Histology ๐Ÿ‘ฉโ€๐Ÿ”ฌ Flashcards

1
Q

Outline simple columnar epithelia

A

Taller than wide
Oval nucleus with longer parts adjacent to the longer sides of the cell
Often either have cilia (resp tract) or microvilli (gut erythrocytes)

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2
Q

Outline intestinal epithelium

A

Enterocytes interspersed with goblet cells
More goblet cells in large intestine than small intestine
Brush border of microvilli

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3
Q

Microvilli- what, why, make up, where

A

Projections from columnar cells
Canโ€™t see them individually but seen as a brush border
Increased SA for absorption
Glycocalyx on outer surface
Found on most epithelial cells esp. on absorptive ones e.g in gut + kidney
Contain actin and myosin filaments

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4
Q

Ciliated epithelium- where, how many per cell and what does it do

A
  • Lines nose, larynx +bronchial tree w goblet cells
  • 300ish cilia per cell, help move mucus to the throat after it has trapped inhaled particles
  • Also found in the fallopian tube to transport the ovum
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5
Q

Outline cuboidal epithelium

A
  • Square in profile with a round nucleus
  • Rarely over 2 layers of cells
  • Occur in the ducts of glands e.g sweat and salivary and the pancreas
  • Form much of nephron in the kidney
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6
Q

Outline squamous epithelia

A
  • Single layer
  • Surrounds most thor +abd organs (aka serosa)
  • Also lines pleural and peritoneal cavities
  • Flattened cells
  • Kept moist by watery (serous) extrudate -> lubes it so organs can slide over each other
  • If destroyed organs can stick together forming adhesions
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7
Q

Outline compound (stratified) epithelia

A
  • Multi layered
  • Found in wear and tear situations
  • Most common is stratified squamous
  • Keratinised form forms epidermal layer of skin
  • Cells replaced from stem cells in basal layer of tissue
  • Cells discarded when they reach the top layer
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8
Q

Outline the layers of keratinising stratified squamous epithelium

A
  • Lower layers similar to moist stratified
  • Upper layers synthesise proteins which interacts with cytoskeleton to produce keratin
  • Once filled with keratin the upper layers die off
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9
Q

Outline Pseudo-stratified epithelium

A
  • Appears stratified but is more like simple epithelium
  • Appears multi-layered but is actually single layered when stretched
  • Lines trachea + bronchi allowing for expansion in inspiration (also in urothelium)
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10
Q

Outline cell junctions

A
  • Cells have to be tightly joined together to act as barriers so macromolecules +/or fluids canโ€™t go past
  • 3 typed of cell-cell contact: Desmosomes, tight (adherent) junctions and gap junctions
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11
Q

Outline epithelia

A
  • One or more sheet of cells resting on basement membrane
  • For protection, absorption and secretion
  • Simple - single layer
  • Stratified - 2 or more layers
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12
Q

How does cilia move?

A

Using tubulin and dynein

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13
Q

What is basement membrane mostly made up of?

A

Type 4 collagen

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14
Q

What do desmosomes do?

A

Bind cells to eachother

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15
Q

What do hemidesmosomes do?

A

Bind cells to the basement membrane

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16
Q

What are the 3 types of cell junctions?

A

Occluding junctions
Anchoring junctions
Communicating junctions

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17
Q

Outline occluding junctions

A
  • Links cells to form impermeable barrier
  • In secretory or absorpatory tissue
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18
Q

Outline the scaffolding of tissues

A
  • Most tissues have scaffolding of extracellular fibres set in a jelly like matrix
  • Governs functional organisation of the tissue and dictates the shape of organs
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19
Q

Outline the main fibres of the extracellular scaffolding of tissues

A
  • Main fibres collagen and elastin
    Used because of:
  • High molecular weight
  • Strongly hydrophilic and negatively charged polysaccharide polymers
    -> Retain water to help with turgor pressure
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20
Q

What are glycosaminoglycans?

A

Jelly like complexes

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21
Q

What synthesises glycosaminoglycans?

A

Can be synthesised by many different cells incl. epithelial, muscle, cartilage and bone
But mainly by fibroblasts which can synthesise many different extracellular constituents depending on the environment and mode of stimulation

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22
Q

What can undifferentiated mesenchymal cells become?

A

Osteoblasts (bone)
Chondroblast (cartilage)
Fibroblast (connective tissue)

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23
Q

Outline soft connective tissue

A

Flexible and gel-like
Present in most tissues between major tissue elements
Divisible into fibrous or fatty connective tissue

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24
Q

Outline hard connective tissue

A

Various forms of cartilage and bone

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25
Q

Outline fibrous connective tissue

A

Contains a large number of fibres e.g collagen, elastin or reticulin
Described as loose irregular if few visible fibres that are random or dense irregular if lots of fibres but random
Dense regular contains lots of fibres arranged in long parallel bundles

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26
Q

Outline fatty connective tissue

A

Contains mainly fat cells with intervening blood vessels particularly capillaries

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27
Q

Outline differentiation between types of collagen

A

With conventional stained histology you can tell if there are differences in length and thickness but precise composition canโ€™t be determined
At least 12 types of collagen- biochemical compositions are different
But all collagen fibres are not elastic or contractile

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28
Q

What does type I collagen do?

A

Type I- Skin, Bones, teeth, capsules of organs

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29
Q

What does type II collagen do?

A

Cartilage

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30
Q

What does type III collagen do?

A

Liver, kidney, spleen arteries, uterus

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31
Q

What does type IV collagen do?

A

Type IV- Basement membranes

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32
Q

What does type V collagen do?

A

Placenta

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33
Q

Outline the structure of collagen

A

Individual collagen fibrils are made up of overlapping linear strands of tropocollagen (gives rise to characteristic bonding of collagen)
Fibrils are aligned side to side to create larger collagen fibres of variable thickness

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34
Q

Outline the tropocollagen subunits

A

Made up of 3 linear polypeptide chains (2 similar and 1 not)
Wound together in an alpha helix

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35
Q

Outline the connective tissues of the penis

A

Loose to dense irregular
3 erectile compartments surrounded by a capsule of dense irregular connective tissue surrounding and a tissue with fewer fibres between nerves, blood vessels + lymphatic vessels are also components of connective tissues

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36
Q

Outline the structure of elastic tissue

A

Consists of microfibres of fibrillin and an amorphous matrix of elastin
Forms fine fibres or flat sheets

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37
Q

Where is elastic tissue found?

A

Present in most connective tissues and in walls of blood vessels

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38
Q

Outline the staining of elastic tissue

A

Elastin fibres stain pink with H+E stain
Sometimes hard to distinguish from collagen but may stain more strongly than collagen and sometimes produce a glassy and refracting light appearance

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39
Q

Outline adipose tissue

A

Some connective tissues contain it
2 types- white and brown

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40
Q

Outline white adipose tissue

A

Most abundant
Large cells each with a single fat droplet
Protect vital organs and serve as energy stores
Fat is deposited alongside capillaries and so usually displays a rich network of fine blood vessels

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41
Q

Outline brown fat

A

Brown fat is abundant in newborns but less so in later life
Described as multi-locular as cells contains numerous droplets of fat rather than a single one

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42
Q

How is cartilage related to bone?

A

Along with bone is rigid
Closely related to it
Bone is ossified cartilage

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43
Q

Outline the formation of cartilage

A

Initially formed by chondroblasts- get trapped in a dense glycosamino rich matrix
Matures into chondrocytes
Surrounded by fibrous capsule of collagen and perichondrium
Contains undifferentiated progenitor- capable of differentiating into chondroblasts if needed
Variable amounts of collagen and elastic tissue

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44
Q

What are the 3 types of cartilage?

