Chapter 5 + 6 Flashcards
Stimulus response model
Stimulus Receptor Transmission of message/Control centre Effector Response
Cell signalling steps
Signal reception
Transduction
Response
Signal transduction
The cascade of events originating outside of the cell leading to a specific cellular response
Signal transduction basis
Amplification
Types of signalling
Autocrine, paracrine, synaptic, endocrine
Autocrine signalling
Secreting cell acts on itself by secreting hormone into extracellular fluid
Paracrine signalling
Secreting cell acts on nearby target cells by secreting hormones into extracellular fluid
Synaptic signalling
Nerve cell releases neurotransmitter into synaptic cleft, stimulating target cell
Endocrine system
System of ductless glands that produce hormones and release them directly into the bloodstream
Signalling molecules
Carry signals or messages from one cell to another
Hormones
Signalling molecule that is produced in an endocrine gland that is release into and transported via the bloodstream to target cells/tissues where it elicits a specific response
Internal environment
The fluid surrounding living cells within a multicellular organism
Examples of internal environment
Lymph, plasma, extracellular fluid, cerebrospinal fluid,
Plasma
The fluid portion of blood in which blood cells are suspended
How is extracellular fluid and plasma separated
Capillaries
Does internal/external environment vary much
Internal not much, external can
Cerebrospinal fluid
Fluid that bathes the brain and spinal cord
What exchanges occur between extracellular fluid and plasma
Passing nutrients, gasses, waste, glucose
What exchanges occur between extracellular fluid and cells
Nutrients, waste, glucose, amino acids
Intracellular fluid is
Cytosol
Homeostasis definition
The maintenance of a relatively stable internal environment within narrow limits
What’s involved in homeostasis
Detecting change, counteracting change
Variables controlled in body
Nutrients, blood volume, temperature, blood pressure, water, oxygen gas, ions, carbon dioxide gas, pH
Nutrients are required for
Energy, repair and growth
Two systems used to communicate and coordinate functions in body
Endocrine and nervous
Difference between hormone and neuron pathways
Speed, blood vs neurons, hormones longer lasting, hormones take longer time to respond to
Similarities with endocrine and nervous
Rely on chemical messengers
Negative feedback system
System of control in which change in a variable is detected and action occurs to produce a change in the opposite direction
Positive feedback
Physiological mechanism that enhances further change in a particular variable that provoked the initial change
Two ways signalling molecules cause cell to elicit a response
Pass through membrane, enter nucleus and bind to receptor
Bind to receptor in membrane, undergoes change in shape, second messengers, they travel along cell and activate other proteins which activates other proteins, until response occurs
cAMP
Cyclic adenosine mono phosphate
Three types of signalling molecules
Peptide, steroid hormones, amino acid derivatives signalling molecules
Hydrophilic
Peptide, amino acid derivative
Lipophilic
Steroid
Lifespan of steroid
Synthesised on demand, leaves by diffusion, long lifespans
Lifespan of protein and amino
Made in advance, stored, short lifespan, exocytosis
Exception
Thyroxine is hydrophobic
cAMP
Second messenger
Core temperature
Temperature of internal cells
pH of enzymes and nerve cells
Generally 7.4
Receptors
Chemical structures, often on the surface of cells that receive signals from hormones, neurons or cytokines
Target cells
Cells with appropriate receptors able to receive particular hormonal or nervous message
Second messenger molecule
Often protein, that acts as an intermediary in the transfer of message e.g. G protein
What happens after hormones have delivered message to target cells
Digested by enzymes
Detecting and responding
Production of signal Detecting of signal Transfer of signal Response Switching off signal
Endocrine signalling
Hormones act on cells
Pheromones
chemicals that, when released by one animal, elicit a response in another animal of the same species; in particular, act as a sex attractant for mating in many insect species
Pheromones are…
specific
Central nervous system (CNS)
in vertebrates, the brain and spinal cord.
Peripheral Nervous System (PNS)
in vertebrates, all nerve cells that in whole or part lie outside the brain and spinal cord.