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Foundations Of Medicine > Week 3 > Flashcards

Week 3 Flashcards

1
Q

Outline the functions of blood.

• List the components of blood and define their respective functions.

A
  • Plasma 55%
    ○ 92% water-medium, volume for dissolved solutes and transport of materials
    ○ 7% protein-pH buffering, carrier/transport proteins, antibodies, immunoglobins, coagulation factors
    ○ 1% ions-membrane ptoential, volume regulation, pH regulation, osmalality
    ○ Nutrients-metabolic waste, hormones, amino acids, sugars, dissolved gases, lipids
    • Erythrocytes 45%
      ○ Carry O2 and CO2
    • Leukocytes <1%
      Never-Neutrophil (60%)-destroy and engulf invading bacteria
      Let-Leaukacytes (30%)-allergic response parasitic response
      Monkeys-Monocytes (6%)-maintain foreign pathogens and debris engulfing
      Eat-eonsophils (3%)-allergic response, histamine, heparin, anticoagulate, vasodilate,
      Bananas-basophils( 1%)-acellular vital for haemotaisus, no nuclei, thromopoeitien stimulains
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2
Q

• Outline the processes of haemostasis.

A
  • Activating platelets to being adherent and contractile and converting soluble fibronigen to insoluble fibrinogen so platelts can act on it and form a platelet plug and stable clot to stem blood flow
    1. Platelts adhere to and activated by exposed collagen at tear
    2. Activated platelets release ADP and A2- a
    3. Chemical messages activate platelets nearby
    4. Newly activated platelets aggregate and form platelt plug and release even more platelet attracting chemicals
      Uninjured endothelium releases prostacyclin and nitrous oxide to inhibit platelet aggregation so it is restricted to injury site
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3
Q

• Outline the processes of haematopoiesis.

A
  • Pluripotentent haemapoetic stem cells
    • In baby-made in liver, spleen and bone marrow
    • In adult-made in pelvis, spine, ribs, cranium, end of long bones
    • Unspecialised stem cell mulitples and transform into precursor cells
    • Pluripotent stem cell-myeloid stem cell-erthyroblast(has nucleus and organelles)-reticulocyte(remnants of roganelles)-erthryocyte(no nuclei)
    • Pluripotent stem cell-myeloid stem cell-granulocyte precursor, megakaryocyte precursor,monocyte precursor, erthyrocyte precursor-granulocyte, megakaryocyte, monocyte, erthyrocyte
      Pluripotent stem cell-myeloid stem cell-lymphoid stem cell-lymhocytes in lymphtissue-B or T lymphocytes
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4
Q

WALLS Describe the structure and functions of blood vessels (arteries, veins and capillaries).

A 
- Wall strucutre
		○ Tunica intima
			§ Closest to lumen
			§ Thin
			§ Endothelium
			§ Smooth
			§ Antithrombogenic
			§ Internal elastic lamina
			§ Subendothelial CT-collagen fibres and elastic fibres
		○ Tunica media
			Middle layer
				□ Thickest in arteries
				□ Smooth muscle-contraction relaxation
				□ Elastic fenestrations in laminae
		○ Tunica externa/adventitia-melds with CT
			§ Outermost
				□ Abundant collagen and elastic fibres
				□ Dense CT
				□ Abundant collagen less elastic
				□ External elastic lamina  EEL
				□ Smooth muscles in veins
				□ Vasa vorum-supply O2 and nutrients to walls
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5
Q

VEINS AND ARTERIES Describe the structure and functions of blood vessels (arteries, veins and capillaries).

A
  • Arteries
    ○ Elastic-more elastin
    ○ Arterioles-<5mm diameter, thicker wall comperared to lumen, less complex wall
    ○ Muscle -more smooth muscle
    • Veins
      ○ Venules-tunica intima only endothelium, tunica media-1-2 layers of smooth muscles, tunica adventitia fuses with surrounding tissue, valves
      ○ medium veins-involes of tunica intima form valves, low muscle content, adventitia largest layer
      ○ Large veins-involves high collagen, no EEL, vasa vorum
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6
Q

CAPILLARIES Describe the structure and functions of blood vessels (arteries, veins and capillaries).

