Cardiovascular system

Question 1

Does the Bundle of His have contractile proteins?

Answer 1

No. This is why it is not involved in the direct pumping of blood.

Question 2

Where is every heartbeat initiated?

Answer 2

In the SA node. Located in the right atrium, near the superior vena cava.

Question 3

Which atrium contracts first and why?

Answer 3

The right atrium contracts just before the left atrium because of the short time taken for the signal to travel through the tissue to the AVN.

Question 4

What are the valves called?

Answer 4

AV valves ( mitral- Left/bicuspid and tricuspid- right)
Semi lunar- pulmonary and aortic ( tricuspid)

Question 5

What is the Bundle of His?

Answer 5

Modified muscle fibres in the septum of the heart.

Question 6

In what direction do the ventricles contract and why?

Answer 6

They contract from the apex upwards. This is due to the purkinje fibres ( distal portion of the right and left branches from the bundle of His).

Question 7

What type of artery is the aorta and why?

Answer 7

It is an elastic artery.
It allow the aorta to accommodate surges in blood entering the aorta at high pressure from the left ventricle. When the ventricles contract, the aorta recoils and pushes the oxygenated blood onwards into the systemic circulation at high pressure.

Question 8

Describe the three main parts of hepatic circulation?

Answer 8

1) Hepatic artery- delivers oxygenated blood to liver ( which has high oxygen demands)
2) Hepatic portal vein ( takes blood from the capillary beds in the digestive tracts and transports it to the capillary beds in the liver)
3) Hepatic veins- blood is then grained in the GI tract and spleen where it enter the hepatic veins and is taken back into the heart).

Question 9

Describe renal circulation?

Answer 9

Renal artery- carries oxygenated blood and high concentrations of solutes such as urea, creatinine and sodium ions to the kidneys
Renal vein- returns deoxygenated blood from the kidneys to the general circulation. It will have a lower concentration of urea, creatinine and the blood pH, along with the ratio of sodium to potassium ions, will be regulated.

Question 10

What triggers the SA node to fire electrical impulses?

Answer 10

The venous return to the heart instates the expansion in the vena cavae- this triggers the SA node to fire.

Question 11

How often do events in the cardiac cycle occur?

Answer 11

During one heartbeat

0.8 seconds to complete each cycle.

Question 12

What does the SAN do?

Answer 12

Initiates cardiac contraction( although all heart cells possess the ability to generate electrical impulses ( action potentials))

Question 13

In the absence of extrinsic neural and hormonal controls how many beats per minute will the SAN initiate?

Answer 13

60-100 bpm

Question 14

Describe the neural control of the heart?

Answer 14

Parasympathetic nerves only change heart rate, they cannot change the force of contraction ( because they only innervate the SAN and AVN).

Sympathetic nervous system- increase the force of heart muscle contraction because they innervate the atria and ventricles as well as the SA and AV nodes.

Question 15

How are cardiac muscles best described?

Answer 15

Involuntary, striated muscle.
Unique tissue- structurally similar to both sommoth and skeletal muscle.
Very similar structure to skeletal muscle with visible cross striations and contractile proteins.
Extensive branching exists between cardiac myocyctes at the intercalated discs and is unique to cardiac muscle cells. The branching enables the myocytes to develop force in many different directions.

Question 16

What does myogenic mean?

Answer 16

It means it can naturally contract and relax without received electrical impulses from nerves. 
Cardiac muscle ( myocytes) are myogenic.

Question 17

What is a functional syncytium?

Answer 17

When cardiac muscle cells are placed next to another, they will beat in unison= functional syncytium.

Question 18

Do all arteries carry oxygenated blood and all veins transport deoxygenated blood?

Answer 18

No. The pulmonary artery is the only artery in the body that carries deoxygenated blood, which the pulmonary vein is the only vein transporting oxygenated blood.

Question 19

What does the femoral artery/vein do?

Answer 19

Supply and returns oxygenated blood to and from the lower limbs

Blood in the femoral vein may contain high concentrations of lactic acid ( after exercise. They contain numerous valves to prevent pooling in the limbs.

Question 20

What does the brachial artery and vein do?