A

Hyaline
Elastic
Fibrous

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45
Q

Outline the makeup of hyaline cartilage

A

Has fine fibrils of collagen and elastic
(Canโ€™t see elastic on light microscope but have glossy appearance on matrix)

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46
Q

Hyaline cartilage with staining

A

Stains poorly with H+E stain

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47
Q

Where do you find hyaline cartilage?

A

Articular surfaces e.g cartilage in trachea
All bones are formed from hyaline cartilage which is replaced by bone in a process called endochondral ossification

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48
Q

Outline the structure of the elastic cartilage

A

Fibres a re irregularly arranged and can be seen in the matrix, contains chondrocytes and lots of elastic fibres

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49
Q

Where can you find elastic cartilage?

A

Epiglottis and pinna of ear

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50
Q

Outline fibrous cartilage make up

A

Matrix of cartilage fibrils filled with collagen in bands

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51
Q

What is made up of fibrous cartilage?

A

Intervertebral discs

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52
Q

What are the 3 types of muscles and where do you find it?

A

Smooth muscle- many internal organs and blood vessels
Cardiac muscle- heart
Skeletal- mainly attached to bony skeleton + is responsible for its stability and movement

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53
Q

Outline other cells with contractile properties

A

Pericytes- along small blood vessels
Myofibroblasts- involved in scar formation
Myoepithelial cells- assist in expression of milk during lactation

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54
Q

Outline the structure of smooth muscle

A

Discrete cells coupled together by cell junctions
They appear fusiform with cylindrical nuclei when cut longitudinally (and round when transversely)
Contractile proteins in it are not arranged regularly in repeating sarcomeres (anchored focally in clumps to cell membrane

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55
Q

Key features of smooth muscle cells that help it to function

A

Secrete reticulin external lamina (basement membrane)
Joined by gap junctions which permit the stimulus to pass rapidly through the muscle
Also have surface receptors to respond to hormonal stimuli

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56
Q

Outline gap junctions

A

Joins 2 smooth muscle cells together
Vital for coordinated contraction of smooth muscle
The guarded central pole allows small signal molecules to pass from one cell to the next in the chain
It electrically couples them and means the signal doesnโ€™t need to be transported across the membranes

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57
Q

What is the gap junction?

A

Each one consists of 6 connection proteins that span the cell membranes
Forming a central pole

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58
Q

Layers of blood vessels from inner to outer

A

Endothelium
Basement membrane
Intima
Internal elastic lamina
Media
External elastic lamina
Adventitia

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59
Q

Outline elastic arteries

A

Near the heart- aorta and pulmonary
Media contains abundant concentric sheets of elastin (seen as red lines)

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60
Q

Outline muscular arteries

A

Most abundant
Media made up of layers of smooth muscle with little elastin
E.g radial artery, splenic artery

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61
Q

Outline arterioles

A

Resistance vessels
Have 3 or fewer layers or fewer muscle layers in their media
Up to 100 um diameter
Elastic laminae poorly defined

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62
Q

Outline structure of capillaries

A

Only have lumen, endothelium and basement membrane
Pericytes on outside to regulate size-> discontinuous layer on outside of small ones which become continuous as they get larger
No surrounding muscles or connective tissue

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63
Q

Outline fenestrated capillaries

A

Most tissues have closed capillaries but some have leaky/ fenestrated ones e.g kidney + liver
Have holes in endothelium for movement into and out of surrounding tissues

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64
Q

Outline veins

A

No external elastic lamina
Thinner walls and larger lumen- media is thinner (than arteries) although large veins thicker compared to venules
Smooth muscle in wall might be circular or longitudinal

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65
Q

Outline venules

A

Associated with arterioles
Thin walled
Contractile pericytes wrap around the outside of endothelial cells and form a complete layer as venules get larger
Pericytes replaced by smooth muscle as venules become veins

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66
Q

Outline lymphatics

A

Thin walled similar to capillaries and veins
Have valves
No blood
Contains eosinophilic lymph and maybe lymphocytes (those are mostly in blood tho)

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67
Q

nerves

A
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68
Q

Outline plasma

A

It is blood without the cells
Made of water, salt + minerals, plasma proteins (albumin globulins and fibrinogen), hormones, signal molecules, other clotting factors ect.

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69
Q

What is serum?

A

Plasma without clotting factors

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70
Q

Outline erythrocytes

A

Enucleate biconcave discs
6.5-8.5 um in diameter (slightly larger than the smallest capillaries)
Live for 4 months
Main protein is haemoglobin
Cell membrane has an important endoskeleton attached (in which the main protein is spectin)

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71
Q

Where are erythrocytes produced and destroyed?

A

Produced in the liver (foetus) and bone marrow
Destroyed in the liver and the spleen producing bilirubin

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72
Q

What are the different types of leukocytes?

A

Granulocytes: Neutrophils (40-75%), Eosinophils (5%), Basophils (0.5%)
Agranulocytes: Lymphocytes (20-50%), Monocytes (1-5%)

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73
Q

Outline neutrophils

A

Commonest wbc and granulocyte
Multi lobed nucleus, granular cytoplasm, 12-14 um in diameter
Circulate in the blood and invade tissue spaces
Contain myeloperoxidase- for respiratory burst

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74
Q

outline the phagocytic nature of neutrophils

A

engulf and destroy bacteria and other foreign macromolecules via respiratory burst

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75
Q

What are the 3 types of cytoplasmic granule?

A

Primary granules
Secondary granules
Tertiary granules

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76
Q

Outline primary granules

A

Lysosomes (myeloperoxidases + acid hydrolases)

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77
Q

Outline secondary granules

A

Specific granules (secrete substances that mobilise inflammatory mediators

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78
Q

Outline tertiary granules

A

Gelatinases and adhesion molecules

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79
Q

Outline Eosinophils

A

1% of total number of wbcs
12-17 um in diameter
Bi-lobed nucleus
Distinctive large red cytoplasmic granules with crystalline inclusions
Have receptors for IgE

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80
Q

Outline granules in eosinophils

A

Large and red with crystalline cores
lozenge shaped granules

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81
Q

What do eosinophils do?

A

Numbers increase in parasitic infections or allergic conditions
Antagonistic action to basophils- play a role in phagocytosis and to mast cells as they inhibit their secretion
Phagocytic with a particular affinity for antigen/antibody complexes
Neutralise histamine- restricting inflammatory response

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82
Q

Outline basophils

A

0.5% of white cell series
14-16 um in diameter
Bi-lobed nucleus + prominent dark blue-stained cytoplasmic granules
Granules contain histamine
Have receptors for IgE
Circulating form of the tissue mast cell

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83
Q

What do basophils do?

A

Involved in inflammatory regulations and act to prevent coagulation and agglutination
Release histamine and vaso-active agents in response to allergens -> results in immediate hypersensitivity reaction - Aka anaphylaxis

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84
Q

Outline lymphocytes

A

Most common agranulocytes
2 main sub types-
B Cells
T Cells
Very few cytoplasmic inclusions so clear blue/grey cytoplasm
All subtypes look the same in histological sections on H+E - have to use histochemistry
Only blood cell capable of cell division

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85
Q

Outline B cells

A

Become plasma cells and secrete antibodies
Called B cells bc they mature in bone marrow

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86
Q

Outline T Cells

A

Are involved in cell mediated immunity
Called that because they mature in the thymus

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87
Q

Outline T Helper (TH) cells

A

Help B cells and activate macrophages

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88
Q

Outline T cytotoxic (TC) cells

A

Kill previously marked target cells

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89
Q

Outline T Suppressor (TS) cells

A

Suppress the TH cells so suppress the immune response

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90
Q

Natural killer (NK) cells

A

Mainly kill virus infected cells

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91
Q

Outline monocytes

A

Characteristic reniform nucleus (bean shaped)
Although an agranulocyte- it has small cytoplasmic granules (mostly lysosomes)

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92
Q

What do monocytes do?

