Body Logistics Flashcards
What does homeostasis mean?
Homeo-same
Stasis-standing still
What type of equilibrium is homeostasis?
Dynamic equilibrium
What is homeostasis?
Maintaining a constant internal environment
What needs to be maintained in homeostasis?
Conc. of O2, CO2, salt, electrolytes Conc. of nutrients, waste products pH Temperature Volume/Pressure of body fluid compartments
Which technique does the body use to maintain homeostasis?
Feedback loops (positive and negative)
What is positive feedback?
A substance stimulates another substance, which in turn stimulates the fist substance. Amplification of an effect.
What is negative feedback?
Returning levels back to normal. One substance will inhibit another.
What are the types of glands?
Endocrine and exocrine.
What does an endocrine gland do?
Produce and secrete hormones into the blood.
What does an exocrine gland do?
Produce and secrete chemicals through ducts onto an epithelial surface e.g. Skin.
Examples of glands
Hypothalamus Adrenal Pituitary Parathyroid Thyroid Pancreas Gonads Thymus
What are the requirements for light microscopy?
Preserve tissue -e.g. In formalin
Embed tissue in substance that allows it to be sliced very thinly -e.g. In paraffin
Stain tissue so you can see cell components -e.g. Haematoxylin and Eosin (H&E)
How do Haematoxylin and Eosin stain samples?
H stains nucleus blue most strongly
E stains cytoplasm and extracellular matrix pink most strongly
What are the advantages/disadvantages of frozen section?
Adv- quicker (10mins vs. 16hrs)
Dis- lower technical quality
What is polarised light?
Light travelling in one direction
How many nanolitres in a microlitre?
1000
How many microlitres in a millilitre?
1000
How many decilitres in a litre?
10
What mass do you take to be the mass of a human?
70kg
How much of the human body by % is water?
60% (42L in 70kg person)
How much water is extracellular/intracellular?
1/3 is extracellular (14L in 70kg person)
2/3 is intracellular (28L in 70kg person)
Of the extracellular fluid in a 70kg person how much is interstitial and how much is in the blood?
Interstitial- 11L
Blood- 3L
What is haematocrit?
Proportion by volume of circulating blood that is red blood cells (40%)
What is the circulating blood volume?
5L-3L plasma, 2L RBC
What is the normal haematocrit?
40%
How often does the total blood volume circulate?
Once per minute
What do macrophages do?
Recognise foreign antigens and take them into the macrophage. It then breaks it down using lysosomal enzymes and gets rid of the debris. It often presents part of the antigen on the surface.
What do B lymphocytes do?
Naïve B cells sense the shape of a foreign antigen and produce antibodies with a complementary variable site to that antigen. Also B memory cells are produced, so that if the same antigen is found again an immune response can occur more quickly.
Where are B lymphocytes made?
Bone marrow
What type of response are B lymphocytes and macrophages part of?
Humoral
Where are T lymphocytes made?
Bone marrow, and mature in thymus
What do T lymphocytes do?
They create killer T lymphocytes which then dock next to cells infected with virus (or cancer cells) and kill them. Memory T lymphocytes are also made.
What type of response are T lymphocytes part of?
Cell mediated
What do T helper cells do?
They sense the shape of the foreign antigen displayed by a macrophage (and become activated). It then tells this shape to the B cells and activates macrophages. It also activates killer T lymphocytes.
What are monoclonal antibodies?
Antibodies that all originate from the same cell (hybridoma).
What is a hybridoma?
Fusion of B cell and myeloma (cancer cell)
What are some properties of hybridomas?
Immortal
Highly specific
What is an epitope?
A binding site found on antigens
What do antibodies do?
Bind to complementary antigens which stops them entering cells and stops them growing. It also groups them in one place so they can easily be killed by macrophages.
What is a conjugated antibody?
An antibody with a radioactive marker attached
How does autoradiography work?
A radioactive marker is injected into a live animal/cell culture
A histological section is coated with a photographic emulsion which shows molecules labelled with the radioactive marker
What is the typical magnification in light microscopy?
x1000
What is the distance between resolvable points in light microscopy?
0.2 micrometers
How does ultrasound work?
The transducer contains piezoelectric crystals which vibrate when an electric signal is applied which produces ultrasound waves. The ultrasound waves pass through the skin and into the internal anatomy. As the waves encounter tissues with different characteristics and densities they produce echoes which reflect back to the transducer. The piezoelectric crystals then produce an electrical signal which a computer converts into points of brightness on an image.
