Topic 2 - Dysfunction of the circulatory system

Question 1

Ischaemia

Answer 1

The reduced supply of
oxygenated blood is called ischaemia

Question 2

hypoxia

Answer 2

reduced levels
of oxygen

can be caused by ischaemia

Question 3

anoxia

Answer 3

no oxygen in tissues

(causes death of tissue)

Question 4

2 main types of aterial dysfunction

Answer 4

• Obstruction
• Rupture

Question 5

Ways in which n arterial can be obstructed

Answer 5

• thrombus
• embolus
• compression
• structural changes
• spasm

Question 6

What is a trhombus

Answer 6

A thrombus is a blood clot (made up of platelets and fibrin) attached to the inside wall of an artery or vein.

Question 7

what is an embolus?

Answer 7

An embolus is a foreign object that circulates in the bloodstream until it becomes lodged in a vessel.

An emboli my be a blood clot, fat. fibrofatty material and air.

Question 8

What is a thromboembolus?

Answer 8

A thrombus that has detached froma vessel wall becomes a embolus and is often called a thromboembolus

Question 9

What is Ateriosclerosis?

Answer 9

is chronic hardening of he arteries

Question 10

Describe what happens in Arteriosclerosis

Answer 10

the inner lining of the artery(the tunica intima) stiffens and thickens. This causes the artery to get narrower and narrower, which therefore increases its resistance to blood flow*peripheral resistance)

Question 11

What causes Ateriosclerosis

Answer 11

Most common cause is

ATHEROSCLEROSIS

Question 12

Atheroclerosis

Answer 12

deposits of fatty material on the inner lining of arteries which become covered with smooth muscle and connective tissue form on the inside of arteries

Question 13

Atherosclerosis contributing factors

Answer 13

diet high in fats

and

inflaimed arteries

thourgh injury to the cells of the walls of the arteries

• smoking
• hypertension
• diabetes
• autoimmune disease and infection periodontal infection

Question 14

Atherosclerotic occlusive disease

Answer 14

is the gradual occlusion of an artery by atherosclerotic material

Question 15

What is an aterial aneurysms

Answer 15

An aneurysm is an abnormal localised vessel dilation caused by a weakness in the vessel wall

Question 16

How can aneurysms cause damage?

Answer 16

Aneurysms can reduce the blood supply
to surrounding tissue by compression, but they can also rupture and cause considerable damage. A ruptured
aneurysm can cause ischaemia of the tissue supplied by that artery or arteriole and the expanding haematoma at
the site of the rupture can damage a lot of tissue by compression.

Question 17

What are 4 different types of aneurysms?

Answer 17

• Saccular aneurysm
• Circumferential aneurysm
• Dissecting aneurysm
• False aneurysm

Question 18

Discribe a Saccular Aneurysm

Answer 18

A sac bulging out of the side of an artery.

Question 19

circumferential aneurysm

Answer 19

A circumferential aneurysm is considered to be more serious and is dilation of the entire vessel up to 20cm
diameter, and can be quite long. These are common in the aorta (abdominal and also thoracic).

Question 20

dissecting aneurysm

Answer 20

A dissecting aneurysm doesn’t involve a stretching of all the layers in the wall of the artery. Instead, following
a break in the inner wall of the artery (the tunica intima), blood is forced between the tunica intima and either
the tunica media or tunica externa.

• can develope suddenly
• is an acute event
• can be life threatening as it is very high risk of rupture

Question 21

false aneurysm

Answer 21

A false aneurysm is a clot attached to the outside of an artery following rupture of the vessel.

Question 22

What factors contribute to weakness of arterial wall and may lead to aneurysm formation

Answer 22

• congenital defect
• trauma
• hypertension
• infection
• arteriosclerosis

Question 23

Concerns about rupture of an aneurysm

Answer 23

• is life threatening
• bleeding hemorrhage
• repair is possible and succes rate is reasonable if occurs before the aneurysm has ruptured

Question 24

Thromboangitis obliterans

BUERGER’S DISEASE

Answer 24

BUERGER’S DISEASE

• inflammatory disorder
• general of an artery
• leads to formation of blood clots
• they block arterioles
• this reduces levels of oxygen causing pain in affected tissue
• risk factor: males between 25-40 who are smokers

Question 25

What is Raynaud disease?