A

Immature cells circulate briefly in the blood
Differentiate into several different cell types within tissue
Major phagocytic and defensive role
Some cells become APCs, passing antigen fragments to lymphocytes

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93
Q

What do monocytes differentiate into?

A

Tissue macrophages (anywhere)
Kupffer cells (liver)
Osteoclasts (bone)
APCs (everywhere)
Alveolar macrophages (lung)

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94
Q

Outline platelets

A

Fragments of cells derived from large multi-nucleated megakaryocytes in bone marrow
1-3 um in diameter
Surrounded by cell membrane
Contains vesicles with coagulation factors
Responsible for clotting of blood notably when endothelium lining blood vessels is breached

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95
Q

Outline haematopoiesis

A

All blood cells form in the haematopoietic bone marrow in adults
And liver in foetus

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96
Q

Outline myelon series

A

Lies next to bone and gives rise to white blood cells

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97
Q

Outline erythron series

A

Lies in between trabeculae and gives rise to erythrocytes

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98
Q

Outline megakaryocytes

A

Lie in between bony trabeculae and gives rise to platelets

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99
Q

Outline erythropoiesis

A

Reducing cell size -> haemoglobin production increases -> reduction + loss of organelles -> basophillian early precursors changes to eosinophillian late precursors -> loss of nucleus -> mediated by erythropoeitin

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100
Q

Outline Granulopoiesis

A

Morphologically similar for neutrophils, eosinophils + basophils
Increasing number of granules
Increasing complex shape of the nucleus

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101
Q

Outline the storage of wbcs

A

Large pool of stored mature neutrophils in marrow
No storage of monocytes and lymphocytes complete their precursor maturation either in the thymus or the lymph nodes

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102
Q

Outline pericardium

A

Outermost layer of the heart
Has a layer of squamous mesothelial cells resting on thin layer of connective tissue
Visceral (outer surface of the heart)
Parietal (inner surface of fibrous sack containing the heart)

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103
Q

Outline the epicardium

A

Sometimes used interchangeably with pericardium
Strictly it is adipose connective tissue, vessels and nerves
Between pericardium and myocardium

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104
Q

Outline the myocardium

A

Thickest layer of the heart
Specialised cardiac muscle
Endomysium
Largest myocytes in wall of left ventricle- smallest in atria
Contain perinuclear endocrine granules (atrial naturetic peptide)
The heart is an endocrine organ

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105
Q

What is a key difference between the action of atrial myocytes and ventricular myocytes?

A

Atrial myocytes secrete hormones but ventricular myocytes donโ€™t

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106
Q

Outline the cardiac muscle

A

Striated, central nuclei (only 1), branching, intercalated discs (only found in myocardium)

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107
Q

What is endomysium?

A

Loose fibrous connective tissue between muscle fibres

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108
Q

What are intercalated discs?

A

Connect adjacent myocytes
Contain: gap junctions, adhering junctions, desmosomes

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109
Q

Outline the parts of the conducting system of the heart

A

Sinoatrial node, atrioventricular node, bundle of His, purkinje fibres- specialised myocytes
Stains with periodic acid shift- highlights glycogen rich cells
Subendocardial, large vacuolated muscle cells

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110
Q

Outline the endocardium

A

Innermost layer of the heart
Thin layer of fibrous connective tissue
Endothelial cells on innermost layer

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111
Q

Outline valves

A

Covered by endothelium
Attached to central fibrous body
Fibrosa (dense fibrous CT)
Spongiosa (loose fibrous CT)
Ventricularis (collagen + elastin)

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112
Q

Outline skeletal muscle

A

Striations - yes
Nuclei - multinucleated and on the edge
Branching - no

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113
Q

Outline cardiac muscle

A

Striations - yes
Nuclei - uni-nucleated and centred
Branching - yes (via intercalated discs)

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114
Q

Outline smooth muscle

A

Striations - No
Nuclei - Uni-nucleated
Branching - No

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115
Q

Outline respiratory epithelium

A

Lines tubular portion of the respiratory system
Pseudostratified- all cells connected to the basement membrane
Ciliated epithelial cells interspersed with goblet cells

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116
Q

What is the purpose of the nose?

A

Filtration
Humidification
Warming
Olfaction

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117
Q

What is the nose lined with?

A

Made of keratinising and non-keratinising squamous epithelium and respiratory epithelium

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118
Q

Key tissue that makes up the nose

A

Richly vascular lamina propria containing seromucinous glands

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119
Q

Borders of the olfactory area

A

Roof of nasal cavity extending down the septum and lateral wall

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120
Q

What is the olfactory area lined with and what glands does it have?

A

Pseudostratified columnar epithelium of olfactory receptor cells with supporting sustentacular cells and basal cells
Glands- serous glands of bowman

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121
Q

Outline the nasopharynx functions and epithelial lining

A

Functions- gas transport, humidification, warming, olfaction
Lined by respiratory epithelium

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122
Q

Outline the nasal sinuses function and epithelial lining

A

Functions- lower the weight of the skull, add resonance to the voice, humidify and warm inspired air
Lined by respiratory epithelium

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123
Q

Outline the larynx function and what it is made up of

A

Cartilaginous box (hyaline cartilage)
Function- voice production
Made of - respiratory epithelium, loose fibrocollagenous stroma with seromucinous glands
lymphatics and blood vessels common

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124
Q

Outline the function of and what vocal cords are made from

A

Function- voice production
Made of - stratified squamous epithelium overlying loose irregular fibrous tissue
Also no lymphatics but has blood vessels

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125
Q

Outline reinkeโ€™s space

A

A potential space between the vocal ligament and the overlying mucosa.

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126
Q

Outline the trachea function and what it is made of

A

Function- conducts air to and from the lungs
Made of- respiratory epithelium, seromucinous glands in the submucosa
Trachealis muscle posteriorly, c-shaped cartilagenous rings
Gap filled by vertically orientated smooth muscle called treachealus

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127
Q

Layers of the bronchi

A

Smooth muscle
Partial cartilagenous rings
Respiratory epithelium
Some basal neuroendocrine cells
Seromucinous glands and goblet cells

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128
Q

What are the layers of bronchioles?

A

Smooth muscle
Ciliated columnar epithelium
Some basal neuroendocrine cells
Few goblet cells and clara cells

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129
Q

Outline Clara cells make up and location

A

Most numerous in terminal bronchioles
Contain mitochondria, smooth ER, secretory granules
Donโ€™t contain cilia and have vesicular cytoplasm

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130
Q

What do we think that clara cells do?

