exam 2 Flashcards
what is a special feature of plant’s architecture?
they are dynamic- always growing
what does a seed contain?
embryo (root and shoot apical meristems, 1-2 cotyledons, stored food in endosperm or cotyledons)
when does seed growth resume?
during germination
how do seeds build their body?
in response to internal and external cues
what is the first trigger for germination?
an external cue of receiving water (universal- all plants need water to grow)
what are some additional cues that some plants need for germination?
light, fire, mechanical breakdown of the seed coat (scarification), or chilling (stratification)
what is imbibition?
when the seed takes up water
what does imbibition to?
activates the embryo and begins germination
what hormone does the plant embryo produce?
gibberellic acid (or GA)
what does the hormone GA (or gibberellic acid) do?
it diffuses throughout the seed and targets the aleurone- this triggers the release of alpha-amylase (an enzyme)
what does the enzyme alpha-amylase do?
triggers the release of sugars from the endosperm (where starch is stored) and they go to the embryo (and seedling growth)
how does GA cause aleurone cells to make alpha-amylase?
transcription factor binds to the promoter and kept in check by the repressor; the GA bings to the receptor and enters the nucleus; a complex removes repressor, and alpha-amylase is produced
what are main roles of GA in growth and development?
stem elongation, stimulation of fruit enlargement, and germination
what does GA counteract the effects of?
ABA (abscisic acid)
what do plant hormones do?
regulate growth, coordinate physiological processes, mediate environmental responses, excitation
True or False: Plant hormones can only work in the places they are produced.
False- they can work where they are formed as well as in other tissues and organs
what does a hormones’ effect depend on?
concentration, location, and presence and concentration of other hormones
who discovered the hormone auxin?
Charles Darwin and his son
where is auxin produced?
the plant’s tip
how does auxin move through a plant?
rootward to induce stem growth
where is indole acetic acid (IAA) produced?
terminal bud
what does IAA suppress?
axillary buds closest to tip (remove terminal bud, branches grow out)
what promotes branch growth?
cytokinin
what does the hormone cytokinin do?
shoot induction, axillary bud outgrowth, prevention of leaf death
what does the hormone abscisic acid do?
water stress response, stomata closing, dormancy (in seeds and winter buds)
what is abscisic acid similar to?
carotenoids
what is cytokinin similar to?
adenine
what does the hormone ethylene do?
fruit ripening, leaf death (breakdown of chlorophyll), and lead abscission (leaf falling off)
which plant hormone is a gas?
ethylene
what is an external cue for plants?
light
how is energy for photosynthesis converted to chemical energy?
absorption by chlorophyll
how do plants set their internal clock?
by using light
what is always required for seed germination?
light
what does blue light trigger?
phototropism
what is phototropin?
a pigment in plasma membrane that absorbs blue light, goes through a conformational change, and exposes an active kinase site; also mediates stomate opening in response to blue light
how can you determine what wavelength of light is most effective in driving a biological process?
expose plant to light of different wavelengths and observe its response
what is responsible for red light response in plants?
phytochrome
what does phytochrome do?
seed germination and control of flowering
what are the 2 interconvertible states of phytochrome?
Pr (inactive), Pfr (active)
what is the action of phytochrome?
Pfr (active) can enter nucleus- exposed kinase phosphorylates itself, other targets, and activates transcription factors; leads to GA biosynthesis, which triggers alpha-amylase production
what activates the genes for biosynthesis of GA?
Pfr (active phytochrome)
what does the first division in embryogenesis result in?
terminal cell and basal cell
what does the terminal cell turn into?
embryo
what does the basal cell turn into?
suspensor
what is the suspensor in a plant embryo?
conduit for nutrients
what are the 4 steps in embryogenesis?
embryo (globular stage) -> morphogenesis (layers form, apical meristems organized) -> growth (storage molecules accumulate) -> prepare for physiological independence
what is a plant’s ovule?
a seed
what does the ovule in a plant contain?
embryo and endosperm
what is a seed coat?
covering on the ovule
what is a plant’s ovary?
a fruit (ripened, mature ovary)
how does fruit develop?
as ovules develop into seeds, changes occur in ovary wall
how do fruits promote the dispersal of seeds?
fleshy fruits “pay” animals to move the seed, dry fruits use mechanical dispersal
what is dormancy?
has a very slow metabolism, and waits for good growing conditions (down to 10% water)
in an angiosperm, what is the male gametophyte?
pollen
in an angiosperm, what is the female gametophyte?
embryo sac
what are the components of a flower?
sepals, petals, stamen, pistils
what are sepals?
leaflike, protect flower bud while developing
what are petals?
attract pollinators and sometimes have sacs of sugars
what are stamen?
produces pollen
what is a pistil?
the most complex of the floral organs, usually at the very center and bears ovules
how are floral organs arranged?
in whorls
what are the steps of the angiosperm life cycle?
meiosis, gametophyte development, pollination, fertilization, embryo development, and seed formation
where are the cells located that undergo meiosis?
inside the ovule and anther
where are microspores?
anthers
how do microspores develop into pollen?
a diploid cell undergoes meiosis and produces 4 haploid cells, and all 4 develop into pollen
what does one pollen contain?
sperm and a tube nucleus
where are megaspores?
ovule
how do megaspores develop into an embryo sac?
a diploid cell undergoes meiosis and forms 4 haploid cells, and only 1 survives to develop into the sac
how many rounds of meiosis occur in developing the embryo sac?
