What does connective tissue consist of?

Fibres

• Collagen
  • polypeptide chains twisted into a rope
  • long, straight, strong, stains pink
• Reticular
  • same protein as collagen, but finer
  • stabilise position of cells, blood vessels
• elastin
  • branched, wavy in relaxed state
  • forms fibres (connecting vertebrae) or sheets (skin, lung blood)

Ground Substance

• surrounds cells and fibres

Fixed Cells

• fibroblasts
  • most abundant, differentiate to other cells
  • secrete ground substance/fibres
• mesenchymal cells
  • multipotent - capillaries
• adipose cells
• macrophages (monocytes)
  • lie along fibres, large irregular nucleus, phagocytose dead cells, debris etc

Migratory Cells

• mast cells
  • basophilic (blue) granular nuclei (can be two)
  • similar to basophils in blood but mast cells once enter tissue
• plasma cells
  • eccentric (one side) nucleus
  • many in lymph nodes

Chondroblasts (immature cell) 

- lay down the cartilage matrix, are found towards outside of cartilage

Chondrocyte (mature cell)

-sits within lacunae in matrix

Interstitial growth

• from within, chondrocytes divide to form isogenous nests (cell clusters)
• start excreting matrix which pushes them apart

Appositional growth

• chondroblasts divide
• produce the matrix then differentiate into chondrocytes

Layer surrounding cartilage

outer layer - dense irregular connective tissue

inner layer - cellular layer (chondroblasts) - involved in growth.

doesn't exist at articular surfaces

Types of bone cells, location and function

[image]

diaphysis, metaphysis, epiphysis, medullary cavity, 

cancellous bone sandwiched between compact bone layers.

no medullary cavity

_{What is the periosteum and where is it found?}

_{What is the endosteum and where is it found?}

Periosteum

• on the outer surface of compact bone layers
• has outer fibrous layer and inner cellular layer that contains osteoblasts and fibroblasts.
  • Has osteogenic properties (fibroblasts)

Endosteum

• thin cellular layer in the lining of the medullary cavity and around the trabeculae (Network of bones) in cancellous bone

Canaliculi - extend from osteocytes in to blood vessels and allow communication.

Haversion systems - vertical canals that contain blood vessels 

Volkman's canals - horizontal canals to connect Haversion systems

interstitial lamella - between Haversion systems

[image]

Microscopic organisation of cancellous bone?

No Haversian systems, nutrients reach osteocytes through diffusion along canaliculi

[image]

1. mesenchymal cells cluster and secrete matrix
2. cells turn into osteoblasts and secrete bony matrix
3. osteoblasts become trapped in matrix then become osteocytes
4. blood vessels grow in and matrix becomes fully calcified

Starts out as cancellous bone and forms compact bone later on

1. Chondrocytes die, and the surrounding matrix becomes calcified
2. perchondrium cells become osteoblasts to lay down bone around surface of the cartilage
3. blood vessels grow
4. left over growth plates of cartilage where the animal can continue to grow

is primary centres (bone grows in middle of bones) and secondary (bone grows in the epiphysial areas)

How do long bones continue to grow in length?

Diameter?

Length

• chondrocytes multiply at epiphysial plate, die, capillaries grow in
• more osteoprogenitor cells brought in and lay matrix
• diaphysial end bone eroded by osteoclasts to destroy bone to expand marrow cavity
• epiphysial plate remains a constant length until growth ended

diameter growth

• osteoblasts lay down new bone under periosteum
• osteoclasts remove bone from inside collar to expand medullary cavity

What are Leukocytes? Two groups?

white blood cells

Granular Leukocytes

• Basophils
• neutrophils
• eosinophils

Non-granular Leukocytes

• lymphocytes
• monocytes

Integral Proteins

• embedded in layer
• move compound across membrane
• Channel proteins - tunnel, allows free movement of water and some ions/molecules (partially selective)
• carrier proteins - change structure when ion/molecule attaches so moves to other side of membrane

Peripheral Proteins

• bound to one side of membrane

Roles

• transport, receptors, enzymes to catalyse reactions, anchoring of cells

Diffusion and active transport

Substances moving constantly (heat), move across concentration gradient. Important to know net rate of diffusion. Ficks Law factors affecting diffusion rate:

• concentration gradient, permeability of membrane, surface area (larger = more  molecules to pass), molecular weight of substance, distance diffusion must occur, membrane electrical potential (will achieve equal membrane charge, pressure changes 

Osmosis - diffusion of water

Tonicity - strength of solution compared to water

isotonic - solute conc. same on each side of membrane (red blood cells in 0.9% NaCl)

Hypotonic - solution more water (less solute) than cell - cell bursts

Hypertonic -less water higher solute than cell - cell shrinks 

Hydrostatic pressure - water from hypotonic to hypertonic means increase in hydrostatic pressure. when equals osmotic pressure, water movement stops

