L2 and 3- Homeostasis and Regulation Flashcards
4 cellular functions
- Self-organization
-obtaining nrg and raw materials, eliminating waste,
making proteins, etc. - Self-regulation
-maintaining self-integrity in the face of disturbances - Support and movement
-cell contains structures that give it form, cell moves
materials, cell moves through environment. - Self-replication
-Reproducing to repair damage and carry on species
The process of correcting deviation in internal conditions, which threaten other functions is called
homeostasis
Who is the father of modern physiology?
Claude Bernard
Define homeostasis
the dynamic steady state in which the changes that do occur are minimized by compensatory physiological processes.
Animals keep their internal environment around some optimal level within a narrow limit by carefully regulating mechanisms.
How do cels which do not have contact with external environment get what they need?
Via extracellular fluid.
Membrane of cells exchange material between ECF and ICF
ECF is made up of 2 components:
Blood plasma + interstitial fluid
Central theme of homeostasis
Cells make up body systems. Body systems maintain homeostasis. Homeostasis is essential for the survival of cells (it’s a cycle).
Factors of the internal environment that are homeostatically regulated:
- Concentrations of:
a. nrg rich molecules
b. O2 and CO2
c. waste products
d. pH
e. Water, salt, and other electrolytes - Some animals also regulate:
a. volume and pressure
b. temperature
c. Social parameters (ex: termites)
Climate change, predators, acute disease/injury are all examples of….
ways in which homeostasis can be disrupted
What happens to the mean recovery time of fish the longer they are exposed to air?
It increases.
Takes longer for fish to re-achieve homeostasis the longer they’re out of water.
Air exposure disrupts homeostasis, ESPECIALLY AT WARMER TEMPS.
Mortality increases with higher air exposure time.
2 main strategies to maintain homeostasis:
- Regulators
- Conformers
also (but not a main strategy): 3. avoiders
What do regulators do to maintain homeostasis?
Use internal mechanisms to define a constant state (ex: monkeys)
What do conformers do to maintain homeostasis
Internal state varies with that of the environment (ex: snail)
What do avoiders do to maintain homeostasis
minimize internal variation by avoiding environmental disturbances (ex: monarch butterflies)
Define enantiostasis
Organism can maintain its normal function despite outside environment changing, but does it whilst NOT maintaining homeostasis (ex: animals that dwell in tidal zones)
T/F The blue crab maintains internal homeostasis
False. The blue crab maintains ENANTIOSTASIS.
At LOW environmental salt, oxygen binding is inhibited. Therefore the crab increases ammonia concentration, which makes inner fluid LESS ACIDIC and increases oxygen binding.
Thus, crab gets needed O2, but changes internal conditions.
Using a drawing, describe how cells obtain/excrete material
Ex:
Draw lungs, blood plasma, interstitial fluid, and cells
O2 from lungs to blood, to interstitial fluid, to cells, CO2 from cells to interstitial fluid, to blood, to lungs.
Or:
Gastrointestinal tract sends nutrients to blood, to interstitial fluid, to cells. Cells exchange H2O and ions with gastrointestinal tract.
The primary way animals regulate their internal environment is through ______ _______
Negative feedback
Define negative feedback
A change in a controlled variable triggers a response that opposes the change, driving the variable in the opposite direction of the initial change.
What do control systems regulate?
a “controlled variable”
Control systems consist of 3 elements:
- sensor
- integrator
- effector
Role of a sensor
detects change and communicates “error signal” to the integrator
Role of an integrator
Compares levels of controlled variable to set point and initiates response to correct deviation by sending a signal to the effector
Role of an effector
Restores controlled variable toward set point.
Two alternatives:
1. antagonistic control: 2 effectors with opposite effects (furnace/AC).
2. behaviour as effector: specific movement patterns (ex: avoiders).
Summarize control system
Deviation in controlled variable is detected by the sensor.
The sensor informs the integrator, which compares the variable to a SET POINT and signal the effectors to generate a response.
Effectors bring about COMPENSATORY RESPONSE.
Compensatory response results in controlled variable being restored to normal. This results in NEGATIVE FEEDBACK to shut off the system responsible for the response.
Body temperature control system
Fall in body temperature is detected by temperature-monitoring nerve cells (sensor). These cells inform the temp control center (integrator), which compares the temp to a set point and signals skeletal muscles (and other effectors). Body heat is increased through muscle shivering and other means. Body temp increases to set point and negative feedback occurs to shut off the system.
Problems with Neg feedback and how the body corrects them.
- Problem: Delayed response. ie. there must be a disturbance before the system can correct itself and then further delay once system is perceived and corrected.
Solution: ANTICIPATION or FEEDFORWARD SYSTEM: reduces the delay by detecting or predicting oncoming disturbance before perturbation beyond set-point.
ex: temp sensing nerves on skin feel temp before internal temp changes. - Problem: System is environment or situation-specific. ie. may not work if animal changes environments.