3 rounds producing 7 cells
what are the components of the embryo sac?
eggs and the central cell (containing 2 nuclei)
what does the central cell turn into when pollinated?
endosperm
what is pollination?
transfer of pollen from anther to the stigma of the pistil
what are the 2 types of pollination?
targeted and non-targeted
what is targeted pollination?
less pollen is needed, but an animal must be attracted to flower
what type of pollination is used by 3/4 of angiosperms?
targeted pollination
what is non-targeted pollination?
copious amounts of pollen is needed, and it is transferred via wind and water
how does pollen growth occur?
it lands on a compatible stigma and forms a pollen tube to carry nonmotile sperm to the ovule
how is the growth of the pollen tube directed?
by gene expression in the tube nucleus
most flowers are hermaphroditic, meaning what?
they contain both sexes, meaning they can self-pollinate
what is a downside to self-pollination?
inbreeding, as it can lead to an accumulation of genetic defects
what is outcrossing?
process that prevents self-pollination
how do plants conduct outcrossing?
animal pollination, different timing of pistil and stamen maturity, unisexual flowers, and self-incompatibility
what is monoecy?
both male and female flowers on one plant
what is dioecy?
separate male and female plants
what is self-incompatibility?
if the pollen is too similar to the ovule DNA, fertilization is blocked
if pollen is recognized at stigma as being compatible, what happens?
it forms a pollen tube, grows through the style, and reaches ovules to release sperm into embryo sac and then germinates
what is double fertilization?
2 sperm are in each pollen- one fuses with the egg forming a zygote, and one fuses with the central cell forming the endosperm
what is the beginning of the new sporophyte generation?
zygote –> embryo
what ploidy is the endosperm?
triploid (1N from sperm, 1N + 1N from 2 polar nuclei in central cell)
what plants experience double fertilization?
only angiosperms
what is the endosperm?
nutritive tissue that persists until germination unless consumed earlier
what is embryogenesis in plants?
an early period when a plant is contained within and is nutritionally dependent on maternal tissues
what type of growth occurs first in plants?
vegetative
the SAM forms ______ organs, then _____ organs.
vegetative; reproductive
True or False: Flowering influences how long a plant lives
True
what are perennial plants?
plants that flower year after year
what are annual plants?
plants that complete their life cycle in one year
what are biennial plants?
plants that complete their life cycle in two years
what do biennials require before they flower?
a chilling period
what makes the SAM switch from vegetative to reproductive growth?
internal cues (in all plants) and external cues (in many plants)
what are internal cues that trigger the switch to reproductive growth?
maturation of “phase change”
what are external cues that trigger the switch to reproductive growth?
day length (photoperiodism) and chilling (vernalization)
what is characteristic of a plant phase change?
the seed germinates and it is incapable of flowering (juvenile); after some period of growth it gains the ability to flower (adult)
what are advantages of the juvenile phase?
flowering is expensive, the flower could build up resources needed to successfully complete flowering and seed production
what are characteristics of the photoperiod in plant reproductive growth?
seasonal variation in flower production, temperature and water variability, and day length
what are short day plants?
they flower when days are short
what are long day plants?
they flower under long days
that are day neutral plants?
day length does not affect flowering time
what is the critical daylength?
a threshold that must be reached (days must be shorter than it for short day plants to flower, and longer than it for long day plants to flower); differs based on species
what organ perceives photoperiod?
the leaves
what are general characteristics of an animal?
multicellularity, heterotrophic metabolism, internal digestion, movement, nervous systems, lack cell walls, specialized cell junctions, conserved HOX genes
what do animals need to survive?
eat nutrients, take in oxygen, expel wastes, protect themselves, grow, reproduce, etc.
what is the closest outgroup of all animals?
colony of choanoflagellate protists
what are components of animal body plans?
symmetry, digestive system, coelom (body cavity), segmentation, appendages, and a nervous system
what are the 3 types of symmetry?
spherical, radial, and bilateral
what is spherical symmetry?
there is a single point from which any plant that bisects it results in similar halves (no apparent top/bottom)
what is radial/bilateral symmetry?
there is an anterior/posterior (anterior end typically the mouth)
what are 3 characteristics of bilateral symmetry?
true dorsal/ventral, right/left, and greater mobility on land
what are the 2 types of digestive systems?
sac design and tube
what is a sac design digestive system?
only one opening for both eating food and waste excretion; circulation, gas exchange, hydrostatic skeleton
what do sac design digestive systems lack?
specializations for ingestion/regurgitation, and organs for specialized digestion/absorption
what do organisms with sac digestive systems look like?
they remain small and thin
what is a tube digestive system?
a gut and 2 openings: mouth (eating) and anus (excreting)
what else is the tube digestive system used for other than digestion?
gas exchange across gut
what are tube digestive systems associated with, size-wise?
more complex forms and greater size and thickness
what is a coelom?
a body cavity
what are acoelomates?
no coelom (filled with masses of cells) and often lack complex organs; move by beating cilia
acoelomates sometimes refers only to _____blastic organisms, but often used for _____blastic organisms too.
triploblastic; diploblastic
what are pseudocoelomates?