Simple - directly through lipid bilayer (lipid soluble molecule) (channel proteins)

facilitated - carrier protein

Potassium channel - K+ out of the cell, made of 4 subunits lined with carbonyl oxygen, hydrated K+ interacts and strips water so K+ can pass through, sodium too small to interact.

sodium channel: surface lined with negative amino acids. pulls small Na away from water so can fit through channels whereas other molecules are too large

Voltage Gating

confirmational change due to change in electrical potential. Inside of cell negatively charged (ions), when cell depolarised, charge difference is reduced and gate opens to allow ions through. eg. sodium and potassium channels

Ligand gating

gates opened by binding of other molecule. eg. neurotransmitter channels in nerve and muscle cell.

1:

the rate of facilitated diffusion depends on the availability of carrier proteins (carrier proteins speed diffusion), also called saturation of carrier proteins or Vmax. 

2:

other molecules can compete for binding with carrier protein. (presence of molecule A can limit rate of molecule B entering cell)

molecules being moved against their concentration, electrical or pressure gradient gradient. energy must be expended to do this

Primary active transport

energy derived from breakdown of ATP

sodium-potassium pump - receptors on inside of cell to pump na out, receptors on outside to pump k in. controls electrical charge in cell and cell volume (most internal molecules negative so attracts lots of water, sodium-potassium pomp expels more ions than takes in=net loss of ions)

secondary active transport

uses energy from the ionic concentration gradient. Two types

co-transport

sodium-glucose symport = since there is a large na concentration outside cell, it can pull other molecules with it inside the cell. can only occur if both molecule are bound

counter-transport

sodium-calcium antiport = sodium wants to move in, calcium wants to move out, when both bound, confirmational change

ENDOCYTOSIS
transport into the cell - often foreign molecules or molecules too large to enter through cell membrane (can have many outcomes - degraded/recycled/stored). key roles in cell signalling. 

Phaocytosis

cell eating - consumption large particles, only few do (macrophages and neutrophils take in waste/damaged cells)

Pinocytosis

cell drinking - take in extracellular fluid and solutes, most cells occurs continually, but rate varies.

Receptor-mediated

specific to which molecules enter. allows moelcules to enter without large amounts of ECF. 

EXOCYTOSIS
within cell to outside cell. Molecules in vesicles transported from the golgi to cell membrane. vesicles release proteins/wastes and replenish the cell membrane from exocytosis

Constitutive

In all cells. waste products packaged in ER and repackaged in golgi, replenishes cell membrane

Regulated

products stored for release at specific time (hormones, neurotransmitters). VESICLE DOESN'T REPLENISH CELL MEMBRANE

transport - oxygen, hormones, waste

homeostasis - regulation of temperature, pH

portection against infections - white blood cells/antibodies

Red blood cells contain haemoglobin, ther primary function to transport respiratory gases (O2 some dissolved in plasma, most combined with haemoglobin CO2 some in hG and some disslved in blood, most as bicarbonate ion).

alveolar - in lungs through membranes. diffuses fast because concentration of gas in blood less than atmosphere. alveolar air different to atmospheric air - not all air in alveolar replaced with each breath - protects against air poisoning

OXYHAEMOGLOBIN

temperature and carbon dioxide affect uptake (usually up to 4 o2 molecules)

high temperature = less saturated haemoglobin - shift dissociation curve to right and increasing release of haemoglobin.

decrease in pH = same effect as above

can be combined with haemoglobin or as bicarbonate ions.

made to bicarbonate ions in red blood cell, takes to alveolus where diffuses out of red blood cells and into alveolus to be exhaled

1. supplies oxygen for cellular respiration and disposes of CO2 in blood (vector of gas exchange)

2. from high partial pressure to low partial pressure, occurs across thin respiratory surfaces

3. by haemoglobin - saturated with oxygen in lungs, unloads at tissues. this process forms oxygen dissociation curve

4. shift to the right - heamoglobin more unlikely to release oxygen

5. mainly by bicarbonate, or with haemoglobin. more likely to be held in tissues, less likely in lungs

6. coagulation, immune response, homeostasis

extracellular and intracellular fluid

extracellular - interstitial fluid between cells and plasm

intracellular - highest volume, within cells

both in osmotic equilibrium, but different chemical composition

in order to move between all compartments, must pass between each (to get to external environment, intracellular-extracellular-plasma-organs-external environmetn)

proteins and phosphates can't easily exit intracellular fluid and proteins can't easily exit plasma

maintenance of constant internal envirnoment

requires

constant monitoring (feedback systems)

capacity to make changes - endocrine response

defence against external environmetn (temperature, water etc)

1. polar so good for biochemical reactions, transport, temperature homeostasis. ionic substances dissociate in water

2. intracellular fluid and extraceullular fluid, in osmotic equilibrium but differene compositions. intracellular largest proportion in body, extracellular made up of plasma, intracellular fluid and transcellular fluid

3. depends on permeability of membrane, otherwise transport like pumps and ion channels are used.

