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Flashcards in ANAT2008 Deck (141)
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1

Cytology

Study of the structure of cells

2

Histology

Study of Tissues

3

5 Types of Tissues

Can classify the basic tissues types by identifying the basic arrangement of cells.
1. Epithelial
2. Connective
3. Muscular
4. Nervous
5. Adipose

4

Epithelial Tissue

Separates the body from the environment e.g skin
Cells are tightly packed together
Often responsible for major work

5

Connective Tissue

Holds other tissues types together
Cells packed loosely

6

Nervous Tissue

Consists of cells called neurons (specialised to conduct electrical impulses)
Cells packed tightly

7

Muscle Tissue

Contain cells specialised for contraction
Cells not normally closely packed
Different types: smooth, skeletal, heart

8

Adipose Tissue (fat)

Consists of cells which contain lipids
Cells separated by narrow spaces but not as tightly packed as epithelial
Type of connective tissue

9

Micrometer

um
10^-6 M

10

Nanometer

nm
10^-9 M

11

Cell Theory

1. Living things only consist of cells and the products of cells.
2. Cells consist of one of more nuclei surrounded by a nuclear membrane which is surrounded by a cytoplasm containing organelles which is, in turn, surrounded by a plasma membrane.
3. All cells arise from pre-existing cells by cell division (life arose once on this planet and then evolved).

12

Two Principle Types of Cells

1. Prokaryotic: genetic material not contained within a specific unit.
2. Eukaryotic: genetic material contained within a particular site (nucleus).

13

The Plasma Membrane

Surrounds cell
Semi-permeable (selects what enters and exits the cell)
Trilaminar appearance: 3 layers (dark, light, dark)
Made up of three molecules: lipids, proteins and carbohydrates.

14

Plasma Membrane - Fluid Mosaic Model

Phospholipid bi-layer: hydrophobic heads and hydrophobic tails.
Integral Proteins: Pass into membrane.
Peripheral Proteins: on edge of bi-layer
Carbohydrates: contently bonded to lipids and proteins, found only on outer surface of membrane, form glycocalyx (seen with electron microscope).
NOTE: the plasma membrane is the only membrane with the glycocalyx

15

Plasma Membrane - Freeze Fracture Technique

Rapidly freeze a cell and then hit it with a knife. Fractures the membrane and allows it to be examined using a microscope.
Provides a visual conformation that the fluid mosaic model accurately depicts the arrangement of lipids, proteins and carbohydrates.

16

Plasma Membrane - Functions

Regulates the movement of molecules in and out of a cell.
Ion transport: passive and active
Receptor sites
Exocytosis and Endocytosis
Cohesion: the plasma membranes of cells stick together to form tissues.
Communication

17

Cytoskeleton

Located within the cytosol
Seen under the microscope when stained
Microtubles, microfilaments and intermediate filaments

18

Cytoskeleton - microtubles

Made of a protein called tublin
24nm in diameter
Vary in length -> tubular molecules added or subtracted to each end
Transport

19

Cytoskeleton - microfilaments

Actin and myosin
Located under cell membrane - stabilize

20

Cytoskeleton - intermediate filaments

Different in different eukaryotic cells - made up of different proteins -> can be used as a diagnostic tool.

21

Cytoskeleton - Function

Maintain cell shape
Intracellular transport
Movement of cells e.g during phagocytosis
Cellular reception e.g hearing

22

Centriole

Pair near nucleus
Tubular structure: 9 groups of 3 microtubles form the wall of a centriole

23

Centriole - Function

Master organiser of cell shape
Cell division (produces spindle fibres)
Creates basal body (critical structure in formation of cilia)

24

Ribosomes

Equal parts protein and RNA
Free in cytoplasm or attached to ER
Individual or in groups (polysomes)
Ribosomes in polysomes are active -> spiral structure
Synthesise protein

25

Endomembrane System

Nuclear envelope, golgi body, ER

26

Endoplasmic Reticulum

Two shapes -> tubular + cisternae (sheets)
Rough ER and Smooth ER

27

Rough ER

Cisternae structure
Ribosomes attached
Proteins synthesised

28

Smooth ER

Tubular shape
No ribosomes
Synthesis of steroids ( cells which secrete steroids e.g ovaries have a lot of smooth ER)
Contain enzymes which detoxify drugs
Transport of ions
Breaking down of carbohydrates

29

Golgi Body

Packages proteins for secretion
Proteins produced by ribosomes on the RER packaged into transport vesicles -> enter Golgi -> golgi packages proteins into large secretory vesicles -> secretory vesicles fuse together to form secretory granules and then exit the cell by exocytosis
ALSO modifies proteins (post translation modification -> required for some proteins to be active).