If an ultrasound wave has high frequency what qualities does it have?
Short wavelength
Good resolution
Travels quickly
Why does an electron microscope have a higher resolution than a light microscope?
Because it has a shorter wavelength
What is the typical magnification of an electron microscope?
x250,000
How does a transmission electron microscope work?
Only works in a vacuum (all samples are dead).
An electron beam passes through the sample and any beams that pass through are detected. Where beams pass through the sample this part of the image will be bright, where they don’t it will be dark.
What is freeze fracture EM?
Tissue is frozen to -160 degrees C and fractured by hitting with a knife edge. The fracture line passes through the plasma membrane exposing its interior which can then be imaged (in vacuum with EM)
How does a scanning electron microscope work?
Only works in a vacuum (dead sample). Electron beams are fired at the sample. They then reflect back from the surface and are received by a cathode ray tube.
What was MRI adapted from?
NMR
What is the function of an epithelial cell?
Separating the inside from the outside of the body and separating different environments of the body.
What are cell junctions?
They are found between adjacent epithelial cells and ensure the cells are tightly adhered to one another.
What are the 3 main types of cell junctions?
Tight junctions-firmly adhere adjacent cells to one another.
Desmosomes-strengthen the tight junctions and are resistant to stretching and twisting.
Gap junctions (communication junctions)-allow adjacent cells to talk to each other.
How are tight junctions made and what is their function?
The plasmalemma of adjacent epithelial cells are fused together. It forms a seal which stops molecules passing between the cells, so it must go through the epithelial cells.
How are desmosomes made and what is their function?
They are found just under or next to tight junctions. They strengthen the bond between cells. They are formed by proteins which are interlocked and connect the cells.
How are gap junctions made and what is their function?
They are found between adjacent cells and allow them to communicate with each other and coordinate functions. Proteins called connexons form small channels that allow ions and small molecules to move back and forth between cells. They allow messages to pass between cells.
What is the basement membrane?
It is the structural site for overlying cells and underlying connective tissue. It anchors down the epithelium to its loose connective tissue underneath.
How can cells attach to the basement membrane?
Hemidesmosomes:integrins connect the plasma membrane to the basement membrane. (Found in tissues subject to abrasion).
Focal adhesions: anchor intracellular actin filaments to the basement membrane. Integrins attach the actin filament complex through the cell membrane to the extracellular matrix. (Important in call movement e.g. Migration of epithelial cells in wound repair).
What are integrins?
They are transmembrane proteins that attach the cell cytoskeleton to the extracellular matrix and sense whether adhesion has occurred.
What are the 2 main functions of integrins?
Attachment of the cell to the ECM.
Signal transduction from the ECM to the cell.
(Also involved in immune patrolling and cell migration).
What is required for cell cultures to survive?
Provide nutrients, control pH, temperature and oxygen. Prevent bacterial contamination
How do you separate cells from tissues?
Use collagenase or microdissection. They can they be cultured in Petri dishes.
What are you the drawbacks of cultured cells?
They behave and look different to cells in tissues.
They demonstrate contact inhibition (when touch each other they stop growing).
Have a limited life span due to senescence.
What are the methods by which cells can die?
Necrosis and apoptosis
What is necrosis?
Caused by physical disruption to the cell by injury/bacterial toxins/nutritional deprivation. The cell loses functional control and osmotic pressure causes swelling in organelles, the chromatin clumps and the cell bursts. Cytotoxic cellular components spill out from the membrane and cause tissue damage and inflammation.
What is apoptosis?
Programmed cell death. Proteins inhibit and induce apoptosis. When apoptosis is induced catabolic processes begin throughout the cell. Enzymes digest cytostolic components and fragments of nuclear DNA. Capsases (protease) target proteins in nuclear laminar and cytoskeleton. Cell is repackaged for safe removal: chromatin condenses, cell shrinks and fragments into small apoptotic bodies. It is then phagocytised by adjoining cells.
What is endocytosis?
Bulk transport into the cell.
The cell membrane folds into a pouch surrounding the particles outside the cell. A vesicles is formed and carries the particles into the cell where they can be released.
What is phagocytosis?
A type of endocytosis. WBC engulf bacteria and unwanted cells and form a vesicle. This vesicle fuses with a lysosome which contains digestive enzymes which destroy the bacteria/unwanted cells.
What is exocytosis?
