animal structure and function

• all features that have evolved in ways that enable survival in animal's environment

  anatomy
• the biological functions an organism performs

  physiology
• comparative study of animals reveal that form and function are closely related
• basic principle: adaptation through natural selection (variation meets environment)
• size and shape affect the way an animal interacts with its environment
• evolutionary convergence reflects different species' adaptations to a similar environmental challenge.
• the dense property of water limit the shapes of fast swimmers:

  • tapered on both ends
  • sleek - overdoing drag during swimming
• animal's size and shape directly affect how it exchanges energy and materials with its surroundings
• exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells' plasma membranes.
• rate of exchange (nutrients, waste products, gases) correlates with membrane surface area. Amount of material to be exchanged correlates with cell volume.
• multicellular organizations works only if every cell has access to a suitable aqueous environment (inside and outside the body)
• more complex organisms have highly folded internal surfaces for exchanging materials: increasing cell number decreases the ratio of outer surface area to total volume

  • branching and foldings increase the surface area
• What fluid fills the space between cells in vertebrates, which allow for the movement of materials into and out of cells.

  interstitial fluid
• complex body plan helps an animals in a variable environment to maintain a relatively stable internal environment
• most animals are composed of specialized cells organized into tissues that have different functions
• different types of tissues make up organs, which together make up organ systems that entail a higher level of organization and coordination
• different tissues have different structures that are suited to their function
• what are the four main categories of tissues?

  epithelial, connective, muscle, and nervous
• epithelial tissue

  • epithelial tissue covers the outside of the body and lines the organs and cavities within the body
  • contains cells that are closely joined
  • many shapes as seen in the photo:

  
• connective tissue

  • connective tissue mainly binds and supports other tissues
• connective tissue

  contains sparsely packed cells scattered throughout an extracellular matrix (contains fibroblasts that secrete fibre proteins, and macrophages that engulf foreign particles and cell debris through phagocytosis).
• connective tissue

  the matrix consists of fibres in a liquid, jellylike, or solid foundation
• types of connective tissue

  loose connective tissue

  • collagenous fiber
  • elastic fiber
  • provide strength and flexibility
  • stretch and snap back to their original lengths
• types of connective tissue

  fibrous connective tissue

  • nuclei
  • found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints
• types of connective tissue

  bone

  • osteon
  • central canal
  • mineralized and forms the skeleton
• types of connective tissue

  cartilage

  • chondrocytes
  • chondroitin sulfate
  • strong and flexible support material
• types of connective tissue

  adipose tissue

  • fat droplets
  • stores fat for insulation and fuel
• types of connective tissue

  blood

  • white blood cells
  • red blood cells
  • plasma
  • composed of blood cells (erythrocytes - RBC and leukocytes - WBC) and cell fragments in blood plasma
• muscle tissue

  • long cells (muscle fibres) which contract in response to nerve signals
• types of muscle tissues

  skeletal muscle

  • multiple nuclei
  • muscle fiber
  • sarcomere
  • also called striated muscle, is attached to bones and is responsible for voluntary movement
• types of muscle tissue

  smooth muscle

  • nucleus
  • muscle fibers
  • mainly lines internal organs and is responsible for involuntary body activities
• types of muscle tissue

  cardiac muscle

  • nucleus
  • intercalated disk
  • responsible for contraction of the heart
• nervous tissue

  nervous tissue senses stimuli and transmits signals throughout the animals
• what does nervous tissue contain?

  • neurons, or nerve cells, that transmit nerve impulses
  • glial cells, or glia, that help nourish, insulate, and replenish neurons
• control and coordination within a body depend on the endocrine system and the nervous system
• the endocrine system transmits chemical signals called hormones to receptive (target) cells throughout the body via blood
• hormone may affect one or more region throughout the body
• hormones can be fast (epinephrine outside CNS - as SMS) or slow acting(release of thyroid-stimulating hormone) but can have long-lasting effects (as snail mail)
• the nervous system transmits information between specific locations
• information conveyed depends on signal's pathway, not the type of signal