30

Trans Golgi Network

Collection of membranes associated with RER and golgi -> produce lysosomes

31

Lysosomes

Darkly stained vesicles
Formed in trans golgi network -> part of membrane buds off -> enzymes added
Intracellular digestion

32

Lysosomes - heterophagy

Cell digests material different from itself
1. phagocytosis = large insoluble materials ingested -> fuse to form a phagosome
2. endocytosis = small soluble materials ingested -> fuse to form an endosome
Phagosomes + endosomes fuse with lysosomes and are broken down.

33

Lysosomes - autophagy

Cells digest their own damaged or unwanted components
Vesicles form around unwanted part -> autophagosome -> fuse with lysosome

34

Deroxisomes

Vesicles related to lysosomes
Contain catalyse ->able to break down hydrogen peroxide (toxic biproduct of cellular metabolism)

35

Mitochondria

Outer membrane: Smooth -> defines shape of organelle
Inner membrane: folded (cristae) -> more cristae = more energy produced.
Matrix: gel substance in mitochondria
Contain some of their own DNA -> synthesis some of the proteins involved in ATP production.

36

Nucleus - nuclear envelope

Double membrane
Regulates what enters + exits
Pores -> made up of a ring of proteins

37

Nucleus - nucleoplasm

No membrane -> diffusion of molecules
40% protein and therefore most likely highly organised

38

Nucleus - nucleolus

Dense rounded structure
The bigger the nucleolus the more active the cell
Contain rRNA, ribosomal protein + DNA -> synthesis and pre-assembly of ribosomes

39

Nucleus - Chromatin

DNA + protein
Heterochromatin: chromosome state -> more densely packed -> darkly stained -> inactive DNA
Euchromatin: nucleosome or solenoid state -> loosely packed -> lighter stain -> active DNA
THE MORE ACTIVE A CELL THE LIGHT ITS NUCLEUS

40

Epithelial Tissue

Separates constant internal environment from hostile external environment e.g digestive tract, lungs
Endothelium: lines blood vessels
Mesothelium: lines all hollow organs except the heart

41

Epithelial Tissue - Structural and Functional Characteristics

Cellularity
Polarity
Specilized contacts
Lateral communication
Basal Lamina
Cell replacement

42

Epithelial Tissue - Cellularity

Tissue only consists of epithelial cells
Tightly packed together in sheets
Stains darkly

43

Epithelial Tissue - Polarity

Cells are polarised (different at different ends)
Apical = faces outside
Basal = faces inside
Lateral = sides
Differences seen in different specializations of the plasma membrane.

44

Epithelial Tissue - Specilized Contacts

Junctions

45

Epithelial Tissue - Lateral Communication

Pass information sideways -> made possible by the GAP junction in the plasma membrane

46

Epithelial Tissue - Basal Laminar

Fine layer of proteins and filaments -> epithelial cells connected to it
Supports cells, filters, defines the space where epithelial cells are supposed to exist.

47

Epithelial Tissue - Cell Replacement

Very high rate -> consequence of being exposed to toxic environment
More replication = more likely to mutate -> cell replicate away from external environment and move upwards.

48

Epithelial Cells: Specilizations of the apical plasma membrane

1. Special Proteins: glycoproteins (receptors), alkaline phosphate (removes phosphate group), integral proteins, transport molecules.
2. Microvilli: projection of the plasma membrane -> increase SA. Actin filaments run through the microvilli and join to a horizontal group of actin filaments (terminal web)
3. Stereocilia: Long microvili -> increase SA + sensory receptors.
4. Cilia + Flagella: motile structures. Cilia -> move fluid over a cell's surface -> special arrangement of microtubles (axoneme) 9 pairs of microtubles and 2 in the center.