Bulk transport out of the cell.
A vesicle containing waste or cells products moves toward the cell membrane. The membrane around the vesicle fuses with the cell membrane. The contents of the vesicle are secreted as the membrane smooths out.
How often do cells in the body renew?
It depends. Some cells are static (CNS, cardiac and skeletal muscle cells)/stable (fibroblasts, endothelium, smooth muscle cells)/renewing (blood, skin epithelium, gut epithelium).
What are the two main types of organisms?
Prokaryotes and eukaryotes (endosymbiosis. mitochondrion/chloroplast engulfed by them).
What are the 4 basic types of tissues?
Epithelial
Muscle
Nerve
Connective
What are the different specialised connective tissues?
Adipose Lymphatic Blood Haemopoietic Cartilage Bone
What parts of the body are epithelium?
Covers exterior body surface
Lines internal closed cavities and body tubes that communicate with the exterior
Forms secretory portion of glands and lines their ducts
Specialised- receptors for special senses
What are the epithelial cell domains?
Apical domain- attach to nothin
Lateral domain- attach to each other
Basal domain- attache to basement membrane
Do epithelial cells exhibit polarity?
Yes
What specialisations can be on the apical domain?
Microvilli
Stereovilli
Cilia
What are microvilli?
Cytoplasmic processes that extend from the cell surface.
What are stereovilli
Particularly long microvilli e.g. In ear
What are cilia?
Motile cytoplasmic processes that beat in synchrony with a rapid forward movement (effective stroke) and a slower return movement (recovery stroke).
Why do necrotic cells swell and burst?
Failure of action of Na K ATPase (sodium potassium pump)
Which moves 3 Na+ out and 2 K+ in using ATP for energy
What is osmosis?
The net movement of water molecules from a high water potential to a low water potential through a selectively permeable membrane.
What is osmolarity?
Amount of solute/protein in water.
Concentration of a solution expressed as the number of solute particles per kg of solution. mOsm/kg
Usually 300mOsm/kg in plasma.
What is oncotic pressure?
Amount of protein in water
What is the electrical difference between the inside and outside of the cell membrane?
Membrane potential (-70mV)
Sodium and potassium in plasma vs. Intracellular
High sodium in plasma
High potassium in intracellular
What can happen if the stomach loses mucus?
Gastric ulceration and perforation.
What is pH?
pH= -log [H+]
What does a one unit change in the pH scale mean?
A ten fold change in the normal scale
What can cause abnormal plasma pH?
Major organ dysfunction e.g. Lungs/kidney/liver
Shock-poor tissue perfusion
What is shock?
A state of globally cellular and tissue hypoxia due to reduced oxygen delivery, usually due to hypoperfusion.
What are the types of shock?
Cardiogenic, hypovolaemic, septic shock
What happens when tissues are poorly perfused?
Anaerobic respiration leads to lactic acid production and lactic acidosis which impairs cardiac function.
What are the functions of connective tissue?
Connects cells to form tissues, tissues to form organs and organs to form the body. Can also provide support.
Transportation- provide a medium for diffusion of nutrients and wastes
Protection- provide a cushion between tissues and organs and provides insulation.
Storage (adipose tissue)
Defence against infection
Wound healing
What is the bulk of connective tissue made up of?
Extracellular material (matrix)
What are the 3 types of connective tissue?
CT proper e.g. loose/dense
Specialised CT e.g. blood/lymph
Supporting CT e.g. bone/cartilage/bone marrow
What is connective tissue made up of?
Ground substance
Fibres
Specialised Cells
(Cells make fibres and ground substance
Matrix=fibres and ground substance)
Does connective tissue or epithelial tissue have an abundant blood supply?
Connective tissue
What are the types of CT proper?
Loose and dense CT
What do loose and dense CT do?
Fill the space between organs and keep them in tact.
What is the most abundant type of CT?
Loose CT
What does loose CT contain?
Reticular, collagen and elastic fibres
Viscous Ground substance
Fixed cells e.g. fibroblast responsible for general maintenance of tissue
Wandering cells e.g. defence cells responsible for defending and repairing damaged tissue
Types of cells and what they do (loose CT)
Fixed:
Melanocytes-produce melanin
Macrophages-immune cells
Mast cells-stimulate local inflammation by releasing histamines
Fibroblasts-produce extracellular fibres
Adipocytes-store fatty reserves
Mesenchymal- stem cells responsible for repair of tissue
Wandering: Plasma cells Wandering macrophages Leucocytes Monocytes Eosinophils Basophils
What fibres are in loose CT?
