Module 8 Homeostasis Flashcards
Homeostasis
the process by which an organism maintains a stable internal environment, despite fluctuating external environmental conditions
Why is homeostasis important (2 reasons)
Maintain constant conditions (temperature, pH, levels of water, etc.) in the body, so that enzymes can carry out functions efficiently. Secondly, cells survive best in an isotonic solution so they do not shirk or expand, and can carry out functions efficiently.
Two stages of Homestasis
1: body detects changes from the stable state. 2: body counteracts the changes
Parts of a Negative Feedback Loop
Stimulus, receptor, control centre, effectors, response
Temperature Homeostasis (cooling)
Increase in temperature detected by thermoreceptor sensors in the skin, message is sent to hypothalamus by nervous system, message sent to effectors causing the body to sweat and blood vessels to dilate.
Temperature Homeostasis (heating)
Decrease in temperature detected by the thermo-receptor sensors in skin, message is sent to hypothalamus by nervous system, message sent to effectors causing the body to shiver and blood vessels to constrict.
Glucose Homeostasis (To lower levels)
High blood glucose levels detected by insulin-secreting pancreas cells, liver takes up glucose and stores it as glycogen, blood glucose levels decline to a set point, stimulus for insulin release diminishes, and homeostasis returns.
Glucose Homeostasis (To rise levels)
Low blood glucose levels are detected by glucogen-releasing pancreas cells, liver breaks down glycogen stores and releases glucose into the blood, blood glucose levels rise to a set point, stimulus for glucogen release diminishes, and homeostasis returns.
Endotherms
Organisms that are able to maintain a constant internal body temperature, independent of the environment.
Behavioural Adaptations for Endotherms to maintain homeostasis
Movement, deliberate use of muscles, sunbaking, licking, drinking water.
Structual Adaptations for Endotherms to maintain homeostasis
Insulation, surface area to volume ratio.
Physiological Adaptations for Endotherms to maintain homeostasis
Vasoconstriction, metabolic rates, muscle contraction, sweating, panting.
Internal coordination systems for homeostasis
Hormones and neural pathways
What are hormones?
Hormones are signalling molecules used by the body to regulate physiology and behaviour.
How do hormones affect cells?
They bind to specific receptors on their surfaces, enacting changes in a process called signal transduction.
3 Steps of signal transduction
Reception, transduction, response
What makes up the Central Nervous System (CNS)?
Brain and spinal cord
What does the CNS do?
Control centre that coordinates responses in the body, receives information from the PNS, interprets information, and then initiates an appropriate response by sending messages to the RNS to enact effector responses.
What makes up the Peripheral Nervous System (PNS)?
Nerves branching from the CNS throughout the body.
What does the PNS do?
Facilitates communication in the body, passes messages too and from the CNS rapidly, allowing the body to respond to changes (internal and external).
What is the nervous system composed of?
Neurons (neural cells) that pass information in the form of chemical signals around the body.
What facilitates nerve impulse movements?
The transmission of an action potential along the nerve axon, triggering the release of neurotransmitters, and creating a signal transduction between cells.
How is transpiration regulation achieved in plants?
Smaller leaves, closing stomates, movement, dropping, large cavities for water in stems/trunks.
What is transpiration? (TCHT)
Evaporation of water throuhg the stomata of plants.
