Histology Flashcards
1
Q
Definitions
- Cytology
- Histology
A
- Cytology: study of cell structure
- Histology: Study of tissues
- looks at how specialized cells come together to form tissues
2
Q
Variety and Specialisation of cells
- Erythrocytes
- Adipocyte
- Myocyte
A
- Erythrocytes: Isolated, anucleate, flexible, abundant haemoglobin
- Adipocyte: have large lipid vacuole (main function of cell = fat storage), peripheral condensed nucleus (squished to side)
- Myocytes: Contractile filaments, respond to nerve input
3
Q
Tissues - defn
-2 parts of an organ
A
- Tissues: Collections of cell performing related functions
- Are 2 parts to tissues;
- Parenchyma: The functional cells within an organ
- Stroma: The supportive role within an organ
e.g. In liver, parenchyma = hepatocytes; stroma = blood vessels, liver capsule and supporting CT
4
Q
4 Tissue types (and the 5th one sometimes used)
A
- Epithelium: Barrier b/w body and external environment
- line internal and external surfaces and lining of tubes
- Muscle: Contraction; generation of force
- Connective Tissue: Connect, anchor, support
- Nervous Tissue: initiate and transmit nervous impulses
- Round cells: Cells that don’t form a coherent tissue but are individual cells that can move widely throughout body
- e.g. macrophages
5
Q
Epithelia
- definition and features
- what it forms (3 things)
- where it stops
A
- Is continuous sheet-like layer of cells in combo with a thin, underlying, non-cellular basement membrane (blood vessels don’t cross)
- forms barrier/active interface
- lines hollow organs and forms glands
- can even form more solid structures like the liver
- is supported by layer of ECM (basal lamina) -> made from type 4 collagen and other components
6
Q
5 major functional categories of Epithelia
A
- Protective: outer surface of body and opening of cavities (oesophagus)
- Exchange: rapid exchange of gases (is therefore a thin endothelial lining)
- Transporting: exchange of nongaseous materials; selective (gut and kidney)
- Ciliated: move fluid across surface (respir. airways, female reproductive tract)
- Secretory
i) Exocrine: Syn. and release secretory products to external environment (serous; salivary glands, pancreas)
ii) Endocrine: secrete products into extracellular space and the bloodstream (e.g. hormones)
7
Q
Locations of Ciliated epithelia and Protective epithelia
A
- Ciliated epithelium: respiratory system and female reproductive system (move mucous coat along surface)
- in Female; ciliated epithelia is simple- pseudostratified in Resp. system
- Protective epithelium = skin, lining mouth, oesophagus and anus
- skin: stratified epithelium (cells become squamous at top)
- highly keratinised (to avoid abrasion) = skin, footpad
- Less keratinised (to moisten surfaces) = oesophagus, orgal cavity, cervix, vagina
- skin: stratified epithelium (cells become squamous at top)
8
Q
Layers of skin epithelia (5)
-from superficial to deep
A
- Stratum corneum (looks loose and wispy b.c. oils removed)
- Stratum lucidum
- Stratum Granulosum
- Stratum Spinuousus
- Stratum Basale
9
Q
Types of cells in exchange epithelium and transport epithelium
A
- Exchange epithelium = simple squamous (allows easy exchange)
- Transport epithelium = columnar (small intestine)
10
Q
Intracellular junctions (3 types) -definitions
A
- Intercellular junctions: key feature of epithelial cells
- tight junctions restrict movement of material passing between transport epithelial cells
- Anchoring junctions: cell-cell (desmosomes) and cell-basement membrane (hemidesmosomes
- Gap junctions: cytoplasmic bridge allows electrical continuity and synchronised contraction
- allow communication
- cardiac myocyte have them
11
Q
Secretory epithelia - what they do
-2 types
A
- Form clusters or glands rather than sheets and secrete substances
- may also be individual cells scattered (e.g. goblet cells - Exocrine glands: have ducts and secrete onto internal or external surface (sweat, saliva, mammary)
- Endocrine cells: secrete into the bloodstream (e.g. Islets of Langerhans and insulin, thyroid, adrenal and pituitary)
12
Q
Gland development
A
- Exocrine glands: hollow centre forms,, creating a duct that provides passageway for secretion sot move to surface
- Endocrine glands: Lose connecting bridge of cells that link them to parent epithelium -> secretions go straight to bloodstream
13
Q
Kidney
A
- Nephron = renal coruscle + tubule
- blood filtered w/in kidney by passing along nephron
- filtered material passes along tubule of nephron
- transport epithelia found in proximal and distal convoluted tubules (and loop of Henle)
- blood enters and exits corpuscle -> filtrate forms and moves down convoluted tubule and through system
- filtrate modified - Proximal convoluted tubule = fuzzy surface (has tiny microvilli to increase SA for absorption)
- lining of surrounding capillaries: endothelium (flat squamous cells)
- podacytes sit outside capillary -> comblike structure helps filter blood physically and electrically (has footlike structures)
- basement membrane, endothelium and podocyte = filtration system
14
Q
Epithelium in Jejunum
A
- single layer of epithelium in internal surface -> renews v. quickly (renewal occurs in crypts)
- microvilli on epithelia (to increase SA)
- columnar epithelia
15
Q
Epithelia in Liver - how cells arranged
A
- sheets of 6 sided hepatocytes arranged into lobules
- bathed by sinusoidal blood on 2 sides
- b/w each row of hepatocytes are canaliculi into which bile flows (eventually become ducts)
- bile helps break down fats
16
Q
Muscle tissue - 3 types
-e.g.
