KINESIOL 2Y03 Final: FINAL EXAM NOTES
Anatomy 2Y03 Notes
Homeostasis
• Homeostasis: the existence and maintenance of a relatively constant environment within the body
• The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes
o Example – marathon des sables, tour de France (both are extremely difficult challenges to the body, both are
completed in extreme environments)
o The body temperature will increase during exercise alone and in order to cool down we sweat (to maintain
internal body temperature)
▪ Sweat comes from a variety of different body water sources (like blood), but too much sweat will
decrease your blood volume (if exercising for long or in hot environment) ,If blood volume starts to
decrease, blood pressure drops and without a certain blood pressure were not able to maintain adequate
cardiovascular pressure therefore in order to increase blood flow we send out signals, one is to increase
our heart rate (will also increase pressure), but this is only a temporary fix during exercise as it keeps
cycling
▪ Increase thirst sensation leads to increased water intake (replenish body)
What is normal?
• Values of variables fluctuate around the set point to establish a normal range of values
• Set point: the idea normal value of a variable or measure in your body that can also fluctuate around a normal range of
values
• What is the set point for body temperature?
o Typical is around 37 degrees Celsius (normal body temp at rest), but throughout the day there are fluctuations
around the set point
How does the body maintain homeostasis?
• The role of organ systems:
o Help otol the od’s iteal eioet
o Communication between cells, tissues and organ systems is crucial
o Nervous system and endocrine system play a large role, together they gather sensory information from internal
and external environments in order to respond and return the body to homeostasis
• Feedback systems:
Homeostasis (1.1)
• provides relative stability of the internal environment
• results from constant adjustments
• regulated by regulatory processes
• requires system interplay
Homeostasis – range of body conditions (2.1)
• changes in the internal environment can vary from minor to significant
• vary from normal limits → temporary stresses→ disruptions requiring medical intervention → disruptions incompatible
with life
Homeostasis – normal limits (2.2)
• equilibrium points can change over a narrow range, normal limits are narrow ranges on either side of the equilibrium
point
• normal limits provide guidelines for medical testing (medical testing results are compared to the narrow limit guidelines to
check if homeostasis has been disrupted)
Homeostasis- mild stresses (2.3)
• internal and external stresses disrupt homeostasis
• the od’s egulato sstes a uikl espod ad restore homeostasis when stress is mild and temporary
• shieig ould e a eaple of this as eig old auses ou’e od to shie ad the oeet esults i ath
Homeostasis – severe stresses (2.4)
• severe stress disrupts homeostasis and can cause a disease state that requires medical intervention
• if disruptions are extreme the regulation of homeostasis may fail and death occurs
Communication and regulation – body systems (3.1)
• ouiatio etee the od’s ells, tissues ad oga sstes is crucial to effectively regulate and maintain
homeostasis
• nervous system and endocrine system play important roles to complete these major tasks
• primary responsibility for communication and regulation in the body is shared by the nervous and endocrine systems
find more resources at oneclass.com
find more resources at oneclass.com
• the 2 systems work alone or together in specialized physiological processes called feedback systems to maintain
homeostasis
Feedback systems – components (4.1)
• feedback systems – or loops- ae oe of the od’s ost ipotat as of aitaiig homeostasis
• a cycle is triggered by a stimulus that alters a controlled condition
• the three components of the feedback loop are the receptor, control center and effector
Feedback systems – receptors (4.2)
• most receptors are sensory neurons (nerve cells) that monitor changes in controlled conditions
• sensory nerves communicate via electrical impulses providing input to the control center
Feedback systems – control center (4.3)
• most often in the hypothalamus (important integrating center for nervous and hormonal regulatory processes)
• sets the range of values for a controlled condition
• evaluated the input, compares it to normal values and determines actions to be taken by effectors
• communicates regulatory commands via motor nerve impulses, causing the release of neurotransmitters that bind to cell
membrane receptor proteins in target cells
• communicates regulatory commands via secreted hormones carried to target cells in the blood
Feedback systems – effectors (4.4)
• target cells receive output from the control center and effect a response that adjusts the altered controlled condition
• effectors are the cells of any body structure that receives output from the control center, and produce a response that
adjusts the altered control condition
• neurotransmitters communicate the needed adjustments to target cells in muscles or glandes
• hormones from the blood attach to cell membrane receptor proteins and act on target cells
Feedback systems- negative or positive (4.5)
• most of the body uses negative feedback systems to maintain homeostasis, called negative because they reverse the
altered controlled condition (if stimulus causes a rise in blood pressure, it will decrease it)
• negative feedback loops reverse the altered controlled condition caused by a stress or stimulus and return the body to
homeostasis
• positie feedak loops eifoe a alteed otolled oditio that does’t ou e ofte ad teiate as a esult
of a mechanism outside of the system (such as the birth of a baby)
o 3 components:
▪ receptor: monitors the value of some variable
