Chapter 5 - Coordination and Regulation: Endocrine Systems Flashcards
stimulus response model definition
a change in the environment is received by a receptor and the organism interprets that change and responds in a way to protect the organism (restore stability)
steps of stimulus response model
SRCER stimulus: change receptor: detect change communication systems: signalling molecules effector: initiates response response: change
signalling molecule
molecules that carry signals or messages from one cell to another
enable cells to communicate
principles of cell communication
PDTRC
production of signalling molecule
detection of the signal by a receptor protein
transduction of this signal through the cell
response of the cell
control of regulation
hormone
signalling molecule that brings about a response in a target cell
do not last indefinitely
some hormones may:
act on the same cells that produce them
be secreted into the extracellular fluid and act on cells close by
enter the blood stream and act on distant cells
how does a hormone stimulate a repsonse
must find bind to receptor
receptor hormone complex
complementary hormone and receptor bonded
why don’t hormones last indefinitely
delivered signal to target cells
desired effect has occurred
degraded by cell enzymes
excreted (urine/faeces)
two hormone types
lipid based (steroid) hormones protein based hormones
lipid based (steroid) hormones
lipophilic
easily pass through membranes
intracellular receptors
e.g. testosterone, oestrogen
protein based hormones
hydrophilic
can’t pass through membranes
extracellular receptors: on surface of plasma membrane
e.g. insulin, glucagon
signal transduction
cascade of events linking an external signal to a specific cellular response
information passed from receptor to effect
steps of signal transduction
reception: info received by cell’s receptor
transduction: info from receptors passed onto effectors
induction / response: various cellular responses initiated
example of responses to signal transduction
activation of genetic material -> production of proteins
production of another signalling molecule
pheromones
chemical signalling molecules secreted by animals that evoke a response in another animal of the same species
species specific
why do plants secrete hormones
help coordinate plant development in response to the environment
apoptosis
regulate or programmed cell death
instances when apoptosis is needed
menstruation: shedding of endometrium
metamorphosis: tadpole to frog
formation of fingers and toes in foetus
cancer cells
viruses
where are hormones produced
endocrine system
where are neurotransmitters produced
axon terminal
where are pheromones produced
animals
where are plant growth regulators produced
plants
where do hormones transport
travel in extracellular fluid or bloodstream
where do neurotransmitters transport
across synaptic gaps
where do pheromones transport
secreted into external environment
where do plant growth regulators transport
carried in plant vascular tissue (xylem and phloem)
what do hormones target
specific cells respond to each hormone
what do neurotransmitters target
dendrites of other neurons to continue impulse
what do pheromones target
other members of the same species
what do plant growth regulators target
plant tissues to stimulate activities such as growth, flowering and fruiting
Homeostasis
The main range of a relatively stable internal environment, within narrow limits, despite changes in the external environment
Auxin
Control enlargement and elongation of plant cells
Ethylene
Causes leaves to fall off
Ripens fruits
Gibberellins
Promote plant growth
Stimulates cell elongation and reproduction
Tropism
The growth of a plant in response to a stimulus such as light or water
Phototropism
When a plant moves in response to light
Positive if toward light
Why do plants bend toward light
Auxin moves away from light
Promotes growth on one side more
Bends towards light
Geotropism
Response if shoot or root to gravity
Cytokinins
Promote cell reproduction in plants
Abscission
Falling of cells or fruit
Glucagon
Hormone produced by alpha cells of the pancreas that acts on the liver cells resulting in an increase release of glucose from the liver cells into the bloodstream
Phloem
Transports sugar
Xylem
Transports water and minerals
