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M4 Y1 > FCS > Flashcards

FCS Flashcards

1
Q

What is meant by partial pressure?

A

The pressure that would be exerted by one of the gases in a mixture if it occupied the same volume on its own

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2
Q

How is the total O2 content of blood expressed?

A

Volume of O2 being carried in each litre of blood, including O2 dissolved in plasma & bound to Hb - ml/L.

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3
Q

What is O2 saturation, and two main locations to measure?

A

% of total available haemoglobin binding sites that are occupied by oxygen.

  • Sa = measured directly in arterial blood
  • Sp = estimated by pulse oximetry
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4
Q

Describe the purpose of haemoglobin

A
  • Is essential for transport as oxygen has low solubility in plasma - to dissolve required oxygen, alveolar PO2 would have to be impossibly high
  • Haemoglobin increases carrying capacity, enabling O2 to be concentrated within blood
  • > 98% of oxygen transported by blood is bound to haemoglobin
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5
Q

Give a brief description of the structure of haemoglobin with & without O2

A
  • Protein tetramer consisting of 4 x peptides, each linked to a haem group containing an iron atom in the ferrous state (Fe2+)
  • An O2 molecule binds each ferrous iron to give oxyhaemoglobin (O2Hb), therefore each molecule molecule can bind four oxygen molecules, forming iron-porphyrin complexes
  • Peptides are 2 x alpha and 2 x beta subunits (globin chains) and 4 x haem groups
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6
Q

What is meant by cooperativity in haemoglobin?

A

Cooperativity - As O2 binds to the haemoglobin, the structure subtly changes, increasing affinity for the next O2 molecule. This causes sigmoidal appearance of dissociation curve.

Goes from tense (low affinity) to relaxed state (high affinity)

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7
Q

Draw out and explain what happens to CO2 at respiring tissues

A

See image https://www.notion.so/Haemoglobin-O2-Transport-3283b4e9ac0f481386d9275c0a31e29e#b0bf795c77014ff39155573cc8b018da

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8
Q

Draw out & explain CO2 release at lungs

A

https://www.notion.so/Haemoglobin-O2-Transport-3283b4e9ac0f481386d9275c0a31e29e#b0bf795c77014ff39155573cc8b018da

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9
Q

Give a brief overview of the bicarbonate buffer system

A
  • Carbonic anhydrase quickly converts CO2 into carbonic acid (H2CO3) after it diffuses into the RBC
  • Carbonic acid is an unstable intermediate molecule that immediately dissociates into bicarbonate ions & H ions
    • This reaction allows for continued uptake of CO2 into the blood down it’s concentration gradient.
      • Also produces H+ ions, reducing pH
        • Hb binds free H+ ions, preventing from becoming too acidic
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10
Q

Describe the Bohr effect

A

The effect of acidity on haemoglobin, reducing the carrying capacity for O2:

  • CO2 can dissolve in plasma to form carbonic acid (H2CO3) which can dissociate to increase [H ions]
  • If high CO2 is produced by metabolising tissues, some of that CO2 will dissolve in the plasma & begin to increase H+ lowering pH, shifting curve to the right
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11
Q

What percentages of CO2 exist as carbaminohaemoglobin, in plasma, and as bicarbonate HCO3-

A

20%, 10% 70%

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12
Q

What is the oxygen haemoglobin dissociation curve? What does it show?

A

The ODC shows that Hb sats with O2 depends on the pO2 of plasma. As kPa of O2 increases, so does O2Hb saturation.

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13
Q

What causes left and right shift of the Hb-O2 dissociation curve, respectively?

A

Left shift - increased affinity, caused by CO2 drop, alkalosis, drop in temperature

Right shift - In hard working tissues, affinity decreases, giving up O2 easier. Caused by acidosis, increase in CO2 or temperature

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14
Q

Describe the key differences between normal and foetal haemoglobin

A

Foetal haemoglobin has a higher affinity to O2 (to ‘steal’ O2 from mother’s Hb, and is made up of 2 x alpha & 2 x gamma chains

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15
Q

What is anaemia, and some causes?