4. movement of other substances and osmotic differences between membranes

5. cells will activate processes to return to homeostasis when appropriate water levels in cells aren't met. 

6. keeps extracellular fluid in homeostasis by balancing water by modifying intake and elimination

hydrogen - acids

bicrabonate - bases

acidosis - pH below 7.3

alkalosis - pH above 7.5

venous blood - more acidic because has more H+ ions as a result of carbon dioxide dissociation. it is heading towards the lungs

arterial blood - higher pH as contains more oxygen, heading away from the lungs

1. chemical buffers in blood - react quickly. binds to free acid or base to neutralise

2. respiratory regulation - breather faster to rid excess CO2, slower to decrase pH - reacts within minutes

3. renal regulation - takes hours. excess acis excreted by kidneys in form of ammonia, can also absorb bases to combat acidosis. can alter amount of acid or base excreted, but takes several days

cellular metabolism - releases carbohydrates as waster product. diffuses into blood where acid produced as result of carbon dioxide called volatile acid. haemoglobin neutralises H+ within the red blood cells

changes nerve functions (pH decrease causes suppression of nervous system, pH increase opposit effect), influences enzyme activity and potassium levels

if caused by respiratory issue - respiratory acidosis/alkalosis

if caused by vomiting/diarhhoea,  ineffective buffering of kidney issues, metabolic acidosis/alkalossis

can alter shape of enzyme making it non-functional. can result in accelerated or decelerated metabolic function

acidosis - diarrhoea, normally fluid with bicarbonate ions reabsorbed, instead lost decreasing pH

alkalosis - vomiting, loss of many h+ from the gut

EXOCRINE - release to surface epithelium by presense of a duct

ENDOCRINE - release into blood/lymph, no duct

merocrine - vesicles released on fusion with cell membrane (most common)

apocrine - vesicles pinched off from cell membrane (membrane is lost)

holocrine - product accumulates until cell death

unicellular - goblet cell, expanded apical portion, release by merocrine secretion

simple (one duct), simple branched (tow or more secretory into one duct), compound (multiple ducts)

tubular, alveolar (rounded), tubulo-alveolar

mucoid, serous, mixed

usually continually released, can be changed by hormones

usually release hormones, protein, steroids. release as required. usualy merocrine secretion

physical barrier, environmental barrier, sensory, locomotion, parasites etc. (there's many)

hypodermis - lower layer (not really skin) contains adipocytes

dermis - derived from mesoderm

epidermis

stratum germinativum - separated from dermis by basal almina

stratum spinosum - thickest layer, prickle cell layer (many desmosomes holding together)

stratum lucidum - not always present, unknown function

stratum corneum - dead keratinised cells

cell types in epidermis - melanocytes in stratum gernimativum, make up skin pigment

keratinocytes - cells that are filled with keratin

langerhans cells - first line of defence, in all layers. have antigens, engulf foreign object and give to lymphocytes

merkel cells - mechanoreceptors for touch

papillary layer - uppermost, thinner than reticular layer

reticular layer - dense connective tissue

fibroblasts, macrophages, mast cells, plasma cells. also contains many elastin fibres and also blood and lymph vessels nerves and sebaceous glands

anchor dermis and epidermis together in thick skin/skin with lots of moevement

actual hair: medulla (cuboidal cells), cortex (dense keratinised cells with melanin), cuticle (exact shape is species-specific)

cuticle: inner root sheath - root sheath cuticle (similar to har cuticle), huxley's layer (1-3 layers cuboidal epithelium), Henle's layer (single flat cell layer)

outer root sheath - number of cell layers, has a glassy membrane separating from dermis (unknown function)

sebaceous and sweat glands

large hairs with blood-filled cavity where many nerve endings to detect vibrations in blood

tori - pads of feet with thick stratum corneum

scales - made of keratin folden over dermis

hairs - can have double coat primary/guard hairs and secondary hairs

primary (guard, larger, can have arrector pili muscle, sebaceous and sweat gland) and secondary (smaller, sebaceous but no sweat, more superficial). can be in single (one hair) or compound (multiple hairs in one follicle)

three stages: anagen (active growth, matrix cells divide), catagen (bulb regresses, matrix stops dividing and bulb fuses to hair shaft) and telogen (sits at sebaceous gland level, will remain until pushed out by new hair)

claw plate - hard keratin surface on top of nail

claw fold - skin fold over top of claw

ventral sole - soft underside of claw

determines shape and size of the horn (horns are made of keratin)