Reticular
Collagen
Elastic
What do reticular fibres do?
They form branching networks which protect the organs.
What do collagen fibres do?
They provide resilience and strength
What do elastic fibres do?
They can recoil after stretching
What are the 3 types of loose CT?
Areolar
Adipose
Reticular
Where do you find areolar tissue?
Beneath all epithelial layers
What cell types does areolar tissue contain?
All cell types previously mentioned
What are the characteristics of adipose tissue and where is it found?
It has limited extracellular space and lots of adipocytes which form a cushion around delicate organs. Also found under skin for insulation and protection.
Which fibre dominates reticular CT and what does it do?
Reticular fibres dominate to form tough flexible scaffolds for delicate structures e.g. glands
How does dense CT differ from loose CT?
More fibres
Less ground substance
Fewer cells (fibroblast is main cell)
What are the 3 types of dense CT?
Dense regular- collagen fibres in parallel bundles
Dense irregular- collagen fibres in haphazard direction
Elastic- more elastic than collagen fibres
Where is dense regular CT found?
Tendons and ligaments
How many directions can dense regular CT resist stress?
One
Where is dense irregular CT found?
Dermis of the skin
Sheets surrounding organs (fascia)
How many directions can dense irregular CT resist stress?
Many directions
Where is elastic CT found?
Between the spinal vertebrae
What are the connective sheets called?
Fascia
What do fascia do?
Support and compartmentalise parts of the body
Hold muscle bundles together
What is ground substance?
A viscous, clear substance with a high water content. It is composed of proteoglycans.
What is a proteoglcan?
A large macromolecule which is made up of a core protein to which glycosaminoglycans are covalently bonded to
What are glycosaminoglycans and what do they do?
Long chained polysaccharides
They attract water to form a hydrated gel that permits rapid diffusion and resists compression
What is different about the ground substance of cartilage?
The proteoglycans are connected to hyaluronic acid by a linker protein
Where is loose CT located?
Beneath epithelial- to facilitate diffusion
Associated with epithelium of glands
Located around small blood vessels
What is aponeurosis?
A flat sheet of regular CT with bundles of fibres in one layer often arranged at 90 degrees to those in adjacent layers.
How are the collagen fibres in ligaments arranged?
Densely packed in a parallel arrangement but the undulate and are arranged in fascicles separated by loose CT.
What do fibroblasts do?
Synthesise and secrete ground substance and fibres
Important in wound healing and wound contraction.
What is in the granules that mast cells contain?
Histamine
Heparin
Substances that attract eosinophils and neutrophils
What are the main types of collagen?
Type 1
Type 3- makes reticulin
What is the structure of type 1 collagen?
Triple alpha helix
How is collagen made?
Fibroblasts secrete procollagen which Is converted to collagen outside the cell. They are the. Aggregated to form collagen fibrils. These can then be grouped together to form collagen fibres.
What are the types of fat cells?
White and brown.
Most is white
Where is the nucleus found in white adipocytes?
The periphery
What do brown adipocytes contain?
Many lipid droplets and a central nucleus
Why are brown adipocytes brown?
Abundant vascular supply al they ha e a high respiratory capacity for the generation of heat so non-shivering thermogenesis can occur.
What is the anatomical position?
Face forward with eyes and toes pointing in same direction.
Arms by sides palms facing forward.
Lower limbs close together with feet parallel to each other.
What does superior and inferior mean?
Superior=above
Inferior=below
What does anterior and posterior mean?
Anterior=in front
Posterior=behind
What is the coronal plane?
Slice parallel to face
What is the sagittal plane?
Slice through face
What is the transverse plane?
Slice parallel to ground
What does superficial mean?
Nearer to surface
What does intermediate mean?
Between a superficial and deep structure
What does deep mean?
Further from surface
What do palmar and dorsal mean?
Palmar- palm/sole surface
Dorsal- back of hand/top of foot
What does proximal mean?
Nearer to trunk or point of origin
What does distal mean?
Further from trunk or point of origin
What do ipsilateral and contralateral mean?
Ipsilateral-on same side
Contralateral-on opposite sides
What plane do flexion and extension occur in?
Sagittal plane
What are flexion and Extension?
Flexion- make angle smaller
Extension-make angle bigger
What are abduction and adduction?
