20240122 | animal tissues

• analysis of organisms on a multicellular level (specialized cells)
• tissues: groups of similar cells with similar embryonic development and function
• organs: groups of similar tissues
• organ systems
• organism: an individual, in this case a multicellular one that possesses organ systems → organs → tissues
• histology: tissue structure/function (derived from hist/o-, tissue or web)
  types of animal tissues: epithelial, connective, muscle, nervous

epithelial

• from epi-, outer; thelium (p. thelia), nipple/papilla/projection; -al, of or pertaining to or adjectival
• tightly-packed, tightly-junctioned tissues which prevent materials from passing
• basement membrane: secreted protein and glycoprotein membrane which anchors epithelial tissue to rest of organ
• identify via number of cell layers and shape of cells
  • number of layers:
    • simple epithelial: singular layer
      • areas of passage (absorption/secretion — lungs and intestine)
    • stratified epithelial: multiple layers
      • areas of frictional stress and cover (skin, mouth and throat lining)
    • pseudostratified epithelial: single layer that appears stratified due to illusion of depth, created by differences in height amongst epithelial cells
  • shape:
    • squamous: thin and flat; derives from squame, squama: covering that is scale, plate, or flake-like; fish or reptile-like
    • cuboidal: you know… like a cube… cuboid…
    • columnar: you know… like a column…
• naming conventions based on number/shape
  • for a stratified tissue: tissue is named by free, unattached surface of epithelial tissue layer
• epidermis: outer layer; epi- + -dermis
• nephron: microscopic tubules found in the kidneys, surrounded by blood vessel; used for the processing of urine and the primary component of the kidney
• lumen: free space within a cell
• villi (sg. villus); finger-like projections (derived from a latin word which references a thick tuft of hair, like fleece)
  • may be pseudostratified
  • evolved structures that increase the surface area of cellular lining of intestinal lumen → increase productivity of transport proteins and absorption of nutrients through intestinal wall
    • microvilli: microscopic folds in the cellular plasma membrane with identical function
• brush border: the free, unattached surface of the cells surrounding the lumen
• goblet cells: vase or goblet-shaped cells that contain light-staining mucous
  • secretion of mucous for lubrication and protection

connective

• diverse junction and support tissues, including blood cell
• contains a matrix: dividers made from extracellular material (secreted within tissues in the fibroblast cell) that separate cells in a given tissue
  • proteinaceous fibers: collagenous or elastic or etc. fibers; made from a given protein and submerged in a ground substance that keeps them from separating
    • collagen vs. elastin proteins; some have both, some only one
    • string-like
  • ground substance: dense liquid or gelatinous combination of glycoproteins and polysaccharides
• named by density and fiber or protein
• macrophages: large, grain-textured phagocytic cells made from wbcs
• adipocytes: adipose tissue cells; tight packing with transparent/colorless triglycerides
  • “chicken wire” appearance
  • within fat vacuoles in adipose tissue
• chondrocytes: cartilage tissue cells (ex. hyaline cartilage)
  • organ is packed with chondrin ground substance and collagenous fibers
    • glass/fog appearance of chondrin matrix
  • semi-solid matrix with lacunae holes for cells
  • no blood vessels in cartilage; slow diffusion through ground substance
  • side: hyaline cartilage is paired with adipose tissue
• osteocytes: bone tissue cells with a spiderlike appearance created by thin cytoplasmic projections
  • within the lacunae of the solid crystalline matrix in bone
  • Haversian system is all osteons: groupings of lamellae layers (ring structure) and a central Haversian canal
    • smaller canals: canaliculi → “solid, crack-like” appearance
• blood cells are divided into two types
  • rbc: erythrocyte
  • wbc: leukocyte
• blood cell matrix: plasma; serum ground substance, albumin proteins → blood viscosity and others → blood clots
• mammalian erythrocytes are anucleated; concave hemoglobin disks that lack nuclei
  • non-mammalian are nucleated
• five types of leukocytes; all are colorless

muscle

• skeletal, cardiac, smooth muscle (digestive, blood, tract, involuntary movement muscles)
• all muscle tissues can contract, perform mechanical work
• distinguished muscle tissues
• skeletal: long, multinucleic, ribbed pattern (striation) caused by arrangement of protein fibers used in contraction; cylindric; nuclei are on edges of tissue
  • voluntary contractions
• cardiac: striated, uninucleic, short, y-shape cells; posses intercalcated disks → dark, thick junctions that connect cardiac cells
  • only animal hearts
  • involuntary
• smooth: no striation → name; thin, spindle-shape/tapering, uninucleic cells;
  • may be confused with dense fibrous connective tissue; nuclei are ovaline in smooth muscles and compressed in dfct

nervous

• brain; electrical signaling → responses to stimuli and communications; action potential generates responses
• large physiology unit
• neuron: basic cell of nervous system; → dendrons; cell body with parts attached that rip off when spliced for slidework
• large, star-shape cell body composed of motor neurons: possesses a single nucleus and nucleolus
  • neurofibrils; small, dark in stains
• axon v. dendrite: axon is long-distance, transmits to other tissue cells; dendrite is short, transmits between neurons; thin axons are easy to tear
• glial cell (Schwann cells are linear) → grow around axons, increase speed of transmission,

20240124 | phylogenetics

• outgroup: distantly related taxa ie wolves and lions
  • family, genus
• pinnae: ear flaps vs merged earholes (“ear pinning”)
• summary code: symbolic representation of variation in characters
  • ie 0: ancestral state for character (assigned to outgroup)
  • 1+: evolutionary novelty
• distance matrix: calculate number of differences between taxa and use to calculate sister groups and distance on trees in values of number of differences
  • used for larger phylogenies
• convergent evolution: common evolution in distinct separate species / systems due to similar environmental pressures
  • tasmanian wolf vs timber wolf
• cytochrome c: cellular respiration

20240204

• hypothesis: proposal that might be true -> experiments
  • null hypothesis: predicts no difference or change between observed and expected (ratio), no difference across populations; no actual change
    • there is no difference between the expected genotype ratio of 25AA:50Aa:25aa and the observed ratio.
  • straightforward, understand what is being tested. boring tm
• statistics determine meaningfulness or chance of experiment results; likelihood of repetition for outcome
• chi square: ratio format data; observed to expected
• compare o v e genotype, allele, phenotypic frequencies
• genotype frq: 2 deg freedom (3 classes in hwe)