Lecture test

The average pressure in arteries is approximately

100 mm Hg

A 70 year old patient had a systolic blood pressure 130 and diastolic 85, what will be his pulse pressure and mean arterial pressure?

45-100

Compare and contrast how Aldosterone, Antidiuretic Hormone (ADH) and Atrial Natriuretic Peptide (ANP) hormone affect blood pressure.

Aldosterone causes our kidneys to take in more water and sodium, therefore increasing our blood pressure.It is released from the adrenal cortex, and triggered by angiotensin II. ADH, on the other hand, is released from the posterior pituitary gland and triggered by low blood volume. Similarly to aldosterone, it can be released due to effects of angiotensin II. ADH also causes increased absorption of water in the kidneys (but not salt) in order to increase blood pressure. ADH and Aldosterone both discourage urination. ANP aims to do the exact opposite. Released from the heart in cases of high blood volume, ANP decreases blood volume and blood pressure through vasoconstriction and increased release of urine.

Identify and describe the components of an ECG reading. Include the 3 waves and 2 segments in your response.

An ECG, or an electrocardiogram, is a test that is used to measure your heart's activity and electrical activity. It can be broken down into 3 waves and 2 segments. The first wave, P wave, reflects the electrical changes that occur during atrial depolarization which occurs due to the SA node. The next wave is the QRS complex, which represents the electrical signals that occur due to ventricular depolarization (and atrial repolarization). This part of the ECG is much larger than the rest due to the larger size of the ventricles when compared to the atria. The third was, T wave, is the electrical charge associated with ventricular repolarization. In between each wave there are segments which is the electrical events between waves, each corresponding with a plateau. The P-Q segments (between P and Q wave) are associated with the atrial plateau. Similarly, the S-T segment (between S and T wave) is associated with the ventricular plateau. During these plateaus is when Ca++ is trying to enter cardiac muscle cells, which causes a longer refractory period, which in turn blocks the heart from being able to receive another action potential to prevent tetany of the cardiac muscles.

Which type of muscle cell exhibits a longer refractory period?

Cardiac muscle cell

Describe the 3 electrical events of an action potential in cardiac muscle cells. Include the ions involved and their direction of movement.

Depolarization- opening of voltage-gated Na+ channels in sarcolemma of cardiac muscle cells. This changes the membrane potential from (-90mv to +30mv) plateau- triggered by depolarization, the opening of K+ channels, and K+ exits the cardiac muscle cells (slight change in membrane potential) this causes voltage-gated Ca2+ channels in sarcolemma to open and Ca2+ enters cardiac muscle cells. the exit of positively charged K+ from sarcoplasma and simultaneous entrance of positively charged Ca2+ into sarcoplasma result in no electrical change at sarcolemma. The plateau prolongs the action potential by prolonging the depolarized state. repolarization- voltage-gated Ca2+ channels close and K+ channels remain open to complete repolarization. a lot of K+ exits the cardiac muscle cells to change the membrane potential back to -90mv (the rmp)

True / False : Purkinje fibers are small fibers within the atria that conduct impulses rapidly

False

true / false : Increases in angiotensin II levels cause decreases in blood pressure.

False

Like SA nodal cells, cardiac muscle cells have an RMP value of -60 mV.

False - -90mv

When the heart is at rest prior to atrial contraction (atrial systole), one of the primary heart characteristics is the AV valves are closed. t/f

False -one of the primary heart characteristics is the AV valves are open.

Cardiac muscle tissue contains fewer mitochondria than are found in skeletal muscle tissue.

False- more mitochondria

Which of the following does not contribute to the ability of cardiac muscle to meet it's energy demands?

Glycolytic enzymes

One of these is a vasodilator.

Histamine

Compare and contrast the two pressures, hydrostatic and colloid osmotic pressures. How do these pressures relate to filtration and reabsorption at a capillary?