49

Epithelial Cells: Specilizations of the Lateral plasma membrane

1. Proteins: associated with transport in + out of the cell
2. Specialized junctions: Tight junction, adherence junction, desmosomes, GAP junction.

50

Lateral Plasma Membrane Epithelial: Tight Junction

Proteins in adjacent cells make head-to-head contact -> 'zipper' cells together -> reduces the movement of molecules from outside down in between cells.
Tight = no movement of substances
Loose = movement of some substances between cells.

51

Lateral Plasma Membrane Epithelial: Adherence Junctions

Ring of cadherens proteins all around the top of the cell -> strengthens + reinforces the apex of the cell.

52

Lateral Plasma Membrane Epithelial: Desosomes

Specific spot where intermediate filaments run into cytoplasmic plate + transmember linkers link the plates of adjacent cells.

53

Lateral Plasma Membrane Epithelial: GAP Junction

Connexin proteins make head-to-head contact -> have a small pore in center -> allow passage of small molecules

54

Epithelial Cells: Specilizations of the Basal plasma membrane

1. Hemi-desmosomes: anchor cell to underlying connective tissue
2. Pedicles: protrusions of the plasma membrane into undelying connective tissue -> increase SA for adhesion.
3. Membrane infolding: Fold = more plasma membrane = more ion pumps = more efficient. Mitochondria = needed to fuel active transport of ion pumps.

55

Epithelial: Simple Squamous

Found in areas of exchange: aveoli + kidney
Thin, leaky tight junctions + lost of vesicles

56

Epithelial: Simple Cuboidal

Kidney tubles, reproductive tract, thyroid
Absorption and/or secretion

57

Epithelial: Simple Collumnar

Intestines, reproductive tract
Absorptive: lots of microvili -> increase SA -> increase absorption.
Secretory: secrete protein -> ER + Glogi. If secretory vesicles stored -> large secretory granules in the cell.
Deep + tight junctions -> DON'T want leaking between cells.
Mixed: contain different types of cells e.g goblet cells produce mucous.

58

Epithelial: Stratified Squamous

Many cells think -> top cell used for classification
'Wear + tear' epithelium e.g skin -> divide rapidly
Lots of desmosomes + hemi desmosomes
Keratin -> protein found in outer layer of dead cells (squames) -> strong + impermeable to water e.g skin
Most cells dont have keratin -> mouth, anus, oesophagus etc.

59

Epithelial: Stratified Cuboidal/Collumnar

2-3 cells thick
Found in large ducts + space between 2 different types of epithelial.

60

Epithelial: Pseudostratified

Looks layered but only 1 cell thick
Nuclei at different heights
E.g lining of trachea

61

Epithelial: Transitional

Changes appearance
E.g bladder: empty: 7-8 cells thick -> full: 2-3 cells thick
Bladder: large apical cells with 2 nuclei have refractile boarders -> thickened plasma membrane which is impermeable to water -> stops loss of water + blocks toxins from urine.

62

Glands + Salivary Glands

Contain epithelial specilised for secretion
Exocrine glands: grow downwards into connective tissue -> duct in middle -> secrete onto surface of cells -> local effect. Branch to increase SA -> increase amount of secretion.
Endocrine Glands: form in same way however duct is lost -> invested with blood vessels -> products (hormones) secreted into blood vessels -> cause effects throughout the body.

63

Structure of a duct

Acinus: 95% of secretory portion produced here
Intercalated duct
Striated duct: changes the composition of saliva by pumpting ions in/out
Interlobular duct

64

Cells in secretory portion of duct

Serous: produce protein (produce enzyme which breaks down food)
Mucous; stains lightly
Myoepithelia: surround secretory cells -> contract to squeeze secretion into the duct.

65

Salivary Glands

Minor: mucous secreting
Major: Parotid (composed of 70-80% serous cells), Submandibular (60% serous + 40% mucous -> floor of mouth), Sunlingual (70% mucous -> floor of mouth).

