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BL Flashcards

1
Q

What is the normal core temperature of the body?

A

36.5 degrees celsius to 37.5 degrees celsius

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2
Q

Below which temperature is someone considered to have hypothermia.

A

35 degrees celsius

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3
Q

How can you measure core temperature?

A

Accurate- place probe into the oesophagus, pulmonary artery and urinary bladder.
Good estimation- place probe in the rectum, oral cavity, axilla, forehead where the temporal artery is or external auditory canal.

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4
Q

What is pyrexia?

A

A high core body temperature. This can cause rigor (sudden exaggerated shaking) in adults or febrile seizures in children.

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5
Q

What is the role and main neurotransmitter in the parasympathetic system?

A

Rest and digest

Acetylcholine

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6
Q

What is the main role and neurotransmitter involved in the sympathetic nervous system?

A

Fight or flight

Noradrenaline

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7
Q

What is the main neurotransmitter in the somatic nervous system?

A

Acetylcholine

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8
Q

How are tissues prepared in order to be viewed by light microscopy?

A

Fixation- structure of tissue is preserved using formalin
Embedding medium- tissue is embedded in melted paraffin that sets hard when cooled so it allows it to be thinly sliced
Stain- H&E

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9
Q

What do haemotoxylin and eosin stain?

A

Haemotoxylin - basic so taken up by acidic components, stains nucleus blue strongly
Eosin- acidic so taken up by basic components, stains cytoplasm and extracellular matrix pink strongly

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10
Q

What are frozen sections and when are they used?

A

The tissue sample is freezed to make it solid. Inside a cryostat, a microtome cuts sections very thinly. The thin sections are stained. Pathological diagnosis may determine how surgery proceeds and this is a quick method to view tissues although technical quality is quite poor.

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11
Q

Give an example of how polarised light microscopy be used in the diagnosis of diseases.

A

Polarised light microscopy can be used to identify structures that are birefringent (can rotate the plane of polarised light).
Gout - monosodium urate crystals (MSU) show strong negative befringence
Pseudogout - calcium pyrophosphate dihydrate crystals show weak positive befringence (CPPD)

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12
Q

Give an example where fluorescent microscopy can be used in medicine.

A

Direct and indirect immunofluorescence. Monoclonal antibodies bind to specific antigens acting as markers.

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13
Q

What kind of microscopy do CAT scans resemble the imaging process of?

A

Confocal microscopy which can be used for 3D visualisation of living specimens.

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14
Q

Describe autoradiography.

A

A radioactive marker is injected into a cell culture.
A histological section that contains target molecules is coated with photographic emulsion.
This enables the places where the radioactive marker has bound to be seen.

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15
Q

What is the difference in magnification and resolution between a light microscope and transmission electron microscope.

A

Light microscope, mag- 1000x res- 0.2micrometres

transmission electron microscope, mag-250,000x res-1nm

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16
Q

Why does a transmission electron microscope have a better resolution than a light microscope?

A

The beam of electrons used in a transmission electron microscope have a shorter wave length than light.

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17
Q

Which investigative technique can be used to view plasma membranes?

A

Freeze-fracture electron microscopy

The tissue sample is frozen. It is hit with the edge of a knife so the fracture line passes through the plasma membrane.

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18
Q

Which investigative technique would allow the filiform papillae on the surface of the tongue to be viewed?

A

Scanning electron microscopy

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19
Q

Which chemical technique does MRI scanning use?

A

NMR spectroscopy

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20
Q

Which cells in the body exist normally in single cell form?

A

Spermatazoa
Ova
Blood cells

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21
Q

What temperature and for how long are red blood cells packed?

A

At 6 degrees celsius for up to 42 days

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22
Q

How are cells attached to one another laterally?

A

Tight junctions- fused plasmalemma that forms a seal preventing water and other molecules from moving through
Desmosomes- found under tight junctions and strengthen them by proteins firmly adhering the cells to one another
Gap junctions- proteins called connexons form channels that create a direct connection between cells

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23
Q

What is the basement membrane?

A

The basement membrane is the structural site for overlying cells and underlying connective tissue.

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24
Q

What is the role of integrins in integrating cells into tissues?

A
  • attachment of the cell cytoskeleton to the extracellular matrix
  • signal transduction from the extracellular matrix to the cell, they can sense whether adhesion has occurred
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25
Q

How are cells anchored on to the basement membrane?

A

Hemidesmosomes- firmly adhere cells to the basement membrane
Focal adhesions- anchor intracellular actin filaments to the basement membrane. They play a prominent role is cell movement such as the migration of epithelial cells in wound repair. They detect and transduce signals from outside of the cell.

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26
Q

How can cells in a tissue be seperated and cultured?

A

Using collegenase/microdissection

Cultured using nutrients, pH, temp, O2, need to prevent bacterial contamination

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27
Q

How do cultured cells different cells in tissues?

A

Behave and look different
Demonstrate contact inhibition
Limited life span

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28
Q

What is neurocrine communication and where does this occur?

A

Nerve cells secrete neurotransmitters into the blood stream from which they reach target cells.
Anterior pituitary, posterior pituitary, adrenal medulla

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29
Q

What are the two types of cell death?

A

Necrosis-pathological process

Apoptosis-physiological process

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30
Q

Where is cell renewal static?

A

CNS, cardiac and skeletal muscle cells

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31
Q

Where is cell renewal stable?

A

Fibroblasts, endothelium, smooth muscle cells

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32
Q

Where is cell renewal renewing?

A

Blood, skin epithelium, gut epithelium

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33
Q

How did mitochondria arise?

A

An aerobic bacterium was taken up by an anaerobic eukaryocyte.

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34
Q

What does epithelioid mean?

A

These epithelial cells do not have an apical surface.

Eg. Leydig cells in testes, Islets of langerhans in pancreas, parenchyma of adrenal gland.

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35
Q

The molecular weight (molar mass) of glucose is 180 g/mol. How many moles are there in 1 litre of a 5% solution? What is the calculated osmolality therefore of a 5% dextrose solution?

A

278mOsmol/kg

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36
Q

What is shock (tissue perfusion)?

A

A state of global cellular and tissue hypoxia due to reduced oxygen delivery caused by hypoperfusion (less blood transported to this region.)

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37
Q

What is normal plasma pH? What are our limits of survival.

A
  1. 36-7.44 is normal plasma pH

6. 8-7.8 are the pH limits of survival

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38
Q

Why are normal saline and 5% dextrose used to rehydrate patients rather than water?

A

These solutions have a similar osmolality to plasma osmolality so will not cause osmotic change whereas water is hypotonic and would cause cells to burst.

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39
Q

What units are used to measure osmolality?

A

mOsmol/kg (milliosmoles per kg)

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40
Q

What is normal plasma osmolality?

A

290mOsmol/kg

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41
Q

How do you work out osmolality?

A

Osmolality of a solution in mOsmol/kg is equal to the number of millimoles/L in solution.

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42
Q

What is the difference between osmotic and oncotic pressure?

A

Osmotic pressure refers to the pressure exerted by solutes and proteins whereas oncotic pressure refers to the pressure exerted by proteins.

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43
Q

Why do cirrhosis patients have ascites?

A

Less albumin is produced by the liver so the blood has a lower oncotic pressure which means less tissue fluid enters the capillary at the venule end. The accumulation of tissue fluid forms ascites.

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44
Q

What are the functions of connective tissue?

A

Connection - connects tissues to one another, connects organs
Protection - cushions organs and provides insulation (adipose)
Transportation - provides a medium for substances to diffuse through
Storage - (adipose tissue)
Defence - (blood lymph, fixed and wandering cells of immune system)
Wound healing - (fibroblasts, myofibroblasts, macrophages)

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45
Q

What are the three main components of any connective tissue?

A

Cells
Ground substance
Fibres

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46
Q

What is the ground substance in connective tissue.

A

It has a large water content and many proteoglycan molecules. Proteoglycan macromolecules consist of a core protein which is attached to many Glycosaminoglycans (GAGS) which are polysaccharides. GAGs attract water. Hyaluronic acid is an example of GAG and is connected to proteoglycan monomers by link proteins. Hyaluronic acid is present in cartilage.

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47
Q

What is the function of ground substance in connective tissue?

A

Transportation-provides a medium through which rapid diffusion can occur
Resists compression without inhibiting flexibility- high water content

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48
Q

What are the different types of collagen? Where are they found?