A

Insufficient RBCs or Hb.

Causes include iron deficiency, haemorrhage

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16
Q

What is cyanosis?

A

Cyanosis= purple discoloration of the skin that occurs when [deoxyhaemoglobin]becomes excessive

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17
Q

Describe what happens to Hb when CO is introduced

A

Hb binds CO 2-250x more readily than O2, so CO displaces the O (even at high PaO2) forming HbCO

Binding CO causes conformational changes that shift the disocc curve to the left (binding O2 more tightly), in addition to occupying a binding site - O2 carrying capacity would decrease

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18
Q

What are the normal dailuy inputs and outputs of fluid in the body?

A

Outputs - Sweat (100ml), faeces (100), urine (150), insensible (skin & lungs 700ml)

Inputs - 2-2.5L water/day

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19
Q

Briefly describe Fick’s law of diffusion.

A

describes the relationship between the rate of diffusion and the three factors that affect diffusion. It states that ‘the rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane’.

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20
Q

Give a quick overview of the body’s fluid compartments

A

60:40:20% body weight
Total:ICF:ECF

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21
Q

What is Starling’s principle of fluid exchange?

A

The Starling Principle states that fluid movements between blood and tissues are determined by differences in hydrostatic and colloid osmotic (oncotic) pressures between plasma inside microvessels and fluid outside them

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22
Q

What is tonicity?

A

Tonicity = the capability of a solution to modify the volume of cells by altering their water content

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23
Q

What would happen to a human cell if placed in hypotonic & hypertonic solutions, respectively?

A

Hypotonic - Cell swells & lyses due to water drawn in
Hypertonic - cell shrivels

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24
Q

What does it mean if a solution is hypertonic?

A

The solution has greater osmolality than inside cells, so cells will shrivel

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25
Q

What detects changes in fluid balance?

A

Osmoreceptors in hypothalamus, filling receptors in heart (arterial baroreceptors & atrial volume receptors) and juxtoglomerular apparatus in kidney

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26
Q

What would be the treatment for loss of hypOosmotic fluid? what would be the central theme, causes & compensation?

A

Theme - loss of plasma volume with increased plasma osmolality. Water moves from ICF to ECF as a result, shrinking cells.

Causes - decreased water intake, excess sweating, insensible loss, fever

Tretament - replace fluid with 0.9% NaCl

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27
Q

What would be the movement of fluid in the extracellular & intracellular fluid compartments, in the instance of hypernatraemic dehydration?

A

Loss of plasma volume with increased plasma osmolality - so fluid moves from ICF to ECF

ECF - decrease
ICF - increase
Osmolality (plasma) - increase

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28
Q

What happens to fluid in left & right sided heart failure, respectively?

A
  • R sided heart failure → increased fluid retention in peripheral circulation
    • Build up of fluid in veins → increased filtration → peripheral oedema (e.g. swollen ankles)
  • L-sided heart failure → increased fluid retention in pulmonary circulation
    • Fluid can build up in lungs → pulmonary oedema → serious!
29
Q

What are the four types of tissue, and their origins?

A

Connective - mesoderm
Epithelial - all
Muscle - mesoderm
Neural - ectoderm

30
Q

Show the general structure of a neuron cell

A

Show cell body, dendrites, soma, myelin, nodes of ranvier, axon, & terminal boutons.

https://www.notion.so/Intro-to-Nervous-System-8f616aa6fa574002b9bc9fc2707830ad#2e2458f5976a40bfa8b59366506f814a

31
Q

What glial cells would you find in the PNS & CNS, & what are their functions?

A
  • PNS
    • Schwann cells - Insulation (myelin) for neurones
    • Satellite cells - physical support
  • CNS
    • Astrocytes (Atroglia) - physical & nutritional support + cleaning up brain debris
    • Microglia - digests parts of dead neurons
    • Oligodendroglia - myelin for CNS
32
Q

What is neuronal tissue derived from?