66

From Egg to Embryo

Zygote -> blastula (ectodern + endoderm) -> grastrula (ectodern + endoderm + mesoderm)

67

Blastocyst

Ball of cell embedded in the uterus
Contain epiblasts and hypoblasts with trophoblasts surrounding
Amniotic cavity begins to form as epiblasts release amniotic fluid.
Eiblasts begin to migrate along the primtive groove -> replace hypoblast cells with endoderm cells
The endoderm cells then influence the migrating epiblast cells to differentiate into mesoderm cells
The original epiblast layer differentiates into ectoderm cells

68

Ectoderm Cells

Form 2 types of tissue
1. Epidermal ectoderm: skin, hair etc
2. Neuroectoderm: neural tube, neural crest cells -> form CNS (brain + spinal cord)
LOOK AT DIAGRAM IN NOTES FOR PROCESS OF DIFFERENTIATION

69

Mesoderm Cells

Different types of mesoderm give rise to different structures e.g paraxial = bone tissue, lateral = red blood cells
Mainly supporting structures

70

Endoderm Cells

Pancreatic cells, thyroid cells, lung cells

71

Epithelial Mesenchymal Trancition (EMT)

Stationary epithelial cells differentiate into migratory mesenchymal cells -> gets signal to detach from surrounding cells + basement membrane -> invade tissue and form organs in new places
Also important in formation of mesoderm + neural crest cells
Can be seen in adults during wound healing, cancer metasis (invade blood tissue) + fibrotic pathologies e.g cataract.

72

Connective Tissue

Connects and supports other tissue types (functional and structural connection).
Cells + extracellular matrix (cells spread apart + surrounded by extracellular matrix -> protein fibres + ground substance).
Types: proper + specilised

73

Connective Tissue Proper

All organs
Loose = more ground substance than fibres -> found beneath epithelial cells (seseptible to invasion + therefore many immune cells).
Dense = more fibres than ground substance -> few cells (mainly fibroblasts).
Irregular: fibres orientated in different directions -> tentile strength in all directions.
Regular: fibres arranged parallel -> tentile strength only in one direction e.g tendons + ligaments
ECM: fibres (collagen, reticular + elastic) + ground substance

74

Connective Tissue Proper ECM Fibres - Collagen

Thickest + most abundant
3 strands of collagen molecules are wound together (winding gives strength) -> form a collagen fibril
Bundles of fibrils form a collagen fibre -> can be different diameters due to different number of fibrils in the bundle.
NOTE: different types of collagen molecules produce different types of collagen fibres.

75

Connective Tissue Proper ECM Fibres - Reticular

Made of collagen fibres containing collagen type III molecules.
Organised framework for cells to sit on.
Highlighted by a special stain.

76

Connective Tissue Proper ECM Fibres - Elastic

Thinnest
Both collagen + elastic fibres
Elastic fibres made of elastic proteins coiled up -> coil allows stretch

77

Connective Tissue Proper ECM - Ground Substance

Mostly water -> some proteins + sugar to make more viscous
Produced by fibroblasts
Allow diffusion of ions + molecules
Proteoglycans: extend into extracellular matrix -> cushion cells
Glycoproteins: link ECM to cells

78

Cells in Connective Tissue Proper

Resident: stay in CT all the time = fibroblasts, adipocytes, mesenchymal stem cells, machrophage, mast cells
Transient: move in + out the CT e.g lymphocytes

79

Cells in Connective Tissue Proper - Fibroblasts

Most common
Produce extracellular fibres + ground substance (secretion).
If active have light hetrachromatin.

80

Cells in Connective Tissue Proper - Adipocytes

Store fats in their cytoplasm
Found individually + in small groups in loose CT
Accumulate in large numbers -> adipose tissue
Under light microscope: appear transparent with a thin ring of cytoplasm

81

Cells in Connective Tissue Proper - Mesenchymal Stem cells

Differentiate into cells for tissue repair
Part of supportive CT structure

82

Cells in Connective Tissue Proper - Macrophages

Phagocytic
Abundant lysosomes -> break down
Immune defence

83

Cells in Connective Tissue Proper - Mast Cells

Develop in bone marrow
Granules contain inflammatory mediators -> attract transient immune cells -> immune defence.

