Lecture 23

Question 1

What are the determinants of blood pressure?

Answer 1

Cardiac output (determined by stroke volume, heart rate and heart contractility) and Peripheral vascular resistance determined at the level of the arterioles by neural and humoral factors

Question 2

What is the definition of hypertension?

Answer 2

Abnormally high blood pressure in a vascular bed

Question 3

Why does blood pressure need to be measured several times over the course of several weeks to gain an adequate diagnosis of hypertension?

Answer 3

As blood pressure varies greatly with things such as posture, exercise and stress more than one reading is required to gain a true value of what the patients blood pressure is

Question 4

What pressures are officially considered to be hypertension?

Answer 4

Diastolic pressures of >90mmHg
Systolic pressures of >140 mmHg
(Using these criteria 800 million people world round are affected)

Question 5

What two categories can hypertension be divided into?

Answer 5

Secondary/malignant hypertension and Primary/essential/benign hypertension

Question 6

What are the genetic predispositions towards hypertension?

Answer 6

Candidate genes for angiotensin converting enzyme, renin and nitric oxide synthase

Question 7

What is interesting about the gene coding for angiotensinogen?

Answer 7

Polymorhpisms are linked to increased circulating levels of angiotensinogen and increased blood pressure levels

Question 8

What environmental factors contribute to hypertension?

Answer 8

High sodium levels, stress, smoking and inactivity

Question 9

What conditions have an increased of occuring if hypertension is present?

Answer 9

Atehrosclerosis and related complications
Left ventricular hypertrophy
Cardiac Failure
Cerebral haemorrhage
Aortic dissection
Small blood vessel disease
Renal insufficiency and renal failure

Question 10

What is aortic dissection?

Answer 10

When blood enters the aorta and dissects along its different tunics which can potentially occlude major vessel branches and aortic rupture

Question 11

What is heart failure?

Answer 11

Failure of the heart to maintain an output of blood that is adequate for the demands of the body

Question 12

What is low output heart failure?

Answer 12

Failure to maintain normal cardiac output because of conditions which affect the heart

Question 13

What is high output heart failure?

Answer 13

The heart is unable to meet the increased demand for blood by the body

Question 14

What is the naming system for heart failure?

Answer 14

Acute/Chronic, Left/right/both, high/low

Question 15

What are the adaptive mechanisms which are initially used in heart failure to maintain cardiac output?

Answer 15

Hypertrophy
Dilatation
Increased Circulating volume (via Renin-Angiotensin-Aldosterone axis)
Increased Catecholamine release from adrenal glands and Sympathetic nervous system

Question 16

What is cardiac decompenstion?

Answer 16

If the heart failure is progressive or prolonged, the adaptions will not be effective and infact may cause harm as the hypertrophied cardiac myocytes will result in an increased metabolic demand not able to be met by the coronary blood supply and increased dilation results in mechanical disadvantage while pumping

Question 17

What are the end results of heart failure?

Answer 17

Reduced cardiac output with hypoxic effects on other organs

Damming back of blood in veins with congestive effects on multiple organs

Question 18

What causes tissue oedema?

Answer 18

The tightly controlled homeostatic mechanisms which regulate vessel wall integrity and osmolarity of the blood are changed, resulting in there being a large osmotic gradient for fluid flow into the tissue, if fluid flow exceeds the draining capacity of the lymphatic system then fluid build up occurs

Question 19

What causes inflammatory oedema?

Answer 19

Increased blood flow and vascular permeability with oedema fluid being the protein rich exidate with >1.02 gravity
This process is actively controlled

Question 20

What occurs in non-inflammatory oedema?

Answer 20

The fluid is protein poor transudate with <1.02 gravity

Question 21

What are the causes of non-inflammatory oedema?

Answer 21

Increased intravascular hydrostatic pressure
Reduced plasma osmotic pressure
Lymphatic obstruction
Sodium rentention

Question 22

What is hyperaemia?

Answer 22

Active process in which arteriolar dilatation increases inflow to a capillary bed

Question 23

What is congestion?

Answer 23

Passive process where there is decreased outflow from a capillary bed resultin in a build up of fluid in the capillaries this can be a systemic process from heart failure or a local process from loacised venous obstruction/oedema

Question 24

What is haemorrhage?

Answer 24

Loss of blood due to vessel rupture, occurs from vessel injury caused by trauma,atherosclerosis or erosion

Question 25

What are haemorrhagic diatheses?

Answer 25

Disease that increase the risk of haemorrhage including low platelet counts, clotting factor defects and vessel fragility

Question 26

What is thrombocytopaenia?

Answer 26

Low platelet count

Question 27

What is amyloidosis?

Answer 27

Increased vessel fragility

Question 28

What is haematoma?

Answer 28

Haemorrhages enclosed in tissue

Question 29

What factors influence the clinical relevance of haemorrhages?

Answer 29

The volume of blood lost and the location in which it occurs as even small haemorrhages in places like the brain can have significant effects

Question 30

What is shock?

Answer 30

When there is a systemic hypofusion caused by a reduction in cardiac output and/or reduction in effective circulating volume