A

Type I - 90% of body’s collagen. Fibrils form fibres. Present in skin dermis, tendons, ligaments.
Type II - fibrils do not form fibres. Present in hyaline and elastic cartilage.
Type III collagen (reticulun) - fibrils form fibres to create a supporting framework. Present within lymphatic tissues and organs, around muscle and nerve cells.
Type IV collagen- present in the basal lamina of the basement membrane

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49
Q

What different types of fibres are found in connective tissue?

A 
Collagen (type I and II) - high tensile strength
Reticular fibres (type III collagen)- forms a supporting framework or sponge
Elastic fibres- allows recoil after stretch or distension (made up of elastin surrounded by microfibrils called fibrilin)
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50
Q

What are the main differences between loose and dense connective tissue?

A

Many cells in loose CT, few cells (mainly fibroblasts) in dense CT
Abundant ground substance in loose CT, little ground substance in dense CT
Sparse fibres in loose CT, many fibres in dense CT

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51
Q

What are the fixed and wandering cells in connective tissue?

A

Fixed (involved in general maintenance)
(Myo)fibroblasts, mesenchymal stem cells, macrophages, melanocytes, mast cells, adipocytes
Wandering (cells of immune system)
leukocytes, plasma cells, eosinophils, basophils, monocytes

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52
Q

What are the role of fibroblasts in connective tissue?

A

They secrete both the ground substance and procollagen which forms collagen outside of the cell.
They play an important role in wound healing and the formation of scar tissue.

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53
Q

What are myofibroblasts?

A

They are modified fibroblasts with actin filaments. They play an important role in the wound contraction when tissue loss has occurred.

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54
Q

What are the different types of dense connective tissue?

A

Dense regular CT- collagen arranged in parallel bundles, tendons, ligaments, aponeuroses
Dense irregular CT- collagen arranged in bundles orientated in various directions, dermis of skin, submucosa of intestine
Dense elastic CT- more elastic fibres than collagen, vertebrae of spinal column

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55
Q

Where is loose connective tissue often found?

A

-beneath epithelia (superficial layer of skin, submucosa of colon)
-around small blood vessels
-associated with epithelia of glands
Because they are adapted for defence (wandering cells) and transportation (ground substance)

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56
Q

What is the difference between brown and white adipose tissue?

A

They is only one lipid droplet in each white adipose cell whereas there are many lipid droplets in each brown adipose cell. The nucleus is at the periphery of white adipose cells whereas there the nucleus is in the centre of brown adipose cells. Brown adipose cells have lots of mitochondria.

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57
Q

What is the function of white adipose tissue?

A

Fuel reserve
Insulation
Shock absorption

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58
Q

What is the purpose of brown adipose tissue?

A

Non shivering thermogenesis

Lots of mitochondria mean they have a high respiratory capacity and almost all energy is converted to heat energy.

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59
Q

What is scurvy?

A

Caused by vitamin C deficiency. Fibroblasts cannot form procollagen so collagen does not form properly. This causes impaired wound healing and impaired bone formation.

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60
Q

What is osteogenesis imperfecta?

A

This is a genetic condition in which abnormal type 1 collagen is formed. This causes bones to break easily often from little or no apparent cause.

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61
Q

What is marfan’s syndrome?

A

This is a genetic disorder that is autosomal dominant. It is caused by a mutation in the gene that codes for the production of fibrilin. Therefore, elastic fibres are abnormal. Patients are abnormally tall, exhibit arachnodactyly, frequent joint dislocation and catastrophic aortic rupture.

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62
Q

What is another term for superior?

A

Cranial (towards the head); above

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63
Q

What is another term for inferior?

A

Caudal (away from the head); below

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64
Q

What is another word for anterior?

A

Ventral; in front of

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65
Q

What is another word for posterior?

A

Dorsal; behind

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66
Q

What does medial mean?

A

Towards the midline of the body

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67
Q

What does lateral mean?

A

Away from the midline of the body

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68
Q

What does intermediate mean?

A

Between a medial and more lateral structure; inbetween

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69
Q

What does proximal mean?

A

Towards the point of attachment to a limb/close to the origin of the body

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70
Q

What does distal mean?

A

Away from the point of attachment of a limb; away from the origin of the body

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71
Q

What is a directional term for the anterior surface of the hand?

A

Palmar

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72
Q

What is the posterior surface of the hand called?

A

Dorsum (dorsal region)

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73
Q

What is a directional term for the inferior surface of the foot?

A

Plantar

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74
Q

What is the directional term for the superior foot surface?

A

Dorsal

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75
Q

Structures on the same side are…

A

Ipsilateral

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76
Q

Structures on opposite sides are…

A

Contralateral

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77
Q

Movements in the sagittal plane are…

A

Flexion-bending a joint by decreasing the angle between two adjoining bones
Extension-straightening the joint by increasing the angle between two adjoining bones

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78
Q

Movements in the coronal plane are…

A

Abduction-movement away from the midline

Adduction-movement towards the midline

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79
Q

A combination of flexion, extension, abduction and adduction is…

A

Circumduction

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80
Q

Movements in the traverse plane are…

Where can this occur?

A

Lateral and medial rotation at the shoulder and hip joints

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81
Q

Special movements in the forearm are…

A

Pronation- palm facing backwards or downwards

Supination- palm facing forwards or upwards

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82
Q

Why does flexion of the thumb occur in the coronal plane and abduction of the thumb occur in the sagittal plane?

A

The thumb is placed at a 90 degree angle to the other digits. The other digits are in the coronal plane whereas the thumb is in the sagittal plane.

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83
Q

What is dorsiflexion?

A

Bending of the ankle joint towards the leg

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84
Q

What is bending of the ankle joint away from the leg called?

A

Plantarflexion

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85
Q

What are the different types of blood cells

A

Erythrocytes- carry o2 in the blood
Leukocytes- provide defence from pathegons
Thrombocytes- form a surface for clotting factors to form a definitive clot

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86
Q

How are erythrocytes adapted for their function? (3)

A

Biconcave shape-large SA: volume
Small and flexible-can squeeze through capillaries
Not many organelles - no nucleus and mitochondria so there is space for lots of haemoglobin

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87
Q

What are the cells involved in the inflammatory response?

A

Monocytes (macrophages)

Neutrophils

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88
Q

Which cells are involved in the immune response?

A

B and T lymphocytes

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89
Q

Which cells are professional antigen presenting cells?

A

Macrophages and B lymphocytes

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90
Q

What do plasma cells do?

A

Produce antibodies

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91
Q

Which cell do all blood cells originate from?

A

Haemocytoblast (multipotential haematopoietic stem cell)

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92
Q

Which cells originate from a lymphoid stem cell?

A

Lymphocytes

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93
Q

From which cell do all blood cells apart from lymphocytes originate from?

A

Myeloid stem cell

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94
Q

What do neutrophils do?

A

They are phagocytes. They are the most abundant leukocytes and can squeeze out of blood cells to where required. They are usually the first cells involved in an inflammatory response.

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95
Q

What do eosinophils do?

A

They kill parasitic worms with digestive enzymes and play a complex role in asthma

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96
Q

What do basophils do?

A

They release histamine at sites of inflammation

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97
Q

Why might a child with chicken pox develop appendicitis?

A

The vermiform appendix is a lymphatic nodule which becomes inflamed when fighting infection. This blocks the fluid in the appendix causing appendicitis.

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98
Q

What can cause inflammation?

A

Infections and autoimmune diseases

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99
Q

Describe phagocytosis.

A

Endocytosis- the cell membrane of the phagocyte forms a pouch surrounding the pathogen outside of the cell.
Phagosome- a vesicle is formed inside of the cell consisting of the pathogens contents.
Destroying and digestion- a lysosome fuses with this phagosome releasing hydrolytic enzymes that breakdown the contents of the pathogen. Reactive oxygen species are released that destroy the contents.

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100
Q

Mast cells have granules. What do these granules contain. (3)

A

Histamine- increases permeability of blood vessels
Heparin- anticoagulant
Substances that attract eosinophils and neutrophils

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101
Q

What molecules do mast cells become coated with and what does this molecule do?

A

Immunoglobulin E (IgE molecules). When IgE binds with specific allergens, contents of the granules are immediately released into cells.

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102
Q

What reactions do mast cells cause?

A

Hypersensitivity reactions, allergy and anaphylaxis

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103
Q

What are the two types of immunity mediated by lymphocytes.

A

Humoural immunity-B cells

Cell-mediated immunity-T cells

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104
Q

Are NK cells lymphocytes? Are they part of the innate response or the immune response?

A

NK cells are lymphocytes and are part of the innate response. They stimulate apoptosis in infected/abnormal cells by making holes in the cell membrane.

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105
Q

What is the cell-mediated response important in the defence of?