tubular - over dermal papillae and between spaces are filled with non-tubular horn

cornual nerve branch, goats have an additional infratrochlear nerve

horns made of bone, covered in a soft keratin layer (velvet). velvet and bone dies in response to ecreasing day length. grow due to testosterone

the duct of a glad that drains into a hair follicle. cells lyse in central when full of sebum (Holocrine). reduce water loss, pheromones, help prevent bacteria

apocrine - located in dermis or hypodermis, only around primary hairs, serous secretion

merocrine - sit deeper and are independent of hairs, less common, unknown function

regulation of body temperature, controlled by catecholamines (adrenaline) reached by release from sympathetic nerve endings

in external auditory meatus - sebaceous and apocrine glands to producy waxy substance in ears

meibomian gladn on eyelid - contribute to waxy coating on eyelids, lubrication

circumoral glands in cats - around mouth, used for territory marking (sebaceous glands)

mammary glands - modified apocrine sweat glands

anal sacs - glands empty into sac, apocrine and merocrine (merocrine only in cats)

circumanal glands - superficial part is sebaceous glands, deeper is hepatoid (unknown function)

deep plexus (hypodermis), intermediate plexus (reticular layer), superficial plexus (papillary dermis)

varies with area, branches into the epidermis. many different receptors in dermis and epidermis

free nerve endings - many in sinus hairs, temperature touch and pain receptors

encapsulated endings - surrounded by connective tissue cells (touch receptors eg. meissner's corpuscles)

lamellated endings -layers of connective tissue cells (foot pads), pressure receptors 

too little can cause brain function issues, and too much can cause osmotic water loss and blood cell damage

enzymes that catalyse reactions, hormones control the enzymes (insulin - promotes glucose uptake, glucagon - promotes synthesis (increases level in blood))

different effect on different tissues (muscle - take in quick for use in exercise, liver - storage) alters: gene transcription, metabolic enzymes, protein synthesis

binds to specific receptors, they then cause signal cascade where glucose can be taken into cell by glucose transporter on cell membrane

GLUT 1: foetal tissue and blood cells, all over mammal tissue but low levels uptake. One-way glucose transport with two confirmations - T1 binding site on outside, T2 on inside

GLUT 2: Liver, pancreas, kidney. Bidirectional as liver needs to release as well as consume. In pancreas so can gauge blood glucose levels. Kidneys - across renal cells so don't lose glucose. Kidney and pancreas don't need insulin. As concen. gradient increase, insulin released so increase glucose uptake. 

GLUT 3: in neurons, need lots of glucose to take up even when low levels (can't store it). 

GLUT 4: muscle and fat cells responsible for storage. when low insulin, is stored in intracellular vesicles. 

chemicals - nos/tongue, activate receptor proteins to open ion channel

pressure - squeezing can cause to open.

mechanoreceptors - activate touch, temp, pressure all over body

chemoreceptors - smell, taste, monitor internal environment

photoreceptors - when light hits opsin receptor, cell hyperpolarises and sends signal to brain

depolarisation - minimising electrical difference (inside of neuron more positive),

hyperpolarisation - inside more negative

used to stop "useless" signals. chloride ions are transferred into cell, making it more negative and therefore preventing action potential (GABA and glycine most common). 

neurotransmitter binds to receptor, causes ligand-gated channel to change shape, lets ions flow in, inflow of ions continues action potential.

ionotrophic -  opens ion channel, common = acetylcholine

metabotrophic - in brain and spinal cord, needs secodary messenger to open ion channels (slower)

survival, even growth, cell differentiation. will die without proper signal

small virus-like vesicles filled with proteins, lipids and glycans. taken in by endocytosis and are messengers

trigger - immediate change in cell metabolism/electrical charge/ changes in gene expression

pathways - synthesis and package of secreted molecules/exosomes. activate internal molecule's signalling pathway (often feedback loop)

paracrine - shorter distance hormone signalling, interstitial fluid of blood, neurotransmitters

autocrine - longer distance

contact-dependent signalling - cells must be touching

synaptic - only targets single cell usually, different nerve cells can use same transmitter

endocrine - secrete hormone into blood, signals only specific cells. 

receptor molecule interacts with many molecules inside cell to create different pathways. can also amplify signal so only small number of signals needed to create large response. states that can be induced: antiviral, cell duplication, change in metabolism. 

agonist - causes response of same type as nedogenous ligand

antagonist - blocks response

high affinity for ligands, selective usually for specific ligand. receptor numbers can be up- or down-regulated, and ligand must engase to initiate response.

ION CHANNEL-LINKED: usually involved in rapid signalling, confirmational change causes influx of ions. Ligand-gated different from voltage-gated as not specific to type of ion allowed in or out.