Abduction takes structures away from midline whereas adduction brings structures back towards the midline.
What is circumduction?
A circular movement
What is supination and pronation?
Supination is turning palm up and pronation is turning palm down
What are opposition and reposition?
Opposition is when you bring the thumb and pinky towards each other. Reposition is when you move them away from each other.
What are dorsiflexion and plantarflexion?
Dorsiflexion is rotating ankle up, plantarflexion is rotating ankle down.
What are eversion and inversion?
Eversion is rotating ankle out and inversion is rotating ankle in
Which systems does the lymphatic system support?
Cardiovascular and immune systems
What are the main parts of the lymphatic system?
Lymph Lymphatic vessels Lymph nodes Lymphoid organs Lymph ducts
What is lymph?
Watery fluid that flows through lymphatic system. Mostly originally blood plasma.
What do lymphatic vessels do?
Help reabsorb fluid
What do lymph nodes do?
They are checkpoints that monitor and cleanse lymph
What are some examples of lymphoid organs?
Tonsils
Adenoids
Thymus
Spleen
Why is lymph fluid formed?
Not all the plasma which is forced out of the capillaries returns to the capillaries so it is instead picked up by lymphatic capillaries.
What is the structure of lymphatic capillaries?
Loosely overlapping endothelial cells which form flaplike minivalves that open when the pressure in the interstitial space is higher than the pressure in the lymphatic capillary.
What are lymph ducts?
Feed lymph back into the lowest pressure areas of the circulatory system.
What lymph does the right lymphatic duct drain and what into what?
Upper right area of torso, right arm and right half of head into the internal jugular vein
How do lymphatic vessels work?
Like veins.
Valves to prevent back flow.
Low pressure.
Helped by smooth muscle contraction in vessel walls and skeletal muscle movement-larger lymphatics
Pressure changes in thorax during breathing.
What WBC are found in lymph nodes?
B cells
Macrophages
T cells
(Neutophils)
What can lymphocytes in the lymph nodes do?
Release macrophages
Activate general immune response
Where do lymphocytes mature?
Loose reticular CT which makes up a large part of nodes and lymphoid organs
What do MALTs do?
Checkpoint for GI tract and respiratory system for pathogens
Examples of MALTs?
Tonsils
Peyer’s patches in small intestine
Appendix
How many litres of interstitial fluid per day does the lymphatic system collect?
3 litres
Where do lymphatic vessels lie?
Adjacent to arteries and veins.
What is lymph oedema?
Swelling due to not enough lymph nodes or them not working correctly leading to a build up of interstitial fluid
What are the 3 types of tonsil?
Pharyngeal
Palatine
Lingual
Where do arteries and veins enter/leave the lymph node?
Hilum
What do the blood capillaries surround in the lymph node?
Lymphatic nodule
What is the middle part of the lymph node called?
Medulla
What are follicular dendritic cells and where are they located?
They are located in the germinal centres of the lymphatic nodules.
Antigen antibody complexed adhere to the dendritic processes and the cell can retain the antigen for months.
They cause proliferation of B cells (especially B memory cells).
What are examples of professional antigen presenting cells?
B cells and macrophages.
Lymph nodes contain these.
Which cells mediate an inflammatory response?
Neutrophils and macrophages.
Which cells need APCs to recognise antigens?
T cells
What is lymphadenopathy?
Enlarged lymph nodes
Which is the largest lymphatic organ?
Spleen
What does the spleen do?
Filters blood
Immune functions: antigen presentation by APCs, activation and proliferation of B and T cells, production of antibodies, removal of macromolecular antigen com blood
Haemopoietic function ions: removal and destruction of old, damaged and abnormal RBC and platelets, removal of iron from haemoglobin.
What and where is the thymus?
It is in the superior mediastinum
Matures bone marrow derived stem cells into T cells
What is complement and what does it do?
Consists of a group of serum proteins that activate inflammation, cell destruction and opsonisation.
What is opsonisation?
Making a cell more susceptible to phagocytosis.
What is the complement cascade?
The complement proteins responding in a sequential manner
How can the complement cascade be activated?
By the classical or alternative pathway.
What does the complement cascade result in?
Inflammation
Opsonisation
Membrane attack complex
What do capillaries connect?
Arterioles and venules
What are precapillary sphincters?
The are sphincters before the capillaries which can contract and stop blood entering the capillaries. Blood just flows through the thoroughfare channel from the arteriole to the venule.
What are starling forces?
