Tissues Of The Body Flashcards
What different types of glands are there?
- Simple
- Compound
Describe the difference between endocrine and exocrine.
- Exocrine: glands with ducts
- Endocrine: ‘ductless glands’ secrete directly into the bloodstream.
What different types of secretions are there?
- Mucous: mucus rich in mucins
- Watery and free of mucus secretions
What is a visceral and parietal pleura?
- Visceral (inner)
- Parietal (outer)
What are the 4 layers of the intestinal lining?
- Mucosa
- Submucosa
- External muscular layers
- Serosa
What layers does the mucosa consist of?
- Muscularis mucosae
- Lamina propria
- Epithelium
What is the Submucosa?
- Layer of connective tissue bearing glands, arteries, veins and nerves
How are luminal contents moved along the intestine?
- 2 layers of smooth muscle form Muscularis externa which create a peristaltic wave
What is exocytosis also known as and what is it?
- Merocrine secretion
- Membrane bound component approaches cell surface
- Fuses with plasma membrane
- Contents are released into extracellular space.
- Membrane reforms.
What is Apocrine secretion?
- Non membrane bound structure moves to cell surface
- Contact and pushes up apical membrane
- Apical cytoplasm surrounds droplet
- Membrane surrounding droplet pinches off
- Membrane added to regain SA
What is holocrine secretion and where is it found?
- Disintegration of cell
- Release of contents
- Discharge of whole cell
- ONLY in sebaceous glands
What is transepithelial transport?
- Endocytosis at one surface
- Transport vesicle shuttles across cytoplasm
- Exocytosis at opposite end.
What is the function if the Golgi apparatus?
- Sorting into different compartments
- Packaging via condensation of contents
- Glycosylation (addition of sugars to proteins and lipids)
- Transport
What happens to the products of the Golgi?
- Majority to secretory vesicles
- Retained in cells for use (lysosomes)
- Transported to plasma membrane (Glycocalyx)
What is Glycocalyx?
- Sweet husk, proteoglycans, glycoprotein and glycolipids
- Protection of epithelial cells
- Intracellular communication
- Intracellular adhesion
- Intracellular adhesion
What are the different types of secretion control?
- Nervous (sympathetic stimulation of adrenal medullary cells for adrenaline)
- Endocrine (stimulates cortex of adrenal gland to secrete hormones)
- Neuro-endocrine (nervous cells stimulate hormone secretion)
Give 3 examples of exocrine secretion.
- Unicellular gland in jejunum and colon
- Parotid glands
- Submandibular glands
Give 3 examples of endocrine secretion.
- Pancreas
- Thyroid
- Adrenal (suprarenal)
Where in the body can mucous membranes be found?
Linings of internal tubes that have contact with the exterior environment, e.g respiratory tract
Where is a serous membrane and where is it found?
- Thin, two part membranes which line closed bodily cavities to secrete a lubricating fluid, to allow friction free movement of structures they surround.
- Peritoneum (abdominal organs)
- Pleural sacs (lungs)
- Pericardial sacs (heart)
What are serous membranes composed of?
- Simple squamous epithelium, secretes watery lubricating fluid
- Thin layer of connective tissue.
What are the different types of biopsies and where on the body are they use?
- Smear: cervix, buccaneer cavity
- Curettage: endometrial lining of the uterus
- Needle: brain, breast, liver, kidney, muscle
- Direct incision: skin, mouth, larynx
- Endoscope: lungs,intestine,bladder
- Transvascular: heart, liver
What are the 3 main types of stain and what do they stain?
- Haematoxylin - acidic components (nucleus/chromatin) blue/purple
- Eosin - basic (cytoplasmic proteins, extra cellular fibres) pink
- Periodic Acid Schiff - (glycoproteins, carbohydrates) magenta
How does processing of a specimen lead to shrinkage artefacts?
- Dehydration, rehydration and dehydration again
Why do tissues need repair?
- Preserves cell structure
- Prevents autolysis and putrefaction
What is an epithelium?
- Sheets of contiguous cells, varying in origin, that line the inner surfaces and cover outer surfaces.
Where is the basement membrane found and what is it’s function?
- Between epithelial tissues and connective tissue
- Strong flexible layer for cellular adhesion and a molecular filter.
Where are pseudostratified cells found in the body?
- Upper nasal cavity
- Ear
- Upper respiratory system
Where are simple squamous cells found and what’s their roles?