A

Viral, fungal, myobacterial infections
Tumour cells
Transplant rejection

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106
Q

What are the roles of T lymphocytes? (3)

A

Can directly kill infected cells by making holes in the cell membrane
Stimulate proliferation of specific B lymphocytes
Monitor antibody production and can suppress immune system when required

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107
Q

What is complement?

A

A group of serum proteins that activates:
Opsonisation-coating pathegons with an antibody to make phagocytosis more effective
Apoptosis of infected cells
Inflammation

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108
Q

When is complement activated?

A

Many different molecules activate complement. These are usually released by our cells when responding to a pathogen.

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109
Q

How does complement activate opsonisation, inflammation and apoptosis?

A

Complement proteins respond in a sequential manner called the complement cascade. This cascade is activated by the classical pathway or the alternative pathway
Classical pathway-c1 activated when bound to antigen antibody complex
Alternative pathway-c3b activated when bound to antigens
Both pathways follow the same sequence after c3

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110
Q

How many litres of fluid is picked up from tissue beds each day by the lymphatic system?

A

3 litres

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111
Q

How does lymph travel through the body

A

From the right side of the head, thorax and the right arm through lymphatic vessels to lymph nodes to the right lymphatic duct to the internal jugular vein.
From the rest of the body through lymphatic vessels to lymph nodes to the thoracic duct to the subclavian vein.

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112
Q

How do lymphatic capillaries differ to blood capillaries?

A

Lymphatic capillaries are more permeable and their endothelial cells form minivalves that allow fluid and proteins into the lymphatic capillaries.
Lymphatic capillaries are blunt ended whereas blood capillaries form a continuum feeding into venules.

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113
Q

What is the benefit of having fewer efferent than afferent lymphatic vessels in the lymphatic nodes?

A

The outlet is smaller than the inlet to the lymph node so the lymph fluid stagnates briefly giving macrophages and lymphocytes time to monitor the lymph for pathegons and process them.

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114
Q

What is the advantage of Peyer’s patches and lymphatic tissue being present in the appendix?

A

Peyer’s patches are located in the distal part of the illeum of the small intestine. The appendix is a tubelike offshoot of the first part of the large intestine. They are in an ideal position to capture and destroy bacteria that may have refluxed from the large intestine to the small intestine.

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115
Q

Which lymphatic organ gets rid of aged red blood cells and platelets?

A

Spleen

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116
Q

What propels lymph along the lymphatics? (4)

A

Skeletal muscle movement
Pressure changes in the thorax during breathing
Pulsations in adjacent arteries
Larger lymphatics in the abdomen/thorax have smooth muscle in their walls

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117
Q

What are the different types of lymphatic tissue and where are they located? (4)

A 
Diffuse =MALT (GALT and BALT)
Lymphatic nodules=
Vermiform appendix (tubelike structure connected to beginning of large intestine
Peyer's patches (distal part of small intestine-illeum)
Tonsils= pharyngeal (back of mouth), lingual (under tongue) palatine (back of nasal cavity)
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118
Q

What is the difference between lymphatic nodules and lymph nodes?

A

Lymphatic nodules have no afferent lymphatics draining into them so do not act as filters for lymph like lymph nodes do to trap antigens, process antigens and present them to T cells. Instead, lymphatic nodules act as a site of immunity where lymphocytes, macrophages and other cells of the immune system are found.

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119
Q

What are the vessels that enter and leave the lymph nodes and where are they located in the lymph node?

A 
Convex surface:
Afferent vessels-drain into lymph node 
Hilum consists of:
Efferent vessels-leave the lymph node
Vein-leaves the lymph node
Artery-enters the lymph node
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120
Q

What are the two functions of the spleen?

A

Immune function
Antigen processing presentation to T cells
Removal of macromolecular antigens
Haemopoietic function
Removal of damages old erythrocytes/platelets
Retrieval of iron from erythrocyte haemoglobin

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121
Q

When does the thymus turn into fat and lose its function?

A

After puberty

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122
Q

What is the function of the thymus?

A

Maturation of bone marrow derived lymphoid stem cells into immunocompetent T cells (thymic cell education)

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123
Q

What are the main cells involved in the lymphatic system? (5)

A

Lymphocytes= B cells, T cells, NK cells

Supporting cells=Follicular dendritic cells, macrophages

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124
Q

What is the function of follicular dendritic cells?

A

Antibody antigen complexes adhere to their dendritic processes and the cell can retain the antigen for months causing proliferation of B cells, in particular memory cells.

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125
Q

What are antigen presenting cells?

A

B cells and macrophages

They possess specific immunostimulatory receptors that allow enhanced activation of T cells.

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126
Q

Does lymph oedema pit?

A

No-fibrous tissue forms and no where for fluid to move to

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127
Q

What are the implications of splenectomy? (2)

A

Increases risk of infection by encapsulated bacteria and malaria
Increases the risk of pulmonary embolism and deep vein thrombosis due to increased platelet count

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128
Q

What are the principles of clinical examination?

A

Inspection
Palpation
Percussion
Auscultation

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129
Q

How do you assess joint function and pathology?

A

Look-redness, asymmetry
Feel-temperature, grinding
Move- active v passive

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130
Q

What type of CT makes up the deep fascia?

A

Dense irregular connective tissue

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131
Q

What type of CT makes up superficial fascia?

A

Loose areolar CT

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132
Q

What could be the causes of enlarged lymph nodes (2)

A

Infection- germinal centres fill with lymphocytes

Lymphoma-Cancers can metastasise via afferent lymphatics

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133
Q

Where are mucous membranes found?

A

They line internal tubes that open up to the exterior so they form the lining of:

  • the alimentary tract
  • the respiratory tract
  • the urinary tract
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134
Q

Where are serous membranes found?

A

Envelopes the heart-pericardium
Envelopes the lungs-pleural sacs
Enveloped abdominal organs-peritoneum

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135
Q

What are serous membranes made up of?

A

A visceral serosa
Lubricating fluid
Parietal serosa

The visceral and parietal serosa have mesothelium that secrete the lubricating fluid and a thin layer of connective tissue with nerves and blood vessels

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136
Q

What are mucous membranes made up of?

A

Endothelium-type depends where the mucous membrane is
Lamina propria-connective tissue
Muscularis mucosae-thin layer of smooth muscle in alimentary tract

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137
Q

What do mucous membranes do?

A

They form a viscous and slimy layer to trap pathegons and harmful material from the exterior

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138
Q

What do serous membranes do?

A

They provide a lubricating surface to allow movement of the organs within them without friction

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139
Q

Where is simple squamous epithelia found?

A

Endothelium
Mesothelium
Gas exchange surface of pulmonary alveoli

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140
Q

Where are simple columnar epithelia found?

A

The GI tract- the stomach and gastric glands, small intestine and colon

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141
Q

Where are stratified keratinous epithelia found?

A

In the epidermis of the skin

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142
Q

Where are pseudostratified epithelia found?

A

Lining of the nasal cavity, trachea and bronchi

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143
Q

Which epithelia are found in the thyroid follicles?

A

Simple cuboidal epithelium

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144
Q

What is the basement membrane made up of?

A 
The basal lamina laid down by the epithelial cells.
Reticular fibres (type III collagen) laid down by underlying CT
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145
Q

What epithelia is found in the upper respiratory tract?

A

Stratified non keratinous epithelia

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146
Q

Where is transitional epithelia found?

A

The urinary tract

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147
Q

What is the main difference between exocrine and endocrine glands?

A

Exocrine glands have ducts and release substances onto an epithelial surface
Endocrine glands are ductless and release hormones into the bloodstream

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148
Q

What are the three main methods of secretion by glands?

A

Merocrine - most exocrine glands, exocytosis eg. Sweat glands
Holocrine- the cell undergoes apoptosis and the secretory product along with cell debris is discharged into the lumen gland eg. Sebaceous glands of skin
Apocrine- secretory product is released in the apical portion of the cell surrounded by cytoplasm and plasma membrane eg. Mammary glands

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149
Q

What systems are affected by cystic fibrosis?

A 
The respiratory system
The gastrointestinal system 
The skin 
The vas deferens flows not develop 
The pancreas
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150
Q

What happens in cystic fibrosis?

A

The CFTR channel does not anchor into the apical membrane of epithelial cells or the CFTR gene is absent. Therefore, the movement of chloride ions is compromised. Less water leaves epithelial cells and mucus becomes viscous.

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151
Q

What is the difference between acinar and tubular glands?

A

Acinar glands look like a flask whereas tubular glands look like a tube.

152
Q

What are the main cells in the epidermis?

