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Pathology SEM 1 > The heart and the vascular system > Flashcards

The heart and the vascular system Flashcards

1
Q

Describe the 3 layered structure of blood vessels -

A
  • Tunica Intima
  • Tunica media - smooth muscle and connective tissue , binding the inner and outer layers
  • Tunica externa - connective tissue sheath and stabilizing system to create attachments
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2
Q

Describe the structure and function of Arteries -

A
  • Muscular or elastic
  • Muscle are more abundant
  • Tunica interna - elastic
  • Media - smooth muscle depending on whether is a muscular or elastic muscle
  • Tunica externa - collagen and elastic fibres
  • High pressure changes
  • Propel blood onwards
  • even out pressure changes
  • ANS stimulation causing vasodilation and vasoconstriction
  • Constriction during damage
  • Conducting vessels
  • Little resistance
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3
Q

Describe the structure and function of arterioles-

A
  • Smallest branches of arteries
  • lead into the capillaries
  • resistance vessels - regulate arterial blood pressure and distribute blood
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4
Q

Describe the structure and function of Capillaries-

A
  • Smallest vessels with thin walls
  • Permeate all active tissues
  • Exchange vessels
  • materials diffuse between blood and interstitial system
  • Don’t have the 3 layers , just the tunica interna
  • Multiple capillaries working together - capillary networks
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5
Q

Describe the structure and function of Venules-

A
  • Smallest branches of the veins
  • Allows blood to return from the capillary bed to the venous system
  • Have the same function as veins.
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6
Q

Describe the structure and function of veins-

A
  • Regulate and return the blood back to the heart
  • same 3 layers
  • Much thinner walls
  • Unable to withstand high pressures
  • Requires skeletal muscle pump to assist venous return
  • One-way valve prevent backflow and aid venous return
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7
Q

Outline Venous return-

A
  • Low blood pressure
  • To overcome gravity = Valves , muscle pump and respiratory pump
  • Inhale = pressures drop , drawing blood up.
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8
Q

Give the factors contributing to blood pressure -

A
  • Cardiac output
  • Peripheral resistance
  • Blood volume
  • Hypotension - low pressure
  • Hypertension - High pressure - greater than 140/90 , essential and secondary hypertension , risk factors - genetics, age and pathology , smocking , diet etc. = damage to the blood vessels
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9
Q

Give some pathologies of the arterial wall -

A
  • Arteriosclerosis - Hardening and loss of elasticity of large and medium arteries
  • Arteriolosclerosis - Hardening and loss of elasticity of arterioles.
  • Atherosclerosis - Hardening of an artery due to the deposition of an Atherosclerotic plaque - LDL- cholesterol.
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10
Q

Outline the cause of an Aneurysm-

A

Excessive localised enlargement of an artery caused by weakness in the arterial wall .
Common Locations , Aortic aneurysm and cerebral aneurysm

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11
Q

Outline the cause of deep vein thrombosis-

A
  • Thrombus formed in large veins
  • Risk factors - Inability, family history , recent surgery and obesity
  • Symptoms- Discolouration, Pain , swelling and Homans Test - dorsiflex the ankle= pain
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12
Q

Outline the cause of Varicose veins-

A
  • Bulging of the Veins , valves being incompetent.

Chronic Venous Insufficiency

  • Valves aren’t working
  • Blood not moving , lack of oxygen= Narcosis

Both treated with exercise ^

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13
Q

Describe the structure of red blood cells (Erythrocytes)

A

1 - Red Blood cells

2- Disc shaped - thin in middle and thicker as edge

Lack nuclei , mitochondria and ribosomes

3- contain haemoglobin - Oxygen carrying

4- Programmed to die after 120 days

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14
Q

Describe the structure of white blood cells (Leucocytes)

A

1- Role in inflammation and the immune response

2-Have nuclei and other organelles

3-Small numbers in blood

4- Connective tissue proper and Lymphatic system organs

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15
Q

Name the Granulocytes- Nucleus present

A

Neutrophils - Phagocytosis of bacteria/pus formed

Eosinophils- Allergic reactions , defence against parasites , control inflammation.

Basophils- Allergic reactions inflammatory reactions.

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16
Q

Name the Agranulocytes- No nucleus

A

Lymphocytes - Immunity t and b cells

Monocytes- Phagocytosis of large particles pathogens - attract immune system cells

17
Q

Describe the structure of Platelets ( Thrombocytes)

A

1-small colourless disc shaped cell fragment without a nucleus , found in large numbers in bloof

2-Release important clotting chemicals

3-Temporarily patch damaged vessel walls

4-Actively contract tissue after clot formation.

