4a learing objectives Flashcards
Define homeostasis and list the types of bodily conditions that are regulated by homeostatic mechanisms; define endotherm and ectotherm.
Homeostasis - the ability of an organism to maintain its internal environment within narrow limits that allow optimal cell function.
Endotherm - produced most of their heat through metabolic reactions.
Ectotherm - derive most of their heat from the environment (reptiles, amphibians, invertebrates and most fish)
Explain the roles of positive and negative feedback in maintaining a constant internal environment .
Positive - creates cycles of which changes amplify themselves.
Negative - which counteract the internal changes, this is the basis for homeostasis. There are three principles , Sensor, Control centre (hypothalamus) , Effector.
Describe the organisation of the animal body into functional units of increasing size and complexity (i.e. cells, tissues, organs, organ systems).
Cells - fundamentals
Tissues - similar cell working together to perform single function
Organs - structures that compete complex functions and have two or more varying tissue types.
Organ system - groups of organs that are coordinated to each perform a specific task that is apart of a larger task
List the major tissue systems in the animal body and the types of cells that comprise them: epithelial tissue, connective tissue, muscle tissue, and nerve tissue.
Epithelial tissue - line ducts and hollow organs as well and external surfaces. Made from simple epithelium (one cell thick) , stratified epithelium (more layers) , squamous cells (flat and thin) Cuboidal cells (cube shaped) Columnar cells (elongated)
Connective tissue - supports and aids in binding tissues. Loose connective tissue (fat) dense connective made from collagen fibres parallel (tendons, ligaments) specialised tissue (cartilage, bone, fat, blood, lymph)
Muscle tissue - can contract they are skeletal (voluntary) , cardiac (heart involuntary and made from intercalated discs) and smooth (not striped, involuntary)
Nerve tissue - neurons (dendrites, cell body, axon and terminals) and glial cells which support electrical insulate and protect neurons as well as regulate composition of interstitial fluid.
Define the terms organ and organ system.
Organ - structures that compete complex functions and have two or more varying tissue types.
Organ system - groups of organs that are coordinated to each perform a specific task that is apart of a larger task
List the four major methods by which cells communicate with each other (direct, synaptic, paracrine, endocrine) and the general mechanism by which endocrine hormones communicate with their target cells.
Direct - direct contact, ions flow from each cell by gap junctions (cardiac cells)
Synaptic - chemicals released by cells diffuse through extracellular fluid, transmits electrical signals to each cell (neurotransmitters) (nervous system)
Paracrine - chemicals released by cells diffuse through extracellular fluid, effects are short - local hormones (prostaglandins)
Endocrine - chemicals secreted through the bloodstream, (insulin)
List the three major classes of vertebrate endocrine hormones and describe how these different hormone types affect changes in their target cells.
Steroid hormones - synthesised from cholesterol they are lipid soluble so they can diffuse through plasma membranes, they bind to receptor cells inside target cells. (testosterone, oestrogen, progesterone.)
Peptide hormones - chains of amino acids , which cannot diffuse through the bilayer, they must bind to receptors on the cell surface. (thyroxine, Melatonin.)
Amino acid derived hormones - made of amino acids they also bind to receptors on the cell surface. (growth hormone, Insulin, Leptin.)