A

Keratinocytes-produce keratins that give skin its strength
Langerhan cells-present antigens to T cells
Melanocytes-produce melanin which absorbs UV light

153
Q

What are the layers in the epidermis starting from the surface?

A

Stratum corneum (horny layer) -corneocytes (barrier)
Granular layer - differentiation into corneocytes
Prickle cell layer - terminal differentiation
Basal layer- mitosis of keratinocytes

154
Q

Where are the blood vessels, sweat glands, sebaceous glands and hair follicles in the skin?

A

Dermis

155
Q

What tissue is the deep layer of the dermis?

A

Dense irregular connective tissue-withstands forced from multiple directions to prevent tearing and. Elastic fibres allow a degree of stretch and recoil after the skin is folded

156
Q

What is the subcutaneous layer of the skin?

A

Adipose tissue-shock absorber

157
Q

What are the functions of the skin? (7)

A 
Barrier from external insults - infection, physical, chemical Physiological - electrolyte and fluid balance 
Temperature regulation 
Sensation 
Immunological 
Vitamin D synthesis 
Psychosocial/cosmetic
158
Q

What is psoriasis?

A

Hyperproliferation of epidermis. Skins divide faster than they can be shed leading to a build up of skin cells.

159
Q

How does albinism increase the risk of cancer?

A

No melanin produced
Melanin absorbs UV radiation
UV radiation penetrates skin and damages DNA
More pyrimadine dimers to be repaired

160
Q

How does inflammation occur?

A

Vasodilation
Increased permeability of capillaries
Influx of leukocytes

161
Q

What are signs of inflammation in the skin?

A 
Redness
Heat
Pain
Swelling
Loss of function
162
Q

Describe the composition of cartilage in terms of its cells and extracellular matrix.

A

Cartilage consists of sparse chondrocytes that produce and maintain the extracellular matrix.
The ECM consists of collagen type II fibrils (dont form fibres) and many proteoglycan monomers connected to hyaluronic acid by a link protein to form large macromolecules.
There is a high ratio of GAGs to collagen. The negative charges of GAGs and the hyalorinic acid attract large volumes of water.

163
Q

95% of cartilage is extracellular matrix. Why is this important?

A

The large amount of ground substance provides a medium through which diffusion can occur from surrounding connective tissue to provide nutrients to the chondrocytes as cartilage is avascular.
The ground substance has a hydrated gel consistency which is firm but pliable allowing it to resist repeated application of pressure.

164
Q

What in cartilage attracts water?

A

Negative charges on GAGs

165
Q

What are the different types of cartilage?

A

Hyaline cartilage
Elastic cartilage
Fibrocartilage

166
Q

What type of collagen is in all types of cartilage?

A

Type II collagen

167
Q

What is the difference between hyaline and elastic cartilage?

A

Elastic cartilage has the composition of hyaline cartilage with the addition of elastic fibres.

168
Q

What is the difference between hyaline cartilage and fibrocartilage?

A

Fibrocartilage has type I collagen in addition to type II collagen. Hyaline cartilage has chondrocytes and chondroblasts whereas fibrocartilage has fibroblasts and chondrocytes.

169
Q

Which types of cartilage have a perichondrium?

A 
Hyaline cartilage (except for articular cartilage and cartilage at the epiphyseal plate)
Elastic cartilage
170
Q

How does cartilage grow?

A

Appostional growth- perichondrium has fibroblast like cells that develop into chondroblasts and thereafter chondrocytes
Interstitial growth-chondrocytes in the cartilage from isogenous groups as they divide. They then separate as they lay down extracellular matrix

171
Q

Why can’t cartilage repair easily?

A

It is avascular so there are no nutrients present

172
Q

Where is hyaline cartilage found?

A

Articulating surfaces
Epiphyseal plate until growth ceases
Trachea/bronchi/larynx
Parts of the rib cage

173
Q

Where is elastic cartilage found?

A

External ear (pinna)
Epiglottis
Eustachian tube

174
Q

Where is fibrocartilage found?

A

Intervertebral discs
Some enthesis
Pubic symphysis

175
Q

What is the last stage of endochondral ossification in an embryo?

A

Central cartilage calcifies

Nutrient artery penetrates supplying bone depositing osteogenic cells at the primary ossification centre

176
Q

What stage of endochondral ossification occurs in a baby?

A

The medulla becomes cancellous bone. Cartilage forms epiphyseal growth plates. Epiphyses develop secondary centres of ossification

177
Q

What stage of endochondral ossification occurs in prepubertal individuals?

A

The epiphyses ossify and growth plates continue to move apart, lengthening the bone.

178
Q

Which bones develop by intramembranous ossification?

A

Flat bones-skull, clavicle, scapula, pelvic bones

Appositional growth of long bones-from periosteal surfaces

179
Q

What is the difference between endochondral and intramembranous ossification?

A

In endochondral ossification, hyaline cartilage forms a template for bone to be formed.
In intramembranous ossification, differentiation of mesenchymal cells into osteoblasts.

180
Q

Which cells are involved in bone remodelling?

A

Osteoclasts=large multinucleate cells that absorb bone tissue
Osteoblasts=a cell which secretes an extracellular matrix containing type 1 collagen (osteoids)

181
Q

In which direction do resorption canals in bones form?

A

Resorption canals in mature bone run parallel wth the osteons long axes.

182
Q

Which type of collagen is present in bone?

A

Type 1

183
Q

What is the difference between spongy and compact bone?

A

Spongy bone-forms a network of trabecular to combine strength with lightness
Compact bone-regular structure composed of osteons with lamellae Haversian canals and Volksmann canals, 80% of skeletal mass

184
Q

What is the difference between haversian and volksmann canals?

A

Haversian canals run in the same line as osteons whereas volksmann canals run at a right angle to the osteons.

185
Q

Where is bone marrow in bone?

A

In the spaces between the trabeculae of spongy bone

186
Q

What four steps are involved in bone fracture repair?

A

Haematoma formation
Fibrocartilaginous callus formation
Bony callus formation
Bone remodelling

187
Q

When is bony callus formation not possible?

A

If a fracture involves loss of bone fragments. Bone banks can supply bone.

188
Q

What is osteoporosis?

A

Metabolic bone disease in which mineralised bone is decreased in mass to the point that it no longer provides adequate mechanical support. Osteoporosis always reflects increased bone resorption relative to bone formation.

189
Q

What is the difference between type 1 and type 2 osteoporosis

A

Type 1 -postmenopausal women due to decreased oestrogen which inhibits osteoclasts and stimulates osteoblasts
Type 2- elderly of both sexes due to attenuated osteoblast function

190
Q

What are the risk factors of osteoporosis?

A

Genetic-peak bone mass is higher in blacks than whites/asians
Insufficient calcium intake
Insufficient calcium absorption due to insufficient vitamin D
Exercise
Cigarette smoking in women

191
Q

What are the different types of muscle?

A

Skeletal
Cardiac
Smooth

192
Q

Which types of muscle are striated?

A

Skeletal and cardiac

193
Q

What is a myofibril?

A

A skeletal muscle fibre is made up of myofibrils. This is made up of many sarcomeres.

194
Q

What are the main differences in the structure of a skeletal muscle fibre and cardiac muscle fibre? (3)

A

Skeletal muscle fibres are longer
Skeletal muscle fibres have no cell to cell junctions whereas there intercalated discs between cardiac muscle cells
Skeletal muscle cells are multinucleate with peripheral nuclei whereas cardiac muscle cells have 1 or 2 central nuclei

195
Q

Which type of muscle is voluntary and which type of muscle is autonomic?

A

Cardiac and smooth = autonomic

Skeletal = voluntary

196
Q

Is regeneration of skeletal muscle possible?

A

Yes by the mitotic activity of satellite cells but this is limited

197
Q

What is muscle atrophy?

A

Destruction of contractile proteins > regeneration of contractile proteins
Muscle fibre decreases in diameter
Muscle wastage and power lost

198
Q

What are the different causes of muscle atrophy?

A

Disuse atrophy
Denervation atrophy
Atrophy with age

199
Q

In an electron micrograph of skeletal muscle, some fibres appear darker than others. Why?

A

Darker fibres = red muscle fibres

Lighter fibres = white muscle fibres

200
Q

Does white or red skeletal muscle fatigue more quickly and why?

A

White because there are fewer mitochondria, it is more poorly vascularised. More anaerobic respiration. Increased lactate production.

201
Q

Is there a higher proportion of red or white skeletal muscle in the postural muscles of the back. Why?

A

Red. Fatigue less easily

202
Q

What connective tissue is present in a skeletal muscle?

