Lesson 1: Homeostasis Flashcards
we start life as a single cell, how many do we end up with?
10^14 all with different structures and functions and they work together over an organism to maintain life
why do organ systems work the way they do?
in an attempt to maintain an optimal environment for internal cellular function
what is homeostasis?
a relatively stable condition of extracellular fluid that results from regulatory system actions
- all of the fluid and substance that surrounds the extracellular fluid of the body
- the ability of a cell or organism to regulate its internal conditions
it is the condition of what that allows for an optimal cell function?
homeostasis
we need to maintain ___________ and ___________ ____________ in the face of changing conditions.
maintain function and internal environment
which organismal level do we talk about most in physiology II?
the body system level (ex. the digestive system)
what is the goal for the human body?
make sure the conditions are right for the body system level
to coordinate a response for homeostasis, what needs to be integrated?
multiple systems need to be integrated for a response of homeostasis
ex. its not just the lungs that coordinate us holding our breath
our _____ make up ________ ______ which maintain _________ which is essential for the survival of _______.
cells, body systems, homeostasis, cells
what are factors that are homeostatically regulated?
- concentration of nutrient molecules (sugars, fats)
- concentration of O2 and CO2 (especially in respiration)
- concentration of waste products (pyruvate, lactate)
- pH (acidity, basic)
- concentration of water, salt and other electrolytes
- blood plasma volume and pressure
- temperature
does an acidic cell function properly?
no
what pH do we want cells to be?
7.4 (right in the middle)
what do we need in order to coordinate responses of different organs?
we need a feedback system
what does a feedback system consist of?
- sensory system
- relay station
- response system
what are feedback systems specific to?
organ/tissue and environment/stimulus specific
- however, they work together to ensure that a response is made to maintain homeostasis
most of the systems, molecules, substances exist at?
set points
(ex. body temperature, water levels, oxygen concentration in blood)
in the negative feedback system, what does the response counteract?
the initial stimulus
- when you heat up, you sweat to cool off
which feedback system is most common?
negative
which levels does the negative feedback system occur at?
the whole body, organ, tissue and cell levels
flowchart of negative feedback cycle?
variable with a set point –> sensor –> integrator –> effector (adjusts to oppose change in set variable) –> turns off
what does the response of the positive feedback regulation do?
adds to the initial stimulus (further from homeostasis and potentially toward death)
- less common form of feedback
what is an example of positive feedback regulation?
uterine contractions become increasingly stronger until the birth of the baby
- also allergic reactions
what do we get feedback from in our body?
physiological sensors in the body directly related to that system
what is feedforward regulation?
- prime the system for challenges to come
you’re feeding forward regulation from other parts of the brain - ex. we breath but do not think about it. if our brain feeds forward (we now consciously breath, our breathing will change… probably get deeper… more voluntary)
- ex. salivating
- ex. when we intake food, we digest it. but when we have no food and we just think about it, our stomach starts to churn
what are the generalizations in homeostatic control?
- Stability achieved by balancing inputs and outputs.
- Need some form of sensory mechanism to detect
deviations from set points. - Set points are maintained over a small range.
- Set points can be reset (up or down).
- Heirarchy of control: some things are more important
than others.