have an interior sterile cavity that is not completely enclosed by the mesoderm; cavity is fluid-filled
why do we care what an organism has in their body cavity?
movement
what does segmentation allow for?
specialization of body regions that help changes in body shape
changes in segmentation can often result from what?
changes in the expression of Hox genes
what allowed the radiation of arthropods?
changes in segmentation
what are types of appendages?
feet, hands, and antennae
what does the nervous system do?
it allows for the coordination of movement and processes sensory inputs
what is a nerve net?
no central processing center, but can sense, relay, and react
what is a simple “brain”?
ganglia at the head end for integration and more complex actions
what is adherence of cells?
cells in an animal are arranged into tissues (cells must be able to stick to each other and to the extracellular matrix for tissues to be successful
what evolved to allow cells to “stick”?
cell adhesion molecules (CAMs) and integrins
what do integrins do?
attach cell cytoskeleton to collagen and other proteins in the extracellular matrix; it is often rearranged during cellular movement
what happens when integrin’s 3D structure changes?
it cannot bind to the extracellular matrix- the cell detaches
what are 3 types of animal cell junctions?
tight junctions, desmosomes, gap junctions
what are tight junctions?
prevent materials in extracellular matrix from leaking between the cells and proteins in the plasma membranes from migrating to other side of cell
what are desmosomes?
binds cells tightly but does not prevent movement of material between cells or within the cells’ membranes
what are gap junctions?
pores which flow adjacent cells to exchange material
what are the 4 animal tissue types?
epithelial, muscle, connective, nervous
what does epithelial tissue do?
barriers, exchange (secretion/absorption), storage, communication (chemical signal), reproduction, coordination
what are the 3 types of muscle?
skeletal, cardiac, smooth
what is characteristic of skeletal muscle?
multinucleate, striated, voluntary, fast
what is characteristic of cardiac muscle?
cells coordinated by gap junctions, some striations, myogenic, and rhythmic
what is characteristic of smooth muscle?
some tissues coordinated by gap junctions, while others not; not striated, many regulated unconsciously by enteric nervous system, involuntary and slow
what types of muscle is involuntary?
cardiac and smooth
what is connective tissue?
typically has fewer cells and more solid/liquid extracellular matrix, often with protein fibers like collagen and elastin in matrix
what are the types of connective tissue?
adipose (fat), cartilage, bone, and blood
what do neurons do?
fast electrochemical communication, sensory and communication
what are organs?
2+ different tissue types arranged spatially to perform a particular function or a particular set of functions
what is an organ system?
individual organs are usually part of a system that works together for a particular function
what is cephalization?
concentration of sensory organs and nervous tissues at the anterior end
why is an organisms motion important?
finding a mate, acquiring food, avoid predators, finding a suitable habitat
what was the major split in primate phylogeny 90 million years ago?
wet nosed and dry nosed primates
what was the split in primate phylogeny 35 million years ago?
apes and old world monkeys
when did humans split from orangutans?
~22 million years ago
what is characteristic of hominin phylogeny?
bipedal locomotion (the ability to walk on 2 legs)
what is characteristic of a bipedal primate?
a larger bicondylar angle
what do muscles do?
they interact to develop forces to move (they are the basis for behaviors)
what makes up ~1/2 of our body mass?
muscles
what are skeletal muscles?
throughout the body; muscles attached by tendons to bones, packed with actin and myosin
what are cardiac muscles?
in the heart; shorter muscle cells that are branched and in an interlinked network
what are smooth muscles?
in excretory system and blood vessels; loose network of actin and myosin (no bundles)
what is the function of skeletal muscle?
locomotion- movement of body parts
what is the function of cardiac muscle?
pumping blood within circulatory system
what is the function of smooth muscle?
movement of internal organs
what is a contraction?
development of force in a muscle (not always shortening)
what is the sliding-filament theory?
during contraction, small filaments seem to slide past each other
what is the structure of a skeletal muscle
clusters of myofibrils make up a muscle fiber, and clusters of muscle fibers make up a muscle
what is the z line in a muscle?
the ends of each sarcomere
what is the H zone?
the area between the actin and myosin filaments (contains the M line)
what is the A band?
the entire length of myosin in one sarcomere
what is the I band?
the area between the myosin filaments (contains the Z line)
what is a muscle fiber?
a muscle cell
what is actin?
a contractile protein in a muscle fiber; filaments are organized and thin
what is myosin in the muscle?
a contractile protein in a muscle fiber; filaments are organized and thick
what are myofibrils?
long, longitudinally oriented internal component of a muscle fiber made of actin and myosin
what is a sarcomere?
contractile unit of muscle cells; repeating units of myofibril
what is titin?
molecules of a protein that hold together the thick myosin filaments and returns the sarcomere to shorter length after stretching
what is tropomyosin?
protein that twists around each actin chain that controls interactions between actin and myosin; blocks or unblocks myosin-binding sites
what is troponin?
protein molecules that are attached to tropomyosin that help control position of tropomyosin; plays a role in controlling actin and myosin
what are cross-bridges in muscles?
bridge-like links between actin and myosin filaments, connected by myosin heads
what does it mean that a skeletal muscle fiber is “innervated”?
a nerve provides it a neural input
what is a neuromuscular junction?
a synapse where a motor neuron axon makes contact with a muscle fiber
what is excitation?
when a nerve impulse arrives at a neuromuscular junction and initiates an action potential
what is excitation-contraction coupling?
a process where electrical excitation of membrane leads to contractile activity by proteins
what is a transverse tubule (T tubule)?
indentations of the cell membrane at regular intervals over the surface of the muscle cell that conduct electrical excitation into the cell’s interior
what is the sarcoplasmic reticulum?
endoplasmic reticulum of a muscle cell that is used for Ca2+ storage and release
how is a muscle contraction conducted?