Answer 20

Service the upper limbs

Question 21

What are the main blood artery and vein for the GI tract?

Answer 21

mesenteric artery and hepatic vein,

Question 22

What does the carotid artery do and how is it unique?

Answer 22

It supplies oxygenated blood to the head and neck.
Within it’s walls there are baroreceptors for detecting change in blood pressure and chemoreceptors for detecting changes in carbon dioxide and oxygen in the blood.

Question 23

Cardiac output is the amount of blood pumped by

Answer 23

1 ventricle in 1 minute

Question 24

CO = ?

Answer 24

CO= HR X SV

Question 25

What is the CO of a 70kg male?

Answer 25

5-6 litres per minute

Question 26

What is venous returns relationship to cardiac output

Answer 26

should be equal ( under normal conditions)

Question 27

How are arteries different from arterioles?

Answer 27

``` Larger Thicker Less numerous arteries have three or more layers of smooth muscle in their walls. Arterioles- thinner walls ```

Question 28

Do venules have valves?

Answer 28

Yes

Question 29

What happens to blood pressure as blood is propelled from aorta around the body?

Answer 29

Blood pressure drops. In the arterioles BP is normally around 40mmHg.

Question 30

Starlings law?

Answer 30

Increasing venous return increases stroke volume The volume of blood entering the heart should always equal the volume of blood leaving the heart. The heart is able to change the force of its contraction ( and therefore it's SV in response to changes in venous return)

Question 31

How is CO synchronised with venous return and arterial blood supply?

Answer 31

The more the wall is stretched, the more the ventricle muscles contract and more blood is pumped out of the heart. This stimulates stretch receptors which trigger a reflex to increase heart rate.

Question 32

What is a U wave on an ECG?

Answer 32

Occurs in 50-75% of cases. | Small and typically follows the t wave

Question 33

What is the baseline voltage of an ECG known as and when does it occur?

Answer 33

The isolelectric line and is measured as the portion of the tracing following the t wave and preceding the next p wave.

Question 34

Describe the ECG parts ( briefly?)

Answer 34

P wave- depolarisation during contraction of atria QRS Complex- depolarisation during contraction of both ventricles and simultaneous repolarisation of atria T Wave- recovery wave represents ventricular repolarisation. The interval from the beginning of the QRS complex to the apex ( highest point) of the T wave is referred to as the absolute refractory period; during this phase no action potential can be generated. The last half of the T wave is referred to as the relative refractory period.

Question 35

What can cause the changes in BP values?

Answer 35

age, sex, exercise, sleep and emotion. Age for age BP is lower in females than males. In the older adult BP tends to be higher due to the decrease in elasticity of the blood vessels that accompanies the ageing process.

Question 36

What are the two main factors for determining blood pressure?

Answer 36

CO ( SV X HR) and peripheral resistance

Question 37

What are the two heart sounds heard during the cardiac cycle?

Answer 37

Lub- AV valves close | Dub- SL valves close

Question 38

What nervous reflexes regulate heart rate?

Answer 38

Sensory nerves in the wall of the aorta and atria respond to stretching in these vessels ( as a result of increased venous return). In the aorta these baroreceptors detect increasing blood pressure. When this is too high they trigger a reflex which slows the heart and reduces cardiac output and blood pressure. Arteries and arterioles are regulated by the ANS and the vasomotor centre in the medulla oblongata. During sympathetic nervous control, the vasomotor centre stimulate overall vasoconstriction causing an increase in systemic blood pressure.

Question 39

What do baroreceptors do?

Answer 39

They detect the stretching of the blood vessels walls caused by blood flowing through them and send a signal to the CNS in response to the stretch. The CNS responds to increases or decreases in total peripheral resistance and CO. It is a negative feedback loop called the barorceptor reflex. e.g if BP becomes elevated the baroreceptors are stimulated and the reflex decreases BP. If BP drops the reflex is SUPPRESSED which allows BP to rise.

Question 40

Describe the long and short term control of BP

Answer 40

However, baroreceptors can only respond to short term changes in BP. Long term control of BP involves regulation of blood volume by the kidneys and the renin- angiotensin-aldosterone system

Question 41

What are the organs and tissues of the lymphatic system?

Answer 41

``` Tonsils ( pharyngeal and palantine) Sub mandibular lymph nodes Thymus gland Axillary lymph nodes Spleen Peyer's patches Appendiz Inguinal ( femoral) lymph nodes Lymphatic vessels Bone marrow Right lymphatic duct Thoracic duct ```

Question 42

What is the difference between lymphatic nodules and lymph nodes?