Hydrostatic and oncotic forces involved in the movement of fluid across capillary membranes.
What is arteriolar capillary hydrostatic pressure?
35 mmHg
What is venular capillary hydrostatic pressure?
15 mmHg
What is blood colloid osmotic pressure?
25 mmHg
Explain the movement of fluid through the capillary membrane?
At the arterial end there is net filtration (movement out of capillary) because the capillary hydrostatic pressure is greater than the blood colloidal osmotic pressure.
In the mid capillary there is no net movement because the capillary hydrostatic pressure is equal to the blood colloidal osmotic pressure.
At the venous end there is net reabsorption (movement into capillary) because the capillary hydrostatic pressure is lower than the blood colloidal osmotic pressure.
What type of oedema does not pit?
Lymph oedema
Why does venous hypertension lead to haemosiderin staining?
RBC pushed out of vein due to high blood pressure. When phagocytes ingest and digest this they oxidise the red iron turning it brown.
What is palpation?
Putting your hand on and feeling
What is percussion?
Tapping
What is auscultation?
Listening with a stethoscope
Where does the abdominal aorta split in two?
Level with the belly button
Why would you not be able to feel the radial pulse?
Low blood pressure Dead Pressing too hard which occludes artery Not pressing hard enough which would mean you aren't compressing the artery so can't feel it Wrong place Fat wrist
Where is the mastoid process?
Bony lump behind ear lobe
Is the nasal bone inferior or superior to the nasal cartilage?
Superior
What is the zygomatic arch?
Cheekbone
What is the angle of mandible?
Corner of jaw
Where is the hyoid bone?
In the neck just under the face
What is the thyroid cartilage also known as?
Adam’s apple
Where is the cricoid cartilage?
Inferior to the thyroid cartilage
Where is the sternocleidomastoid muscle?
Connects the clavicle to the mastoid process
Where is the manubriosternal joint?
Where the body of the sternum meets the manubrium of the sternum
What does the nipple level show?
It shows the superior border of the liver
What is the costal margin?
It is the bottom of the ribcage at the front
What is an intercostal space?
Space between ribs
What can the position of the umbilicus be used for?
To separate the abdomen into 4 quadrants
What is the medial epicondyle?
Bone on medial side of elbow
Where does the ulnar nerve run?
Between the medial epicondyle and the tip of the elbow
What is the olecranon?
Tip of the elbow
Where is the head of ulna?
Bony part on medial side of distal forearm
What is the thenar eminence?
Muscle below thumb
What is the iliac crest?
Top back of pelvis
What is the greater trochanter?
Lateral surface of thigh. Bony part of femur.
What is the tibial tuberosity?
Part of bone below knee that sticks out
What is the tibia?
Shin bone
What is the medial and lateral malleoli?
Inside and outside ankle
What is the calcaneum?
Heel bone
What is another name for the mucous membrane?
Mucosa
What is another name for the serous membrane?
Serosa
Where would you find mucous membranes?
Line internal tubes which open to the exterior
Alimentary tract
Respiratory tract
Urinary tract
What does a mucous membrane consist of?
Epithelium
Connective tissue - lamina propria
In alimentary tract there is a layer of smooth muscle- muscularis mucosae
Where would you find serous membranes?
They line closed body cavities e.g. peritoneum, pleural sacs, pericardial sac
What is the serous membrane?
They are thin, two-part membranes
What do serous membranes consist of?
Simple squamous epithelium (mesothelium) which secretes a watery lubricating fluid.
A thin layer of connective tissue which attaches the epithelium to adjacent tissues.
What are the inside and outside parts of the serous membrane lining a body cavity called?
Outside- parietal serosa (pleura for lungs)
Inside- visceral serosa
Which surfaces have epithelial linings?
Skin GI tract Reps tract Genitourinary tract Pericardial sac Pleural sacs Peritoneum Blood vessels Lymphatic vessels
What are the two main types of epithelia?
Simple- one cell layer thick
Stratified/compound- more than one cell layer thick
What are the tiles of simple epithelia?
Squamous
Cuboidal
Columnar
Pseudostratified
What are the types of stratified epithelia?
Squamous
Cuboidal
Columnar
Transitional
What shape are simple squamous epithelia?
Quite flat
Where would you find simple squamous epithelia?
Lining of blood and lymph vessels (endothelium) Lining of body cavities-pleura etc. Gas exchange epithelium Bowman's capsule Loop of Henle in kidney
Functions of simple squamous epithelia?