Ca2+ is released from sarcoplasmic reticulum, which binds troponin and exposes myosin-binding sites on actin, allowing myosin to bind to actin and a power stroke begins
after a power stroke, how does a muscle contraction end?
ATP binds to the myosin head which unbinds it from the actin, and then the ATP is hydrolyzed and releases energy from myosin
what is the endoskeleton?
skeleton inside other tissues
what is the exoskeleton?
skeleton encases the rest of the body
what is bone?
made of extracellular matrix of collagen crystals among them
what is cartilage?
a flexible skeletal tissue that gives flexibility
what are joints?
the place where bones and muscles work together
what are tendons?
flexible connective tissue that attach muscles to bones
what is an antagonistic pair?
muscles that work together in opposite actions (one contracts, the other relaxes)
in a fish, where are the swimming muscles located?
the middle of the body, but they connect to the tail via tendons so only the tail moves during swimming
what are slow oxidative cells in fish?
slow-twitch cells that are red
what are fast glycolytic cells in fish?
fast-twitch cells that are white
how are exoskeleton muscles different from endoskeletal muscles?
they pull on the interior surface (on the apodeme, which is a part of exoskeleton that projects inside of the body in which muscles attach to)
what is a hydrostatic skeleton?
when a part or the whole body can become stiff like a skeleton due to a high fluid pressure inside
what is power, in relation to muscles?
the rate at which work is done
what is an oxidative system?
production of ATP by aerobic metabolism ramps up in the first minute and can be indefinitely sustained (citric acid cycle and e- transport)
what is a glycolytic system?
anaerobic glycolysis accelerates its synthesis of ATP to its peak rate within seconds, but is self limiting
what is an immediate system?
performed ATP is immediately available but quickly exhausted
what is endurance exercise?
steady, long-duration exercise
what is resistance exercise?
generates large forces in a few repetitions of movement in a short time
what type of muscle cells are more common in a long distance runner?
slow oxidative cells
what type of muscle cells are more common in a sprinter?
fast glycolytic cell
what are slow-twitch fibers better adapted for?
sustained aerobic activity
what are fast-twitch fibers better adapted for?
generating maximum tension quickly, but also fatiguing quickly
what type of muscle cell has a lot of mitochondria?
slow-twitch fiber
what type of muscle cell has few mitochondria?
fast-twitch fiber
in which type of muscle fiber is partial contraction possible?
slow-twitch fiber
what is the source of ATP in fast-twitch fibers?
fermentation
what is the source of ATP in slow-twitch fibers?
aerobic respiration
how much does genetics explain the difference in muscle performance?
2-3%
what is involuntary movement?
contraction and relaxation of internal muscles
how many nuclei are in one skeletal muscle fiber?
many
how many nuclei are in one cardiac muscle fiber?
one
True or False: Cardiac muscle is not striated.
False- actin and myosin filaments are arranged in patterns in sarcomeres
what are intercalated discs?
the location where two cardiac muscle cells are connected (gap junctions)
what is the general shape of one smooth muscle cell?
spindle-shaped
how many nuclei are in one smooth muscle fiber?
one
are there striations in smooth muscle?
no (actin and myosin aren’t in the same pattern)
what controls smooth muscle?
the autonomic nervous system
what are asynchronous flight muscles?
each excitation causes many contractions in invertebrate muscles
what is a catch muscle?
adductor muscles able to sustain contraction forces that close the 2 sides of the shell together in invertebrates (ex: clams)
where is most of the water in mammals?
inside cells
what is the purpose of extracellular fluid?
gives cells nutrients and removes cellular wastes
what is the definition of homeostasis?
the stability of the internal environment of an individual, such as a constant body temp and the physiological or behavioral feedback responses that maintain that stability
what is Walter Cannon’s definition of homeostasis?
the coordinated physiological processes which maintain most of the constant states in the organism
what are 2 general approaches of homeostasis?
conformation and regulation
how is heat exchange regulated in the skin?
blood vessels constrict or dilate depending on the temperature
what happens to blood vessels near the surface when it is too cold?
they constrict
what happens to blood vessels near the surface when it is too hot?
they dilate
what are a few parameters of homeostasis?
thermoregulation*, pH, blood glucose, behavioral feedback responses, [O2], [CO2], [Na+], blood pressure, heartbeat, body fluids, etc.
why is homeostasis important for an organism?
organisms need to maintain stable environments inside because its likely that they live in a different type of environment, requiring some work or energy (or physical mechanism) to keep stability
why is thermoregulation important?
temperature affects rates of enzyme catalyzed reactions, and effects of these reactions vary so coordinating the metabolism at different temps is challenging
what is the Q10 temperature coefficient?
a measure of sensitivity of a reaction or physiological process to a change in temp (within a limited range)
what is a homeotherm?
an animal that keeps a steady internal body temperature
what are examples of homeotherms?