A

Secrete a lipoprotein that helps to prevent luminal collapse during exhalation and keeps from sticking together
Might play a role in oxidising inhaled toxins, antiprotease function, surfactant production/elimination, stem cells

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131
Q

Outline the function and make up of respiratory bronchioles

A

First part of the distal respiratory tract
Function- gas exchange as well as transport, they link terminal bronchioles and alveolar ducts
Made up of- cuboidal ciliated epithelium and spirally arranged smooth muscle but no cartilage

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132
Q

Size and number of alveoli

A

150-400 million/lung
250 um in diameter

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133
Q

Function of alveoli

A

Gas exchange

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134
Q

Cell types in alveoli

A

Type 1 pneumocytes
Type 2 pneumocytes
Alveolar macrophages

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135
Q

Outline type 1 pneumocytes

A

40% of cell population but 90% of surface area
Made up of flattened cells, flattened nucleus + few organelles

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136
Q

Type 2 pneumocytes

A

60% of cell population + 5-10% of surface area
Made up of rounded cells, round nucleus, rich in mitochondria, smooth and rough ER, spherical bodies
Produce surfactant

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137
Q

Outline alveolar macrophages

A

Luminal cells also present in the interstitium, phagocytose particulates including dusts and bacteria-> then either lymphatics or leave via mucocilary escalator

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138
Q

Outline the blood air barrier

A

Made of type 1 pneumocytes- fused basement membrane of pneumocyte and capillary vascular endothelial cells
200-800 nm thick

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139
Q

Outline the interstitium

A

Where endothelial cells are not in direct contact with pneumocytes
Made of collagen and elastin fibres, fibroblasts, macrophages
Contains pores of Khon- holes in the wall of alveoli helping to equalise pressure

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140
Q

Outline visceral pleura

A

Made of- flat mesothelial cells, loose fibrocollagenous connective tissue
Layers- irregular external elastic layer, interstitial fibrocollagenous layer, irregular internal elastic layer

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141
Q

Outline oral cavity

A

What does it do -> receive food, chews food, starts digestion
Epithelium -> stratified squamous epithelium on top of connective tissue with keratin layer on top
Pathology -> oral cancer-> from SE-> squamous cell carcinoma

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142
Q

Outline oesophagus

A

What does it do-> swallows food
Epithelium -> squamous epithelium
Submucosal glands

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143
Q

Outline stomach

A

What does it do-> digests food
Made up of gastric fundic mucosa => mucus, gastric body mucosa, parietal cells => hydrochloric acid, chief cells => pepsinogen and lipase, gastric antral mucosa
Pathology- sometimes contains helicobacter pylori - causes inflammation

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144
Q

Intestines function and features to maximise this

A

What does it do-> digests food, absorbs food, absorbs water, resist bugs

Arranged in crypts and villi for larger surface area

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145
Q

Layers of the intestines

A

Epithelium -> Mucosa glandular epithelium all the way down, contains endocrine cells affects timing movement
submucosa (all connective tissue)
Muscularis propria

146
Q

Crypts- what are they and what do they do

A

Are moat-like invaginations of the epithelium around the villi. Are lined largely with younger epithelial cells involved primarily in secretion.
Contain stem cells at their base, which continually divide and provide the source of all the epithelial cells in the crypts and on the villi.
Extend down to the muscularis mucosae.

147
Q

Outline the muscularis propria

A

2 layers, all smooth muscle, contains ganglion cells
Interstitial cells of kahal (pacemaker cells)- can cause tumours called GIST

148
Q

Outline the serosal surface

A

Outside of the transverse colon
Contains- blood vessels, mesentry, mesothelium

149
Q

Parts of the small intestine and what are they covered in

A

Duodenum, jejunum, ileum
Have villi on the folds and microvilli on them
contains mucosa associated lymphoid tissue

150
Q

Outline the function of the duodenum

A

Digests food, absorbs food and resists bugs, bile and digestive enzymes come into it

151
Q

Outline the functions of the jejunum and ileum

A

Digests food, absorbs food and resists bugs

152
Q

Some diseases of the small intestine

A

Giardia lambila- parasites on the mucosa
Coeliac disease- villi lost and crypt hypoplasia
lots of lymphocytes, response to gluten

153
Q

Outline the appendix

A

What does it do -> Safehouse for the bugs in the gut in case they are all cleared out in response to infection
Epithelium -> flat mucosa bc less absorption

154
Q

Outline the colon

A

Parts of it -> Ascending, transverse, descending, sigmoid
What does it do -> absorbs (some) food and water + kills bugs
Features-> Villi + folds in the colon
Pathology -> ulcerative colitis (inflammation of the mucosa)

155
Q

What are the layers of the muscularis of the stomach?

A

Innermost oblique layer
Middle circular layer
Outermost longitudinal layer

156
Q

What is in the portal tract?

A

Portal veins
Arteries
Bile ducts

157
Q

Describe make up of the liver

A

Made up of hepatocytes arranged in cords with intervening sinusoids
Liver is divided into lobules

158
Q

Outline the โ€˜classic lobuleโ€™

A

Area drained by one central hepatic venule
artificial construct so we can understand hepatic architecture
Roughly hexagonal
Some hepatocytes will be more richly oxygenated than others

159
Q

Outline the acini of the liver

A

An architectural concept based around the blood supply rather than the drainage
An artificial construct for understanding hepatic architecture

160
Q

Outline hepatocytes

A

Principle functional cells of the liver
Polyhedral epithelial cells

161
Q

What are the 3 important surfaces of hepatocytes?

A

Sinusoidal (70%)- permits exchange of material with blood (space of Disse)
Canalicular (15%)- permits the excretion of bile
Intercellular (15%)

162
Q

What do hepatocytes contain?

A

-Abundant mitochondria (looks like granules)
-Large central spherical nuclei
-Prominent nucleoli
-Might be binucleate
-Active golgi apparatus
-Prominent endoplasmic reticulum
-Numerous peroxisomes

163
Q

Outline sinusoids

A

Highly specialised blood vessels
Thin, discontinuous fenestrated endothelium
No basement membrane
Contains scattered Kupffer cells

164
Q

Outline the inter-hepatic biliary tree

A

Epithelium- Simple to cuboidal to columnar epithelium
Small: canaliculi -> Bile ductules -> trabecular ducts -> bile ducts :Large

165
Q

Outline canaliculi

A

Lie between hepatocytes
Canโ€™t be seen on light microscopy

166
Q

Outline the gallbladder

A

Functions- concentrates and stores bile, expels bile via common bile duct into duodenum
No muscularis mucosa but does contain specialised mucosa and smooth muscle layer

167
Q

Outline specialised mucosa in the gallbladder

A

Simple columnar epithelium with microvilli
Thrown into folds, adapted for water and salt absorption
Contains connective tissue - lamina propria

168
Q

Outline the exocrine pancreas

A

Functions -> To synthesise + secrete enzymes + bicarbonate-rich fluid into the duodenum
Has a poorly defined fibrous capsule with septa dividing gland into lobules
Epithelial cells arranges in acini

169
Q

Outline acinar cells

A

Epithelial cells, pyramidal shape
Basally - rich in RER
Apically - zymogen granules (enzyme precursors)

170
Q

Outline ducts of the liver

A

Centro acinar cells (fuse to form each other), intercalated ducts, interlobular ducts, main pancreatic duct

171
Q

What are the 3 areas of the kidney?

A

Cortex
Medulla
Pelvis

172
Q

What is in the renal cortex?

A

Glomeruli
PCTs
DCTs

173
Q

What is a medullary ray?

A

A collection of loops of Henle and collecting ducts that are in the cortex
It occurs when then nephrons have their glomeruli close to the renal capsule

174
Q

Outline the contents of the renal medulla

A

Comprised of loops of Henle and collecting ducts as well as blood vessels orientated radially from the cortex to the medulla

175
Q

Outline the glomerulus

A

Tuft of convoluted fenestrated capillaries
Glomerular basement membrane
Lined by podocytes
Supported by mesangial cells
Encased in Bowmanโ€™s capsule
Most cells are either glomerular endothelial cells or mesangial cells

176
Q

Outline the glomerular endothelial cells

A

Nuclei on the inside of capillaries
Endothelial cells line the capillaries

177
Q

Outline mesangial cells

A

Nuclei lie between capillaries
Comprise smooth muscle and structural support for the kidney
Contraction of it tightens capillaries + reduces glomerular filtration rate
Important part of tubular glomerular feedback caused by chemical changes in the glomerulus

178
Q

What are the 3 layers of cells of the glomerulus?