84

Tissue Section VS Spread Preparation

Section = cut through tissue + mount on a slide
Spread = tissue thin enough -> remains whole e.g mesentry (thin layer of loose CT between two layers of simple squamous epithelium).

85

Types of Specilised Connective Tissue

Blood
Adipose
Cartilage
Bone

86

Specilised Connective Tissue - Bone

Fluid CT
Blood cells + plasma

87

Specilised Connective Tissue - Adipose

Under the skin
Accumulation of adipocytes
Functions: energy storage, thermal insulation, cushioning of organs + tissue, hormone secretion.

88

Specilised Connective Tissue - Cartilage

Cells = chondrocytes -> produce + maintain ECM
Avascular = no blood vessels, lymph vessels or nerves -> all oxygen, nutrients + wastes diffuse through ECM.
Three types: Hyaline, Elastic and fibrocartilage

89

Specilised Connective Tissue - Cartilage - Hyaline

Most abundant
ECM contains: type II collagen fibres (structure + strength), Proteoglycans (bind water), Multiadhesive glycoproteins (anchor chondrocytes + proteoglycans to ECM).
60-80% by water by weight -> cushioning + allows diffusion of molecules (important as no blood vessels)
Calcium can bind -> turn into bone
Surrounded by perichondrium

90

Where is Hyaline CT found ?

Lubricates articular surfaces of joins e.g knee + elbow joints
Costal cartilage of ribs -> allows flexibility of ribcage during respiration
Foundation for growth + development of bones (foetal skeleton) + cartilage growth plates in adult bones
Structural support for respiratory system -> keeps airways open + stops them collapsing

91

Specilised Connective Tissue - Cartilage - Elastic

Elastic + collagen fibres in ECM
Flexible
Surrounded by perichondrium
Does not calcify
Found: external ear + epiglottis

92

Perichondrium

Dense, irregular CT proper attached to hyaline + elastic CT -> provide blood supply + new chondrocytes for growth + repair.

93

Specilised Connective Tissue - Cartilage - Fibrocartilage

Combination of hyaline cartilage + dense regular CT
Chondrocytes + fibroblast
ECM = collagen type I + II
Resistant to sheer force + compression (shock absorber)
Anchor vertebrae together + stop them being crushed
Found: intervertebral disc + in meniscus of joints
No perichondrium + no calcification

94

Specilised Connective Tissue - Bone

Osteocytes (cells) in a mineralised ECM -> extremely hard
BOTH collagen + ground substance in ECM become mineralised
Function: support body weight, protect organs, levers for muscle movement
Store calcium + phosphate -> hydroxyapatite crystals
ECM -> collagen type I, proteins make up ground substance -> Proteoglycans (compressive strength), Growths factors (regulate bone growth, remodeling + repair), Multiadhesive glycoproteins (attach cells + collagen fibres to ECM), other proteins (e.g osteocalcin -> remove calcium from circulation).
Types of bone: Compact, Spongy and Immature

95

Specilised Connective Tissue - Compact Bone

80% of body's bone by weight -> strong, tough + rigid (structural)
Composed of Haversian systems -> central canal containing blood vessels + a nerve -> surrounded by concentric rings of lamella (form an osteon) -> osteons have interstitial lamella (remnant of old osteons) surrounding them.
Horizontal connecting channels = Volkmann's canal
Lamella: alternating dark + light rings (due to collagen fibres having alternating orientation -> gives strength)
Lacunae = small cavities in the bone -> contain osteocytes.
Canaliculi = channel between lacunae + central canal -> allow passage of substances to/from central canal.

96

Specilised Connective Tissue - Spongy Bone

Network of trabeculae
Soft, weak + flexible
HIgh SA (exchange of calcium + phosphate)
Spaces in between trabeculae filled with bone marrow (site of haematopoiesis)
Contain lamellae but do NOT form haversian systems

97

Specilised Connective Tissue - Immature Bone

Foetal skeleton + adults during repair
Non-lamellar bone
Collagen fibres interlace
More cells + ground substance
Initially not heavily mineralised however becomes calcified.