A
  • Capillaries
    ○ 1 cell thick
    ○ Endothelium-fenestrations, tight junctions, pinocytotic vessels, basement membrane
    ○ Periocytes
    ○ Fenestrated
    § Endothelial cell cytoplasm peirced by pores
    § Thin diaphragm
    § Extensive exchange between blood and tissue
    ○ Continuous
    § Tight junctions, many pinocytotic vessels for exchange
    § No gaps between endothelial cells
    § CNS
    § Across endothelial itself
    ○ Sinusoidal capillaries
    § Large diameter
    § Incomplete endothelial lining
    § Numerous large number of fenestrations
    § Discontinous basal lamina Many fenstrations
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7
Q

• Compare and contrast the structure of the blood vessel wall (arteries, veins and capillaries).

A
  • Artery high pressure, vein low
    • Artery pressure resoir, vein blood resevoir
    • Artery full blood capacity, vein 30-70% blood capacity
    • Artery no valves, vein valves
    • Artery well defined circumferential muscle, vein less defined muscle, patchy
      Artery thinner adventitia, vein thicker adventitia
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8
Q
  • Distinguish between elastic and muscular arteries, and arterioles on the basis of structure, location, and function.
  • Describe the structure and function of elastic and muscular arteries.
A
  • Elastic-thick wall thick diameter close to wall, high elastin content
    ○ Laminae stretch during systole, and recoil during diastole
    ○ Reduce amplitude of fluctuations in BP propel blood forward
    • Muscle arteries-distributing arteries, more smooth muscle than elastic muscle
      ○ Organisation adapted for vasoconstriction and vasodilation to adjust blood flow
    • Arterioles
      ○ Smaller, thinner, complex walls than arteries
      ○ Constriction and dilation of muscle varies with diameter
      ○ Reduce BP for capillary flow
      Regulates blood distribution and flow through capillaries
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9
Q

• Describe the basic structure of a capillary bed.

A

Interwoven network of capillaries that supplies an organ
The leakiness of various capillary beds is therefore a function of
how tightly the endothelial cells are joined (how wide the intercellular spaces are) and whether fenestrations are present
Capillaries typically branch either directly from an arteriole or from a thoroughfare channel known as a metarteriole, which runs between
an arteriole and a venule.

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10
Q

• Explain the structure and function of venous valves.

A
  • Tunical intima folding

Prevents backflow of blood

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11
Q

Describe the structure and location of lymphatic vessels.

A
  • Start open ended
    • Arteries and veins always connected-closed system
    • Everything filted from capillaries but not reabsorbed in venules is in lymph
    • Drains into lymph nodes
    • Then it is transported back to heart
    • Have valves to direct lymph flow
      Thin walls
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12
Q

Describe the functions of the heart.

A
  • Pumps blood to rest of body

Muscular pump

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13
Q

• State the location, shape and size of the heart.

A
  • Apex 5th intercoastal muscle
    • Left susperior-2nd costal left
    • Right superior-3rd costal right
    • Right inferior-6costal right
    • 200-425g size
      Upside down pear
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14
Q

ENDOCARDIUM Describe the three layers of the heart wall.

A
  • Endocardium
    ○ Inner layer
    ○ Thinest in artia
    ○ Thickest in ventricle
    ○ 3 sublayers: endothelium-in contact with blood vessels, sub endothelial-dense regularly arranged collagen and elastic fibres and deep CT layer-irregular collagen
    ○ Purkinje fibres-modivfied cardiac muscle-larger in diameter, specialised fibres for transmission, large amount of glycogen stores
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15
Q

MYOCARDIUM Describe the three layers of the heart wall.

A
  • Myocardium
    ○ Thickest layer
    ○ Cardiac muscle fibres in firgue 8 pattern atria and ventricles and great vessel proceeding towards apex
    ○ Superifical layers of ventricular muscle
    ○ Vascular CT around muscle
    ○ Loose CT with Endomysium surrounds fibres,Surroinding bundle of fibres-perimysium, Abundant blood capillaries-high O2 demand to sustain heart beating, Nerves-innervation of vessels
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16
Q

EPICARDIUM Describe the three layers of the heart wall.

A
  • Epicardium
    ○ Outer layer of heart contact pericardium cavity-serous pericardium
    ○ Mesothelium secretes pericardial fluid ot reduce friction as heart beats
    ○ Underlying CT with fat cells, coronary vessels
    ○ Wall thickness varies from chamber types
17
Q

• Describe the structure and function of the pericardium.