ENYZYME-LINKED: using enzymes or closely associated to enzymes. protein-kinases are the majority (usually involves inactive or active). tyrosine kinase receptors - when  bound by ligand, will phosphorylation

G PROTEIN-COUPLES RECEPTORS (GPCR): integral membrane proteins. in two states bound GTP (active) and bound GDP (inactive). release of GTP goes to active state

maintain cell shape, resist forces, can be used for motility

ACTIN - (microfilaments), most abundant, proteins bound to form rope, two ropes twisted together to make filament. most concentrated underneath the cell membrane. functions- mechanical strength, maintains chape, can form sarcomeres, cleavage furrow when dividing and pseudopodia. 

INTERMEDIATE FILAMENTS - consists of keratin protein, maintains cell shape, made from a rolled mat of proteins, in neurons give axon shape, different classes that have different roles. 

TUBULIN - Microtubules, made of 13 columns with two protein types. radiates through centrosome, maintains cell shape, helps organelles move (like vesicles), centrioles (9 sets of microtubule triplets), cilia and flagella have 9+2 microtubule arrangement. 

Mesenchyme

- embryological tissue where other types of tissue are derived from. 

stellate, irregular or fusiform shape

multipotent, often along capillaries

purpose - transport across membrane, receptors for signalling, enzymes, anchoring of cells.

types - integral proteins within membrane and peripheral proteins on either side

channel - are a tunnel, can be selective for molecules but not as selective

carrier - binds with ions/molecules and confirmational change to move substance to other side (selective)

diffusion - molecules will diffuse until an equilibrium is reached. Affected by concentration gradient, permeability of membrane, surface area (need max surface area to diffuse fastest), molecular weight (large molecules move slower) and distance to travel (travel in straight line impeded so longer distance takes longer), membrane electrical potential (one side is more positive to the other, molecules will want to achieve equilibrium, chemical driving force). 

SO- driving forces acting on diffusion - concentration gradient and electrostatic force

ISOTONIC - solute concentrations are same on both sides of the membrane, cell will not change side

HYPERTONIC - solution has higher percentage of solute (less water), higher than 0.9%, cell will shrink

HYPOTONIC - solution has lower percentage of solute (more water), cell will burst, lower than 0..9% NaCl

what two forces act on osmosis

what is meant by higher osmolarity

hydrostatic pressure - movement of water from hypotonic to hypertonic solution causes increase in hydrostatic pressure in hypertonic area. 

osmotic pressure

cell cytoplasm has higher concentration of solutes (high osmolarity)

most numerous granulocyte, are multilobed nucleus, have U or S shape when immature. proportion immature to mature clinically significant. have neutral coloured cytoplasm

function - phagocytose bacteria and degraded within by enzymes. mobilised in large number to focus around infection

what are eosinophils and their function

granulocytes, have large acidophilic granules (appear red), bilobed nucleus.

function - phagocytose antigen/antibody and kill helminths. also involved in hypersensitivity reactions

rare, precursor to mast cells, large basophilic (blue) granules in cytoplasm. often invisible bilobed nucleus

functions - unknown, but seem to help activate t-lymphocytes and similar roles to eosinophils

concentrated in lymphoid tissue, have very large nucleus compared to cytoplasm

function - 3 classes: 

T cells: cell-mediated immune response, release granules to kill virus-infected and tumour cells. small lymphocytes

B cells: produce antibodies (combat specific antigen). small lymphocytes

Natural Killer cell: cell-mediated immune response, also kill viruse infected and tumour cells. large lymphocytes

nucleus usually horseshoe shaped and pale staining

function - when enter tissues, become macrophage/histiocytes and respond to necrotic tissue/microorganisms and inflammation. can form multinucleate giant cells by fusion of macrophages

platelets, only fragments of original cell

function - respond to damaged endothelium and forms plug to stop haemorrhage. catalyse the formation of more permanent seal

what is haematopoiesis and where does it occur

how are red blood cells formed

production of new blood cells. occurs in bone marrow, lymphatic organs and liver in young animals

erythropoiesis - stem cells in bone marrow gives rise to large cell with nucleus. nucleus chromatin condenses and removed, then enter circulation as reticulocyte. all blood cells have common precursor cell

what are the types of blood vessels leaving the heart

what is the difference between veins and arteries and how to tell the difference

what is the purpose of valves in blood vessels

how are lymph vessels similar to blood vessels 

elastic arteries (stretch and recoil as blood pumped through), muscular arteries, arterioles (very small, 1-2 layers muscle), capillaries (thin walled)

arteries take blood away from heart, veins return blood to heart. arteries have thicker walls. veins will collapse but arteries stay circular. folded endothelium in arteries, smooth in veins

prevent backflow of blood

flow of lymph is unidirectional, similar structure to blood vessels

what are the main cell types in cartilage, what are lacunae and how do nutrients get into the cells.