A

Glomerular capillary wall
Basement membrane
Foot processes of podocytes

179
Q

Outline the endothelial cells of the glomerular basement membrane

A

Inner layer
Fenestrated
Not so much that it lets big molecules like albumin

180
Q

Outline the basement membrane of the bowmanโ€™s capsule

A

Double thickness
Fusion of bms, podocytes and epithelial basement membrane
Has a lamina lucida, double thickness lamina densa and a lamina externa
Contains collagen and -ively charged heparin sulphate molecules
So -ive ions in plasma experience repulsive force

181
Q

Outline podocytes in the glomerular basement membrane

A

Have foot process that interdigitate
Made up of several proteins
Leaves a small space bridged by a -ively charged membrane

182
Q

Outline juxtaglomerular apparatus

A

2 components- afferent arteriole, distal convoluted tubule
Afferent arteriole contributes granular cells
Secrete renin in response to low BP
DCT has macula densa cells

183
Q

Outline macula densa cells

A

Patch of closely packed endothelial cells along the tubule
Senses NaCl conc. and regulates tuboglomerular feedback

184
Q

Outline lacis cells

A

In juxtoglomerular apparatus
Donโ€™t know what they do

185
Q

Outline the lining of the proximal convoluted tubule

A

Lined by cuboidal epithelium
Round central/ basal nuclei
Brush border of microvilli on apical end
Many mitochondria so appears eosinophillic

186
Q

What is the function of the PCT and where is it?

A

Reabsorption of NaCl, proteins, polypeptides, amino acids, glucose
In renal cortex

187
Q

Outline the loop of Henle

A

Descending and ascending limbs
Both with thick and thin segments
supplied by rich vasa recta in between the loop

188
Q

Epithelial lining of the loop of Henle

A

Simple squamous epithelium

189
Q

Outline the epithelial lining of the DCT

A

Simple cuboidal epithelium
Numerous mitochondria
Shorter than PCT

190
Q

What does the DCT do?

A

Regulates acid base by secreting H+ and absorbing HCO3- (via cellular carbonic anhydrase)
Regulates Na+ level by exchanging Na+ for K+

191
Q

Outline the collecting duct

A

Principal cells respond to aldosterone and ADH
Intercalated cells exchange H+ for HCO3-
3 types: cortical, medullary and papillary ducts

192
Q

What are the 3 types of collecting ducts lined with?

A

Cortical collecting ducts - simple cuboidal epithelium
Medullary collecting ducts - simple columnar epithelium
Papillary ducts - simple columnar epithelium

193
Q

Progression of the kidney blood supply (from source to nephron)

A

Abd aorta -> Renal artery at L1 -> Anterior + posterior division -> Interlobar artery -> Arcuate artery (corticomedullary) -> Interlobular artery -> Afferent arteriole

194
Q

Progression of the blood supply to the loop of Henle

A

Efferent arteriole (from renal corpuscle) -> Peritubular arteries -> Vasa recta -> Renal veins -> Inferior vena cava

195
Q

Outline the renal pelvis

A

Collecting ducts drain into it
Lined by urothelium - multi-layered stratified
Transmits filtrate from nephron to ureter

196
Q

Outline urothelium

A

Specialised epithelium found in the collection/ drainage parts of the urinary tract
Complex stratified epithelium

197
Q

What are the layers of the urothelium

A

Layer of large dome shaped umbrella cells overlies a pseudostratified layer of polygonal cells
Intermediate layer
Basal layer- cuboidal cells can stretch

198
Q

Outline ureters

A

Lined by urothelium (transition epithelium)
Spiral muscular tube
Inner โ€˜longitudinalโ€™
Outer โ€˜circularโ€™
(different to GI arrangement)
No serosa
Loose adventitis

199
Q

Outline the layers of the urinary bladder

A

Layers- urothelium, lamina propria, muscularis mucosa (poorly developed), submucosa, muscularis propria(well developed), subserosa, serosa
Functional valve prevents reflux into ureter
bc of passage of ureters thru muscularis propria

200
Q

Outline the female urethra

A

4-5cm long
Lined by -> Proximally: transitional epithelium; Distally: squamous epithelium
Paraurethral and periurethral glands open into urethra

201
Q

Outline the male urethra

A

20cm long
Parts-
1. Prostatic urethra
2. Membranous urethra- lined by urothelium
3. Penile urethra- lined by pseudostratified epithelium proximally, stratified squamous epithelium distally

202
Q

Outline the testis

A

Paired organ in the scrotum
Average weight 15-19g

203
Q

What are the 3 layers of the capsule of the testis (outer to inner)?

A

Tunica vaginalis-
Tunica albuginea
Tunica vasculosa

204
Q

Outline the tunica vaginalis

A

Projection of the peritoneum
Flattened layer of mesothelial cells on a basement membrane)

205
Q

Outline the tunica albuginea

A

Collagen fibres with some fibroblasts, myocytes and nerve fibres

206
Q

Outline the tunica vasculosa

A

Loose connective tissue containing blood vessels and lymphatics

207
Q

Pathway of spermatozoa out of the testes

A

Seminiferous tubules -> Straight tubules -> Rete testis -> Efferent ductules in the head of the epididymis -> Epididymis -> vas deferens -> Ejaculatory duct -> Membranous urethra -> Penile urethra

208
Q

Describe testicular parenchyma lobules

A

Divided into lobules by septa originating from the capsule
Around 250 lobules
Each lobule contains 1-4 seminiferous tubules

209
Q

What cells are in seminiferous tubules?

A

Germ cells in various stages of maturation
Sertoli cells

210
Q

Progression of sperm maturation from spermatozoon to type A spermatogonia

A

Spermatozoon -> Spermatid -> secondary spermatocyte -> Primary spermatocyte -> Type B spermatogonia -> Type A spermatogonia

211
Q

What are type B spermatogonia?

A

Differentiating progenitor cell
Has spherical nuclei with densely stained masses of chromatin

212
Q

What are the two versions of type A spermatogonia?

A

Darkly stained (Ad)
Pale stained (Ap)

213
Q

Outline sertoli cells

A

Columnar cells on the basement membrane of the tubule
Send cytoplasmic projections around the sperm cells
Nuclei are irregularly shaped, folded and have prominent nucleolus
Cytoplasm is eosinophilic and may contain lipid granules

214
Q

What do sertoli cells do?

A

Supportive, phagocytic and secretory functions

215
Q

What are the different parts of spermatozoa?

A

Head
Neck
Midpiece
Principle piece
End piece

216
Q

What is included in the head of the spermatozoa?

A

Acrosomal cap and nucleus

217
Q

What is included in the midpiece of the nucleus?

A

Spiral mitochondria around the axomere

218
Q

What is in the neck and tail of spermatozoa?

A

Axomere and plasma membrane

219
Q

What does the axomere do?

A

Responsible for cell motility
Basically long cillia

220
Q

Outline leydig cells

A

Present singly and in clusters in the interstitium between tubules
Abundant cytoplasm containing lipid
Contain peinkeโ€™s crystalloids- eosinophilic crystalloids (not seen before puberty)
Produces testosterone

221
Q

Outline the rete testis

A

Anastomosing network of tubules at the hilum of the testis
Receive luminal contents from seminiferous tubules
Lined by simple squamous or low columnar epithelium on a relatively thick basement membrane
Have cilia at luminal surface

222
Q

Function of the rete testis

A

Mixing chamber for contents of the seminiferous tubules
Possible secretions
Reabsorption of protein from luminal contents

223
Q

Outline the efferent duct

A

12-15 convoluted tubules which empty into the epididymis
Lined by ciliated and non ciliated simple columnar epithelium with interspersed cuboidal cells (basal cells) giving pseudostratified appearance

224
Q

Outline the epididymis

A

A tubular structure 4-5cm long containing highly convoluted epididymal duct
Lined by tall columnar cells with long atypical cilia
Epithelium is supported by a thick basement membrane surrounding which is a well defined muscular coat

225
Q

What does the epididymis do?