A

Ectoderm

33
Q

What provides myelination in the NS?

A

PNS - Schwann cells

CNS - oligodendroglia

34
Q

What are the meninges?

A

Three layers of connective tissue that protect the brain & spinal cord.
- Dura Mater - tough thick connective tissue
- Arachnoid
- Pia mater

35
Q

Show the rough structure of a spinal cord, including roots etc

A

https://www.notion.so/Intro-to-Nervous-System-8f616aa6fa574002b9bc9fc2707830ad#479febc3e1c54d428714141f9f54fc65

36
Q

What is a dermatome?

A

An area of skin in which sensory nerves derive from a single spinal nerve root

37
Q

What are the types of sensory nerve endings?

A

Exteroceptors
- Receptors that respond to stimuli outside the body
- Special sensors e.g. photoreceptors
- Body surface sensors e.g. mechanoceptors, chemoreceptors

Proprioceptors
- Stimuli from muscles, tendons & joints
- Vital for balance & movement control

Enteroceptors (visceroceptors)
- Internal surfaces such as walls of viscera & blood vessels

38
Q

Briefly describe the main blood supply to the head.

A

4 x main arteries to head - carotid & vertebral arteries (2x), which join up at the Circle of Willis.

Jugular veins & venous sinuses drain blood.

Cerebral arteries supply the brain (anterior, middle & posterior)

39
Q

Name two organs that arose from the endoderm

A

Lung (cells), Liver (cells).

40
Q

What are haemoglobinopathies?

A

Genetic conditions from either abnormal Hb variants eg HbS (sickle cell) or reduced rate of synthesis of α or ßchains (thalassaemia)

41
Q

What are some causes of Fe deficiency?

A

Poor intake
- Poor Diet
- Malabsorption
- Increased physiological needs
Loss of iron
- Blood loss
- Menstruation, GI tract loss, parasites

42
Q

What are the main divisions of the nervous system?

A

CNS & PNS

PNS then divided into somatic (voluntary) and autonomic.

Autonomic can then be divided into Sympathetic & parasympathetic.

43
Q

When do RBCs lose their nucleus, and what cell do they arise from?

A

Erythroblast ejects nucleus before entering the bloodstream. Arises from myeloid stem cell.

44
Q

Where does erythropoiesis occur? From contraception to adulthood.

A
  • V Early foetal life - yolk sac
  • 2-5 months - liver & spleen
  • Post 5-months gestation & childhood - bone marrow
  • Adult - vertebrae; sternum; ribs; sacrum; pelvis; proximal femur
45
Q

Briefly describe how erythropoiesis is regulated

A

The hormone EPO (erythropoietin) is EPO is constantly produced by & secreted from the kidneys at a low level.

This stimulates bone marrow to produce RBCs. More is released when hypoxia is detected by the kidneys.

46
Q

What cells stimulate erythropoietin synthesis upon detecting hypoxia?

A

Renal intersitital peritubular cells

47
Q

How long do erythrocytes last, and what are they removed by?

A

~120 days. Removed by spleen, liver or bone marrow.

48
Q

What is bilirubin?

A

A yellow pigment produced as a result of haemolysis

49
Q

What are the main functions of the spleen?

A
  • F - Filtration of encapsulated organism & blood cells
  • I - Immunological function
  • S - Storage of blood
  • H - Haematopoiesis (in foetus to neonate)
50
Q

Describe the structure & function of white pulp (Spleen)

A

Structure: Lymphatic tissue arranged around branches of the splenic artery

Function: B & T cells carry out immune functions; macrophages; opsonisation of encapsulated bacteria

51
Q

Describe the structure & function of red pulp (Spleen)

A

Structure
- Blood-filled venous sinuses & cords of splenic tissue called splenic cords which consist of RBCs, macrophages, lymphocytes, plasma cells & granulocytes
- Veins closely associated with red pulp

Function
- Removal of ruptured, worn out or defective blood cells & platelets by macrophages
- Storage of platelets - up to 1/3 of bodies blood supply
- Haematopoiesis - in foetuses

52
Q

What is the haematocrit of blood?