Hydrostatic is responsible for filtration processes between capillary and interstitial fluid which ultimately pushes out. HPb promotes filtration from capillary and is force exerted per unit area by the blood as it presses against the internal surfaces of the vessel wall. HPif is the force of the interstitial fluid on the external surface of the blood vessel however it is assumed to be close to 0) Colloid osmotic pressure is responsible for reabsorption processes between capillary & interstitial fluid. COPb, promotes reabsorption and COPif value is relatively low bc of few proteins are present.

The shutting of the semilunar valves occurs during which phase?

Isovolumic relaxation

What is the correct order of spread of the action potential through the heart's conduction system?

SA node, AV node, AV bundle, Purkinje fibers/cell gap junctions

Describe the five phases of the cardiac cycle. Include the contraction and relaxation of heart chambers and the opening and closing of heart valves.

The Cardiac cycle starts when isovolumic relaxation occurs and this is because ventricles complete repolarization. This means that when repolarized, the ventricles can be stimulated once again. During this, the AV valves remain closed and the semilunar valves close to prevent backflow. The cycle then moves on to atrial relaxation & ventricular filling. During this, AV valves are open because of the pressure that is pushed by the blood filling. The semilunar valves, however, just remain closed. After this, atrial contraction and ventricular filling occurs. During this, atrial depolarization occurs, which means the sarcomeres are stimulated within the cardiac muscle cells of the atria. This is important because when these sarcomeres are stimulated, it causes the atria to contract. This phase of the cycle has the AV valves open and the semilunar closed. The next phase of this cycle is isovolumic contraction, where ventricular depolarization occurs. This means the sarcomeres are stimulated, which causes ventricles to contract. During this, both valves are closed. Moving on to the final stage, ventricle ejection occurs. During this phase, the ventricular plateau takes place and the ventricular plateau prevents ventricles from repolarizing so sarcomeres can relax. The AV valves remain closed and the semilunar valves open. The semilunar valves are open because of the continuation of ventricle contraction. Then it starts over again with isovolumic relaxation.

Describe the initiation and spread of an action potential through the heart's conducting system structures. Identify the "pacemaker" of the heart. Define an ectopic pacemaker.

The initiation of an action potential events take place within the SA Nodal cells which is the hearts pacemaker. It starts with reaching the threshold where voltage-gated cation channels open. Na+ flows into the SA nodal cells. When this happens the membrane potential changes because of the influx of the positively charged ions (-60 mv to -40 mv) Next depolarization takes place because the changing of the membrane potential triggers the opening of voltage-gated Ca2+ channels. Ca+ enters the SA nodal cells and changes membrane potential from -40mv to just above 0 mv After this repolarization makes way when the calcium channels close and voltage-gated K+ channels open causing K+ to flow out of the cell. This changes the membrane potential from a positive back to -60 mv which is restablishing the RMP. This is called repolarization which triggers the opening of the voltage channels again which starts over the whole process. The spread of the action potential is propagated first along the sarcolemma of cardiac muscle cells within the atria and spreads to other atrial cardiac muscles through gap junctions. The action potential after this assrive at the AV node which takes longer to spread because the AV node is slow because of smaller diameters and fewer gap junctions After this the action potential travels from AV node through AV bundle to purkinje fibers. And finally the action potential continues throughout both ventricles via gap junctions. here the action potential is propagated along the sarcolemma of the cardiac muscle cells within the ventricles and spread to other ventricular cardiac muscle cells by gap junctions. -This allows for simultaneous stimulation of all cardiac muscle cells in ventricular walls and simultaneous contraction of both ventricles An ectopic pacemaker is a group of cells that cause premature heart beat outside of the normally functioning SA Node and they depolarize at much slower rates

Check all that occur during ventricular systole.

The semilunar valves open to allow blood to flow into the large arteries. The AV valves close to prevent backflow of blood into the atria.