birds and mammals
what types of animals are regulators (in terms of temp)?
regulators
what are poikilotherms?
animals that vary their body temperature along with the environment
what are examples of poikilotherms?
frogs, lizards, fish (most aquatic animals)
what types of animals are conformers (in terms of temp)?
poikilotherms
what type of animal has a higher metabolic rate, no matter the external temperature?
homeotherms
which type of animal can survive in extreme temperature environments?
homeotherms and poikilotherms
how can reindeer survive in extreme environments?
they have a natural insulation- thick fur and hollow hairs full of nonmoving air
what is an endotherm?
an animal that gets heat primarily from internal sources (metabolism)
what type of animal tries to maintain constant temps- endotherms or ectotherms?
endotherms
what is an ectotherm?
an animal that obtains heat primarily from external sources
what type of animal can have higher or lower body temps than normal- endotherms or ectotherms?
ectotherms
what type of animal often have membranes that leak ions more often?
endotherms
why do endotherms often have membranes that leak ions?
to maintain ion gradients they spend more energy, and have higher metabolic rates and generate more heat
what types of adipose tissue is found in homeotherms?
brown and white adipose tissue
what type of adipose tissue produces heat?
brown adipose tissue
what is nonshivering thermogenesis?
when an animal produces heat without needing to expend more energy from shivering
what is a behavioral strategy that allows small animals to keep warm?
protective microenvironments
what are animals that try to maintain parameters at optimal levels?
regulators
what are animals that, for at least some parameters, allow the internal level to vary with the environment?
conformers
what is often lethal for conformers?
extreme environmental changes
True or False: All parameters will vary drastically in each organism.
False- some parameters are more important to keep constant, and others don’t change much in the environment so they don’t change much in the organism
True or False: There are different degrees of homeostasis.
True
what is the difference between acclimatization and acclimation?
acclimation- adjustments to lab-based environments or adjustments after prior exposure
acclimatization- adjustments to natural environments/seasonality
what is regional hypothermia?
one localized area on an animal can be cold while the remaining parts of the body stays warm
which type of animal can regulate their behavior- endotherms or ectotherms?
both endotherms and ectotherms
what is an example of temperature regulation?
lizards moving to a sunny rock
what is countercurrent flow used for in physiological acclimatization in Grant’s Gazelle?
keeps the brain cool by 2-3 degrees Celsius
what is an example of physiological acclimatization?
sweating and panting releases heat by evaporation
what 4 ways can heat exchange occur?
radiation, convection, conduction, and evaporation
how does evaporation cool the body?
it comes off the body surfaces or breathing passages
what is radiation?
warmer objects lose heat to cooler objects
how is heat lost by convection?
a stream of wind is cooler than the body surface temp
what is conduction?
the direct transfer of heat when objects of different temps come into contact
why is a larger surface area an issue with heat loss?
more surface means more heat is usually lost, but it can also be gained
where is heat generated particularly in endotherms?
volume
what is hibernation?
a state with low body temps and thermal conformity
what types of animals hibernate (most often)?
small mammals
what are heterotherms?
homeothermic during summer, but hibernate in winter
how do bees thermoregulate?
the flight muscles keep the thorax warm; they collect water and spread it on the hive, then fan it to encourage evaporation
what likely drives adaptations for thermoregulation?
changes in DNA
what is a large difference between types of barracuda depending on the temperature they live in?
metabolic enzymes
why do we need to eat?
each cell in your body needs to break down and rebuild 2-3% of its protein molecules daily
how much ATP does each cell use daily?
10^14 ATP molecules
what are different types of feeding?
predation, suspension feeding, and symbiosis
what is suspension feeding?
an animal pulls in water and strains out the food
what is a food web?
map that shows the direction of energy flow through animal populations (who eats who)
what are the components of a homeostatic mechanism?
stressor, sensor with receptor, integrator, effector
what is a stressor in homeostasis?
causes deviation from a set point
what is a sensor with receptor in homeostasis?
detects the error signal produced by the deviation from the set point
what is an integrator in homeostasis?
receives info from sensor and sends compensatory signals to effectors
what is an effector in homeostasis?
produces changes to the internal environment
True or False: A homeostatic component can have one or more mechanistic role.
True
what is feedback?
info about the relationship between the set point of the system and its current state
what is feedforward?
feature of a regulatory system that changes a set point in anticipation (amplifies a response)
what is positive feedback?
type of control that acts to increase differences that arise between levels; speeds up an earlier process in a system
what is negative feedback?
type of control that acts to reduce differences that arise between levels; slows down a process
what type of feedback usually destabilizes a system?
positive feedback
what type of feedback usually stabilizes a system?
negative feedback
homeostasis does not have _______ feedback.
positive
when does feedback occur?
when the rate of an early process is affected by the amount of a later product
what is the homeostatic sensor in animals?
hypothalamus
what type of feedback is mammalian birth an example of?
positive feedback
what is a feedforward system?
organism reacts to stimulus that is not the end product of the pathway by changing downstream responses to the stimulus
what is an example of a feedforward system in plants and animals?
circadian rhythms
what is the central nervous system?
brain and spinal cord
what is the peripheral nervous system?
nerves in the rest of the body
what are spinal nerves?
nerves that come in pairs with one on each side of the body along the length of the spinal cord
what actions does the nervous system allow for?
sensing, integration, analyzation, homeostasis, motor
what are neurons?
cells of the nervous system that are small and elongated
what are nerves?
bundles of neurons (100s-10,000s)
what are sensory neurons?
neurons that carry signals from sense organs to the CNS
what are motor neurons?
neurons that carry signals to muscle
what is the pathway for sense integration?
sensing a stimulus at sensory organ –> CNS –> PNS –> muscle for response
how fast can mammal neurons transmit signals?