A

Result given by FBC, showing % of blood volume as RBCs

53
Q

What does the MCH & MCHC of blood show?

A

Mean corpuscular haemoglobin (of each RBC) & mean corpuscular haemoglovin concentration (of all RBCs given)

54
Q

What does RDW mean (blood)?

A

Range deviation around RBC size

55
Q

What is transferrin, & its associated iron study?

A

Transports Fe around body.

Transferrin saturation can show % of transferrin binding sites that have been occupied by Fe.
Low = iron deficiency

56
Q

What is ferritin & its associated iron study?

A

Primary storage protein for Fe. Low ferritin indicates Fe deficient

Ferritin is increased as part of the inflammation response, which can provide a false negative

57
Q

What are the main variations of beta thalassaemia?

A

Gene variation:
- β0 - absent globin production
- B+ - reduced production

Phenotype variation
- B-thal trait - one gene abnormality

  • B-thal intermedia/major - abnormalities in both genes
    • Transfusion requirements & varying severity
58
Q

Alpha thal - what are the variations in genotype?
What are their associated phenotypes & physiological outcomes?

A

a_/aa - Asymptomatic

_ _ /aa & a_/a_ - Alpha thal trait - Microcytic anaemia

a_/_ _ - HbH disease - Anaemia & haemolysis

_ _ /_ _ Hydrops fetalis - No alpha chain production

59
Q

When does HbF become less present than HbA?

A

Around six months after birth

60
Q

List the divisions of the ANS, & what is its main function?

A

Sympathetic, parasympathetic & enteric.

Function: provides involuntary information from CNS to peripheral organs. Part of the PNS.

61
Q

Describe the general anatomy of an ANS ganglion

A

Two efferent neurones arranged in series conducting electrical activity from CNS to peripheral organ.

Pre & post-ganglionic nerves

62
Q

Describe the main differences between a parasympathetic & sympathetic nerve (length & neurotransmitter)

A

Parasympathetic - long pre & short post ganglion. Vice versa for symp.

Both pre-ganglionic fibres produce ACh for nicotinic receptors.

Parasympathetic post-ganglionic fibres produce ACh at muscarinic receptors

Sympathetic post-ganglionic fibres produce NA at alpha & beta adrenoceptors

63
Q

Post-ganglionic sympathetic nerves release NA which acts at adrenoceptors. What is an exception to this rule?

A

In sweat glands, sympathetic nerves release Ach which acts at muscarinic receptors

64
Q

How does neurotransmitter release work at adrenal glands?

A

Pre-ganglionic sympathetic fibres (ACh at nic) stimulates release of adrenaline (80%) & noradrenaline (20%) from adrenal glands.

NO post-ganglionic fibres are involved

65
Q

List some organs that only have parasympathetic & sympathetic innervation, respectively. Why is this significant?

A

Normally, organs have both symp & parasymp innervation to produce opposite effects.

Only parasymp - pancreas, secretory cells of stomach,

Symp - Sweat glands, kidney, blood vessels

66
Q

A medical student is waiting to enter the exam hall to take their first year paper. They recognise that their heart rate is increased.

What best describes the receptor involved in this response?

a) Alpha adrenoceptor
b) Beta adrenoceptor
c) Muscarinic receptor
d) NANC receptor
e) Nicotinic receptor

A

B

67
Q

A medical student is waiting to enter the exam hall to take their first year paper. The student notices that they are sweating.

What best describes the receptor involved in this response?

a) Alpha adrenoceptor
b) Beta adrenoceptor
c) Muscarinic receptor
d) NANS receptor
e) Nicotinic receptor

A

C

68
Q

What is meant by the equilibrium constant of an agonist? (Pharmacology)

A

The constant at which 50% receptors are bound to the agonist

69
Q

What is meant by the EC50 of a drug?

A

Effective concentration giving 50% biological response

M4 Y1 (6 decks)

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