The mechanical events of cardiac muscle contraction are almost identical to the events of skeletal muscle contraction. Group starts T/F

True

True / False :Blood hydrostatic pressure in systemic capillaries is greater than interstitial fluid hydrostatic pressure

True

If someone suffered from hypertension, such that the blood pressure in their capillaries was elevated, then net filtration pressure would be

above normal

Metabolically, cardiac muscle relies on

aerobic metabolism using many mitochondria and a rich supply of myoglobin.

Which are characteristics of the heart when it is at rest prior to atrial contraction (atrial systole)?

all four chambers of the heart are at rest, passive filling of the ventricles is under way, AV valves are open, semilunar valves are closed, and blood continues to return to the right atrium.

P wave QRS complex T wave P-Q segment ST segment

atrial depolarization ventricular depolarization ventricular repolarization atrial contraction and atrial systole ventricular contraction and ventricular systole

If someone were to have abnormally low levels of protein in their blood, then net filtration pressure would: (Check explanation after you answer a or b) A be lower than normal. B be higher than normal.

be higher than normal

Cardiac output is usually expressed in

beats per minute

Hyaline cartilage has a low degree of vascularization. This means that

blood delivery to this tissue is limited.

Define blood pressure and give an example of a normal blood pressure. Describe pulse pressure and Mean Arterial Pressure (MAP) in the arteries.

blood pressure is the force per unit area that blood exerts against the inside wall of a vessel. normal blood pressure is 120/80 mmHg. Pulse pressure is the additional pressure placed on arteries from when the heart is resting (diastolic blood pressure) to when the heart is contracting (systolic blood pressure). the MAP is the average or mean measure of the blood pressure on the arteries. Ex. Diastolic pressure + 1/3 pulse pressure)

The sequence of events in the transmission of an impulse through the heart muscle is a: AV node b: AV bundle. c: SA node d: through the atria. e: through the ventricles. f: bundle branches. g: Purkinje fibers

c, d, a, b, f, g, e

Define cardiac output. What is the formula for calculating cardiac output? Under what conditions does cardiac output increase or decrease?

cardiac output is defined by the amount of blood that is pumped by a single ventricle in 1 min (liters per min). Cardiac output is determined by heart rate and stroke volume. (HR x SV = CO) beats per min mL ejected per beat =mL ejected per min positive chronotropic agents cause an increase in heart rate due to

The cardiac center of the brainstem includes the:

cardioacceleratory center from which sympathetic pathways extend.

When blood is flowing out of the left ventricle, the bicuspid valve is __________ and the aortic semilunar valve is __________.

closed;open

Vasoconstriction

decreases blood flow and increases blood pressure.

Identify and explain the three types of processes in which gases, solutes, hormones and nutrients move across the blood vessel wall during capillary exchange?

diffusion- when substances such as oxygen, hormones and nutrients move from a high concentration to a lower concentration. vesicular transport- occurs when endothelial cells use pinocytosis to form fluid filled vesicles which are transported to the other side of the cells & released by exocytosis bulk flow- move of large amounts of fluids and dissolved substances in one direction down the pressure gradient. Filtration movement of fluid out of blood through capillary openings. Absorption, movement of fluid back into blood

The relationship F=P/R means that flow is

directly proportional to the pressure gradient and inversely proportional to resistance

Blood flow is

directly related to the pressure gradient but inversely related to the resistance

As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the

exit of potassium through voltage-gated channels

Precapillary sphincters relax as the tissue concentration of nutrients, such as oxygen, glucose, amino acids, and fatty acids, increases. t/f

false

The audible heart sounds are caused by the contraction of the atria and ventricles. t/f

false

The refractory period of skeletal muscle is longer than for cardiac muscle. T/F

false- A refractory period is when muscle cannot be restimulated to contract. The refractory period of cardiac muscle is much longer (250 milliseconds) than for skeletal muscle (1-2 milliseconds).

The __________ is a low-pitched sound caused by vibration of the atrioventricular valves and surrounding fluid as the valves close at the beginning of ventricular systole.

first heart sound

Systolic blood pressure is recorded

in arteries and is the maximal pressure that is recorded during ventricular contraction.