A
- 3 types;
1. Skeletal (striated): voluntary contraction, often agonist/antagonist
e. g. digphragm, tongue, extrinsic eye muscles
2. Smooth: involuntary contraction (autonomic)
e. g. intestinal wall w/ agonist/antagonist, blood vessels, uterus
3. Cardiac: involuntary contraction- in heart
- contraction also important for wounds, scar tissues etc for regions to heal
17
Q
Skeletal muscles
- what composed of and basic function
- features of muscle cells
- e.g.
A
-Composed of myofilaments -> has myosin (thick) and actin (thin) fibres
-divided in sacromeres that align (z disk aligns and makes striations)
-thick heads that can move along actin if ATP available
Features;
-fused cells (so in long parallel arrangements)
-many nuclei
-peripheral nuclei
-cylindical
*can regenerate
e.g. pharynx, diaphragm, tongue, eye, oesophagus
18
Q
Skeletal muscles;
-slow vs fast twitch
A
- Slow twitch (aerobic): fatigue resistant (endurance, postural muscles)
- tend to be red (like chicken leg muscle)
- Fast twitch (anaerobic): strong, precise, fatigue rapidly, sprinters, digits
- tend to be white (like chicken breast)
19
Q
Smooth Muscle
-features and e.g.
A
Features;
- Single cells w/ one central nucleus
- often 2 layers
- perpendicular
- no striations
- spindle-shaped
- diameter varies
-e.g. arrector pili, blood vessels, iris, airways, spleen, uterine wall, bladder
20
Q
Cardiac muscle
- features
- can they regenerate?
A
Features:
- Striations
- branching
- central nucleus
- intercalated discs
- complex pattern
- can’t regenerate as post-mitotic
e. g. Cardiac (heart)
21
Q
Connective Tissues
- functions
- definition
A
- Structural and metabolic support for tissues/organs
- mediate nutrient and metabolite exchange w/ circulation
- cells embedded in mesh of fibres (elastin/collagen) and extracellular matrix
- have extensive ECM
- CT: any structure whose primary function is physical support for other structures
- in broader sense, also encompasses fluids
22
Q
Types of CT (6)
-e.g. of each
A
- Loose: Fibroelastic tissues that underlie epithelia (support, biological packing)
e. g. lamina propria of intestine, surrounds blood vessels - Dense: tissues for strength, flexibility, biomechanical action
- e.g. tendons, ligaments, muscle and nerve sheaths, basement membranes
- Adipose tissue - fat storage (has no real matrix)
- Cartilage: supporting tissue (ear, nose, knee menisci, joints)
- Bone: calcified supporting tissue
- Blood: water matrix - ions and dissolved molecules, soluble proteins
23
Q
Osteoblast, osteoclast and osteocyte
A
Osteoblast: lays new bone matrix
Osteoclast: ‘Clean’ take bone away
Osteocyte: maintain bone (are w/in lacuni)
*same pattern works for other cell types (i.e. chondrocytes)
24
Q
Chondrocytes - appearance
A
- Chondrocytes appear as cells w/in a matrix
- in cartilage, these cells appear in clusters (usu. of 2)
25
Q
Nervous Tissue
- Nerve cells
- Glial cells
*definitions
A
- Nerve cells (neurons): specialised cells that receive, integrate and transmit info in form of electrical signals
- Glial cells (astrocytes for metabolic suuport, Schwann cells and ogliodendrocytes for myelin)
26
Q
Basic neuron structure
-important features
A
- Cell body = nucleus and surround cytoplasm (perikaryon)
- in CNS or peripheral ganglia
- 1 axon (efferent)
- arises from axon hillock
- ends at terminal boutons - 1 + dendrites (are afferent)
*are excitable cells and are post-mitotic (don’t get replaced)
27
Q
3 Types of Neurons
A
- Multipolar Neurons: Multiple dendrites and are able to integrate input from many afferent neurons
e. g. interneurons and motor neurons - Bipolar neurons: single dendrite located opposite the axon hillock
e. g. sensory neurons of sight, smell and balance - Pseudounipolar neuroons: fusion of the origins of the axon and dendrite
e. g. primary sensory neurons (some in eye and ear too)
28
Q
Organisation of the brain
A
- Grey matter = peripheral cortex
- folded in mammals to give sulci and gyri
- small foci of neuronal cell bodies form nuclei deeper w/in brain
- covered in 3 layers of CT meninges (pia mater, arachnoid and dura mater (outermost tough layer)
- cerebrospinal fluid fills subarachnoid space b/w arachnoid and pia mater
29
Q
Glial cells
A
- Oligodendrocytes (called Schwann cells in PNS)
- Astrocytes (regulate metabolistes)
- Microglia
- Ependyma (simple cuboidal/columnar ciliated ep.
- lines ventricles and spinal canal
30
Q
Synapses in Neurons
A
- Neurotransmitters in vesicles
- electrical signals cause release of chemical across synapse
31
Q
Neuromusclar Junction
-what it is, basic features
A
- Similar to basic synapse structure
- Each motor neurone innervates from 1 >1000 muscle fibres
- axon ends at motor end plate, enveloped by Schwann cell
- Ach is neurotransmitter that is broken down after signal sent
32
Q
Organ
A
-Organ: anatomically discrete collection of 2 or more tissue types (often 4) working together to perform a specific function
33
Q
Organ Systems
A
- More than one organ interacting
e. g. Respiratory system
34
Q
Sebaceous Gland
A
- Has hollow middle
- outside gland, epithelial cells rapidly dividing, cells mature and move to middle of gland
- Accumulates oily secretions (sebum)
- nucleus dies and whole cell bursts onto hair follicle -> comes out and goes onto skin surface
- Holocrine secretion: entire cell is shed
35
Q
Sweat gland
A
- Simple tubular gland
- lined by cuboidal epithelium
- discharge secretions into tube