20-100 meters per second
what does a fast nervous system allow for?
the ability to quickly perform tasks
nervous systems are fast and & ______.
addressed (meaning go to a specific location)
what does it mean that neurons are excitable?
the cell membrane can generate and conduct impulses or action potentials
what is an action potential?
state of reversed polarity of the cell membrane
what does it mean when a cell can be depolarized?
when the electrical polarity is less negative
what is a membrane potential?
charge difference across the cell membrane
at rest, the inside of a cell membrane has a _____ charge.
negative
at rest, the outside of a cell membrane has a _____ charge.
negative
what is the resting membrane potential?
membrane potential when not firing an action potential when at rest
what separates the charges inside and outside a cell?
cell membrane
what produces an electrical potential in a cell?
charge imbalance across the membrane
what is the direction of propagation down a neuron?
from the cell body down to the postsynaptic terminals
what is a current in a neuron?
flow of electric charges from place to place
what is voltage in a neuron?
positive charges are connected in one place and negative charges are connected in a different place
what is the process of generation of an action potential?
Na+ enters cell, depolarizing portions of the membrane; Na+ voltage-gated channels nearby open when the membrane reaches a threshold needed for the AP to fire
what hyperpolarizes a neuron?
K+ voltage-gated channels open after the Na+ channels inactivate after a section of the axon is depolarized
how do action potentials jump along axons?
it starts at the beginning, then moves to the next node on the axon
what are the common anatomical features of neurons?
dendrites, cell body, axon, set of presynaptic axon terminals
what do dendrites do?
major site of synaptic input from other neurons
what does the cell body do of a neuron?
contains neuron’s nucleus and organelles; integration
what is the axon hillock?
the spot where the cell body transitions to the axon, and is where a signal is integrated
what does the axon do?
propagates axon potentials over long distances to the axon terminals
what is a synapse?
junction that allows a neuron to communicate with its target cell
what does a presynaptic cell do?
conducts signals into the synapse
what does a postsynaptic cell do?
conducts signals away from the synapse
what is myelin?
concentric layers of the cell membrane wrapped around axons
what are some glial cells that act as myelin?
oligodendrocytes and schwann cells
what is white matter?
parts of nervous system with mostly myelinated axons (named for glistening white appearance)
what is the process of an action potential?
resting membrane potential becomes depolarization and leads to the peak of action potential, then the cell becomes repolarized and the resting membrane potential is restored
what are sensors in the nervous system?
sensory cells and sense organs
what are effectors in the nervous system?
cells or tissues that carry out orders from the control system
what are 3 types of neurons?
interneurons, afferent (sensory) neurons, efferent neurons
where are interneurons found?
neurons that are confined to CNS that connect other neurons together
what do interneurons do?
integration, command, and information-storage functions
what are the most abundant neurons in the CNS?
interneurons
what do afferent (sensory) neurons do?
carry signals from sensory cells to CNS
what do efferent neurons do?
convey signals from CNS to effectors (like muscles)
what are glial cells?
another cell type in the nervous system that is not excitable
what do glial cells do for the brain?
metabolic support for neurons, regulate extracellular fluid composition, and immune system
what do glial cells do during development?
guide growing neurons in CNS
what types of glial cells are in the CNS?
oligodendrocytes, astrocytes, and microglia
what is the most abundant cell in the brain?
astrocyte glial cells
what occurs at a chemical synapse?
neurotransmitter release and transmission that can excite or inhibit the postsynaptic cell
what is a neurotransmitter?
a chemical that can excite or inhibit a postsynaptic cell that is secreted at an axon terminal
what are common neurotransmitters?
acetylcholine (ACh), norepinephrine, dopamine, serotonin, GABA, glycine, nitric acid
is acetylcholine inhibitory or excitatory?
excitatory to vertebrate skeletal muscles; inhibitory at other sites
is norepinephrine inhibitory or excitatory?
both excitatory or inhibitory
is dopamine inhibitory or excitatory?
generally excitatory, but can be inhibitory
where does a neuron connect to a muscle?
neuromuscular junction
what channels are voltage-gated?