- Blood vessels (active transport by pinocytosis)
- Mesothelium (to secrete for lubrication)
- Alveoli (gas exchange)
What are stratified squamous’ role and where are they found?
- Prevent wear loss, UV damages, abrasion
- Skin
- Vagina
- Anus
- Oesophagus
Where are cuboidal cells found, what are their roles?
- Ducts of exocrine glands
- Kidney tubules
- Absorption, hormone secretion.
Where are columnar cells found and what are their roles?
- Small intestine & colon (absorption, secretion & lubrication)
- Stomach lining & gastric glands (secretion)
- Gall bladder (absorption)
- Uterus
- Oviduct (transport)
What are transitional epithelium?
- Layers of cells that have the ability to change shape from cuboidal (relaxed) to squamous (tense)
Where are transitional epithelium found and its role?
- Bladder, ureters.
- Distension and protection of underlying tissues
How long does it take for skin cells to ‘die’?
- 28 days.
Where are keratinised stratified squamous cells found and their roles?
- Skin surface
- Linings of surfaces exposed to the exterior.
- Protection against abrasion & physical trauma
- Prevents water loss, ingress of microbes.
Where are stratified columnar found?
- Conjunctiva of eye
- Lining some large excretory ducts.
Where are stratified cuboidal cells found?
- Lining ducts of sweat glands.
Where does glycosylation of proteins occur?
- Golgi apparatus
What is the process of glycosylation?
- Addition of sugars to proteins and lipids.
- Glycocalyx formation (intercellular communication, adhesion to substrates, contact inhibition)
What are the 4 ways of controlling secretion?
- Neural control (sympathetic stimulation of adrenal medullary cells)
- Hormone control (ACTH promotes secretion of adrenal cortex hormones (cortisol)
- Neuro-endocrine (hypothalamus controls ACTH production)
- Negative feedback (inhibition of production)
What is the limit of resolution?
- The minimum distance between two points that still allow them to be individually resolved.
Why are electron microscopes better at resolving than light microscopes?
- Shorter wavelength, better resolution
resolution is proportional to wavelength
What is heterochromatin?
- Dark in colour, dense & unexpressed
What is euchromatin?
Light in colour, less dense and expressed.
What is a nucleolus?
- Contains RNA for ribosome synthesis and assembly.
What is the role of the Rough Endoplasmic reticulum?
- Synthesise proteins
What is the role of the SER?
- Biosynthesis of lipids
- Steroid production
- intracellular transport
What is the role of the Golgi with respect to proteins?
- Modify, sort and package proteins from the RER
- Movement from Cis to the Trans side.
- Secretion in vesicles or formed into lysosomes.
What is the role of peroxisomes?
- Detoxification (eg alcohols)
- Production and utilisation of H2O2
What subunits make up the cytoskeleton and what is its overall role?
- Microtubules
- Microfilaments
- Intermediate filaments
- Allow for transport of cellular constituents
- Maintain the shape & structure of the cell
What components form connective tissue?
- Cells
- Ground substance
- Fibres: collagen, reticular, elastic
What is the role of ground substance?
- Resistant to impact due to jelly like composition.
What are the roles of the 4 different types of collagen?
1: Fibres/fibre bundles
2: Elastic cartilage
3: Reticulum (fibres around muscle and nerve cells)
4: Present in basal lamina
What is the definition of connective tissue?
- Forms continuum throughout the body, provides metabolic and physiological support, links epithelium, nerves and muscles.
Elastic fibres contain what two components?
- Elastin
- Fibrillin (surrounds enfolded elastic fibres)
What is the role of fibroblasts?
- Synthesises and secretes fibres and ground substance.
Important in wound healing and cells responsible for scar tissue
What are macrophages and their role?
- Phagocytic, degrade foreign organisms and cell debris
Effectively a phagocyte but in connective tissue
What is the role of mast cells?
- Abundant in granules eg. anticoagulant
- Mediate hypertension and allergic reactions.
What is the function of the extracellular matrix?
A hydrating gel.
What is the difference between dense and loose connective tissue?
- Dense: more fibres, less ground substance.
- Loose: fewer fibres, more ground substance.
What’s the difference between irregular and regular dense tissue?
- Irregular, fibres run in all different directions, can resist force in all directions.
- Regular, fibres all run in the same direction, very strong in the direction they run, tendons.
Cells from cartilage are known as?
- Chondrocytes
The extracellular matrix of cartilage contains a high ratio of GAGs, what does this allow?