A

Epimysium-surrounds muscle
Perimysium-surrounds fascicle
Endomysium-surrounds each fibre

203
Q

In an electron micrograph of a sarcomere. There are dark lines and light lines. What are these?

A

Dark lines = A band actin and myosin filaments

Light lines = I band actin filaments

204
Q

Describe the sliding filament mechanism.

A
  1. Myosin head binds to actin binding site. Myosin head has ADP and Pi bound.
  2. Power stroke-myosin head pulls actin towards M line. ADP and Pi released from myosin head.
  3. Myosin head detaches from actin binding site. ATP binds to myosin head.
  4. Myosin head cocks back to original position. ATP is hydrolysed from myosin head.
205
Q

What is rigor mortis and why does it happen?

A

Stiff muscles after death.

No ATP produces so cross bridges cannot detach.

206
Q

Describe the regulatory proteins attached to actin.

A

Tropomyosin is coiled around the actin helix and blocks the binding sites.
Troponin complex bound to the myosin. Ca2+ binds to troponin C and removes the blocking effect of the tropomyosin.

207
Q

What is the frank-starling law?

A

As ventricular end-diastolic volume increases, stroke volume increases up until a certain point after which it decreases.

208
Q

Why does stroke volume decrease after a certain ventricular end-diastolic volume?

A

The cardiomyocytes have been stretched too much. The actin filaments have been pulled so far apart from the M line that the myosin filaments are no longer able to pull the actin filaments towards the M line during contraction

209
Q

What are purkinje fibres?

A

Modified heart muscle cells.
Lots of gap junctions as they carry action potentials
Carry impulses from the Bundle of His to the ventricles

210
Q

Which type of muscle can multiply by mitosis?

A

Smooth muscle

211
Q

Do all muscle cells have sarcomeres?

A

Smooth muscle cells dont

212
Q

Describe the structure of smooth muscle cells (3)

A

Fusiform
Single central nucleus
Gap junctions

213
Q

How do each type of muscle respond to demand?

A

Cardiac and skeletal = hypertrophy

Smooth = hyperplasia and hypertrophy

214
Q

How can muscle length be adjusted?

A

Increased in length = addition of sarcomeres caused by frequent stretching
Decreased in length = loss of sarcomeres caused by infrequent stretching

215
Q

What is fibrillation and fasciculation?

A

Fibrillation- contraction of individual muscle fibres

Fasciculation - contraction of individual fascicles

216
Q

Which enzyme can be used for the diagnosis of muscle injury?

What does an increase in this enzyme show?

A

Creatine kinase- increases in response to muscle use and damage
Increase is proportional to myocardial infarction size

217
Q

What is myoglobinuria?

A

Myoglobin in urine

218
Q

Does red or white skeletal muscle have more myoglobin?

A

Red

219
Q

Which protein can be used as an indicator for a myocardial infarction?

A

Troponin I

220
Q

What does exercise do to muscles?

A

Increase in contractile proteins
Increase in fibre diameter
Hypertrophy of skeletal muscle cells

221
Q

What are ANP and BNP?

A

They are natriuretic peptides synthesised in response to atrial an ventricular distension respectively. They decrease blood pressure by stimulating vasodilation and decreasing reuptake of Na+ in kidneys

222
Q

What can be used as an indicator for left ventricle dysfunction?

A

BNP - left ventricle distension increases

223
Q

What does left ventricle dysfunction cause?

A

Pulmonary oedema

Paroxysmal nocturnal dyspnoea

224
Q

What can aortic valve stenosis cause?

A

Left ventricle dysfunction

225
Q

There is a blockage in the main arteries in the legs. Why is amputation necessary?

A

Dying cells release K+ into the bloodstream. This will affect the electrical activity of the heart and can lead to heart failure.

226
Q

What is resting heart rate?

A

70 beats per minute

227
Q

What is average stroke volume?

A

70ml

228
Q

How long does it take for total blood volume to circulate?

A

1 minute

229
Q

Describe the distribution of blood in the vessels.

A

Peripheral Veins - 65%
Capillaries - 5%
Peripheral Arteries - 10%
Heart and lungs - 50 %

230
Q

How does blood flow through the body?

A

Heart - large elastic arteries - medium muscular arteries - arterioles - metarterioles - capillaries - postcapillary venules - small veins - medium veins - large veins - heart

231
Q

Describe the structure of a blood vessel from inside to outside.

A

Tunica intima - endothelium, subtending endothelial layer, internal elastic lamina
Tunica media - smooth muscle, fibres, external elastic lamina
Tunica adventitia - CT consisting of vasa vasorum, nerves, fibroblasts, macrophages

232
Q

What are the main differences in the structure of arteries and veins.

A

Veins tend to have a larger diameter than their accompanying artery
Veins have a thinner wall than their accompanying artery. The tunica media in veins is thinner than that in arteries.
Veins have a relatively thicker tunica adventitia to their tunica media whereas arteries have a relatively thicker tunica media to their tunica adventitia

233
Q

Describe the wall of capillaries and post capillary venules

A

Endothelial layer

Layer of pericytes- can differentiate into smooth muscle or fibroblasts when new blood vessels form/during wound healing

234
Q

What is an end artery?

A

A terminal artery supplying all or most of the blood to a body part with no significant collateral circulation to the region supplied by this artery.

235
Q

What are the consequences of a blood clot forming in an end artery?

A

Ischaemia
Hypoxia leading to pain as this is detected by pain receptors
Tissue death

236
Q

Give examples of some end arteries.

A 
Coronary artery
Splenic artery
Renal arteries
Central artery to retina
Cerebral arteries
237
Q

What property of coronary arteries means that they do not collapse when the heart contracts?

A

Bridging during systole-when the heart contracts the coronary arteries change by the nature of muscle contraction maintaining circulation. They then return to their original shape so blood flow to the heart is not distrupted

238
Q

When can natural collateral circulation develop?

A

In response to stenosis. It cannot develop when there is an immediate blood clot as it takes weeks to months.

239
Q

What is average blood pressure in a healthy individual?

A

120/80 mm Hg
120 = systolic pressure in aorta
80 = diastolic pressure in aorta

240
Q

Why is the aorta known as a pressure reservoir?

A

During systole, the elastic fibres in the tunica media of the aorta allow the wall to stretch and this stores elastic energy. During systole, the elastic potential stored in the wall is released as the wall recoils. This maintains a high blood pressure between heart beats.

241
Q

Why is the infrarenal abdominal aorta a common site for aneurysms?

A

There are relatively few elastic fibres in the tunica media here so when the wall stretches, there is less recoil. Therefore, the wall is more prone to dilation.

242
Q

Where does vasoconstriction occur?

A

Muscular arteries and arterioles

243
Q

When you have just finished a meal where is blood directed to and taken away from?

A

Directed to gut

Less to skeletal muscle

244
Q

What controls blood supply to capillaries?

A

Pre-capillary sphincters in the metarterioles. This is a ring formed by a single smooth muscle cell around the endothelium at the beginning of a capillary. When the sphincters close, blood bypasses the capillary bed and flows through the thoroughfare channel to the postcapillary venules.

245
Q

Why are veins called capacitance vessels?

A

They have the ability to hold a large volume of blood without a large increase in pressure.

246
Q

How does venous blood get from the legs back to the heart in a standing human? (4)

A

Calf muscles act as a pump for deep veins
Valves prevent back flow through veins
Decreased pressure in thorax when we breath in
Wide lumen and smooth endothelium of veins

247
Q

What causes venous hypertension?

A

Failure of calf muscles to pump blood up

Incompetent valves in veins

248
Q

Why does venous hypertension cause venous ulceration?

A

No pressure gradient between arteries and veins. So blood remains static in the legs. White blood cells accumulate and proteins leak from the veins causing ulceration.

249
Q

What is venous pooling?

A

Too much blood collects in the lower limbs and there is insufficient return of blood to the heart due to insufficient use of calf muscles

250
Q

What is the difference between muscular atrophy and dystrophy?

A

Muscular Dystrophy is the name given to a group of diseases which cause progressive weakness in the muscles due to a genetic defect. Muscular Atrophy describes another group of diseases which cause a progressive degeneration of the spinal nerves and wasting of the muscles that they control.

251
Q

What are the accessory organs of the digestive system? (4)

A

Salivary glands
Liver
Gallbladder
Pancreas

252
Q

What are the different components of the alimentary canal?