A

Site of absorption of testicular fluid
Phagocytosis pf degenerous spermatozoa
Produces secretion rich in glycoproteins, amino acid and glycerophosphyl choline
Play a role in maturation of the spermatozoa

226
Q

Outline the vas deferens

A

30-40cm tubular structure arising from the caudal portion of the epididymis
Distal part enlarged to form the ampulla which joins the excretory duct of the secretory vesicle to form the ejaculatory duct
Lined by pseudostratified columnar epithelium comprising columnar and basal cells
Has a thick muscular wall of 3 layers

227
Q

Shape, weight and position of the prostate

A

Pear shaped glandular organ
Weighs up to 20g in young adults (enlarges with age)
Surrounds the bladder neck and prostatic urethra

228
Q

What are the lobes of the prostate gland?

A

Anterior
Middle
Posterior
2 lateral lobes

229
Q

What are the gland regions of the prostate?

A

Peripheral- (most common site of cancer)
Central
Transitional
Periurethral

230
Q

Key parts of the prostate gland

A

Covered by ill defined fibroconnective tissue capsule
Glandular and non-glandular components
Ducts- large primary and small secondary
Acini- 30-50 tubuloalveolar glands with convoluted edges

231
Q

What are acini of the prostate lined by?

A

Lined by secretory cells, basal cells and neuroendocrine cells
Cells rest on a basement membrane

232
Q

What do secretory cells do and where are they in the acini?

A

Located in the luminal side of the glands Secrete PSA and PAP into the seminal fluid
Helps to liquify the semen

233
Q

What do the basal cells of acini form?

A

A continuous layer

234
Q

What is stroma made up of?

A

Smooth muscle
Fibroelastic fibres
Blood vessels
Nerves

235
Q

What happens to stroma and glands of prostate with increasing age?

A

Undergo hypoplasia

236
Q

Outline seminal vesicles

A

Paired, highly coiled tubular structures posterolateral to the bladder
The duct empties into the ejaculatory duct
Lined by tall, non-ciliated columnar epithelium
Vacuoles and lipofuscin
Secretions act as nutrients for spermatozoa

237
Q

What are the layers of the seminal vesicles?

A

Mucosa (folded)
Smooth muscle (2 layers)
Adventitia

238
Q

Outline the 3 components of the erectile tissue

A

Left and right corpora cavernosa on the dorsal side (lined by vascular endothelial cells)
Corpus spongiosum on the inferior side

239
Q

Outline the make up of erectile tissue of the penis

A

Comprises irregular vascular spaces separated by fibroeslastic tissue and smooth muscle
Has a rich nerve supply

240
Q

Outline the ovary

A

Paired organ either side of the uterus close to the pelvis wall

241
Q

What are the attachments of the ovaries?

A

To broad ligament by mesovarium
To uterus by utero ovarian ligament
To pelvic wall by suspensory ligament

242
Q

What is the ovary made up of?

A

Covered by a single layer of modified mesothelium
A poorly defined connective layer called tunica albuginea
Stroma

243
Q

Outline the stroma of the ovary

A

Divided into the cortex and medulla with indistinct boundaries

244
Q

What is the hilum of the ovary?

A

Point blood vessels and lymphatics enter

245
Q

What is the ovarian cortex?

A

Spindle stromal cells arranged in whorls/storiform pattern

246
Q

What do ovarian follicles contain?

A

Some leutinised cells

247
Q

What is in the ovarian medulla?

A

Loose fibrous elastic tissue with blood vessels, lymphatic and nerves

248
Q

Outline the rete ovary

A

Similar to the rete testis, present at hilum of ovary

249
Q

Outline primordial follicles

A

Located in periphery of the cortex
Contains primary oocyte in a resting state
Surrounded by a single layer of epithelial cells (granulosa cells)
30-40 develop at once

250
Q

Primary follicles- how are they formed

A
  1. Cyclic FSH secretion from ant. pit.
  2. Stimulates follicular development
  3. Follicular epithelial cells proliferate
  4. Oocyte enlarges
  5. Stromal cells organise to form a connective tissue sheath
  6. Zona pellucida forms around oocyte
251
Q

What does the epithelium of the stroma change from and to?

A

Squamous to cuboidal/columnar

252
Q
A

Glycoproteins between granulosa cells and oocyte

253
Q

What is the antrum?

A

Space filled with follicular fluid

254
Q

Describe the formation of secondary follicles

A

Formation of the antrum
Theca differentiates into inner theca interna and outer theca externa
Oocyte is supported in antrum by a stalk of granulosa cells (clumbus oophorus)

255
Q

Outline the mature (graafian) follicles

A

Ovum surrounded by thick zona pellucida, corona radiata, basal lamina, theca interna and externa
Has a cumulus oophorus which suspends the ovum in the grafian follicle

256
Q

Corpus luteum

A

Forms from follicle
Via luteinisation of granulosa cells and theca cells (stimulated by LH)
These cells become polygonal and have lots of cytoplasm containing lipid
Secretes progesterone and oestrogen

257
Q

What is the corona radiata?

A

Layer of granulosa cells that surrounds the oocyte

258
Q

Numbers of eggs made and released in ovaries

A

Approx 1 mill at birth but only 400-500 mature
At ovulation 1 follicle ruptures out of the ovary (leads to bleeding in antral space)

259
Q

Common features of the endocrine system

A
  • Glandular epithelium apart from post. pituitary gland
  • Richly vascularised
  • Secrete a variety of hormones
  • Controlled by +ve and -ve feedback loops
260
Q

Pituitary overview

A
  • Coordinates the endocrine organs through the feedback loops
  • Two functional components:
    • Post. pituitary
    • Ant. pituitary
261
Q

Posterior pituitary

A
  • Downward extension of the hypothalamus
  • Neural tissue:
    • Axons
    • Glial cells
  • Stores/secretes:
    • Oxytocin
    • ADH
262
Q

Anterior pituitary

A
  • Nested epithelial pituicytes
  • Richly vascular fibrous stroma
  • Several different types of pituicyte not distinguishable on H+E
    Can be stained with reticulin
263
Q

Anterior pituitary cell make up

A

Cell % Hormone
Somatotrophs 50% Growth hormone
Lactotrophs 25% Prolactin
Corticotrophs 15-20% ACTH, a-MSH,
b-lipotrophin, b-endorphin
Gonadotrophs 10% FSH, LH
Thyrotrophs 1% TSH

264
Q

Somatotrophs- Ant. pituitary

A
  • Diffuse cytoplasmic GH +ve (stains with it)
  • Lateral wings of ant. pituitary
  • Present throughout gland
265
Q

Lactotrophs - Ant. pituitary

A
  • Polygonal cells
  • Cytoplasmic processes wrap around other cells
  • Variable Prolactin staining- stains cytoplasm brown
266
Q

Thyrotrophs- Anterior pituitary

A
  • Angular chromophobes - Donโ€™t stain with H+E
    -Elongated cytoplasmic processes
  • Variable TSH staining
267
Q

Gonadotrophs- Anterior pituitary

A
  • Scattered round/oval cells
  • Stain with either:
    • Alpha subunit
    • Beta LH
    • Beta FSH
268
Q

Corticotrophs- Anterior pituitary

A
  • Round basophilic cells
  • Stain dark purple on H + E
  • Median of gland
  • Large cytoplasmic vacuoles (โ€œenigmatic bodiesโ€)
269
Q

Supporting cells- Anterior pituitary

A
  • Sustentacular cells
  • Surround the normal follicles
  • S100 +ve (stains brown with it)
270
Q

Pineal gland

A
  • Located just below the posterior end of the corpus callosum - covered by meninges
  • Irregular lobules
  • Pinealocytes in rosettes (neuron-like)
  • Secretes melatonin- in response to autonomic stimulation
  • Eosinophillic cytoplasm + round central nuclei
  • Brain sand- accumulation of calcium
271
Q