what is the perichondrium 

what are the two types of growth

main cell type - chondrobast (lay down matrix on exterior of cartilage, immature) and chondrocyte (mature cell within matrix). 

lacunae - chambers where chondrocytes lie within matrix

nutrients enter by diffusion as no nerves or blood supply

surrounds the cartilage, the outer layer is dense irregular connective tissue and innner is cellular layer where chondroblasts are. not at articular surfaces

interstitial growth - growth from within. chondrocytes divide and form isogenous nests (daughter cells near parent cells) and then begin excreting matrix which push apart from parent cells.

appositional growth - also growth in diameter, chondroblasts from perichondrium divide and produce matrix.

hyaline - tightly pakced collagen, dense perichondrium, similar to regular dense connective tissue

fibrocartilage - lots of collagen, but more irregular chondrocytes are aligned into rows between fibres. is in intervertebral discs as more shock absorbing

elastic - lots of elastin fibres, matrix contains collagen

what are the two types of bone

what are the diaphysis, metaphysis and epiphysis. 

general structure of flat bone

compact - dense, can increaes thickness when stress applied. matrix arranged in circular pattern

cancellous - open network of bony plates (spongy bone)

diaphysis - hollow shaft of long bone with outer layer of compact bone

epiphysis - ends of bone, can be surrounded by cartilage. thin layer of compact bone

metaphysis - area between diaphysis and epiphysis

centre of cancellous bone with think outer layers of compact bone

what is the periosteum and the endosteum

what are the 4 types of cells in bone

periosteum - the outer layer of compact bone, a fibrous layer and inner cellular layer. contains osteoblasts and fibroblasts (have osteogenic properties)

endosteum - thin cellular layer lining medullary cavity and trabeculae of cancellous bone. has osteogenic properties.

osteoprogenitor cells - mesenchymal cells, in cellular layer of periosteum and endosteum

osteoblasts - produce matrix, basophilic, form epithelium layer in active growth

osteocytes - in lacuna and can't divide, maintain mineral content of matrix, can de-differentiate

osteoclasts - cells fuse to become large monocyte-derived cell that digests bone (howship's lacunae is where bone been digested)

lacuna - spaces where cells sit, canaliculi come out from lacunae so cells communicate

contain lamellae (concentric circles where cells lie)

3 forms of lamellae:

HAVERSION SYSTEM: octeocytes in concentric lamellae around central haversion canal that contains blood vessel. Volkmans' Canal are at right angles (heading across bone rather than up and down)

INTERSTITIAL LAMELLA: between haversion systems where layers are non-concentric

CIRCUMFERENTIAL LAMELLAE: surrounds entire bone, under periosteum and endosteum 

what is the microscopic organisation of cancellous bone

what is the general process of intramembranous ossification

the lamellae not arranged into haversian systems, nutrients reach by diffusion from canaliculi that open onto trabeculae (plates within the bone)

(develops from mesenchyme, mostly flat bones)

mesenchmal cells secrete matrix, cells differentiate to osteoblasts, start producing bony matrix, osteoblasts become trapped in matrix and so become osteocytes, blood vessels grow in, matrix becomes fully calcified, initially forms cancellous bone, will later be remodelled into compact bone

how do longs bones continue to grow

how do bones grow in diameter

chondrocytes multiply near epiphysial plate, die, capillaries move in, osteoprogenitor cells brought in and lay matrix, bone at diaphysial end is eroded by osteoclasts to destroy newly created bone to expand marrow cavity. epiphysial plate remains a constant length until growth stopped. 

appositional growth - osteoblasts lay down new bone under periosteum, osteoclasts remove bone from inside bony collar to expand medullary cavity

what is the function of

nucleus, nucleolus, endoplasmic reticulum, ribosomes, gogli apparatus, mitochondria, lysosomes, centrioles

NULCEUS: contain DNA in euchromatin (active) and heterochromatin (inactive)

NUCLEOLUS: invovled in RNA synthesis

ENDOPLASMIC RETICULUM: smooth- storing non-proteins, drug detox, rough- ribosomes so synthesis of proteins

RIBOSOMES: assembly proteins

GOLGI APPARATUS: packs enzymes/hormones etc

MITOCHONDRIA: provides energy

LYSOSOMES: degrade material, digest foods

CENTRIOLES: forms tracks for chromosomes in cell division

GLYCOCALYX: layer on the outside of plasma membrane that helps with adhesion and absorption (forms sticky layer)

TIGHT JUNCTIONS (OCCLUDING): anchor top areas together, forms band around cell called zonula occludens

DESMOSOMES: proteins bound to adjacent cell, called zonula adherens

GAP JUNCTIONS: cells locked by connexins, can open and close to allow nutrients/ions etc. 