A

Mouth, tongue, pharynx, oesophagus, stomach, duodenum, jejunum, ileum, sigmoid colon, ascending colon, transverse colon, descending colon, rectum, anus

253
Q

Describe the general structure of the gut wall from inside to outside

A

Gut mucosa
Submucosa
Muscularis externae
Serosa (for organs that lie within the peritoneum) or adventitia

254
Q

What are the different layers of the mucosa in the gut?

A

Epithelia- simple columnar from stomach to large intestine
Lamina propria- CT bearing glands, lympatics, nerves and blood vessels
Muscularis mucosae-thin layer of muscle

255
Q

What is the gut mesentery?

A

A fold of the peritoneum that attaches the stomach, small intestine, pancreas, spleen and other organs to the posterior abdominal wall

256
Q

How many layers are there in the muscularis externae of the gut? What are they?

A 
2 layers in most of the GI tract
Inner circular muscle layer
Outer longitudinal muscle layer
3 layers in the stomach
Oblique muscle layer
257
Q

What are the functions of the GI tract? (3)

A

Secretion and digestion-digestive enzymes and hormones
Absorption - nutrients and water
Movement - of digested food

258
Q

What is digestion?

A

Conversion of what we eat by physical and chemical disruption into a relatively sterile, isotonic, pH neutral form from which we can absorb sugars , amino acids, fatty acids, minerals and vitamins.

259
Q

What are the functions of saliva? (5)

A

Initial digestion-contains amylase and lipase
Bacteriostatic-immunoglobulin A binds to bacteria to prevent multiplication
Protects teeth-high calcium
Protects from acid reflux-alkaline
Aids swallowing-lubrication

260
Q

In what form does food enter the oesophagus?

How does food travel through the GI tract from here?

A

In a bolus

Longitudinal muscle of muscularis externae produces peristaltic waves

261
Q

What are the functions of the stomach?

A

Storage-we eat faster than we can digest. Wall relaxes so pressure doesn’t rise by receptive relaxation.
Digestion-physically churns food using 3 layers of muscle and mucosal rugae, protealytic enzymes eg. Pepsin digest proteins. Acid breaks down molecules.
Disinfection-acid kills pathegons

262
Q

In what form does food leave the stomach?

A

Incompletely digested chyme

263
Q

What is the role of the duodenum? (4)

A

Dilution-water is drawn from the extracellular tissue fluid to make the hypertonic chyme isotonic
Neutralisation-bile produces by liver and secreted by gall bladder is alkaline and neutralises acidic chyme. Brunner’s glands in the walls secrete bicarbonate rich mucus. Pancreas produces alkaline solution
Digestion-bile emulsifies fat. pancreas and intestine produce enzymes that digest proteins, polysaccharides, fats and nucleic acids.
Absorption-absorbs iron

264
Q

What is the function of the jejunum?

A

Absorbs most sugars, amino acids and fatty acids.

265
Q

What is the function of the ileum?

A

Absorbs vitamin B12, bile acids and remaining nutrients

266
Q

What are the functions of the large intestine?

A

Absorption-water absorbed
The bacteria in the large intestine have the following roles:
-synthesis of vitamin K, B12, thiamine, riboflavine
-breakdown of 1 degree bile acids
-conversion of bilirubin to non-pigmented metabolites
There are then absorbed by the large intestine.

267
Q

Which parts of the gut do we have voluntary control over and why?

A

First 1/3 of oesophagus
Rectum
There is some skeletal muscle present

268
Q

Which epithelia is present in the oesophagus and why?

A

Stratified squamous non-keratinised epithelia.
Withstands abrasion
Reduces water loss but remains moist

269
Q

Describe the structure of the mucosa of the stomach.

A 
Gastric mucosa forms rugae.
-epithelium-simple columnar epithelium
Forms gastric pits 
-lamina propria
-muscularis mucosae
270
Q

What is a gastric pit?

A

This is an invagination of the simple columnar epithelia in the stomach.
Pit - surface mucous cells. mucus secreted is resistant to pepsin degradation. Contains HCO3- that neutralises H+ protecting lining
Isthmus-stem cells-populate gland by upwards/downwards migration
Neck
Base - chief cells-secrete pepsinogens
In the isthmus, neck and base:
parietal cells- secrete H+ into lumen, secrete HCO3- into capillaries
Enteroendocrine cells- G cells secrete gastric into capillaries

271
Q

How is mucus secreted in the stomach? What are the functions of this mucus?

A

Surface mucus cells of the gastric pits secrete mucus.
In response to distension of stomach and acid secretion by parietal cells.
Mucus contains HCO3- which neutralise H+ ions

272
Q

Why are the parietal cells of gastric pits endocrine and exocrine?

A

Exocrine-H+ is secreted into the lumen of the gastric gland
Endocrine-HCO3- is secreted into the nearby capillaries. This is transported the surface mucus cells which secrete the HCO3- in the mucus

273
Q

Which cells of the gastric pits secrete pepsinogens?

Where in the pit are they found?

A

Chief cells

Base of gastric pit

274
Q

Which cells of the gastric pits secrete gastrin into capillaries?

A

Enteroendocrine cells, G cells

275
Q

Where does replacement of cells occur in the gastric gland?

A

Stem cells in isthmus

276
Q

What does the duodenum curve around?

A

The head of the pancreas

277
Q

How is the jejunum adapted for absorption?

A

Large surface area
The mucosa and submucosa forms plicae circularis
The epithelia forms villi (lacteals in centre)
The epithelia have microvilli

278
Q

How much bile do we produce each day?

A

1 litre

279
Q

How much fluid is added to the food we eat by the body each day?

A

14 L

280
Q

Where are the neuronal plexuses that control the digestive system found?

A

Between the muscle layers of the muscularis externae

Between the submucosa and muscularis externae

281
Q

What hormones are involved in the endocrine control of the digestive system?

A

Secretin
Cholecystokinin (CCK)
Gastrin

282
Q

What is the function of secretin?

A

Promotes bicarbonate secretion by pancreas
Promotes bile production by liver
Inhibits acid secretion by parietal cells

283
Q

What does cholecystokinin do?

A

Synthesised and secreted by enteroendocrine cells in duodenum
Stimulates release of digestive enzymes from pancreas
Stimulates release of bile from gall bladder
Hunger surpressant

284
Q

What does gastrin do?

A

Released by G cells in stomach, cells in pancreas and duodenum.
Stimulates HCL production by parietal cells of stomachs

285
Q

The hepatic portal vein transports blood from what sections of the GI tract?

A

Lower oesophagus to the rectum

286
Q

What are the blood supplies to the liver?

What proportion of blood entering the liver comes from these vessels?

A

Hepatic artery - oxygenated blood 25%

Hepatic portal vein - blood from GI tract 75%

287
Q

What is a portal system?
How many portal systems are there in the body?
What are they?

A

2 capillary beds in series.
There 2 in the body
Hepatic portal system
Hypothalamo-Hypophyseal portal system

288
Q

What is travelling in the hepatic portal vein?

A

Water soluble vitamins
Electrolytes
Carbohydrates
Amino acids
Intestinal hormones-particularly pancreatic hormones
Harmful chemicals, bacteria, viruses, tapewords, flukes

289
Q

What is not travelling in the hepatic portal vein?

A

Lipids

Lipid soluble vitamins eg. A D E K

290
Q

How do lipids enter the liver?

A

Processed into chylomicrons by cells of small intestine
Absorbed by lacteals at the centre of villi
Lacteals consist of chyle - lymph and chylomicrons
Drain to thoracic duct via subclavian vein
Enter the liver via hepatic artery

291
Q

What are the functions of the liver?

A

-conversion of ammonia to urea.
This urea is transported in the systemic circulation to the kidneys to be excreted in urine.
-exocrine- 1 litre of bile produced each day
-endocrine- produces angiotensinogen, thrombopoetin, breakdown insulin, glucagon, oestrogen, progesterone
-storage-iron, vitamin K A D B12. Vitamin A by stellate ito cells
-anabolism- plasma proteins eg. Albumin, complement components, glycogen, haematopoiesis in fetes
-catabolism-drugs, hormones, haemoglobin, poisons, can take over RBC removal after splenectomy
Filter-specialised macrophages=kupffer cells

292
Q

What is the main type of cell in the liver?

A

Hepatocytes

293
Q

Describe the structure of a liver lobule.

A

Polygonal
At each point, the portal triad.
Hepatic portal vein and hepatic artery merge into sinusoid which flow towards centre to the hepatic vein.
Bile canaliculi flow in the opposite direction towards bile duct

294
Q

What specialisation do the hepatocytes of the liver lobule have to ensure maximal absorption?

A

Microvilli that extend into the space of disse between the hepatocytes and sinusoid

295
Q

What cells line the sinusoid?