• e.g. blood pressure – receptors will detect changes in our bp
▪ control center: establishes the set point
• usually found in the central nervous system
• e.g. brain will eeie the sigal fo eeptos ad ill deide if thee’s eough deiatio fo
normal to send a signal response to the effector
▪ effector: can change the value of the variable
• do ot sed out sigals uless thee’s a hage
o stimulus: deviation from the set point; detected by the receptor
o response: produced by the effector
o 2 types
▪ negative
• any deviation from the set point is made smaller (resisted)
• examples: regulation of blood pressure, body temperature, blood sugar levels
Introduction (stimulus 1.1)
• blood pressure determine the flow of blood to and from capillaries
• low blood pressure results in reduced blood flow
• high blood pressure can cause blood vessels to break
Baroreceptors (2.1)
• the aortic arch carries blood to the body
• the common carotids carry blood to the head
• baroreceptors measure changes in blood pressure and send nerve impulses up to the brain
• high pressure stretches artery walls
• low blood pressure cause less stretch of the walls
Cardiovascular control center (3.1)
find more resources at oneclass.com
find more resources at oneclass.com
• baroreceptors send information to the CV center in the medulla oblongata in the brain
• low blood pressure causes a slower rate of impulses sending information to the cardiovascular center in the brain
• the CV center outputs its own nerve impulses to the heart and blood vessels
Effectors (4.1)
• the heart responds to increased CV center output by beating faster and with greater strength, increasing the flow of blood
• increased (added) resistance in blood vessels also results from increased nervous stimulation as well as the secretion and
action of hormones
Return to homeostasis
• baroreceptors detect the return of normal blood pressure
• CV center adjusts its output signals to the heart and blood vessels
• Homeostasis is achieved
▪ Positive feedback
• when deviation occurs, the response is to make the deviation greater (makes value farther away
from set point)
• unusual in normal, healthy individuals, leads away from homeostasis and can result in death
• example of harmful positive feedback: after hemorrhage, blood pressure drops and the hearts
ability to pump blood decreases
• example of normal positive feedback: childbirth
Introduction (stimulus) 1.1
• labor during and preceding childbirth is the result of a positive feedback loop (intensifies controlled condition)
• the cycle begins when the baby enters the cervix
Stretch receptors (2.1)
• the cervix stretches or dilates as labor begins
• pressure sensitive receptor cells in the cervix detect the stretch
• these receptors send nerve impulses to the brain
Hypothalamus – control center (3.1)
• the input from the nerves in the cervix go to neurosecretory cells in the hypothalamus of the brain
• the hormone oxytocin is released into the capillaries of the pituitary gland
• the blood then carries the hormone to the uterine tissue
Effector – uterine contractions (4.1)
• oxytocin causes the smooth muscle tissue of the uterine wall to contract more forcefully
• the cervix stretches still more and sends more nerve impulses to the hypothalamus
Repeating cycle – no return to homeostasis (5.1)
• the feedback cycle repeats with greater speed and intensity until the cervix is fully dilated and the baby is born
• after the baby is born the positive feedback loop ceases
Is B.P during exercise non-homeostatic?
• When you exercise BP increases, as intensity increases there are larger and larger increases in pressure
• Depending on the situation the body is in at the time the set point can increase (the normal range or set point in the body
can change for a short period of time), range and set point can actually increase because blood pressure is related to
blood flow and at certain times we need more blood flow
• During exercise we need an increase delivery of oxygen, fuels and blood flow therefore the range and set point
compensate by creating their own normal ranges (when the body has greater demands)
• Body adapts to our external and internal circumstances
Loss of homeostasis
• consequences of homeostasis disruption?
o Disease state
▪ E.g. blood glucose – if leels ae’t aitaied i the od at a egula leel ou wind up with diabetes
and eventually can lead to death
▪ E.g. twins- one grows much more than the other (due to a tumor on the pituitary gland – loss of
homeostasis related to a growth hormone released by the pituitary gland) resulted in disease state as
hoeostasis as’t ale to estit goth hooe fo oe eatig
o Death
Terminology and the Body Plan
Chapter 1: Terminology and the Body Plan
Overview of anatomy and physiology
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Increase thirst sensation leads to increased water intake (replenish body) Homeostasis (1. 1: provides relative stability of the internal environment results from constant adjustments regulated by regulatory processes requires system interplay. Homeostasis range of body conditions (2. 1) changes in the internal environment can vary from minor to significant: vary from normal limits temporary stresses disruptions requiring medical intervention disruptions incompatible with life. Homeostasis severe stresses (2. 4) severe stress disrupts homeostasis and can cause a disease state that requires medical intervention if disruptions are extreme the regulation of homeostasis may fail and death occurs. Feedback systems receptors (4. 2: most receptors are sensory neurons (nerve cells) that monitor changes in controlled conditions sensory nerves communicate via electrical impulses providing input to the control center. Introduction (stimulus 1. 1: blood pressure determine the flow of blood to and from capillaries, high blood pressure can cause blood vessels to break low blood pressure results in reduced blood flow.
