Intro to physiology Flashcards
Lec 2 & 3
What is physiology?
study of how the body fxns. so the physical and chemical processes of cells, tissues, organs, and organ systems that allow them to work individually and together to sustain life (by maintaining homeostasis).
What are the 11 systems in the body?
1) cardiovascular (pumps blood to cells) 2) digestive (gives bl nutrients to be taken to cells, and excretes waste) 3) respiratory (o2 goes into bl and into cells where it becomes deoxygenated co2 and goes back into bl or lymphatic vessel) 4) urinary (takes nitrogenous wastes from cells that go into bl and excrete them through urine) 5) lymphatic (takes 10% of fluid from cells) 6) musculoskeletal (mms produce mvmt) 7) skeletal (bones that form structure of body) 8) integumentary (skin and tissues that protect organs) 9) nervous (control system) 10) endocrine (control system) 11) reproductive (population, and fun)
What is homeostasis?
the ability to maintain relatively stable conditions of the internal enviro despite changes in the external enviro. so maintaining a balance. keeping things in the normal/happy range. monitoring int. and ext. changes. organ systems function together to maintain homeo. disease results if it’s not maintained
How does homeostasis keep cells alive?
cells can only survive within a narrow range of conditions, so they constantly need to be monitored, so that body conditions are maintained within physiological limits.
What are some examples of conditions controlled by homeostasis?
pH, temp, blood gases (o2 and co2), bl pressure, intracellular and extracellular fluid volumes, ions, and more.
What are the regulatory systems’ role in homeostasis?
N.S. and endo syst control all other systems. they act to maintain homeo, and permit departures from homeo in a controlled manner. ie pregnancy, sudden fright, and growth.
How is homeo regulated?
change in int eviro must be detected or anticipated. so a receptor anticipates a change in stimulus/imbalance and then send input to control systems. these systems then need to respond by sending output which is the effector, and alter the system(s) responsible for that condition.
What is an anticipatory response example?
increased resp rate at start of exercise bc mm proprioceptors (receptors) signal mvmt to NS before a change in int conditions. so anticipating that there will be a change in internal conditions.
What is an example of an anticipatory response that’s behavioural/learned?
putting on a jacket before going outside bc you’re anticipating a change in temp. so learned this through experience.
What is a feedback mechanism and what are the three components?
they’re mechanisms that respond to a change in the system. receptors, control centres, and effectors.
What is a receptor and what does it do?
sensors that monitor variables/conditions and respond to stimuli and changes in variables. so they send input to the control centres.
What are the control centres and their purpose?
N.S. and endo. syst. they integrate info and maintain setpoints/ranges by signalling to effectors. so they analyze input and decide the approp response, and send that output to the effectors.
What is a setpoint?
range of values of a variable that do not bring about a response. so the norm range/range want to be at.
What is an effector and what do they do?
create a response that will alter the vriable/condition. so they take the output from the control centres and form a response.
What is the difference btwn input and output?
input is the change that the receptors detected that triggers a response form the control centres. so the detection of departing from setpoint. output is the change triggered by the response form the control centres. so what effectors will use to get back to setpoint.
What is the cycle of feedback mechanisms?
stimulus/change in variable/condition -> receptor detects and sends this input to -> control centres which decide on response and send output to -> effectors which then brings about the response.
What is a negative feedback mechanism?
most common homeostatic control mech. ouput moves variable back to set point so in oppo direction then the input. ex. temp.; input is too high, then output brings down body temp by vasodilation and sweating.
What is a positive feedback mechanism?
not homeostatic and less common. when the output intensifies the input, so they’re moving in the same direction. ie childbirth; uterine contractions (input) are increased by release of oxytocin which increases the intensity and frequency of contractions until the endpoint which is childbirth.
What do neg feedback mechanisms do?
work to minimize changes in the value of controlled variable.
Which process allows us to adjust to either extreme heat of extreme cold?
neg feedback mechanisms. (thermoregulation)
What ends pos feedback mechanisms?
when an end point is reached. ie a blood clot plugging bv tear fully, or childbirth.
Which component of a homeostatic control mechanism carries out a response to a stimulus?
effectors. they carry out the response that the control centres gave them.
What do positive feedback mechanisms do?
the output response amplifies the original stimulus