- Diffusion between chondrocytes and blood vessels.
What is the role of Hyaline cartilage?
- Precursors to bone development by endochondral ossification.
- Present in articulating surfaces (connects ribs to sternum, parts of the respiratory tract)
- Calcifies with age.
What is fibrocartilage?
- Mix of chondrocytes and fibroblasts.
- Combination of dense regulator connective tissue and hyaline cartilage.
- No surrounding perichondrium
- Sites: intervertebral discs, articular discs of joints, meniscus of knee joint and pubic symphysis.
- Shock absorber, resists shearing forces
What is elastic cartilage and its role?
- Many elastic fibres in ECM giving elasticity and resilience.
- Doesn’t calcify with age.
- Sites: External ear, epiglottis, Eustuchian tube.
When adults damage chondrocytes how is it repaired?
- Can’t undergo mitosis of chondrocytes, so deposition of fibrous scar tissue fills the area.
What are the 4 main parts of the bone?
- Spongey bone (deeper and porous, highly vasculated)
- Compact bone (dense, hard, outer layer, Haversian and Volksmann canals)
- Periosteum (tough, vasculated, surrounds bone)
- ECM (Collegenous fibres in calcified matrix)
What is caniliculi?
- Cytoplasmic process, connecting osteocytes that allow the sharing of nutrients.
Outline the bone remodelling system.
- Osteoclasts, ‘cutting cone’ release of H+ and lysosomal enzymes
- Osteoblasts, form new bone.
What are the 3 main macroscopic appearances of the skin and what are they effected by?
- Colour: UV exposure, location, ethnicity
- Hair: Site, sex, ethnicity, age
- Laxity: Age, UV exposure.
What is Vitiligo?
- Autoimmune depigmentation of the skin.
- Tends to be symmetrical.
- More obvious on dark people.
What is Alopecia?
- Autoimmune reaction causing loss of hair.
- Greater psychological effect on women.
What are the 4 strata of the skin?
- Horny (corneum)
- Granular
- Prickle
- Basal
What happens in each of the stratum of the skin?
- Basal: Keratinocyte mitosis
- Prickle: Lose ability to differentiate, keratins synthesised.
- Granular: Lose plasma membrane, differentiate into corneocytes, keratins and other fibrous proteins are aggregated.
- Horny: Flattened corneocytes.
What are Langerhans cells?
- Mediate an immune response, they’re antigen presenting cells.
- Dendritic cells of bone marrow origin.
- Scattered through prickle layer.
What are melanocytes and their role?
- Occurs at intervals in the basal layer.
- Produce melanin (darker people have the SAME number of melanocytes just produce more)
What is produced from hair follicles and what for?
- Sebum
- Lubrication
- Waterproofing
What are sweat glands primarily for?
- Thermoregulation.
Name 3 characteristics of the dermis and its components.
- Tough
- Vascular
- Fibrous
-ECM, blood vessels, nerves, lymphatics, mast cells.
What is the main effect of Psoriasis?
- Major protein, fluids and heat loss.
What’s malignant melanoma?
- Cancer of melanocytes
- Can’t cure once penetrated the basal membrane.
What are the main functions of the skin?
- Barrier
- Sensation
- Thermoregulation
- Psychosexual communication.
What are the 3 types of Cartilage?
- Hyaline
- Elastic
- Fibrocartilage
What does GAG stand for in reference to cartilage and what is its role?
- Glycosaminoglycans
- Allows diffusion between chondrocytes and blood vessels.
Give 3 characteristics of Hyaline cartilage.
- Matrix with proteoglycans
- Single/small clusters (isogenous groups)
- Precursor model for bones, so found in early foetal development (development by endochondral ossification)
Where is Hyaline cartilage found?
- Shoulder
- Elbow
- Wrist
- Feet
What are the characteristics of elastic cartilage.
- Many elastic fibres in ECM. = elasticity and resilience.
- Doesn’t calcify with age
Where is elastic cartilage found?
- External ear
- Epiglottis
- Eustuchian tube.
What are the characteristics of fibrocartilage and its role?
- fibroblasts + chondrocytes
- dense regular connective tissue + hyaline cartilage
- Synthesise and secrete both ground substance and fibres found in ground substance.
- Primarily responsible for scar tissue.
Where is fibrocartilage found?
- Intervertebral discs
- Articular discs of joints
- Menisci of joints
- Pubic symphysis