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Name the organ systems
- nervous
- endocrine
- muscle
- skeletal
- reproductive
- digestive
- respiratory
- cardiovascular
- excretory
- lymphatic
- immune
- skin
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Four basic tissue types
- epithelial
- connective
- muscle
- nerveous
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Epithelial tissue
- sheets of densley packed and tightly connected cells that cover inner and outer body surfaces
- some epithelial tissues have specialized functions: secretion, cilia, taste, smell, protective, absorptive, transport, boundaries
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Muscle Tissue
- made of elongated cells capable of contracting and causing movement by sliding of protein filaments past each other
- most abundant tissues in the body
- three types: skeletal, cardiac, smooth
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skeletal muscle
responsible for locomotion and other body movements (e.g. breathing, shivering
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cardiac muscle
makes up the heart and is responsible for the heartbeat and blood flow
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smooth muscle
involved in movement and generation of forces in internal organs (e.g. gut, blood vessels)
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Neural tissue
comosed of neurons and glial cells
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neurons
- extremely diverse in size and form
- function by generating electrochemical signals in the form of nerve impulses, these impulses are conducted via long extensions to other parts of the body where they communicate (often via chemicals realesed at synapses) with other neurons, muscle cells, or secretory cells to contral activities of organ systems
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glial cells
provide a number of support functions for neurons
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connective tissue
- consists of cells embedded in an extracellular matrix that they secrete
- an important component of the extracellular matrix is protein fibers (e.g. collagen, elastin, cartilage)
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collagen
- most common protein fiber in connective tissue matrix
- very strong fiber
- very dense in tough tendons and ligaments
- forms netlike framework for organs to give shape and strength
- it has low density as loose strands whin it fills in between organs
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elastin
- protein fibers that can be stretched to several times its resting length and then recoil
- tissues that are regularly stretched, such as lung walls and artery walls have abundant elastin
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cartilage
a network of collagen fibers embedded in a flexible matrix of proteins and carbs, chondrocytes secrete matrix
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extracellular matrix of bone
hardened by the deposition of calcium phosphate
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Adipose tissue
- a connective tissue that forms and stores droplets of lipids
- adipose tissue serves as a fuel reserve and as a cushion to protect internal organs. Layers of adipose tissue under the skin help insulate against heat loss
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blood
- a connective tissue made up of cells in a fluid extracellular matrix called blood plasma
- plasma also contains an abundance of proteins
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organ
a discrete structure that carries out a specific function in the body
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organ system
a group of organs that function together
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conditions that can vary in TERRESTRIAL environments
- temp
- gas content
- humidity
- water
- mineral availability
- light
- etc.
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conditions that can vary in AQUATIC environments
- temp
- gas content
- salinity
- pH
- hydrostatic pressure
- light
- etc.
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eury-
spp. that are extremely tolerant of a wide range for a particular parameter
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steno-
spp. that are not very tolerant of range of a particular parameter
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conformers (poikilo-)
species that match their internal environment (as regards to a particular parameter) to the external conditions
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regulators (homeo-)
species that control their internal environment to a particular set-point for a given parameter even though the external environment varie
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homeostasis
the maintenance of constant conditions in the internal environment of an organism
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feedback information
signals any discrepancy between the set point and the conditions present
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set point
the particular desired conditoin level
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error signal
the difference between the set point and the feedback information
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Negative feedback system
control center compares magnitude of variable to the set point value, integrates the information, and controls the response of the effector system(s) which control the magnitude of the variables bringing it back to set-point
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effectors
- cells, tissues and organs that respon to commans from regulatory systems
- called controlled systems
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regulatory systems
obtain, process, and integrate information, then issue commands to controlled systems, which effect change
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negative feedback
imformation that couses a regulatory system to reduce or reverse a process
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positive feedback
information that tells a regulatory system to amplify a response
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feedforward
information signals the system to change the setpoint. May anticipate change
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What is the most important parameter controlling the ranges of organisms?
