Chapter 4 - Detecting & Responding Flashcards
Protein-based: Solubility? Transport? Synthesis? Lifespan? Action?
- Water-soluble
- Blood stream freely; can’t cross membranes
- In advance, stored in secretory vesicles, released by exocytosis
- Short (minutes-hours)
- Rapid (seconds-minutes)
Steroid-based: Solubility? Transport? Synthesis? Lifespan? Action?
- Lipid-soluble
- Requires blood carrier proteins; crosses membranes easily
- Synthesised on demand
- Long (days-hours-months)
- Slow
Phototropism
A response to light (Positive or Negative)
Geotropism
A response to gravity (Positive or Negative)
Hydrotropism
The response to availability and concentration of water(Positive or Negative)
Photoperiodism
The flowering of a plant in response to day length (light times) (Positive or Negative)
Vernalisation
Response to temperature
Thigmotropism
Contact (Positive or Negative)
Action Potential
The electrochemical polarisation and depolarisation that travels across the membrane of a neuron in response to
stimulation
Chemoreceptors
Molecules of substances that have to do with smell (olfactory receptors) and taste.
CNS
The brain and spinal cord, responsible for processing neural and sensory information and responses.
Cytokinins
A plant growth hormone, not to be confused with cytokines
Dendrite
A slender, often branched projection of a neuron that conducts the electrical impulse received from other cells to the cell body
Endocrine
Endocrine glands secrete hormones directly into the bloodstream, these circulate throughout the body to affect distance organs.
Homeostasis
The maintenance of a relatively constant/stable internal environment within narrow limits
Hormone
A chemical messenger secreted into the bloodstream, or other bodily fluids to effect a specific cell type which possesses specific receptor complementary to protein shape.
Interneuron
Relays electrical messages between sensory and motor neurons in the CNS
Interoceptors
Receptor that receives stimuli from the internal environment
Mechanoreceptors
Detects pressure, touch, tension, sound vibrations, position and posture of the body (balance), found in the ears and skin
Motor Neurons
Nerve cell that transmits signals from the central nervous system to effector cells/organs
Myelin Sheath
Fatty layer surrounding the axons off many neurons. Increases the speed at which electrical impulses travel down the nerve
Necrosis
Occurs when cell is damaged by a mechanical or chemical insult.
Cell swells and bursts causing inflammation
Neurohormone
Neurotransmitters secreted by the neuron into the blood stream.
Neuron
Nerve cell
Neurotransmitter
Chemical substance that carries the action potential across a synaptic cleft
Pain receptors
Detect pain, found in free nerve endings in the skin
Pheromones
A chemical produced by a living organism that transmits a message to other members of the same species
Photoreceptors
Detect light, found in the eyes and light sensitive parts of the body in some invertebrates
Plant Growth Regulators
A plant ‘hormone’ or chemical which helps to regulate plant development in response to the environment
Positive feedback
When a change of variable occurs, the response is to change that variable even more in that direction.
Postsynaptic membrane
The membrane directly after the synaptic cleft, the cell receiving the message
Presynaptic membrane
The membrane before the synapse, belongs to the neuron
Prostalglandins
A fatty acid hormone that is continually produced and released by the cell membrane of nearly every cell in the body.
Receptor
A structure that detects a stimulus and produces and electrical or chemical signal
Reflex Action
A response involving a sensory, interneuron and motor neuron but the electrical transmission by-passes the brain and travels through the spinal cord only.
Refractory Period
Short period in after transmitting an impulse, neuron unable to send message due to imbalances in ion concentrations inside and outside the membrane. Sodium potassium pump used to restore balance.
Second Messenger System
Small, molecule which is released in response to the binding of a hormone to a receptor. It is released into the cell and activates enzymes and triggers a response.
Sensory Neurons
A nerve cell that carries information from receptor organs to the CNS
Synaptic Cleft
The space between a neuron and receiving organ or muscle between which a neurotransmitter diffuses
Thermoreceptors
Detect changes in the temperature, found in skin
Tropisms
The response of plants to an external stimulus, e.g. light, gravity, H2O, photoperiod, temperature or contact
Apoptosis definition and Proccess
Self programmed cell death
- Signalling molecule stimulates receptor creating secondary messenger and causing a cascade of events.
- Enzymes are triggered to breakdown cellular components.
- Cell begins to bleb into bubbles encased by membrane.
- Blebs are phagocytised and cell fragments are removed as waste
Process of signal transduction across synapse
- ) Protein receptors on neuron bind to specific neurotransmitter and open chemically gated sodium channels.
- ) Change in polarity is enough (Threshold potential) it triggers further opening of voltage gated sodium and potassium ion channels, and electrical signal is passed along then axon.
- ) Electrical signal arrives at end of neurone stimulating Ca+ ions to diffuse into synaptic knob.
- ) Secretory vesicles move towards presynaptic membrane
- ) Vesicles release neurotransmitter through exocytosis into synaptic cleft where they bind to protein receptors on post synaptic membrane and message is passed on.
Amplification
At each step of a cascade many molecules are activated by a single chemical hence amplifying the magnitude of the original signal.
Cascade
Series of chemical chain reactions which happen in response to one another as a result of a stimulus.
Pathway of Steroid Hormone
Reception: Lipid-based (water insoluble, lipid soluble) signalling molecules are able to pass straight through the cell membrane to bind onto receptors within the cytosol to initiate transduction.
Transduction: Receptor protein triggers cascade of reactions which allow for the transcription of a gene.
Response: Protein(‘s) are synthesised and influence cell function.
Pathway of Protein Hormone
Reception: Protein-based (water soluble, lipid insoluble) signalling molecules, which are unable to pass through the cell wall, bind to receptors on the surface of the cell membrane.
Transduction: Receptor protein activates a second messenger within the cytosol to initiate transduction, resulting in a cascade of reactions.
Response: Range of chemical reactions activate range of proteins which influence cell function.
Ability to alter surface proteins
Antigenic variation