Answer 42

Lymphatic nodules are larger. Lymph nodes are small bodies located in clusters throughout the body along lymphatic vessel. As lymph passes through them it is filtered and any forge in substances are removed and destroyed by phagocytosis or by the T cells of the immune system.

Question 43

What is the Thymus Gland?

Answer 43

Immediately after birth the thymus gland starts making T lymphocytes. After a few months this is complete and the gland has no further function in the immune system. It begins to degenerate with only a non functioning remnant remaining in adulthood.

Question 44

Where do axillary lymph nodes drain lymph from?

Answer 44

The arms and the breasts

Question 45

What is the largest mass of lymphatic tissue in the body?

Answer 45

The spleen. Highly vascular and acts as a resorvoir and filter of the blood BUT NOT LYMPH. It is also involved in the the destruction of old cells and other substances by phagocytosis. Located on left side above the kidneys. The spleen makes antibodies, lymphocytes and plasma cells. Only makes erythrocytes during foetal development.

Question 46

What are Peyer's patches?

Answer 46

a cluster of lymph nodes in the wall of the ileum where they provide protection against pathogens in the GI tract and protect against absorption of toxins from the contents of the GI tract.

Question 47

What role does bone marrow play in blood production?

Answer 47

Blood producing tissue is located in the medullary cavity of certain bones. Stem cells give rise to all of the different types of blood cells during haemaopoeisis.

Question 48

What is haematopoiesis?

Answer 48

Blood cell production

Question 49

What are the two types of bone marrow?

Answer 49

Red and yellow Red marrow- consists of myeloid tissue ( for haematopoiesis). in chicldren all bone marrow is red and involved in the forming of blood cells. Yellow marrow- consists mainly of fat cells.

Question 50

Where can red bone marrow be found in adults?

Answer 50

Bones of the trunk and skull. The bones of the limbs contain yellow marrow which is not involved in making blood cells but can be converted to red bone marrow when more blood is needed.

Question 51

What is the most important lymphatic vessel

Answer 51

Thoracic duct ( left lymphatic duct). Received lymph drained from 75% of areas. Returns it to the general circulation via the left subclavian and left jugular veins.

Question 52

What is the right lymphatic duct?

Answer 52

Receives lymph from the right side of the head, upper right trunk and right arm. It returns the lymph bac at the junction of the right subclavian and right jugular veins.

Question 53

What are all cells bathed in?

Answer 53

Tissue ( interstitial) fluid. | This occupies the space between cells and is their immediate environment.

Question 54

How is tissue fluid formed?

Answer 54

From blood plasma that diffuses from the arteriole end of capillaries.

Question 55

How does tissue fluid differ to plasma?

Answer 55

It is milky clear but does not contain any erythrocytes or big proteins because both are too large to cross the capillary walls ( unless these walls are damaged).

Question 56

How does tissue fluid become lymph?

Answer 56

Some tissue fluid is returned to the capillaries at the venule end. Any fluid that remains is drained into blind ending, thin walled vessels called lymphatic vessels. The fluid is then called lymph.

Question 57

Is the lymphatic system pressurised?

Answer 57

No. There is no pump or the lymphatic system. Instead, fluid oozes into the lymphatic system and moves into the lymph nodes by normal skeletal and muscle motion.

Question 58

How do lymph vessels prevent backflow?

Answer 58

One way valves.

Question 59

What are the three functions of the lymphatic system?

Answer 59

1) Removal of interstitial fluid from tissues 2) Absorption and transportation of fats to the circulatory system 3) Transportation of immune cells to and from the lymph nodes.

Question 60

What is the large vessel running parallel to the spinal column transporting lymph called?

Answer 60

Thoracic duct.

Question 61

What is albumin?

Answer 61

The smallest and most abundant of the plasma proteins. It helps maintain plasma colloid osmotic pressure.