Blood pressure increases with sustained increased resistance because

in order to maintain adequate flow, a greater pressure gradient must be produced.

Sympathetic innervation of the heart: a-increases the heart rate b-decreases the heart rate c-increases the force of contractions d-decreases the force of contractions e- has no effect on contraction of force

increases heart rate and increases the force of contractions

The respiratory pump assists blood movement within the veins of the trunk, because as a person inspires,

intra-abdominal pressure increases and intrathoracic pressure decreases

The blood flow to the body organs

is inversely proportional to the resistance of the arterioles leading to them.

At the capillaries, net filtration pressure is equal to:

net hydrostatic pressure minus the net colloid osmotic pressure.

Define resistance and describe the factors that influence it. Explain the relationship of both blood pressure gradients and resistance to total blood flow.

resistance is defined as the amount of friction the blood experiences as it is transported through the blood vessels. -Blood viscosity refers to the resistance of fluid to its flow (thickness of fluid) -vessel length increases resistance bc longer vessels result in greater friction which the fluid experiences as it is transported through the vessel -Vessel radius blood tends to flow fastest in the center of the vessel lumen, whereas blood near the sides of the vessels slows bc it encounters resistance from nearby vessel wall when the blood pressure gradient increases, total blood flow is greater, and as the blood pressure gradient decreases, total blood flow lessens

Any injury to the body tissues can trigger local release of histamine, which can:

stimulate release of nitric oxide, a vasodilator.

A long-term response to an increase in blood pressure would involve

stimulation of the atrial myocardium increases atrial natriuretic hormone.

Angiotensin II is a hormone that causes a(n):

stimulation of the thirst center, increased release of ADH, and vasoconstriction.

Explain the renin-angiotensin system and its influence on blood pressure.

straddles short term neural regulation and long-term hormonal regulation bc the synthesis of the angiotensin II is initiated by the nervous system and angiotensin II causes the releases of other hormones Increases peripheral resistance and raises blood pressure to a greater extent -stimulates the thirst center within the hypothalamus (increases blood pressure) -directly decrease urine formation which helps maintain blood volume and blood pressure

Atherosclerosis involves a

sustained increase in resistance that leads to increases in arterial pressure to maintain adequate blood flow.

Blood colloid osmotic pressure is largely due to

the proteins in the blood, and it promotes reabsorption

During ventricular contraction

the semilunar valves open and the AV valves close

Angiogenesis is the generation of new blood vessels in tissues that require them. t/f

true

Blood pressure is directly proportional to vessel resistance. t/f

true

If local blood flow in a tissue is inadequate, it may be due to a decrease in total blood flow. t/f

true

If you drank excessive amount of water, the blood will become thinner and the resistance in the blood vessels will decrease.

true

Local control of blood flow is achieved by the periodic relaxation and contraction of precapillary sphincters regulating blood flow through the tissues. t/f

true

SA nodal cells are unique in that they exhibit autorhythmicity, meaning they are capable of depolarizing and firing an action potential spontaneously without any external influence. t/f

true

The cerebral arteries dilate when the systemic BP drops and constrict when it rises. t/f

true

True/ False: The main functions of the cardiovascular system include the transport and exchange of respiratory gases, nutrients, and wastes throughout the body

true

Vasodilator substances are produced in the extracellular fluid as the rate of metabolism increases t/f

true

Angiotensin II causes

vasoconstriction, decrease urine formation, and increased thirst.

Angiotensin II causes:

vasoconstriction, decrease urine formation, and increased thirst.

Blood flow to an organ will increase with

vasodilation

Atrial Natriuretic Peptide (ANP) stimulates

vasodilation, increased urine output, and therefore decreased blood pressure

When blood pressure get lower than the normal...

vasomotor and cardio-acceleratory centers are stimulated.

During which event of the cardiac cycle do the atria both relax and contract?

ventricular filling

If someone gains weight and this might lead to a rise in peripheral resistance in the blood vessels. Can this raise their blood pressure too?

yes