volume which leads to an increase in blood pressure.
-Sodium may also increase the rate at which the body's natural pacemakers (primarily the SA node) depolarize since these pacemaker cells are continuously leaking sodium until they reach the depolarize threshold. More sodium in the body throws off the sodium balance between the inside and outside of the cell. This increases heart rate which can also contribute to increase blood pressure.
pH regulation by the kidney
pH is regulated by secreting (and subsequently excreting) Hydrogen ions (H+) when blood pH is too low. Bicarbonate (HCO3-) is also reabsorbed when blood pH is low.
Blood pH regulation
-Blood pH is regulated first by utilizing the bicarbonate (HCO3-) / Carbonic Acid (H2CO3) blood buffer to maintain a blood pH of about 7.4.
-Blood pH is next regulated by changing the carbon dioxide levels of the blood through active ventilation (breathing) using the following equation:
CO2 + H2O H2CO3 HCO3- + H+
-Moving the equation to the left by exhaling carbon dioxide (increased ventilation) will reduce the free hydrogen, therefore increasing pH.
-The kidneys regulate pH by active secreting and subsequently excreting free hydrogen.
The path of blood through the kidneys
Glomerulus Bowman's capsule Proximal convoluted tubule Descending loop of Henle Ascending loop of Henle Distal convoluted tubule Collecting duct
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