Chapter 5 Flashcards
(22 cards)
Homeostasis
state, maintenance of a constant internal environment(blood plasma and extracellular fluid) within narrow limits
Flowchart
Signal, reception, transduction, effector, cellular response
Endocrine signalling
Ligands secreted into the bloodstream
Paracrine signalling
Secreted in the extracellular fluid to neighbouring cells
Autocrine signalling
Secreted by a cell that receives the signal
Contact-dependent signalling
direct membrane contact (gap junctions, plasmodesma, mobile)
Complementary
Ligands and Receptor proteins must be complementary, receptor for every ligand
Hydrophobic hormones (steroid)
Signalling molecule binds to its receptor (cytoplasm), the 3D shape of the receptor is altered, activating the receptor, ligand-receptor complex move into the nucleus and bind with DNA, regulate gene expression, proteins made
Long-lasting
Hydrophilic hormones (amino acid derivatives and peptide)
Signalling molecule is the first messenger, binds to protein receptor, the 3D shape of the receptor is altered and it activates an enzyme which catalyses the second messenger, enzyme cascade (signal is amplified), nucleus, proteins are made
Short-lived
Positive/negative feedback
Oppsoing stimulus to maintain homeostasis
Increasing stimulus
Endocrine system
Secretions directly into internal environment (extracellular fluid)
Exocrine glands
Secretions that pass along ducts to the external environment (tears, sweat)
Hormone
A chemical messenger secreted by endocrine cells that often travels through the bloodstream to a target organ where it effects a response
Insulin
Glucagon
ADH
Thyroxin
Produced by beta cells, uptake of glucose, stored as glycogen, peptide
Produced by alpha cells, breakdown of glycogen releasing glucose into bloodstream, peptide
Prevents extra water loss, higher reabsorption of water, high urea concentration and low urine volume, protein
Increased metabolic rate and heart rate, promotes growth, amino acid derivative
Neurons
Nucleus, cell body, dendrites, axon, myelin sheaths, schwann cell, axon terminals, synapse
Apoptosis and Necrosis
Natural programmed cell death, maintain cell numbers, defence against damaged/dangerous cells (virus infected, DNA damaged), depend on caspases
unprogrammed cell death, due to external factors
CNS and PNS
Brain and spinal cord
sensory (photoreceptors, pain receptors, chemoreceptors, thermoreceptors) and motor neurons
Process of Nervous system
Stimuli
Receptors of sensory neurons detect change
Travels to CNS
Interneurons
Motor neurons (neurotransmitters diffuse to receptors on muscle fibres, enzyme inactivates neurotransmitter)
Electrical signal through neurons, chemical in between
Pheromone
chemical ligands released by one animal that effects a physiological or behavioural change in another animal (same species)
Animals have a vomeronasal organ that senses pheromones (different nerve pathway)
Types: trail (ants), alarm, territorial (urine), sex (indicates ready to mate)
Cytokines
Aid cell to cell communication in immune responses and stimulate the movement of cells toward sites of inflammation, infection or trauma
Plant hormones
Ligands produced in one part of a plant that effects a physiological or biochemical change in a specific target tissue (made in meristems and travel through xylem, phloem, air, cell-to-cell)
Not species specific
Auxin Cytokinins Gibberellins Abscisic acid Ethylene
Enlargement, elongation of plant cells cell reproduction Elongation and cell reproduction Dormancy Ripening