Three types of cell surface specialisations

the difference between facilitated and active transport

what is apoptosis and necrosis

Microvili - projections to increase surface area, especially epithelial cells

stereocilia - long microvilli, branching

cilia - motility

facilitated - no energy required but must bind to carrier protein, active - takes energy and transfers regardless of gradient

apoptosis - programmed cell death (doesn't trigger inflammatory response). intrinsic pathway (indused by stress, UV, DNA damage), extrinsic (binding of death ligand)

necrosis - uncontrolled cell death, cells lyse rather than consumed by macrophages. 

what types of tissue develop from each of the germ layers

how is epithelial tissue classified

give an example of where each type of epithelium can be found

ectoderm - skins, nervous

mesoderm - muscle, skeleton, connective, blood vessels, endoderm - digestive, respiratory

arrangement (simple, stratified, pseudostratified), shape (cuboidal, squamous, coumnar, transitional)

simple squamous - alveoli lining, simple cuboidal - thyroid glands, simple columnar - stomach/intestine lining, pseudostratified columnar - epidiymis/respiratory tract, stratified squamous - skin, oesophagus, mouth, stratified cuboidal - salivary ducts, sweat and mammary glands, transitional - urinary tract.

why are enzymes used in the body

what is anabolism and catabolism

what are the four classes of organic compounds

to speed up breakdown or creation of a new molecule

anabolism - build to larger molecules, catabolism - breakdown to smaller

carbohydrates, proteins, nucleic acid, lipids

describe the three stages of cellular respiration

1. glycolysis

occurs in cytoplasm. doesn't require oxygen. no carbon dioxide released. produces: 2 PYRUVIC ACID, 2 NADH AND 2 ATP

pyruvate processed to make acetyl CoA

2. TCA cycle

acetyl CoA enters and produces 2 ATP (so far net total 4 ATP) most energy in NADH and FADH2. in mitochondria

3. Electron transport chain

FADH2 and NADH go through series of redox reactions to make more electronegative. the final step that converts to ATP is by using enzyme ATP synthase (uses H+ gradient within mitochondria to fuel synthesis - this called chemiosmosis). to keep H+ on inside, are pumped to intracellular space (some components can accept and release H+ as well as electrons). makes 32-34 ATP

why is ATP a good energy provider

how does feedback inhibition work in enzymes

how can enzymes lower activation energy

ATP holds lots of energy as the phosphate groups are negatively charged but held tightly together

an end product from the enzyme chain will bind to an earlier enzymes, preventing any more end product being made

binding substrates (things that need converting) to form complx, then convert substrate into the product

CNS - brain, spinal cord

PNS - relays info to CNS afferent (towards CNS), efferent (away CNS, sympathetic - fight or flight, parasympathetic - rest and repose). there is somatic afferent, somatic efferent, visceral afferent and autonomic nervous (sympathetic and parasympathetic)

general structure of a neuron

what are the three classifications of neurons

cell body - contains nucleus, lots of mitochondria

dendrites - extend from cell body, form synapse with next neuron

axon - plasma membrane called axolemma, ends are telodendrons (synaptic terminals), can be insulated by myelin

multipolar - one axon, many dendrites off cell body (motor neurons)

bipolar - one axon (other axon-like structure off cell body), one dendrite (smell/sight receptor)
unipolar - one axon, dendrites only off axon

CNS

astrocytes - structural neuron supports, usually invisible

oligodendrocytes - produce myelin for CNS

ependymal cells - line fluid-filled cavities of brain and spinal cord

microglia - small cells that turn large and respond to tissue damage (phagocytes)

PNS

schwann cells - surround axons, produce myelin

satellite cells - surround cell bodies, physical and metabolic support

what is white matter and why is it called that

why are axons myelinated and why is there a space between schwann cells. 

what are the three layers of the spinal cord

white matter is tissue made of myelinated axons

myelinated to stop diffusion of nerve impulse, space is called node of ranvier and it is where the impulse travels along the axon

dura mater - tough, fibroelastic

arachnoid membrane - contains csf

pia mater - reticular and collagen

What is the general structure of a nerve within the PNS

what is a ganglia and what does it contain

what are two different types of ganglia

axons of a neuron are bundled together to form a nerve fibre, held together by endoneurium.

then forms a fasiculus which is a collection of fibres surrounded by a perineurium

the forms nerve, which is a collection of fasciculi and blood vessels bound by perineurium

is a collection of neuron cell bodies outside the CNS (contains satelitte and schwann cells and blood vessels) surrounded by connective tissue.