A
  • Inner serous parietal and visceral-external heart surface
    ○ Separates heart from pericardialc sac
    ○ Pervents overexpansion, reduce friction, mesothelium
    ○ CT fibrous
    Outermost CT anchors to surrounding strucutres-diaphragm
18
Q

• Identify and describe the heart chambers and valves.

A
  • Left ventricle thickest msucle walls and largest
    • Valves
      ○ Corda tendinae connected to it to enable contraction and opening
      ○ 2 different types-valves that guard artery entrances-semi lunar valves
      ○ Valves that guard atria ventricular valves-attachments choraie tendinaue that anchor to papillary muscle,
      Leaflets of valves have similar histological appearance-Dense CT core-fibrosa Covered by either side by endothelium or CT
19
Q

• Outline the histology of cardiac muscle.

A

• Outline the histology of cardiac muscle.

- Striated
- Branching fibres
- Central nuclei
- Direct cell-to-cell communication via intercalated discs-lines running across fibres
- Abundant mitochondria (25% of fibre volume)
- Large enrgy stores as glycogen
- High O2 demands-aerobic respiration
- Largest diameter fibres in left ventricle where workload is greatest
- Not every fibre has same shape or profile
- There are central nuclei
- Pink spot-section myofibries
- Lots of blood capillariesC
20
Q

Trace the flow of blood through the heart and coronary circulation.

A

RA-via tricuspid->RV-via pulmonary valve->pulmonary artery->lungs-via pulmonary vein->LA-via mitral valve->LV-via aortic valve->aorta->arteries->arterioles->capillaries->venules->veins->SVC & IVC->RA

21
Q

Outline the electrical conduction system of the heart.

A
  • Excitation signal (action potential) SA node depolarisation spreads to atria cuasing it to contract and depolarise
    • to AV node impulse now slow down for short period before continuing down His bundle and purkinje fibres spread wave impulses along the ventricles causing them to contract
      Depolarisation from apex to base
22
Q

• Define the location of the components of the electrical conduction system in the heart.

A
  • SA node RA entry point of superior
    • SA node-localised in the right atrium near entry of superior venacava
    • AV node-right atria just above fibrous tissue ring (cardiac skeleton) that separates and isolates atria from ventricles
    • AV Bundle bundle of his normally distal to AV node next to tricuspide valve still in atria
    • Bundle of branches-run under the endocard (subendoardial) of the interventricular septum toards apex of heart
      Purkinje fibres run subendocardial and deliver exitation to cardiomyocytes
23
Q

• Describe the generation of action potentials in pacemaker cells.

A
  • Special set of ion channels decide on spontaneous generation of AP
    • Pacemake current is essential
    • Slowly increases the membrane potential from usual -70 to -60mV to more positive values until potneial reaches threshold and the AP starts
    • Slowly entry of Na+=membrane potental becomes more positive=depolarisation
    • Then Ca2+ channels (T transient) open=membrane potential becomes more positive depolarisation
    • Then CA2+ channels (L type) open= membrane potential becomes more positive=depolarisation
    • Then K+ channels open and K+ exits cell=membrane potential becomes more negative=hyperpolaisation
24
Q

• Understand the impact of the autonomic nervous system on the heart beat frequency.

A
  • Without control SA node would fire 100 to 110 Aps per min
    • Under rest parasympathetic nerouvs system via vagus nerve acts like brake
    • Acetylecholin from parasymp nerces travel with vagus nerve reduces heart rate 60-80bpm
      Increase heart rate reduce vagal influence
25
Q

Define the circulatory routes of blood as blood transits through the heart.

A
  • Systemic circulation
    • Enter via SVC or IVC and go RA then via TV to RV to PA to lungs to PV to LA to MV to LV to aorta
      Pulmonary circulation
26
Q
  • Define cardiac cycle and output.

* Consider changes in pressure, volume and flow through the cardiac cycle.

A
  • CO-blood ejected from LV per min
    • CC
      ○ Diastole
      § Isovlumetric relaxation-decrease BP
      § Rapid inflow to ventricles-decrease BP, increase BV
      § Diastisis-reduce inflow to ventricles
      § Atrial contraction
      ○ Sysstole
      § Isovulmetric contraction-increase in BP to exceed that of aorta, no change in BV
      § Rapid ventricular contraction-increase in BP, decrease in BV
      Reduced ventricular contraction-reduce BP, slow decrease in BV
27
Q

• Distinguish between systolic pressure, diastolic pressure, pulse pressure, and mean arterial pressure.