Answer 25

Raynaud disease is vasospasm (=constriction) of arteries and arterioles, usually in fingers.

can cause ischemia

• The cause is unknown, but precipitating factors include cold and ‘strong emotion’ and some cases appear to be caused by an over reactive sympathetic nervous system (remember that the ‘fight or flight’ response causes peripheral blood vessels to constrict)
• The McIntyre manoeuvre, where the arms are swung forwards and
  backwards, is designed to force blood into the hands and fingers.

Question 26

Describe normal venous return of blood

Answer 26

Venous return to the heart is largely achieved by ‘inadvertent
pumping’—compression of veins by movement of skeletal muscles. Valves within veins ensure one-way flow.
The inferior vena cava and common iliac veins do not have valves in them, so a person standing upright has the
full weight of a long column of blood pressing down upon the veins in the leg.

Question 27

Describe Varicose veins

Answer 27

Varicose veins are dilated veins of the lower extremities. Veins have relatively thin and weak walls. ‘Deep
veins’ are those deep within tissue, often surrounded by skeletal muscles. Superficial veins are close to the
surface of the body and are therefore not so well supported by surrounding tissue. Superficial veins are therefore
especially susceptible to stretching and ‘ballooning out’. Treatments for superficial varicose veins include elastic
stockings (to support the veins), removal of superficial veins and sclerotherapy (injection of substances which
cause the blood in the veins to clot and be replaced by scar tissue).

Question 28

Describe deep venous thrombosis

Answer 28

is a common condition where a thrombus develops in a major vein.

Thrombus
formation occurs because of blood pooling caused by immobility, vessel damage and hypercoagulatability
(increased tendency for blood to coagulate)

. One danger is that the thrombus may detach and become an
embolus that lodges in a major blood vessel in the heart or lungs.

Question 29

Describe Superior vena cava syndrome

Answer 29

• occurs when the **Superior vena cava ** becomes partly blocked.
• The vast majority of blockages are caused by neoplasms (e.g. lung cancers, enlarged lymph nodes within the thorax that press upon the superior vena cava or tumours that have metastasised from elsewhere).
• There is oedema and distension of the veins draining the upper extremities and face. This condition is often described as ‘an oncological emergency’ because it is caused by a neoplasm

Question 30

Describe what happens with Pressure sores.

Answer 30

It may seem logical to think of external pressure restricting flow in arteries or arterioles,
thereby causing ischemia, but

• obstruction of flow in capillaries and veins will also cause blood to ‘back up’, preventing or reducing blood flow to an area and also causing ischaemia and tissue death.

Movement and redistribution of pressure are important in reducing or preventing local ischemia.

Question 31

Describe Chronic venous insufficiency

Answer 31

Varicose veins can progress to chronic venous insufficiency where the damaged valves and dilated veins result
in inadequate return of blood to the heart over a long period of time (hence the ‘chronic’) from the lower limbs.
This can cause chronic ischaemia of the feet and lower legs, resulting in the death of tissue which then breaks
down and ulcerates. These ulcers are called venous stasis ulcers, which are extremely susceptible to infection because the surrounding tissue is so poorly oxygenated.

Question 32

Describe normal diastolic and systolic pressure

Answer 32

Every time your heart beats, blood is ejected into your aorta (and pulmonary artery) at relatively high pressure.
In between heartbeats the pressure in your arteries is lower. Consequently blood pressure is given as two
readings—the high contractile pressure occurring during the heartbeat (called the systolic pressure) and lower

pressure occurring between heartbeats (called the diastolic pressure). Pressure is given in mm of mercury (mm
Hg). For example, you might see a blood pressure reading of 125/70, which means a systolic pressure of 125mm
Hg and a diastolic pressure of 70mm Hg.

Question 33

Define Hypertension

Answer 33

Hypertension is defined as the consistent elevation of arterial blood pressure, but actual definitions of
hypertension vary. McCance and Huether (page 1149) say it is when the average of two diastolic measurements
is 90mm Hg or more, or the average of two systolic measurements is 140mm Hg or more, on two or more
consecutive clinical visits. In Human Physiology you learned that blood pressure is determined by cardiac
output × peripheral resistance. Blood pressure can be increased by one or more of increased cardiac output,
increased peripheral resistance or increased blood volume.