A

Kupffer cells-specialised macrophages

296
Q

Why is a liver acinus more physiologically important than a liver lobule?

A

If there are bacteria or viruses flowing through the hepatic portal vein or if there is a lack of oxygen/glucose in the hepatic artery, a liver acinus is affected rather than a liver lobule.

297
Q

Why are stellate ito cells thought to have a role in liver cirrhosis?
How does liver cirrhosis lead to portal hypertension?

A

Stellate ito cells lose vitamin a storage
Differentiate into myofibroblasts
Secrete collagen into the space of disse
Liver fibrosis
Collagen surrounds the centra vein constructing it leading to portal hypertension.

298
Q

What is the role of surfactant in alveoli?

A

Decreases surface tension. Surface tension increases pressure so indirectly decreases pressure.

  • allows the alveoli to expand during inspiration. Decreases surface tension more here as the surfactant molecules are closer together
  • prevents the alveoli from collapsing onto themselves during expiration. Decrease surface tension less than they do during inspiration because the surfactant molecules are further apart
299
Q

What is surface tension in the alveoli?

A

There is alveolar fluid on the walls of the alveoli. The water forms hydrogen bonds with other water molecules more readily than it forms bonds with air. The strong attraction of water for water molecules means that it favours a conformation with the smallest surface area and this makes the alveoli have a tendency to collapse. This increases the pressure in the alveoli.

300
Q

Describe 2 ways in which pressure in the alveoli can be decreased.

A

Decreased surface tension

Increased radius

301
Q

What about the structure of alveoli allows it to expand during inspiration?

A

Basketwork of reticular and elastic fibres

302
Q

The pressure of the intrapleural space is always relatively negative to the intrapulmonary pressure. Why is this important?

A

Keeps the lungs firmly adhered to the visceral pleura
Keeps the visceral and parietal pleura close together
Keeps the parietal pleura firmly adhered to chest wall

303
Q

Why does pneumothorax cause the lungs to collapse?

A

Air enters the intrapleural space.
Pressure increases
Lungs are no longer adhered to the visceral pleura and hence the chest wall so they recoil and collapse

304
Q

What is usually in the intrapleural space?

A

Lubricating fluid which prevents friction when the lungs expand and collapse

305
Q

What is the difference between an open and closed pneumothorax?

A

Open- opening in chest wall

Closed- no opening in chest wall, rupture of visceral pleura

306
Q

What is empyema?

A

Pus in the intrapleural space

307
Q

Where is a chest drainage system fitted in?

A

7th intercostal space. Closer to the lower rib because in the costal ridge above there is an artery, vein and nerve. Any lower than this space has risk of hitting diaghragm.

308
Q

What is a pancoast tumour?

A

Tumour in the left/right lung apex

309
Q

Which structures can a pancoast tumour impinge upon and what are the consequences of this? (4)

A 
Left pharyngeal nerve - hoarse voice
Brachial nerve (innervates lower arm) - muscle wastage in hands 
Sympathetic trunk (innervates face particularly eye) - Horner's syndrome. Upper eyelid drooping, no pupil dilation.
Phrenic nerve (innervates diaghragm)- paralysis of ipsilateral diaghragm
310
Q

What is the conductory portion of the respiratory system?

A 
Nasal cavity
Pharynx
Larynx
Trachea
Primary Bronchi
Secondary bronchi
Bronchioles
Terminal bronchioles
311
Q

What is the respiratory portion of the respiratory system?

A

Respiratory bronchioles
Alveolar ducts
Alveoli

312
Q

Which epithelia are present in the respiratory system

A

Upper portion till bronchi -pseudostratified epithelia with cilia and goblet cells
Bronchioles - simple columnar epithelia with cilia and clara cells
Respiratory bronchioles and alveolar ducts - simple cuboidal epithelia with few cilia and clara cells
Alveoli - simple squamous epithelia with Type I and Type II pneumocytes

313
Q

What region in the nose senses odour and what do Bowman’s glands here do?

A

Olfactory regions

Serous glands flush odourants from epithelia surface

314
Q

What type of cartilage is present in the trachea and bronchi and what is the difference between the cartilage present in these structures?

A

Hyaline cartilage
Trachea - C-shaped
Bronchi - Ring

315
Q

In COPD why is there excess mucus?

A

Goblet cell hyperplasia
Submucosal gland hypertrophy
Greater proportion of goblet cells to ciliated cells
More mucus and less ciliated cells to move it

316
Q

Why do asthmatics have more difficulty with expiration than inspiration?

A

There is inappropriate bronchoconstriction narrowing the airways.
During inspiration, the expansion of the alveoli keeps the bronchioles open.
During expiration, the alveoli collapse and there is no force keeping the bronchioles open.

317
Q

What can alveoli open to?

A

Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Another alveolus

318
Q

What type of cells are present in alveoli?

A

Type 1 90% -simple squamous for gas exchange

Type 2 10% - more cuboidal and secrete surfactant

319
Q

What are clara cells?

A

Cells that secrete surfactant which is a lipoprotein that reduces surface tension
Secretes a measurable marker protein
Less protein in bronchoalveolar lavage indicates lung damage
Increased protein in serum indicates leakage between blood air barrier

320
Q

Where are clara cells found?

A

In the respiratory tract as the bronchioles become smaller

321
Q

What is emphysema?

A

Destruction of alveolar walls leading to permanently enlarged air spaces. Alveolar walls usually keep the bronchioles open allowing air to leave the lungs on exhalation. It is more difficult for air to leave as bronchioles collapse and there is a reduced pressure gradient.

322
Q

What is a sign of emphysema?

A

Pursed lip breathing to increase pressure in lungs and keep airways open

323
Q

What is pneumonia?

A

Bacteria in the lungs causes inflammation. Fibrous tissue forms and fluid can leak into the lungs.

324
Q

What type of gland is a mammary gland?

A

Apocrine

325
Q

What hormones stimulate secretion of milk from a mammary gland?

A

Oxytocin and prolactin

326
Q

What prevents bacteria in the colonic wall from invading the underlying tissues?

A

No microvilli

Lots of GALT

327
Q

What are the different divisions of the nervous system?

A

CNS = spinal cord and brain
PNS = spinal and cranial nerves
2 divisions of PNS =
somatic (voluntary) innervates skeletal muscle - spinal nerves
autonomic (involuntary)-innervates cardiac and smooth muscle -cranial nerves

328
Q

Why is the cerebellum highly folded?

A

To fit many neurones into a small volume

329
Q

What are bundles of axons called in the CNS and PNS?

A

CNS - tracts

PNS - nerves

330
Q

What are collections of neuronal cell bodies called in the CNS and PNS?

A

CNS-nuclei

PNS- ganglia

331
Q

Where is the grey matter and white matter located in the spinal cord and brain? What is the difference between them?

A

Grey matter is in the centre of the spinal cord, in the centre of the brain where the nuclei are, and at the periphery of the brain.
This is where collections of nerve cell bodies/inteneurones are and is the location where information processing occurs.
White matter is at the periphery of the spinal cord, in between the grey matter in the brain. This is where the neuronal axons are and where information transfer occurs

332
Q

What are the functions of the 3 different types of nerves in the PNS and where are they?

A

Sensory neurones-pseudo-unipolar cell with only one process to the cell body. Carries sensory information. In the dorsal root.
Interneurones- Information processing occurs here. In the grey matter of the spinal cord.
Motor neurones- multipolar neurone cell with lots of processes (dendrites) to the cell body. Carries motor information. In the ventral root.

333
Q

What connective tissues are present in a spinal nerve?

A

Endoneurium
Perineurium
Epineurium

334
Q

What types of responses does the parasympathetic nervous system control? (At least 4)

A 
Constrict pupils 
Stimulate saliva 
-Slow heartbeat
-Constrict airways 
-Stimulate activity of stomach and small intestines
-Inhibit release of glucose and stimulate gall bladder 
Contract bladder 
Promotes erection of genitals
335
Q

What types of responses does the sympathetic response control? (At least 5)

A

Dilate pupils
-inhibit salivation
-increase heartbeat
-vasoconstriction - more blood directed to heart, brain, muscle by less to skin and digestive organs
-relax airways
-inhibit activity of stomach and small intestines
-stimulate release of glucose and inhibit gallbladder
-secrete adrenaline/noradrenaline from adrenal glands
Relaxation of bladder
Inhibit erection of genitals

336
Q

How is the control of vasoconstriction maintained?