A
  • Pressure during systole
    • Pressure during diastole
    • Pulse pressure-difference between diastole and systole
      MAP=average pressure in arteries of body
28
Q

• Describe the clinical measurement of pulse and blood pressure.

A

-Average pulse-60-100BPM
-Normal BP range: 120/80
HYPERTENSION GRADES
gr1-140-159/90-99
gr2-160-170/100-109
gr3- more than 180/more than 110
isolated systolic hypertension- more than 140/ less than 90

29
Q

• Identify and discuss the variables affecting blood flow and blood pressure.

A
  • smoking
  • alcohol
  • diet
  • age - arteries lose elastin, more sti and diameter decreases
  • viscosity
  • the amount of vessels
  • length of vessels
30
Q

• Identify the primary mechanisms of capillary exchange.

A

materials move in and out of capillaries via mainly diffusion influenced by thin walls, short distance, large SA:V enabling efficient exchange, and slow movement

31
Q

• Define the intrinsic pathways involved in the regulation of the cardiovascular system.

A

Frank-Starling Mechanism
- Increased venous return results in greater cardiac output
- Increased venous return -> Increased atrial pressure -> increased ventricular lling -> increased preload -> increased
ventricular stretching -> more elastic recoil -> increased arterial pressure ->increased cardiac output
- the relationship between venous return and stroke volume increases then plateaus and eventually goes down a little
(reaches an optimal point)

32
Q

• Define the extrinsic pathways (neural and hormonal) involved in the regulation of the cardiovascular system.

A

Sympathetic & Parasympathetic Regulation
- Sympathetic - increases inux going through channels at the sinoatrial node, increases ring rate, hence increasing
heart rate, also impact contractility of heart to aid in increasing heart rate, also acts in vasoconstriction (and
venoconstriction, contributing to frank-starling mechanism) to increase blood pressure, stimulates hormone release
(adrenalin, catecholamines) which act to increase heart rate by increasing calcium release
- Parasympathetic - slower, more gradual inux going through channels at the sinoatrial node, decreases ring rate,
hence decreasing heart rate, also acts in vasodilation to decrease blood pressure
- Vagus nerve increases parasympathetic activity of heart, acting to decrease heart rate
Barorecpetor Reflex
- type of mechanoreceptor, detect stretching of blood vessel walls
- located in carotid sinus, aortic arch
- rest covered in mechanism

33
Q

Define professionalism as it relates to the doctor-patient relationship.

A
  • What is a professionalism
    ○ Mastery of complex changing body of knowledge and skill
    ○ Much debated=circumstances differ for every patient
    ○ Monoply and autonomy-selg regulating eg boards-patients consent and circumstances are unique
    ○ Public trust-paitnet trust
    ○ Codes of practice, enforcement, accreditation, continuing education-new treatments continually discovered, information accessible everywhere
34
Q

• Describe models of healthcare professional-patient relationships

A

○ 1. the paternalistic model
§ Traditional med model
§ Doctor knowls best
§ Base on benifiecence

	○  2. the consumerist model
		§ Patient in control
		§ Pased on respect for autonomy

	○  3. the shared decision-making model.
		§ Both professional and patient are involved in decision-making process
		§ Professional give info
		§ Patient tells professional about goals values and needs and concerns
35
Q

Describe why gaining informed consent is important to the doctor-patient relationship.

A

Important to let the patient know what is happening and if they are comfortable, enables respect for autonomy and upholds fiduciary relationship of respecting patient wishes above own

36
Q

• Understand that different case definitions may change the measure of disease frequency.

A
  • Counts-total number of events of disease that occur in a defined period of time
    • Case defintinion-set of standard criteria used to decide person has particular disease or not. Ensures all counted cases of the same disease have been identified the same way regardless of whom identified case
37
Q

• Understand the difference between crude, specific and adjusted rates.

A
38
Q

Prevalence vs Incedence

A

Prevalence-proportion of population affected by disease (people infected/population at risk)
Incedence-proportion OR rate (cummalitive=no. of new cases in specific period/ people at risk AT BEGINNING * 100, rate=no.of new cases in specific period /amount of people at risk *100)

Foundations Of Medicine (6 decks)

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