Lab 1 Flashcards
In homeostatic control (thermostat in a room), the event or factor being controlled is the
variable, X (room temperature)
variable, X (room temperature) is maintained within a narrow limit around a
set point (level or range, the temperature at which you have set the thermostat)
A ? analyzes the information received from ? and determines a response, which is carried out by ?
- control or integrating center (the thermostat)
- sensors (temperature sensors)
- effectors (furnace or air conditioner)
In the body, information travels from a ? along ? to the ?. This integrates input from other receptors with the ? and adjusts the output of the ? via an ?.
- sensor or receptor
- an afferent pathway
- control center (usually the hypothalamus or midbrain)
- set point
- effector
- efferent pathway
occurs when a change in a variable triggers a response which adjusts in the opposite direction of the initial change
negative feedback
fluctuations constantly occur above or below a set point
dynamic constancy
the average value of the range of the variable
set point
The ? of the negative feedback mechanism can be observed by measuring how much deviation from the set point occurs before a compensating response is activated. Control can be further refined by the addition of ? which have the opposite effect on the variable. Even more efficient control utilizes ?. They are usually antagonistic to each other.
- sensitivity
- antagonistic effectors
- two sensors and two effectors
the response of the effectors to any change in the variable causes an amplification of the changes. In other words, a change causes the effectors to respond in the same direction as the change.
Positive Feedback
When a person undergoes strenuous exercise or is exposed to high environmental temperatures, the body’s homeostatic mechanisms go to work. Under heat stress,? in the skin send messages through the ? to the?. This sends messages via the ? to the ? and ?.
- thermoreceptors
- afferent sensory pathways
- posterior hypothalamus (integrating center)
- efferent autonomic pathways
- sweat glands
- smooth muscles in arterioles (effectors).
occurs when strenuous exercise or high environmental temperatures cause the body’s homeostatic mechanisms to be overtaxed
Heat exhaustion
can follow heat exhaustion if the regulatory center in the hypothalamus fails due to continued high body temperature
Heat stroke
With a drop in body temperature, the ? cause a different response. The ? are constricted in the skin via the ? and sweat production is either decreased or stopped to prevent evaporative heat loss. Other behavioral responses may be used (e.g. adding more clothing, curling up) to keep core body temperature up. Collectively, these responses are referred to as ?. The ? utilizes skeletal muscles to increase body temperature by shivering.
- thermoreceptors, afferent pathways, hypothalamus, and efferent pathways
- arterioles
- sympathetic nervous system
- nonshivering thermogenesis
- efferent somatic nervous system
The ? and glucagon have an opposite effect on maintaining blood glucose levels.
antagonistic effectors insulin,
When blood glucose levels rise (after a meal) ? is released from the beta cells of the pancreatic islets.
insulin
? is released from pancreatic alpha cells in response to low blood sugar.
Glucagon
Glucagon also induces the liver (and some other cells such as muscle) to make glucose out of building blocks obtained from other nutrients found in the body (e.g. protein). This is termed ?.
gluconeogenesis
The four classes of organic molecules
carbohydrates, proteins, lipids, and nucleic acids
Each class of organic molecules is composed of a small organic subunit called a ?, which can combine to form a ?.
monomer, polymer
? involves the removal of a water molecule as monomers are bound together. ? reactions
divide polymers by breaking the chemical bonds between the monomers with the addition of a water
molecule.
Condensation synthesis, Hydrolysis
simple sugar monomers found in carbohydrates
Monosaccharides
two sugars linked together
Disaccharides
long chains of glucose molecules, forming a polymer
Polysaccharides