Solution: ACCLIMATIZATION SYSTEM or PHENOTYPIC PLASTICITY: Mechanisms that alter existing feedback and other components over many days to work in new situations. (ex: mammals developing more hair/fat layers as winter approaches).
If change can’t happen, outcomes like dormancy may occur.
5 types of time frames in which physiology changes:
- acute changes
- chronic changes (acclimatization)
- evolutionary changes
- Developmental changes
- changes controlled by periodic biological clocks
Acute changes definition and example
def’n: changes that individuals exhibit soon after their environment has changed. REVERSIBLE.
ex: plasma cortisol levels in fish get higher with higher capture times
Chronic changes def’n and example
def’n: changes that an individual displays after being in a new environment for days, weeks, or months. REVERSIBLE.
ex: amount of blood hemoglobin increases in higher altitude. This increases amount of oxygen that can be carried.
ex 2: daphnia helmet and spine length increase when in an environment with high predator concentrations.
Evolutionary changes def’n and example
def’n: Changes that occur by alternation of gene frequencies over the course of multiple generations in populations exposed to new environments.
ex: bipedal development in humans.
Developmental changes def’n and example
def’n: Programmed changes in physiology
ex: maturity. Puberty.
Changes controlled by periodical biological clocks def’n and example
def’n: repeated changes in physiology under control of the animal’s internal biological clock.
ex: menstruation
T/F:
Digestion and locomotion are homeostatic functions
FALSE
example of a reset system
sex hormone concentrations during maturity are reset to higher levels.
Positive feedback system
deviation in controlled variable may be sensed by a sensor. Sends signal to integrator. Output (may use an effector). CHANGE IS ACCENTUATED.
ex: neuron action potential.
Intrinsic vs extrinsic controls:
Intrinsic controls:
- Regulated independently by a single tissue or organ
- self-serving
- ex: increased [CO2] in muscle is detected by smooth muscle of blood vessel. Vessel then relaxes and dilates which increases blood flow.
Extrinsic controls:
- regulatory mechanisms initiated OUTSIDE AND ORGAN to alter its activity.
- usually involves TWO OR MORE ORGANS.
- governed by nervous, endocrine, and immune system
- can be overriding to intrinsic controls.
List 2 Whole-body control systems
- Nervous systems
2. endocrine systems
List 2 support and movement systems
- Skeletal systems
2. Muscular systems
6 Maintenance Systems
- Circulatory systems
- Defense or immune systems
- Respiratory systems
- Excretory systems
- Digestive systems
- Integumentary systems
What are integumentary systems?
MAINTENANCE SYSTEMS
Systems that serve as outer, protective physical barriers that prevent internal fluid from being lost from organisms and foreign microorganisms from entering them. These organs are also important for regulating body temp in animals.
Nervous systems
WHOLE-BODY CONTROL SYSTEM
- control and coordinate bodily activities that require SWIFT RESPONSES.
- important in detecting and initiating reactions to changes in the external environment.
- responsible for more complex functions (ex: consciousness, learning, memory, etc)
Endocrine systems
WHOLE-BODY CONTROL SYSTEM
- hormone-secreting glands
- regulate activities that require DURATION rather than speed.
- control reproductive cycles, concentration of nutrients, and the internal environment’s volume and electrolyte composition.
Skeletal systems
SUPPORT AND MOVEMENT SYSTEMS
- Provide support and protection for the soft tissues and organs.
- homeostatic regulation of Ca2+ and plasma electrolytes
- enables movement of animals
Muscular systems
SUPPORT AND MOVEMENT SYSTEMS
- Move the skeletal components to which skeletal muscles are attached
- regulate temp in animals through contractions
Circulatory systems
MAINTENANCE SYSTEMS
-transport systems that carry materials such as nutrients, O2, CO2, nitrogenous wastes, electrolytes, heat, and hormones from one part of the animal to another
Defense and immune systems
MAINTENANCE SYSTEMS
- Defend against foreign invaders and body cells that have become cancerous
- repair and replacement of injured or worn out cells.
Respiratory systems
MAINTENANCE SYSTEMS
- obtain O2 from and eliminate CO2 to the EXTERNAL ENVIRONMENT.
- important in maintaining proper pH of internal environment
Excretory systems
MAINTENANCE SYSTEMS
-removes waste products other than CO2 and excess materials (ie. water, salt, acid, electrolytes, etc)
Digestive systems
MAINTENANCE SYSTEMS
- break down dietary food into small nutrient molecules that can be absorbed into circulatory system for distribution to cells.
- Transfer water and other electrolytes from external to internal environment
- eliminates undigested food residues to external environment as feces
Reproductive systems
- Not essential for homeostasis or survival
- necessary for perpetuation of species
- consist of organs that produce gametes, organs that deliver them, and support systems for offspring (ex: yolk production and embryo/fetus development)