98

Specilised Connective Tissue - Bone - Periosteum

Dense, irregular CT
Surrounds bone
When bone actively growing forms 2 layers -> outer fibrous layer + inner cellular layer (contain active osteoprogenitor cells)
When bone not actively growing -> only outer fibrous layer
Attached to bone by Sharpey's fibres (strong collagen fibres) -> continuous with collagen fibres in bone ECM

99

Specilised Connective Tissue - Bone - Endosteum

Thin cellular CT layer -> lines internal surface of bone
Osteoprogenitor cells differentiate into osteoblasts when needed -> lay down bone matrix.

100

Types of Bone Cells

Osteoprogenitor
Osteoblasts
Osteocytes
Osteoclasts

101

Osteoprogenitor Cells

Origin of osteoblasts + osteocytes but NOT osteoclasts
Found in endosteum + periosteum

102

Osteoblast Cells

Build bone (secrete bone matrix), calcify bone matrix
Active = cuboidal
Inactive = flattened
When surrounded by bone matrix -> osteocyte

103

Osteocyte Cells

Mature bone cells
Found in lacunae
Communicate via cannaliculi
Maintain bone matrix

104

Osteoclast Cells

Break down bone (phagocytic)
Found in Howship's lacunae

105

Cardiovascualar System

Heart: arteries carry oxygenated blood away from the heart, veins carry deoxygenated blood towards the heart. Pulmonary circulation = heart to lungs + back, Systemic circulation = heart to body + back
Blood vessels: form loop -> heart -> artery -> medium muscular artery -> small arteries -> arterioles -> capillaries -> venules -> small veins -> medium veins -> large veins -> heart
NOTE: GRADUAL NOT DISTINCT CHANGE

106

Walls of Blood Vessels

Important for classification
3 layers: tunic intima, tunica media, tunica adventitia

107

Tunica Intima

Inside of vessel
Endothelium -> simple squamous layer of cells with basal lamina (some have a small amount of CT).
Internal elastic membrane -> distinction between t.intima and t.media.

108

Tunica Media

Middle layer
Most useful in classification (lots of muscle tissue = medium muscular artery, lots of elastin = elastic artery)
External elastic medium -> divide between t.media + t.adventilia

109

Tunica Adventilia

Outer layer

110

Main Cells Types of Blood Vessel

Endothelium
Vascular smooth muscle
Pericytes

111

Main Cells Types of Blood Vessel - Endothelium

Regulates blood homeostasis

112

Main Cells Types of Blood Vessel - Vascular Smooth Muscle

Located in t.media -> synthesize collagen + elastin
Support elasticity + contractability

113

Main Cells Types of Blood Vessel - Pericytes

Located in venules -> contract (controlled by nitric oxide) -> controls which parts of the body the blood flows to.

114

Arteries

Classification based on t.media (elastic or muscular)
Thicker t.media + thinner t.adventitia
Large elastic arteries
Medium muscular arteries
Small arteries and arterioles

115

Large Elastic Arteries - Tunica Intima

Endothelium + basal lamina
Subendothelial layer -> collagen, elastic fibres + smooth muscle cells (secrete CT).
Internal elastic lamina

116

Large Elastic Arteries - Tunica Media

Layer of elastic fibres -> fenestrated (layers have holes in them -> allow passage of wastes + nutrients). Number of layers related to age.

117

Large Elastic Arteries - Tunica Adventita

Thin
Loose CT -> stops artery from over expanding
Fibroblasts
Blood vessels + nerves -> supply artery as walls are so thick

118

Medium Muscular Arteries - Tunica Intima

Thinner than large elastic arteries
Endothelium + basal lamina
Subendothelial layer
Prominent internal elastci lamina

119

Medium Muscular Arteries - Tunica Media

Smooth muscle fibres
Some elastic fibres however NO LAYERS
Recognisable external elastic lamina
Contraction of muscle fibres helps maintain blood pressure.