craniospinal - unipolar neurons near brain/spinal cord

autonomic ganglia - prominent nucleolus, multipolar

what is a synapse

what are three types of synapses

where nerve impulse travels between neurons

chemical transmission - uses neurotransmitters made by pre-synaptic neuron. is a SYNAPTIC CLEFT (gap between neurons)

electrical transmission - with ions, travel via GAP JUNCTIONS (touching neurons)

motor end plates - axon terminates in muscle cells, postsynaptic membrane (muscle cell) deep folds, secondary synaptic clefts.

pyramidal motor neurons - in ventral horn of spinal cord, axon terminates on skeletal muscle as motor end plate

sensory neurons - round cell body, dendrites form sensory endings

purkinje cells - large multipolar in cerebellum

granule cells - small, cerebellum, axons contact with purkinje cells

neurosensory cells - special sense organ

neurosecretoyry cells - release hormone instead of neurotransmitter, in hypothalamus

1. high number of potassium inside than out, so lots of potassium constantly diffuse out

2. few sodium ions diffuse back in through leaks (pumps correct this)

3. outward transport of sodium is faster than inward transport of potassium.  creates a polarised membrane (negative on inside and positive on outside)

4. need a constant flow of ions to maintain the membrane potential

1. stimulus opens a sodium ion channel

2. sodium flows inwards (down the concentration gradient)

3. all subsequent channels are voltage-gated

4. sodium influx changes voltage of cell (called depolarisation)

5. produces net change in potential at axon hillock (axon meets cell body)

6. potassium diffuses to exterior to re-establish resting potential

which way will ions always move

how do voltage gated ion channels work

how is the membrane potential established

why is an initial electrical/chemical gradient established

what is the action potential due to

how does an action potential spread

down the concentration gradient

change in voltage will trigger them to open

greater concentration K+ inside and Na+ outside, sodium will be pumped out and K+ diffuse so inside is more negative

so movement of ions can generate action potential

due to an influx of Na+ ions after the threshold has been reached

by causing successive sodium channels to open

what are 6 types of sensory receptors

how does a neurotransmitter work

exteroreceptor, interoreceptor, proprioreceptor (muscle/body position), chemoreceptor (chemical stimulant), mechanoreceptor (mechanical force), photoreceptor (ion channel closes in response to light

neurotransmitter binds to ligand-gated ion channels, sodium enters cell, current spreads

1. action potential reaches axon terminal

2. Ca2+ channels open and changes the voltage inside cells

3. calcium signals the vesicles to move to the membrane

4. vesicles release acetylcholine by exocytosis

5. diffuses across synaptic cleft and binds to receptors

6. binding causes potential on muscle cell

what does connective tissue consist of 

what are the three types of fibres in connective tissue

what are the 4 types of fixed cells in connective tissue

cells (fixed and migratory), protein fibres, fluid ground substance. (fibres and ground substance make up the matrix)

collagen, reticular (same protein as collagen but finer), elastic (made of elastin)

fibroblasts (most abundant, secrete ground substance and can differentiate)

mesenchymal stem cells (multipotent - only form some types of body cells)

adipose cells (fat storage)

macrophages (lie along fibres, lare irregular nucleus, phagocytose)

what are the two types of migratory cells in connective tissue

what are the 5 types of connective tissue

mast cells - can have 2 nuclei, similar to basophils in blood

plasma cells - eccentric (one side) nucleus with halo where golgi is

loose/areolar - loosely binds structures, vascular, mostly ground substance

dense - more collagen, higher strength and low elasticity (irregular and regular)

elastic - irregular or regular, moderate strength

reticular - reticular fibres

adipose - fat cells, insulation, white - unilocular, brown - multilocular (produce lots of heat)

what is the structure of a skeletal muscle bundle

what is a sarcomere

what is sarcolemma and sarcoplasmic reticulum

breifly, how does a muscle fibre contract

a muscle fibre is made up of myofibrils, a fasicle is made up of muscle fibres surrounded by endomysium, skeletal muscle is made up of fascicles with perimysium between them all held together by perimysium

functional unit of muscle and is made up of specific bands and proteins

sarcolemma - surrounds myfirbrils (plasma membrane)

sarcoplasmic reticulum - holds reserve of calcium ions for muscle contraction

calcium interacts with binding sites, myosin head binds bends an moves, pulling actin filaments towards the sarcomere making muscle shorter

how does muscle relaxation happen

how does smooth muscle contraction happen

uptake of calcium, binding sites are covered and no cross bridge formation

calcium binding to calmodulin, phosphorylating the myosin head allowing it to bind with actin

what are the three types of muscle fibres

what are the muscle striations

what is the sarcolemma and how is it similar to other cell's equivalents

red - aerobic, slow oxidative fibres

white - anaerobic - rapid contractions

intermediate - fast, oxidative

A bands - darker remain a constant length

I bands - actin, attaches to z line

sarcomere - region between z lines

different cell types take the same materials but modify to suit purpose, sarcolemma modified membrane