Na+, K+, and Ca2+
how does the muscle work in terms of sensory response?
receptor protein detects stimulus, and this results in an AP in the receptor’s cell or results in release of a signal that eventually produces an AP in a neuron
what are sensory receptor cells?
cells (neurons) that transform energy of a stimulus into an electric signal
what is transduction?
a sensory receptor cell produces an electric signal from stimulus energy
what is characteristic of the cell membrane in a rod cell in the eye?
it is highly folded, allowing for more surface area for more photoreceptor molecules to be present
what is a sensory receptor protein?
membrane protein in sensory receptor cells that first detects a stimulus and produces a graded change in receptor cell’s membrane potential
what is receptor potential?
graded change in membrane potential
what are the 2 receptor cell types?
ionotropic and metabotropic receptor cells
what is an ionotropic receptor cell?
a receptor protein that is a stimulus-gated Na+ channel
what is a metabotropic receptor cell?
receptor protein that activates a G-protein
what are mechanoreceptors?
cells that respond to mechanical distortion of their cell membrane, usually ionotropic
what are thermoreceptors?
cells that detect heat and cold, usually ionotropic
what are chemoreceptors?
cells that respond to presence or absence of specific chemicals
what is characteristic of moth olfactory cells?
they are highly specific and respond to 1 odorant
how does the auditory sense work?
sound pressure waves are alternating high and low pressures and the ear detects this
what kind of noises do high frequencies produce?
high pitch and notes
what kind of frequencies do low frequencies produce?
low pitch and notes
how does a sound wave move into and through the ear (steps)?
tympanic membrane, ossicles, oval window, cochlea, basilar membrane, organ of corti
what is the tympanic membrane?
part of the ear that vibrates when sound pressure waves travel through
what are the 3 ossicles in the ear?
stapes, incus, and malleus
what do the ossicles do?
transmit vibrations of tympanic membrane to oval window
what is the oval window?
where ossicles connect to the cochlea
what happens in the cochlea?
vibrations at oval window create pressure waves in the cochlear fluid
what is the basilar membrane?
when it is flexed, it bends stereocilia on hair cells in organ of Corti
what is transduced into APs in the auditory nerve?
movement of stereocilia
where are the lowest frequencies transduced on the basilar membrane?
at the apical end (the inside of the coil)
what do fibers in the membrane vibrate in response to?
different frequencies of sound/different pitches
what is the most simple function of visual systems?
sense and respond to light
what is a more complex function of visual systems?
more detailed images of the environment
what are photoreceptors?
sensory receptor cells that are light sensitive
what is a sensory receptor protein?
member of a family of closely similar membrane pigments- visual opsins
what is the cornea?
outer layer of the eye made of connective tissue
what is the pupil?
where light enters the light-sensing part of the eye
what is the iris?
small muscles that change diameter of pupil
what is the lens?
crystal clear proteins behind the iris
what is the retina?
space at the back of the eye with a photosensitive layer for focusing images
what is the pathway of light in the eye?
light enters eye, absorbed by rods and cones that send info to nuclei, of which converges on ganglion cells, which send. theAP to the brain
what are the layers of integrating neurons, from the back of the retina to the front?
photoreceptors (rods and cones), then bipolar cells (horizontal cells and amacrine cells), and then ganglion cells which axons combine to lead to the optic nerve
what are the types of photoreceptor cells?
rods and cones
which type of photoreceptor cell is responsible for color vision?
cones
True or False: Rods and cones produce APs just like neurons.
False- they do not produce APs but they make a graded membrane
what are compound eyes?
each eye has many optical units (ommatidia)
what type of organism have compound eyes?
arthropods
how can bats find prey and navigate?
sonar (sound echoes)
how do bats use sonar?
they use larynx (voice box) to make high frequency sound waves that bounce off surfaces
how do tiger moths “jam” bats echolocation?
produce bursts of ultrasonic sound at high intensity
what is a lateral line system?
a sensory organ that detects changes in pressure and movement in water
what types of sensory cells are ionotropic?
mechanoreceptor, thermoreceptor, and electroreceptor
what types of sensory cells are metabotropic?
chemoreceptor and photoreceptor
what are taste buds?
clusters of chemosensory receptor cells
what is centralization?
tendency for neurons to be clustered into centralized, integrating organs
what is cephalization?
trend toward increasing concentration of nervous tissue and sensory organs at the anterior end of an animal
what makes up the central nervous system?
large structures made mostly of integrating neurons and glial cells where most info processing, storage, and retrieval happens
what makes up the peripheral nercous system?
part of the nervous system that isn’t the CNA, made of neurons and parts of them
what types of animals have simple nervous systems?
sea anemones and sea stars
what is the neuronal signaling pathway?
stimulus from sensory system enters PNS, CNS processing and integration of info, and the response is sent to effectors
what are the divisions of the autonomic nervous system?
enteric, sympathetic, and parasympathetic
what is the enteric division of the autonomic nervous system?
it is inside the gut wall and helps with digestion
where does the sympathetic division of the autonomic nervous system connect?
thoracic and lumbar spinal nerves
where does the parasympathetic division of the autonomic nervous system connect?
cranial and sacral nerves
what does the sympathetic division of the nervous system do?
immediate responses (fight or flight)
what does the parasympathetic division of the nervous system?
more restful responses (rest and digest)
what are spinal reflexes?
responses that don’t use the brain and the signals come from the spine initiate motor neuronal signals in response to sensory neuronal signals in the spinal cord
what does the dorsal root of the spinal nerves do?
receive signals from sensory organs
what does the ventral root of the spinal nerves do?
sends signals out to the muscle
how is the body represented in the brain?
somatosensory and motor cortices in the brain
what is binocular vision?