Thyroid

A
  • In neck anterior and lateral to the trachea
  • Combination of follicular cells and colloid
  • Richly vascular
  • Produces thyroxine and calcitonin
272
Q

Parathyroid glands

A
  • 4 glands, variably located in the neck
  • Produce parathyroid hormone (PTH)- important in calcium homeostasis
  • 3 cell types:
    • Chief cells
    • Oxyphils
    • Adipocytes
273
Q

Chief cells- parathyroids

A
  • Functional cells of the gland
  • Polygonal cells
  • Scant cytoplasm - so tissue appears blue bc of lots of nuclei
  • Secrete PTH
  • Raises serum Ca2+
    • Bone
    • Kidney
    • Gut
274
Q

Staining of chief cells (parathyroid)

A
  • Strong immunoreactivity for PTH
  • No calcium oxalate crystals (unlike thyroid so can be used to determine what the tissue is)
275
Q

Oxyphil cells- parathyroid

A
  • Large polygonal cells
  • Increase with age
  • Abundant eosinophilic cytoplasm
  • Finely granular- rich in mitochondria?
  • Unknown function
276
Q

Endocrine pancreas

A

Islets of langerhans

277
Q

Islets of Langerhans

A
  • Approx 1 million
  • Balls of cells
  • Thin fibrous capsule
  • Mostly in pancreatic tail
278
Q

Hormones secreted by the islets of Langerhans

A

Cell % Hormone
B (beta) cells 70% Insulin
A (alpha) cells 20% Glucagon
D (delta) cells 5-10% Somatostatin
PP cells 1-2% Pancreatic polypeptide

279
Q

Adrenal cortex

A
  • Back of abdomen (retroperitoneal) on top of kidneys
  • 2 layers- Cortex and medulla
280
Q

Adrenal cortex

A
  • Zona Glomerulosa
    • Mineralocorticoids
  • Zona Fasciculata
    • Glucocorticoids
  • Zona Reticularis
    • Androgneic steroids
281
Q

Zona glomerulosa (outermost layer of the adrenal cortex)

A
  • Secretes aldosterone
  • Thin, incomplete layer
  • Small cells
  • Vacuolated cytoplasm
282
Q

Zona fasciculata (middle layer of the adrenal cortex)

A
  • Secretes cortisol
  • Most prominent layer
  • Large polygonal cells
  • Almost clear cytoplasm (bc of abundance of lipid)
283
Q

Zona reticularis (inner layer of the adrenal cortex)

A
  • Produces androgenic steroids
  • Anastomosing columns of small polygonal cells
284
Q

Adrenal medulla

A
  • Centre of adrenal gland
  • Chromaffin cells
  • Large, polyhedral
  • S100 +ve (stains with it)
  • Produces adrenaline and noradrenaline
285
Q

Outline the corpus albicans

A

Well circumscribed structure with convoluted borders almost entirely composed of densely packed collagen with occasional follicles
Eventually they may be resorbed/replaced by ovarian stroma

286
Q

What happens to the corpus luteum if there is no pregnancy?

A

It regresses as 8-9 days after ovulation granulosa cells change size and develop pyknotic nuclei + accumulate abnormal lipid
cells then undergo dissolution and are phagocytosed
There is progressive fibrosis by ingrowth of connective tissue

287
Q

What are the 4 segments of the fallopian tube?

A

Intramural- inside uterine wall
Isthmus- 2-3 cm thick walls
Ampulla- expanded area
Infundibulum- trumpet shaped opening to the peritoneum

288
Q

Outline the fallopian tube

A

Run thru the length of the broad ligament
Transport the ovum to the uterus
Fertilisation occurs here

289
Q

Endometrium in menstrual phase

A

Progesterone stimulation withdrawn
Stromal haemorrhage and granulocytes
Stromal and granular fragmentation
Might see mitotic figures

290
Q

Outline the mucosa of the female reproductive tract

A

Thrown into branching folds (plicae)
2 Cell types:
- Secretory- Most prevalent at uterine end
- Ciliated- most prevalent at infundibular end
(peg cells and basal cells)

291
Q

Outline the muscularis (myosal pinx)

A

Inner circular layer- tightly wound spiral
Outer longitudinal layer- looser spiral

292
Q

Fallopian serosa

A

Connective tissue covered by mesothelium

293
Q

Endometrium in menstrual phase

A

Progesterone stimulation withdrawn
stromal haemorrhage and granulocytes
Stromal and granular fragmentation
Might see mitotic figures

294
Q

3 layers of the uterus

A

Endometrium
Myometrium
Serosa

295
Q

Endometrium in secretory phase

A

Progesterone stimulation
Early -> below nuclear glycogen vacuoles
Mid -> vacuoles above and below nucleus and intraluminal secretions, glands more rounded, stromal oedema (no H+E staining)
Late -> Elongated and saw toothed glands with more intraluminal secretions -> stroma-spiral arterioles and decidual change

296
Q

Outline the endometrium in proliferation phase

A

Oestrogen stimulation
Straight proliferating glands with mitotic activity
No luminal secretions
Stromal cells are spindled and show mitotic activity

297
Q

What are the 2 layers of the endometrium?

A

Deep basal layer- stratum basalis- reserve of endometrial cells- replenished
Superficial layer- stratum compactum (towards the surface and stratum spongiosum- lost during each menstrual cycle

298
Q

What does it mean for the endometrium to be hormonally responsive?

A

Its appearance changes depending on the phase of the menstrual phase

299
Q

Outline the myometrium

A

Thick muscular wall with 3 ill defined layers of smooth muscle:
Inner longitudinal
Middle circular
Outer longitudinal

300
Q

What are the 2 layers of the cervix?

A

Endocervix
Ectocervix

301
Q

Outline the endocervix

A

Loose fibromuscular stroma lined by simple columnar ciliated epithelium
Thrown into crypts- crypts not glands as epithelium is all the same

302
Q

Outline the ectocervix

A

Dense smooth muscle stroma lined by non-keratinised stratified squamous epithelium
Site of squamocolumnar junction varies (most common site for cervical cancer) - might lie at os or ectocervix
Atrophic in post menopausal women

303
Q

Mucosa of the vagina

A

Lined by non-keratinising stratified squamous epithelium
Stroma contains elastic fibres and a rich vascular network

304
Q

Key facts about the epithelial lining of the mucosa of the vagina

A

Accumulates glycogen -> maximal around ovulation
It becomes more spongy

305
Q

Outline the muscular wall of the vagina

A

Smooth muscle cells
Inner circular
Outer longitudinal

306
Q

Adventitia of the vagina

A

Loose connective tissue

307
Q

Structures of the vulva

A

Mons pubis, clitoris, labia minora, labia majora, vulvar vestibula, hymen, urethral meatus, skeinโ€™s gland, bartholinโ€™s gland, introitus

308
Q

Outline the labia majora epithelium

A

Looks like normal skin
Lined by keratinising stratified squamous epithelium and has skin adnexae

309
Q

Outline the labia minora epithelium

A

Mostly non- keratinising stratified squamous epithelium

310
Q

Outline Bartholinโ€™s gland

A

Tubuloalveolar glands-> acini
lined by mucus secreting epithelium

311
Q

Minor vestibular glands

A

Simple tubular glands lined by mucus- secreting epithelium

312
Q

Skeinโ€™s glands (periurethral glands)

A

Analogous to prostate
lined by pseudostratified columnar epithelium

313
Q

Outline the lining of the hymen

A

Lined by non-keratinising squamous epithelium

314
Q

Outline the clitoris

A

Erectile tissue rich in blood vessels and nerves

315
Q

Contractile cells that are not muscle

A

Pericytes, myo-fibroblasts, myoepithelial cells

316
Q

Outline skeletal muscle components

A

Myoblasts fused to form multi-celled syncitium
Sarcomeres joined end to end to form myofibrils
Cytoplasm filled with myofibrils to form muscle fibre
Muscle fibres clump together to form fascicles
Held together by connective tissue endomycium, perimycium and epimycium

317
Q

Key facts about skeletal muscle fibres

A

Multi-nucleated- bc formed from multiple cells
Dark stained nuclei (at edges)
Pink stained cytoplasm with striations
10cm long and 50-60um wide- elongated fibres
Voluntary
Non branching

318
Q

What is in a skeletal muscle cell?