Question 34

Types of hypertension

Answer 34

Most people suffering from hypertension show an increase in both their diastolic and systolic pressure and thus
have combined diastolic and systolic blood pressure.

Some, however, suffer from a condition called isolated
systolic blood pressure.Only the systolic pressure is increased, and thisis frequently caused by rigidity of the
aorta and major blood vessels(which do not expand to accommodate the blood pumped out by the heart during
systole, so the systolic pressure is high).

Question 35

Primary and secondry hypertension

Answer 35

• hypertension are of unknown cause, or without evidence of any underlying disease. This is called primary hypertension.
• If there is a known cause, the person has secondary hypertension.

Question 36

Possible causes of primary hypertension

Answer 36

• Emotional stress resulting in activation of the sympathetic nervous system (essentially the fight or flight response which increases cardiac output and peripheral resistance).
• ** High sodium intake**. The role of sodium in the development of hypertension is complex, but some people have a reduced ability to excrete sodium, so their blood sodium levels tend to be elevated. High dietary intake of sodium exacerbates this, and causes increased retention of water (to dilute the sodium) thus increasing blood volume and therefore blood pressure.
• Obesity. The mechanism by which obesity leads to high blood pressure is not well understood but it may be at least partly due to the circulatory system being required to pump blood through a much larger network of capillaries to service extra tissue. Therefore, cardiac output is increased.
• Excess alcohol consumption and cigarette smoking are both associated with primary hypertension. Nicotine is a powerful vasoconstrictor, which increases peripheral resistance.

Question 37

Secondary hypertension is where there is an identifiable underlying cause.

What are identifable underlying causes?

Answer 37

Secondary hypertension is where there is an identifiable underlying cause.

The major causes of
secondary hypertension are kidney disease (dysfunction of the control of blood salt concentration or of the renin
secreting cells in the kidney), arteriosclerosis (causing increased peripheral resistance) or grossly elevated levels
of aldosterone (resulting in retention of sodium which leads to an increase in blood volume).

Question 38

How can we treat hypertension?

Answer 38

Diet/lifestyle modification

• Reducing sodium intake often reduces hypertension for people who have a reduced ability to excrete sodium

Relaxation therapy can reduce hypertension by reducing the activity of the sympathetic nervous system.

• Exercise often results in a small reduction (about 10mm Hg) in both systolic and diastolic blood pressure. It probably has this effect by making the circulatory system more efficient (therefore a relatively lower cardiac output is needed to provide sufficient oxygen to the body) and by decreasing peripheral resistance.

Antihypertensive drugs

• Diuretics reduce blood volume and can reduce blood pressure by reducing the amount of fluid within the circulatory system.
• Adrenergic blockers (especially beta blockers) are compounds that interfere with the action of the sympathetic nervous system by blocking receptors in the heart and arterial walls, thereby preventing the binding of adrenaline (the hormone that increases heart rate and smooth muscle contraction in the walls of arteries and arterioles). This inhibition of muscle contraction reduces the force of the heartbeat and reduces peripheral resistance, both of which affect blood pressure.
• Some drugs interfere with the synthesis of aldosterone, thereby reducing its concentration in the bloodstream, which reduces blood pressure.
• Calcium channel blockers reduce the inflow of calcium to smooth muscle cells (remember from Human Physiology that the release of calcium ions is the ‘signal’ for muscle cells to contract). If less calcium is released the smooth muscle surrounding arterioles does not contract very strongly, so the diameter of the arterioles is not greatly reduced and peripheral resistance does not increase as much as expected when the muscle cells receive a
  nerve message to contract.

Question 39

Why is high blood pressure so dangerous?

Answer 39

• increase the risk that a small artery may rupture, thereby reducing blood supply to tissuesupplied by that artery. The expanding haematoma may also compress and damage surrounding tissue.
• Chronic hypertension can cause severe damage to the walls of arteries and arterioles. The walls of these vessels become thicker and more rigid to withstand the additional pressure. Over time, the excess pressure can damage cells of the lining of arteries, resulting in inflammation that encourages arteriosclerosis, especially the deposition of fatty material that can build up and block the vessel.
• Chronic hypertension can cause the walls of the glomeruli in the kidney to thicken so much that they no longeract as semipermeable membranes, so they do not leak fluid into the nephrons. This can severely reduce kidney function.