temperature
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affect of T on organisms
high temp makes processes go faster (as long as T isn't high enough to kill the organism)
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Q10
- the rate of reaction at a particular temperature (RT) divided by the rate of the reaction at a temperature 10ºC lower (RT-10)
- most biological Q10 values are between 2 and 3
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metabolic compensation
a biochemical adjustment of enzyme systems to counter the effects of temperature
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acclimatization
natural adaption, ex. metabolic compensation
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homeotherms
maintain a constant body temperature, freeing them from Q10 effects
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Poikilotherms
body temperature changes when environmental temperature changes
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heterothem
animals that regulate body temperature at a constant leve some of the time
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temporal heterothermy
hibernating animals
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spatial heterothermy
keep core T constant but allow the periphery to vary if necessary (most homeotherms)
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Ectotherms
(most animals aside from mammals and birds) depend on external heat sources to maintain body temperature
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endotherms
(all mammals and birds) regulate body temp by (1) generating metabolic heat and (2) preventing (controling) heat loss
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metabolic rates in response to temperature
endotherms vs ectotherms
- ectotherms: metabolism decreases as air temperature decreases
- endotherm: metabolic rate increases as temperature decreases
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homeothermy
Heat Loss = Heat gain
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modes of heat loss
conduction convection, radiation, evaporation
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modes of heat gain
conduction, convection, radiation, metabolism
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Conduction
- takes place between two solids in contact with one another. Direct transfer of the kinetic energy of molecular motion
- Rate depends on: temp gradient between the two (T1-T2); surface area in contact (A); coefficient of thermal conductivity (K, expression for the ease of heat flow in a material)
Rate = KA(T1-T2)
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Convection
- takes place between a solid and a fluid, or between two fluids
- factors are same as conduction (K, T gradient, A)
- K is greater for water than for air
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Radiation
- any object above absolute zero loses heat via radiation
- the intensity varies directly with the temperature of the radiating surface
- the wavelength varies inversely with surface T
- objects at physiological T's emit mostly in the middle and long infared
- skin color doesnt matter much for the radiating surface but does matter for how much solar radiation is absorbed
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general mechanisms for control of body temperature
- metabolic rate
- evaporation
- insulation (conduction, convection, radiation)
- vascular control (conduction, convection, radiation)
- behavior (postural changes, burows, huddling, choice of microhabitat)
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mechanisms for temp control WITH significant energy costs
- metabolism
- evaporation
- some behaviors
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mechanisms for temp control WITHOUT significant energetic costs
- insulation
- vascular changes
- some behaviors
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TNZ
- thermal neutral zone
- within this zone the animal uses non-energetically costly meant to control TB
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LCT
- lower critical temperature
- animal must increase metabolism to generate more heat
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UCT
- upper critical temperature
- the animal must use evaporative cooling to maintain TB constant
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adaptations to cold
- decrease conductive, convective and radiation heat loss: insulation, blood flow, behavior, body shape
- decrease evaporative heat loss
- increase metabolic rate
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time scales
- evolutionary
- seasonal
- immediate
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insulation
- all time scales
- fur, feathers, blubber
- fur and feathers trap air (lo "K")
- insulation lowers conductive, convective and radiative heat loss
- better insulation lowers the LCT and decreases the slope of the MR vs TA line
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Vascular regulation of TB
- peripheral vasoconstriction and dilation
- heat exchangers
- heat sinks (thermal windows)
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Hunting response
blood flow to limbs is periodically opened and closed to control heat loss, but not allow hand T to drop too far
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Countercurrent heat exchangers
veins run next to arteries so that the blood going to the core is not as cold and not as much heat is lost to the environment
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heat sinks
lots of blood vessels near the skin
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behavioral adaptions to cold
- postural (decrease SA/ Volume)
- huddling
- microhabitat selection: out of wind, sunny slope, burrow, subnivean (under snow)
- burrowing in snow
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increase metabolic rate (heat production) in response to cold
- increase activity
- shivering
- non-shivering thermogenesis: brown adipose tissue, other (thyroid hormone, etc.)
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brown adipose tissue (brown fat)
- sole function is heat production
- brown fat is commonly found in newborns, animals that hibernate, and many active mammals in winter
- brown fat cells have the protein thermogenin
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thermogenin
protein which uncouples proton movement from ATP production, so that no ATP produced, but heat is released
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Adjustments to high TB and TA
- increase heat loss via conduction, convection and radiation: insulation changes, vascular, behavioral
- metabolic rate
- evaporative water loss
- heat storage
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evaporative cooling
- the major adaptation to hi TA and/or TB
- problems: costs energy, water loss, loss of effectiveness at high humidity
- sweating, panting
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heat storage
- temporary increase in body T
- heat exchangers cool blood perfusing the brain
- found in numerous species especially those capable of long term running, not present in cheetah
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behavioral thermoregulation
- some ectotherms can use behavior to regulate body temperature in the natural environment
- behaviors include basking in the sun, seeking shade, burrowing, or orienting the body with respect to the sun
- endotherms also use behavioral thermoregulation. Most animals select the best thermal environment whenever possible, for example by seeking shade, breezes, etc.
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marine iguana thermoregulation
color change: darker to increase radiation gain, lighter to decrease radiation gain
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advantages of warm fish
- increased swimming power and speed
- faster digestion and absorption (permits smaller stomach, more muscle mass per body volume)
- retina, visual predator
- brain, faster neural processing
- allows range expansion to cooler waters
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hypothalamus
- the vertebrate thermostat
- the temp of the hypothalamus itself is the major source of feedback information in many species
- negative feedback system
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fever
- a rise in body temperature in response to pyrogens, they cause a rise in the hypothalmic set point.
- immune system cells called macrophages attack pyrogens and release interleukins, chemicals that signal other cells and trigger other responses, including release of protaglandins
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exogenous pyrogens
come from foreign substances such as invading bacteria or viruses
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endogenous pyrogens
produced by cells of the immune system
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interleukins
raise hypothalamic set point
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adaptive hypothermia
- animals can save energy by turning down the thermostat below normal
- many animals use regulated hypothermia as a means of surviving periods of cold and food scarcity
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hibernation
regulated hypothermia lasting days or weeks with drops with drops to very low temperatures
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daily torpor
adaptive hypothermia that can drop body temp 10-20ºC and save considerable metabolic energy (hummingbirds)
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