Ch 39 (Exm 2) Flashcards
homeostasis
the maintenance of stable conditions in the internal environment
- to maintain homeostasis, physiological systems must be able to respond and react to changes in the environment
all actions are controlled by
nervous and endocrine systems
change things through stimulus from the external environment
reference point
set point, the normal thing
feedback information
comparing the state of the system with the reference point
error signal
any difference between set point and feedback information is off from homeostasis
responses to stimuli are going to come from
effectors: effect change in environment
to change things
must have a sensor
negative feedback
- most common
- effectors will reduce or reverse the influence of the error signal
positive feedback
- effector will amplify the response to the stimuli
feedforward information
will change the initial set point before the stimulus occurs, anticipated response I.e anxiety can cause heart rate increase etc. before the stimulus actually occurs
4 types of tissues
epithelium, connective, nervous, muscle
epithelium
- covering of body
- includes squamous, columnar and cuboidal epithelial cells
function of epithelium
secretion of stuff, provide nervous system information, create boundary,
Simple squamous epithelium
means one cell layer only. Found in capillaries that surround the alveoli and in tissues. Usually for exchanging nutrients
stratified squamous epithelium
have multiple layers. Ex. Is skin that constantly replenish
columnar epithelium
look like columns. Sometimes have cilia and secrete mucus. They line your stomach and GI tracts and respiratory tracts. The cilia help absorb nutrients or move the mucus up or down.
Cuboidal epithelium
look like cubes. They line the tubes and ducts in the body
muscle tissue
elongated cells that contract to generate force and cause movement. use most energy of the body
three types: skeletal, cardiac, smooth
skeletal muscle
conscious, responsible for locomotion
cardiac muscle
make up the heart, involuntary
smooth muscle
responsible for movement and generation of force in organs, in the Gi tract and blood vessels
involuntary
connective tissues
2 types: collagen and elastin
- dispersed populations of cells in extracellular matrix. matrix varies with type
collagen
- dominant protein in the matrix, most abundant, fibres are strong and resistant to stretch, in between bones, give organs shape
elastin
- another protein in the extracellular matrix
- can be stretched
- found in lungs and arteries
cartilage
- collagen in a flexible matrix of protein-carbs
- lines joints
- resistant to compression and support
bone
extracellular matrix hardened by deposition of calcium phosphate
adipose tissue
loose tissue that contains adipose cells
- cells store lipids, good energy source
- cushions organs
blood
cells in blood plasma
nervous tissue
made up of neutrons and glial cells
neurons
nerve impulses: encode information as electrical signals
axons: long extensions of neutrons that impulses travel over
nerve impulses will release chemical signals that bind to receptors on target cells
glial cells
provide support and protection to neurons
Q10
a measure of temperature sensitivity of chemical reactions
calculations of Q10
Q10 = RT/ RT-10
if it is not temp sensitive, it is 1
if it is 2 or 3, it means that the reaction rate doubles or triples with temp increase by 10
RT
is homeostatic temp
temperature and Q10
temp changes can disrupt physiology
- very few proteins are temp independent
animals and temp change
animals can acclimatize to seasonal temp
- enzymatic processes are slower in winter
ectotherms
animals whose body is determined by external sources of heat
endotherms
animals who can regulate body temp by producing heat metabolically or using mechanisms of heat loss
heterotherm
animal that behaves both ectoderm or endotherm
- hibernation
endotherm heat production
endotherm cells are less efficient at using energy
- loose a lot of ATP in the form of heat
- cells are more leaky to ions so must use energy to maintain concentration
major difference btw end and ectotherms
resting metabolic rates. much higher in endotherms
-
end and ectotherms in changing temp
??
lizards ectotherm behaviour
changes in body temp due to behaviour to alter heat exchange with the environment
- spend time in the burrow, basking in sun
- no metabolic process used
see graphs of temp on the slides
please
4 avenues of body temp regulation
radiation, conduction, convection, evaporation
radiation
heat transfers from warmer objects to cooler ones via exchange of radiation
conduction
heat transfers directly when objects come in contact
convection
heat transfers to a surrounding medium like air that flows over a surface
evaporation
heat transfers away from a surface when water evaporates on its
energy budget
total balance of heat production and heat exchange
Rabs
entering heat- radiation absorbed
Rout
exiting heat, radiation transmitted, convection, conduction, evaporation
metabolism is
Metabolism + R abs = Rout + convection + conduction+ evaporation
blood flow and heat
both ectotherms and endotherms control blood flow to skin
when body temp is cool, blood vessels constrict reducing blood flow to skin
when body temp is increased, blood flow increases
metabolic rate
the rate at which an animal consumes O2 and produces CO2
how do endotherms respond to changes in environment
changing metabolic rate
thermoneutral zone
narrow range of temps where the metabolic rate is low and independent of temp in endotherms
basal metabolic rate
- metabolic rate of a resting animal at a temperature in the thermoneutral zone
- Consuming just enough energy to carry out minimal body functions
• BMRs are correlated with body size and environmental temperature:
• BMRs per gram of tissue increases as animals get smaller
how to endotherms respond to cold
shiver: use contractions of skeletal muscle to consume amp and make heat
brown fat: occurs in specialized adipose tissue, has a lot of mitochondria and rich blood supply
thermogenin
protein that allows movement of protons across mitochondrial membranes rather than having to generate ATP, heat is still released
(way endotherms keep warm)
evaporation of water to dissipate heat
takes of a lot of heat
how do vertebrates use feedback info
thermostat- hypothalamus
very small
-Cooling the hypothalamus causes constriction of blood vessels and increase
in metabolic processes
- Warming of hypothalamus results in dilation of blood vessels, sweating, panting
skin registers temp change –> feedforward information that shifts the hypothalamic set point
when are set points higher
Set points are higher during wake than during sleep
Higher during active part of the day than inactive
- Set point for metabolic heat production is higher when skin is cold, lower when skin is warm
how is cold sometimes feedforward
If you go into cold directly, you won’t feel it immediately. Body can change the set point so you don’t feel as cold and get a little warmer. Does this so you don’t have an effector response all the time.
Fever
body’s set point will change to pyrogens
Pyrogens are chemicals that travel to the hypothalamus to increase the set point
Exogenous (fever)
produced by cells of the immune system in response to infection
come from outside, a foreign entity is telling body to heat up
This means body recognizes the foreign entity and doesn’t like it
Endogenous pyrogens
produced by cells of the immune system in response to infection
come from inside
fever and pyrogens
Presence of a pyrogen causes a rise in the hypothalamic set point
You shiver, cover up until you no longer feel cold…others feel your fever
Hypothermia
a state of below normal body temperature
Some animals use “regulated hypothermia” to survive periods of cold and food scarcity
Daily torpor
dropping body temp during inactive part of night or day
Hibernation
regulated hypothermia that lasts days or weeks. Drop to very low body temperature, maximizes energy conservation