120

Medium Muscular Arteries - Tunica Adventitia

Thick
Same as t.media

121

Small Arteries + Arterioles

Small arteries = up to 8 layers of smooth muscle in t.media
Arterioles = 2-3 layers of smooth muscle in t.media
May or may no have internal elastic lamina
Areterioles: regulate flow to capillary bed. Contraction o smooth muscle = increased vascular resistance = decreased blood flow to capillaries (controls which areas of the body the blood flows to).

122

Capillaries

Smallest diameter
Single layer of endothelium with basal lamina -> need small diffusion distance to allow exchange of oxygen and carbon dioxide.
Red blood cells fill lumen
Classification: different types of capillaries are found in different areas of the body and thus have different functions -> continuous capillaries, discontinuous capillaries, fenestrated capillaries

123

Continuous Capillaries

Do not allow diffusion of large molecules
Uninterrupted endothelium + continuous basal lamina
Found: CT, muscle, lung, skin, CNS

124

Discontinuous Capillaries

Have a discontinuous basal lamina -> allow diffusion of large molecules
Liver, spleen, bone marrow

125

Fenestrated Capillaries

Continuous basal lamina but holes in epithelial cells (fenestrated) -> allow diffusion of specific molecules across capillary wall
Endocrine glands, fluid + metabolite absorption,.

126

Veins

Large lumen -> often collapsed
Tunicas not as well defined as vessel walls are not at thick.
Classification helped by looking at nearby artery -> venules, medium vein, large vein

127

Venules

Post capillary venules: endothelium + basal lamina only
Muscular venules: endothelium + basal lamina + 1-2 layers of smooth muscle

128

Medium Vein

Valves: stop backflow of blood (low pressure by this point)
Tunica intima: endothelium + basal lamina + thin subendothelium. Some have a thin internal elastic lamina.
Tunica media: smooth muscle cells + collagen + elastin.
Tunic adventitia: thicker than t.media, collagen + elastic fibres.

129

Large Veins

Tunica Intima: endothelium, basal lamina, some subendothelial CT + smooth muscle
Tunica media: thin, smooth muscle, CT, some can have cardiac muscle if close to IVC and pulmonary veins
Tunic adventitia: thickest layer, CT + smooth muscle

130

Lymphatic Vessels

Unidirectional flow
Absorps from tissue into lymphatic capillaries -> greater permeability (able to remove protein rich fluid that the blood vessels cant).
Lymphatic vessels: endothelium but no basal lamina (higher permeability), large vessels (thicker wall with CT + muscle), valves.

131

Blood

Plasma = liquid content of the blood
Serum = liquid after the blood if allowed to clot
Made in bond marrow ->haematopoetic process.

132

Cells in the blood

Erthrocytes
Platelets
Leukocytes
Mast Cells
Monocytes + Macrophages
Lymphocytes

133

Erythrocytes

Red blood cells
Produced in bone marrow
No nucleus -> cant repair themselves -> destroyed in the spleen
Enucleation -> condenses nucleus + expells it when in the bone marrow -> allows formation of biconcave discoidal shape
Size + shape can be altered due to disease -> cause anemia (dont have enough RBC/RBC not working. `

134

Platelet

Clots blood
No nucleus but able to respond to environment -> active at sight of haemorrhage
Produced by megakaryocytes -> reside in bone marrow -> very large nucleus. Platelets produced by shedding off part of their cell membrane.

135

Leukocytes (white blood cells)

Granulocytes (neutrophils, eosinophils, basophils)

136

Leukocytes - Neutrophils

Light pink cytoplasm + abnormal nucleus
Engulf + destroy anti-body coated bacteria
Most common

137

Leukocytes - Eosinophils

Cytoplasm stains dark pink
Fight parasites

138

Leukocytes - Basophils

Cytoplasm stains dark blue/purple
Allergic response -> granules contain heparin + histamine
Anti-parasitic response

139

Mast Cells

Found in tissue
Release histamines + heparin -> cause area to be filled with fluid

140

Monocytes + Macrophages

Largest cell in blood
Monocyte when in blood -> during inflammation enters tissue + becomes a macrophage -> phagocytoses bacterial cells

141

Lymphocytes

Controls the immune response
B lymphocytes = found in bone marrow + produce antibodies.
T lymphocytes = produced in thymus + fight viruses.