18
Q

Outline Haemostasis -

A

3 phases

Vascular phase

S1 - Immediate vasospasm - blood vessels contract

S2- Endothelial cells become exposed and release chemicals , which leads to further muscle contraction , cell division of endothelial cells, smooth muscle cells and fibrocytes - repair process

S3- Endothelial cell membranes become sticky and may seal off blood flow

Platelet Phase

S1- Platelet adhesion , begins within 15 seconds

Sticking to endothelial surfaces , basal laminae and exposed collagen fibres

S2- Platelet Aggregation , everything begins to stick together

Coagulation Phase

S1 - Blood clotting , involves a series of steps , converts circulating fibrinogen into insoluble fibrin

Chain reactions of enzymes and proenzymes

19
Q

Haemostasis - 3 Pathways

A

A - Extrinsic Pathway - Begins in the vessel wall and outside the blood stream

B- Intrinsic Pathway - Begins with circulating proenzymes , within the bloodstream

C- Common Pathway - clotting factor number 10 , Prothrombinase , prothrombin - thrombin - fibrinogen - fibrin - Fibrin threads making a mesh + blood cells and plasma - Blood clot

20
Q

Common Pathology -

Anaemia

A

Anaemia - Deficiency in Haemoglobin due to too few RBCs or too little Haemoglobin in the cells.

Various Causes

  • Blood loss
  • Inadequate RBC production
  • Excessive RBC destruction

-Tired , weakness ,pale, shortness of breath, irregular heartbeat , chest pain , dizziness , cold hands and feet and headache.

21
Q

Common Pathology-

Leukocytosis and Leukopenia.

A

Leukocytosis and Leukopenia

Leukocytosis - Increase in white blood cells

  • Infection from bacteria , sometimes viruses , fungi and parasites
  • Inflammation or inflammatory conditions
  • Allergic reactions
  • Leukaemia - acute and chronic

Leukopenia - Low white cell count

  • Bone marrow damage or disorder
  • Lymphoma - Hodgkin’s etc.
  • Autoimmune disorders
  • Dietary deficiencies
22
Q

The Heart - Structure

A
  • 4 chambered organ
  • Atria and Ventricles
  • Located posterior to the sternum , level with 3rd costal cartilage to 5th costal space
  • Mediastinum
  • 7.5cm left of midline
  • Surrounded by Pericardium - Visceral , Epicardial and Parietal , with 15-20ml of pericardial fluid in between
23
Q

How the heart Beats -

A
  • 4 chambered organ
  • Atria and Ventricles
  • Located posterior to the sternum , level with 3rd costal cartilage to 5th costal space
  • Mediastinum
  • 7.5cm left of midline
  • Surrounded by Pericardium - Visceral , Epicardial and Parietal , with 15-20ml of pericardial fluid in between
24
Q

Properties of cardiac muscle -

A
  • Muscular pump
  • Actin and Myosin
  • Muscle cells are connectedby intercalated discs or gap junctions
  • Autorhythmic fibres , inherent rythmical activity , self-excitable , heart beats continually
25
Q

Contraction of cardiac muscle -

A

Depolarisation

  • Resting potential (-90mV)
  • Action potential in adjacent fibre passes via gap junction ( intercalated disc) and opens the Na+ channel - rapid inflow of Na+ - rapid depolarisation
  • Cardiac muscle AP lasts approximately 0.3 sec

Plateau

  • There is a plateau because as Na+ is being pumped put of cell Ca++ slowly enters cell balancing loss of Na+ - balancing membrane potential as 0mV

Repolarisation

  • Repolarisation does eventually occur
  • The Ca++ channels slowly close
  • The K + channels open - K+ Leaves cell
  • Resting potential restored
  • The mechanism of contraction is the same in cardiac muscle as it is in skeletal muscle with the AP causing a mechanical response

Refractory Period

  • Is the time interval before another contraction can take place
  • It lasts longer than a contraction
  • It means the fibres are in relaxation before the next contraction can occur
  • It allows the pumping action of cardiac muscle
26
Q

Explain the coordination of contraction-

A
  • AP needs to be co-ordinated
  • Contract in sequence
  • Pacemaker and conduction pathways
  • SA node is pacemaker with an inherent of 100 APs per minute
  • However this slowed down to 70-75 by the vagus nerve
27
Q

The cardiac cycle-

A

1 - Atrial systole - atrial contraction forces a small amount of additional blood into relaxed ventricles
2-Atrial systole ends , atrial diastole begins
3-Ventricular systole - Ventricular contraction exerts enough pressure on the blood to close AV valves but not enough to open semilunar valves
4- Ventricular systole - Ventricular pressure rises and exceeds pressure in the arteries, semilunar valves open and blood is ejected.
5- Ventricular diastole - Ventricles relax, pressure drops , blood flow back against semilunar valves causing them to close, blood flow into relaxed atria
4- All chambers are relaxed.

28
Q

Components of cardiac output-

A
  • Total blood volume passing through lungs and systemic circulation in one minute
  • CO=SVxHR
  • Stroke volume (SV)= volume of blood ejected during ventricular systole
  • E.g. CO= 70 ml x 75 bpm = 5230 mls/min
  • Close to your total blood volume
  • what happens if the body requires more blood for working tissues
  • Ans= increase CO
  • Cardiac reserve is 4to5 times that at rest
29
Q

Stroke volume - factors.

A
  • Preload - stretch on heart prior to contraction

Frank-starling law - More the heart is filled in diastole , the greater the stretch and the greater the force of systole.

  • Contractility

Strength of contraction due to preload

  • Afterload - Pressue needed to overcome on contraction

Increased afterload results in reduced SV because more blood remains in ventricles at the end of systole.

Pathology SEM 1 (12 decks)

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