Not Confident Yet Flashcards
Four types of tissue
Neural, connective, muscle, epithelial
Three types of connective tissue
Connective tissue proper
Fluid connective tissue
Supportive connective tissue
Functions of epithelial tissue
Provides sensation
Physical protection
Produces secretions
Controls permeability
Types of cell junctions
Gap junctions) connected by cannexons, allows movement of ions and small molecules
Tight junctions) prevents movement of water and solutes between cells, protects basal surface in digestive tract
Desmosome) allows stretch, usually in skin. Linking of cells by CAMs and proteoglycans to the cytoskeleton
How to maintain the integrity of the epithelia
Connections between cells) tight junctions, gap junctions, desmosome
Attachment to the basement membrane) hemidesmosomes
Maintenance and repair of the epithelium) division of stem cells at basement membrane to offer protection
8 Types of epithelium and features
Simple squamous) diffusion. Lines body cavities and heart/ blood vessels. Alveoli
Stratified squamous) protection. In skin
Simple cuboidal) secretion and absorption. In salivary glands
Stratified cuboidal) rare, involved in protection, secretion and absorption. Lines some ducts of sweat glands.
Transitional) tolerates repeated cycles of stretching and recoiling. In urinary bladder. Appearance changes from cuboidal to squamous when stretched.
Simple columnar) absorption, protection, secretion. Has microvilli to increase SA. Generally in digestive tract
Pseudistratifued columnar) protection, secretion, absorption. looks stratified but all cells actually attach to basement membrane, has cilia. respiratory epithelium
Stratified columnar) rare, protection, in eyelids.
Two components of connective tissues
Extracellular part) ground substance and protein fibres
Cellular part) specialised cells
3 roles of connective tissue
Connection) supports and surrounds other tissues
Protection) protects and insulates internal organs
Storage) energy reserves
Types of cells in connective tissue proper
Fibrocytes) secretary’s protein and hyaluronon
Fibroblasts) maintain fibres, produce collagen
Adipocytes) fat cells
Mesenchymal cells) divide when injury occurs and differentiate into other cells types
Others) macrophages, mast cells, lymphocytes, microphages
Four types of membranes
Synovial) produces synovial fluid, protects articulating bone, lacks true epithelium
Serous) lines cavities but do not open to the outside, has visceral and parietal portion
Mucous) lines passageways, have external connections, moist epithelial surface
Cutaneous) skin, thick waterproof and dry
Neuroglia of CNS and PNS
CNS)
astrocytes) regulates environment, maintains blood brain barrier, forms scar tissue
ependymal cells) produce, secrete and monitor cerebrospinal fluid
oligendrocytes) form myelin, insulate axons
microglia) clean cellular debris, waste products and pathogens
PNS
Schwann cells) produce myelin, insulate axons
Satellite cells) similar to astrocytes, regulate environment
Myelin
What is the propagation of an action potential called on an unmyelinated neuron called?
Continuous propagation
Two types of synapses
Electrical) cells are in direct physical contact at gap junctions. Action potential transmitted quickly and efficiently
Chemical) cells not in contact, uses neurotransmitters. Most common type
Steps to neurotransmission
Action potential arrives at axon terminal
Voltage gated calcium channels open
Calcium ions released, increasing cellular calcium ion concentration
Synaptic vesicles fuse with membrane
Neurotransmitter released into cleft
Neurotransmitter diffuses to post synaptic terminal
Excitory vs inhibitory neurotransmitters
Excitory) makes cell membrane potential more positive, depolarisation, promotes generation of action potentials
Eg ACh
Inhibitory) makes membrane potential more negative, hyper-polarisation, inhibits generation if an action potential
Eg GABA
How do long bones form? (6 steps)
Endochondral ossification
1 Cartilage forms from stem cells
2 Cartilage grows due to bursting of cells in the centre, which causes a shift in PH and trigger calcification
3 Primary ossification centre forms, nutrient arteries penetrate the centre of cartilage and sponges bone forms since bone mineral matrix covers spongey bone
4 Medullary cavity forms when bone mineral is reshaped and reformed
5 Secondary ossification centre formed as blood vessels enter the epiphyses (around time of birth) Spongey bone is formed here, but no medullary cavity
6 Cartilage remains of ends of bones/ joints as articulate cartilage
How do long bones get longer?
1 Cartilage grows on growth plate, on the epiphyseal side
2 Cartilage cells are destroyed and replaced by bone at the metaphysis
3 bone gets longer
4 bone stops growing when the growth plate becomes too thin, this leaves an epiphyseal line
Growth of flat bones
Intramembranous Ossification
Bone grows directly from osteoblasts, no growth plate or cartilage formation involves
Fibroblasts differentiate into osteoblasts
Skull plates grow towards each other over time
What is bone made up of?
10% organic collagen matrix
65% mineral (hydroxyapatite, insoluble salt of calcium and phosphorus)
25% water
Trace amounts of magnesium, sodium and bicarbonate
4 Types of bone cells
Osteoblasts) bone forming cells, secrete type 1 collagen (make the collagen chains that form the new matrix), on surface of bone, control deposition of mineral, becomes osteocytes or undergo apoptosis
Osteoclasts) bone resorbing cells, large cells with many nuclei, umbrella shaped, secrete acids and enzymes that degrade bone, undergo apoptosis when finished
Osteocytes) born from osteoblasts that cipher stuck in matrix, maintains bone matrix, has canniculi, forms gap junctions w neighbouring cells, detects changes in environment
Bone lining cells) flat elongated cells, generally inactive, lines surfaces of inactive bone