A

Cell membrane- aka sarcolemma
Nuclei
Contractile proteins
Mitochondria
Endoplasmic reticulum- sarcoplasmic reticulum
Glycogen-rich cytoplasm- sarcoplasm

319
Q

Why is skeletal muscle striated?

A

Myofibrils are in register
So light bands and dark bands of each sarcomere line up

320
Q

Difference between a myocyte, myofibril and sarcomere

A

Myocyte- whole cell
Myofibril- arrangement of contractile proteins in a muscle fibre
Sarcomere- functional units of the myofibrils

321
Q

What makes up the sarcomere?

A

Actin- thin filaments
Myosin- thick filaments
Accessory proteins

322
Q

How are the proteins arranged in sarcomeres

A

Actin filaments anchored by accessory proteins that form Z lines (sarcomere is what is between 2 z-lines)
Areas where there is only actin (i-bands) and only myosin (a-bands)

323
Q

Different types of skeletal muscle fibre

A

2 broad types
Not distinguishable on H+E
Type 1- rich in fibrillar ATPase, slow twitch
Type 2- rich in fibrillar ATPase, fast twitch (also split up into fatigue sensitive and fatigue resistant)

324
Q

How do muscle spindles detect stretch and tension?

A

Fibrocollagenous capsule
Intrafusal muscle fibres (wrapped around by gamma efferent nerve fibres)
Detect stretch and tension

325
Q

Outline Endomysium

A

Collagenous connective tissue between muscle fibres

326
Q

Perimysium

A

Fibrocollagenous connective tissue
Binds muscle fibres to form fascicles

327
Q

Epimysium

A

Connective tissue that binds all of the fascicles together around the outside

328
Q

Sharpeyโ€™s fibres

A

Connect muscle to bone (and penetrate bone)
Bundles of collagen linking epimysium to periosteum
Attach muscle to bone over a wide area
e. g rotator cuff muscles attached to scapula

329
Q

Tendons

A

Connect muscle to bone over a small area
Made of parallel bundles of collagen with intervening fibroblasts
e.g rotator cuff muscles attached to humerus

330
Q

What are the cells that make up bone?

A

Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts

331
Q

What is in the extracellular matrix?

A

Collagen and calcium hydoxyapatite

332
Q

Outline osteoblasts and osteocytes

A
  • Derived from embryonic mesenchyme (osteoprogenitor cells)
  • Secrete osteoid (unmineralised bone)
  • Become trapped in their own matrix
  • Connect to surrounding cells via canaliculi (where oxygen and nutrients diffuse)
333
Q

Difference between osteoblasts and osteocytes

A

Osteocytes are osteoblasts that have moved from the outer layer of the bone into the matrix and have been trapped there

334
Q

Outline osteoclasts

A
  • Derived from monocytes
  • Large, multinucleate cells
  • Absorb bone- sit in Howshipโ€™s lacunae- depressions in the bone
  • Activity is linked to osteoblasts (via rank ligand)
335
Q

What are the ways we can differentiate types of bone?

A

By origin
By gross appearance (2 ways)
By mode of formation

336
Q

What are the two categories of bone differentiation by origin?

A

Primary (woven)
Secondary (lamellar)

337
Q

What are the 2 categories of bone by gross appearance (1)?

A

Spongy/cancellous
Compact

338
Q

What are the 2 categories of bone by bone formation?

A

Membranous
Endochondrial

339
Q

What are the 2 categories of bone by gross appearance (2)?

A

Osteons
Appositional

340
Q

What is osteoid?

A

An extracellular matrix rich in type 1 collagen, glycosaminoglycans and proteoglycans

341
Q

How is bone formed?

A

Osteoblasts lay down osteoid, in which the glycosaminoglycans include osteocalcin which has a strong affinity for calcium ions
Osteoid then mineralised when there is a high conc. of calcium and phosphate ions via osteocalcin and alkaline phosphatase
Calcium deposited in bone as calcium hydroxyapatite

342
Q

Lamellar bone

A

Osteoid is deposited in parallel sheets
Remodelled from woven bone

343
Q

Woven bone (aka primary bone)

A

Osteoid is deposited haphazardly and is laid down rapidly in foetal bone and at fracture sites
Has a disorganised collagen fibre architecture
and is mechanically weak

344
Q

Cement line

A

Faint blue line (on H+E)
Between osteoid and bone

345
Q

Osteocalcin- what does it do?

A

Binds calcium ions to osteoid

346
Q

Outline secondary/lamellar bone

A

Stronger
- Forms as osteons
- Has central Haversian canal containing blood vessel
- Surrounding concentric rings of lamellar bone with osteocytes

347
Q

How is secondary bone usually stained and examined?

A

Typically examined as a decalcified section stained with H+E

348
Q

What bones are formed by intramembranous formation?

A

Flat bones of the skull
Some cortical bone shafts

349
Q

What bones are formed by endochondrial formation?

A

All other bones- formed from cartilagenous formation

350
Q

Key facts about Intramembranous ossification

A

Formation of bone from a membranous precursor
Occurs in the formation of flat bones of the skull
Bone deposited directly in an embryonic mesoderm- without a cartilaginous proforma
Begins in second trimester

351
Q

Outline the process of intramembranous ossification

A

Initially, small clusters of progenitor cells within a primitive mesenchyme transform into osteoblasts and deposit islands of bone
These islands coalesce as the enlarge creating an open meshwork of bone and continue to do so until they form a primary plate of bone
Woven bone then remodelled to lamellar bone

352
Q

Endochondrial ossification

A

Converts a hyaline cartilaginous template into bone
Cartilaginous proformas form in the second trimester

353
Q

Outline the process of endochondral ossification

A

Shaft/dyaphisis becomes calcified and blood vessels grow into developing bone
Osteoprogenitor cells then differentiate into osteoblasts which lay down bone to form a primary centre of ossification
Proforma cartilage is eroded away as new bone forms
Later secondary centres of ossification form head/ epiphysis of bones
As ossification centres expand, cartilage is restricted to epiphyseal growth plates and articular surface

354
Q

Do bones have centres of ossification at birth

A

By birth most bones have primary centres of ossification and some have secondary ones

355
Q

What are epiphyseal growth plates

A

Separate the epiphysis from the diaphysis

356
Q

How is the zone of hyperplasia formed from the resting cartilage?

A

Chondrocytes in the resting cartilage divide creating columns of new cells - a zone of hyperplasia

357
Q

How is the zone of hypertrophy formed from the zone of hyperplasia?

A

Cells of zone of hyperplasia enlarge

358
Q

How is the zone of ossification formed from the zone of hypertrophy?

A

As chondrocytes enlarge they erode the extracellular matrix
The remaining strands of matrix become calcified and serve as a substrate for the attachment of osteoblasts

359
Q

Outline synovium

A
  • Lines the inside of the joint capsule
  • 1-4 layers of synovial cells
  • Type A- phagocytes
  • Type B- rich in RER
  • Variable shapes- squamous to cuboidal
  • Richly vascular and highly innervated
360
Q
A