Lubrication
Gas exchange
Barrier
Active transport by pinocytosis
What shape are simple cuboidal epithelia?
Fat cuboid
Where would you find simple cuboidal epithelia?
Thyroid follicles
Small ducts of exocrine glands
Kidney tubules
Surface of ovary
Functions of simple cuboidal epithelia?
Absorption and conduit
Absorption and secretion
Barrier/covering
Hormone synthesis, storage and mobilisation
What shape are simple columnar epithelia?
Long and thin cuboids.
They can also have microvilli.
Where might you find simple columnar epithelia?
Stomach lining and gastric glands
Small intestine and colon
What are functions of simple columnar epithelium?
Absorption
Secretion
Lubrication
Transport
What shape and arrangement do pseudostratified epithelia have?
Irregular shape and pattern
Where would you find pseudostratified epithelia?
Lining of nasal cavity, trachea and bronchi
What are the functions of pseudostratified epithelia?
Secretion and conduit
Absorption
Mucus secretion
Particle trapping and removal
Where would you find stratified non-keratinised epithelia?
Oral cavity Oesophagus Larynx Vagina Part of anal canal Surface of cornea Inner surface of eyelid
What are the functions of stratified squamous non-keratinised epithelia?
Protection against abrasion and reduction of water loss whilst remaining moist
Where would you find stratified squamous keratinised epithelia?
Surface of skin
Limited distribution in oral cavity
What are the functions of stratified squamous keratinised epithelia?
Protection against abrasion and physical trauma
Prevention of water loss
Preventing ingress of microbes
Shields against UV damage
What is the epidermis of the skin made up of?
Stratified squamous keratinised epithelia
What are the four layers of the epidermis?
Stratum corneum, granular layer, prickle cell layer, basal layer
Which type of cells are in the epidermis and where are they made?
Keratinocytes which are made in the basal layer.
What do keratinocytes do?
They synthesise keratinised which contribute to the strength of the epidermis.
Where do daughter keratinocytes stop being able to divide?
Prickle cell layer
What happens to the keratinocytes in the granular layer?
Keratinocytes lose their plasmalemma and begin differentiating into corneocytes which are the main cells of the stratum corneum.
What does the granular layer of the epidermis contain?
Keratohyalin granules: Keratins Other fibrous proteins Enzymes that degrade the plasmalemma Cross link proteins
What is the stratum corneum made up of?
Flattened corneocytes (major role in skin barrier function).
What are the other cells of the epidermis?
Melanocytes-produce melanin
Langerhans cells-medicate immune reactions and present antigens to T cells
What shape are transitional epithelia?
They vary in shape from columnar/cuboidal when relaxed to flattened when stretched.
Where can you find transitional epithelia?
Renal calyces
Ureters
Bladder
Urethra
What are the functions of transitional epithelia?
Distensibility
Protection of underlying tissue from toxic chemials
What is a gland?
An epithelial cell or collection of cells specialised for secretion.
How can glands be classified?
By destination of secretion
By structure of the gland
By nature of secretion
By method of discharge
How can glands be classified by structure?
Unicellular/multicellular
Acinar/tubular
Coiled/branched
Which ion channel is not present in the apical membranes of cystic fibrosis sufferers?
CTFR
What does the lack of CFTR cause?
Chloride ion transport across the membrane to be compromised, so not enough water leaves the epithelium so the mucus becomes thick.
Blockage of pancreatic ducts
Buildup of mucus in lungs
What is an acinus?
The secretory part of many exocrine glands
How can glands be classified by method of secretion?
Merocrine- exocytosis
Apocrine- secreted droplets covered by plasmalemma
Holocrine- whole cell breaks down
What are the three major salivary glands?
Parotid, submandibular and sublingual
What type of gland is the pancreas?
Endocrine and exocrine
How can cystic fibrosis cause reproductive problems?
No vas deferens
Poor sperm quality/motility
Is cartilage vascular or avascular?
Avascular
What is cartilage made up of?
Chondrocytes and an extensive extracellular matrix (made of proteoglycans)
What do chondrocytes do?
Produce and maintain the extracellular matrix in cartilage
What does the large ratio GAGs to type 2 collagen in the cartilage matrix allow?
Ready diffusion of substances between chondrocytes and blood vessels surrounding the cartilage
What are the 3 types of cartilage?
Hyaline
Elastic
Fibrocartilage