A

Sympathetic nerve fibres innervate all vessels except capillaries and metarterioles.
Increased activity of sympathetic nervous system - strong sympathetic tone. Venoconstriction and vasoconstriction.
Decreased activity of sympathetic nervous system - decreased sympathetic tone. Venodilation and vasodilation.

337
Q

Give three differences between neuronal and endocrine control?

A

Neuronal- short-lived, endocrine- long-lived
Neuronal- fast, endocrine- slow
Neuronal- localised, endocrine- widespread
Neuronal- impulses along neurones, endocrine- hormones in blood stream

338
Q

How does the endocrine system and the nervous system communicate?
Where does this occur

A

Neurocrine communication
Neurotransmitters are secreted into the blood by neurones.
Occurs in the hypothalamus, posterior pituitary and adrenal glands.

339
Q

What are the main endocrine organs?

A 
Pineal gland
Thyroid gland
Parathyroid gland
Adrenal glands
Hypothalamus 
Pituitary gland 
Thymus 
Pancreas
Gonads
340
Q

What is the endocrine function of the skin?

A

Vitamin D production

341
Q

What is the endocrine function of the heart?

A

ANP and BNP production

342
Q

What is the endocrine function of the thymus?

A

Produces thymosin which converts haematapoietic stem cells into immunocompetent T cells - thymic T cell education
The thymus is fully formed and functional at birth. Involutes after puberty and by late teens is mostly fat.

343
Q

What processes do hormones control and regulate? (5)

A 
Reproduction
Metabolic and energy balance
Growth and development
Body defences
General homeostasis, water, nutrient and electrolyte balance of the blood.
344
Q

What is the chemical nature of different types of hormones

A

Peptide hormones eg. Insulin
Steroid hormones eg. Oestrogen
Catecholamines eg. Adrenaline

345
Q

Where is the point of contact between the CNS and the endocrine system?

A

Hypothalamus

346
Q

What hormones does the hypothalamus produce?

A

ADH (antidiuretic hormone) and oxytocin

6 hormones that travel via the hypothalamo-hypophyseal portal system to the anterior pituitary

347
Q

What is the role of the thyroid gland?

A

Controls metabolic rate by producing thyroxin

348
Q

Explain the control of the thyroid gland via the short and long loop.

A

Hypothalamus produces TRH. TRH is secreted into the bloodstream by neurocrine communication to the anterior pituitary.
Cells in the anterior pituitary are stimulated to produce and release TSH.
TSH travels in the blood stream to the thyroid gland. The thyroid gland is stimulated to release thyroxin.

There is a negative feedback loop to the anterior pituitary by the short loop and to the hypothalamus by the long loop.

349
Q

What is physiological stress?

A

Threat to homeostasis
Threat can be real/perceived
Activates range of endocrine, nervous and immune responses.

350
Q

How does the adrenal gland secrete adrenaline?

A

The sympathetic nervous system is activated by a stress stimulus.
Impulses travel from the thoracic and lumbar region to the adrenal gland via myelinated pre-ganglionic nerves
The post-ganglionic nerve is modified to be chromaffin cells. When stimulated by acetylcholine, it releases the neurotransmitter adrenaline into the blood by neurocrine communication.

351
Q

What are the four major effects of adrenaline and noradrenaline?

A

Increased heart rate
Increased blood pressure
Increased blood glucose concentrations is increased metabolism
Blood flow to heart brain and skeletal muscle increases and blood flow to digestive organs and the skin decreases.

352
Q

Why does blood flow to the skin decrease in the sympathetic response?

A

To reduce the risk of injury

353
Q

Does neurocrine communication occur in the anterior or posterior pituitary lobe?

A

Posterior

354
Q

Where is oxytocin and ADH produced and released?

A

Produced in the hypothalamus and transported to the posterior pituitary gland in neuronal axons where it is secreted into the blood stream by neurocrine communication.

355
Q

What hormone does the pineal gland produc and what is this hormone involved in?

A

Melatonin and the control of Cincardian rhythms

356
Q

Which gland calcifies in early adulthood and which gland becomes fat by late teens?

A

Calcifies-pineal gland

Becomes fat-thymus

357
Q

Give the basal concentrations of these free ions in intracellular and extracellular fluid.
Na+ , K+ , Cl- , Ca2+ , HCO3-

A 
Intracellular:
Na+ = 10mM
K+ = 160mM 
Cl- = 3mM 
Ca2+ = 1x10-4mM
HCO3 = 10mM
Extracellular:
Na+ = 145mM
K+ = 4.5mM
Cl- = 114mM
HCO3- = 31mM
358
Q

What is all connective tissue derived from?

A

Mesenchymal stem cells

359
Q

What connective tissue underlies all epithelial tissue providing it with nutrients?

A

Areolar connective tissue

360
Q

Suggest why the epidermis grows from the basal layer upwards rather than from the stratum corneum downwards.

A

The epidermis is avascular because it is an epithelial tissue. It requires nutrients for growth from the areolar connective tissue that underlies the basal layer.

361
Q

Give examples of locations where cells are stable, static and renewing.

A

Stable-fibroblasts, endothelium, smooth muscle
Static-CNS, heart and skeletal muscle
Renewing-blood, skin epidermis, gut epithelia

362
Q

Why are mutations in the p53 gene thought to be a major step in transition from pre-malignant to malignant cancer?

A

Inactivation of the DNA damage response causes cancer.
The DNA damage response either involves:
-repair of DNA
-apoptosis
Activation of the p53 gene stimulates apoptosis. Therefore, mutations of this gene lead to damages DNA persisting in the next generation of cells because apoptosis is not stimulated.

363
Q

What does a higher than usual serum osmolality indicate?

A

Dehydration

364
Q

What does a lower than usual serum osmolality indicate?

A

Over hydration

Oedema

365
Q

Movements occur…

A

In a given plane
At a joint
With reference to the anatomical position

366
Q

What is the bone matrix made up of?

A

Osteoid- unmineralised matrix made up of type 1 collagen and GAGs
Calcium hydroxyapatite- calcium salt that gives bone its rigidity and strength

367
Q

What are the main differences between immature bone and mature bone?

A

Immature bone is woven bone. The type 1 collagen is arranged randomly. Osteocytes are randomly arranged.
Mature bone is lamellar bone. The type 1 collagen is arranged in a parallel manner in regular rings. Osteocytes are arranged in between lamellae.

368
Q

Distinguish the following: Haversian canal, Volkmann’s canal, canaliculi.

A

Haversian canals are central channels in bone that contain nerves, vessels, and lymphatics. They all run parallel to each other but are connected perpendicularly by Volkmann’s canals. Canaliculi are tiny extensions of the osteocytes through the bone matrix. They allow these isolated cells to communicate with one another.

369
Q

List the layers of a long bone starting from the outside.

A 
Periosteal surface of compact bone
Outer circumferential lamellae
Compact bone (Haversian systems) - interstitial lamellae of osteons
Inner circumferential lamellae
Endosteal surface of compact bone
Trabecular bone
370
Q

Which bones are formed by intramembranous ossification?

A

Flat bones- skull, clavicle, pelvis, scapula

371
Q

Describe growth at the epiphyseal growth plate.

A

Reserve cartilage
Proliferation- cells actively dividing forming columns and they secrete matrix
Hypertrophy- cells enlarge
Calcified cartilage-cells degenerate, matrix calcifies
Resorption-chondrocytes die and bone is laid down on cartilage spicules upon which osteoids are laid

372
Q

When does bony callus formation occur after a fracture?

What is the duration of bony callus formation?

A

2 days after fracture in young people
1 week after fracture in older people
Continues for around 2 months until a very firm union is formed

373
Q

Why is the final remodelled bone the same shape as the original bone?
What is the duration of bone remodelling?

A

Osteoblasts and osteoclasts respond to the same mechanical pressures.
Duration-several months

374
Q

What reaction does creatine kinase catalyse?

A

Creatine + ATP —> phosphocreatine + ADP

375
Q

What is muscular dystrophy? What causes it?

A

Muscular dystrophy is an inherited disease that causes weakening and progressive degeneration of the muscles. Depending on the type of muscular dystrophy, different muscles are wasted and the age of onset varies. It is caused by a mutation in the dystrophin gene. This one of the largest genes in the human genome so there is a high mutation rate here.

376
Q

How is acidic chyme neutralised in the duodenum?

A

Brunner’s glands in the mucosa of the epithelium produce hco3-
Alkaline secretions including enzymes from the pancreas
Alkaline bile from gall bladder

377
Q

Which cells make up 80% of the macrophages in your body?

Where are they?

A

Kupffer cells in sinusoidal lining in liver lobules

zESA1 (5 decks)

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