2 eyes show overlapping visual fields (and how we can see objects in 3D)
what is the optic chiasm?
where the optic nerves meet
what is the cerebral cortex?
outermost layer of cerebral hemispheres, thin layer of cell bodies
what does the cerebellum do?
integrates sensory and motor info
what are the 3 divisions of vertebrate brain evolution?
forebrain, midbrain, and hindbrain
what does the forebrain become in development?
cerebrum
what does the hindbrain become in evolution?
pons, medulla, and cerebellum
what is the amygdala?
brain center responsible for emotion and memory of fear
what does ecstasy/MDMA do to the brain?
causes continual release of serotonin, causing cell overstimulation
what can ecstasy/MDMA do to the body?
rapid breathing/heart rate/BP/temp –> organ system failure –> death
what do addictive drugs trigger?
the release of dopamine (and can stop the uptake)
what does naloxone do?
blocks opioid receptors in CNS and periphery
what type of drug (Na+ or K+ blocker) prolongs the AP?
K+ blocker
what type of drug (Na+ or K+ blocker) decreases speed of conduction?
Na+ blocker
what type of drug (Na+ or K+ blocker) prolongs the refractory period?
K+ blocker
what type of drug (Na+ or K+ blocker) suppresses the ability to reach threshold?
Na+ blocker
what type of drug (Na+ or K+ blocker) increases the threshold?
Na+ blocker
what type of drug (Na+ or K+ blocker) prolongs repolarization?
K+ blocker
what is the path of oxygen in the respiratory system?
O2 enters lungs and crosses 2 simple epithelia, then goes into the blood and down to the muscle; then crosses epithelial wall into muscle cell, then into cytoplasm and enters mitochondria
how does dog ventilation work?
bulk flow ventilation
why do our cells need oxygen?
cell works to break down glucose and other food molecules to get energy for making ATP; electrons are released from food to oxygen
what are respiratory gases?
oxygen and carbon dioxide
how does air move?
bulk flow and diffusion
what is bulk flow?
flow of gases from one place to another, from an area of high pressure to low
what is diffusion?
particles move toward a state of equilibrium at random
what are the steps of alternation of bulk flow and diffusion?
breathing in oxygen (BF), oxygen does into lungs and blood (Diff.), circulation of blood (BF), oxygen out of capillary, into cell membrane, cytoplasm, then mitochondria (Diff.)
what are gas exchange membranes?
location where respiratory gases move between animals environment and thin internal tissues
what is breathing?
external respiration- moving oxygen in and carbon dioxide out of lungs
True or False: All animals need specialized breathing organs.
False- some can breathe through their skin
what is similar in the structure of gills and lungs?
tissue folding and branching
how is gill tissue folded?
folded outward (evaginated)
how is lung tissue branched?
folded inward (invaginated)
what is tidal airflow?
air flow changes direction in same air passage
what does unidirectional airflow?
airflow is in one direction in air passages
what are elements of specialized breathing organs?
ventilation system, thin gas exchange membranes with large surface area, high rate of blood perfusion
what is perfusion?
fast blood flow through capillaries or smaller blood vessels of a tissue
why do we need a fast rate of blood perfusion provided by circulatory system?
to get oxygen distributed quickly to cells
True or False: Diffusion happens faster in air than liquid.
True
what are the 2 gas exchange methods?
countercurrent and cocurrent
what is cocurrent gas exchange?
water and blood moves in the same direction
what is countercurrent gas exchange?
water and blood move in different directions
what kind of gas exchange is more efficient?
countercurrent gas exchange
what are systemic tissues?
non breathing organ tissues
what type of airflow do most vertebrates use?
tidal because there is nowhere else for the air to go
what type of airflow do most birds and crocodiles use?
unidirectional- rigid airways that don’t change volume during inhalation/exhalation
how are airways distributed in insects?
they are throughout their bodies- gas filled invaginated tubules
what type of breathing system do insects have?
tracheal breathing system (gas-filled tubules)
what are internal gills?
gills within body chambers providing a covering for protection and prevents drying
what are external gills?
extend outside body, so no protection
what types of animals have no specialized breathing organs?
flatworms and sponges
what is the trachea?
windpipe that branches into 2 tubes, which further branches even more
what are alveolar sacs?
located at the end of each final branch and allows for a high surface area for gas exchange
what are conducting airways?
airways that are not directly involved in oxygen and carbon dioxide exchange
what are respiratory airways?
where oxygen and carbon dioxide are exchanged between air and blood via diffusion
what is tidal volume?
how much air can be moved in and out in a mammal’s lung
what is the diaphragm?
muscle below lungs connected to ribcage
what are intercostal muscles?
muscles between ribs
what is exhalation?
elastic recoil of lung tissues (results in relaxed lung muscles)- breathe. out
what is inhalation?
muscles of diaphragm and some intercostal contract- breathe in
what part of breathing, inhalation or exhalation, is passive?
exhalation
what type of feedback control is breathing under?
negative-feedback
what would happen if we were somehow able to generate less carbon dioxide?
breathing would slow since it is negative-feedback
in rodent brains, where does the breathing rhythm originate?
pre-Botzinger complexes
in human brains, where does the breathing rhythm originate?
the medulla, but the entire brainstem is needed to breathe
what is the circulatory system?
a pump made of the heart, blood, and blood vessels
what does it mean for the circulatory system to be closed?
the blood is always contained
what does it mean for the circulatory system to be open?
the blood leaves the vessels into the body
what is the primary function of the circulatory system?
transportation of oxygen
what is the primary function of the circulatory system in insects?
nutrients
what types of animals have closed circulatory systems?
vertebrates, mollusks, and annelids
what are arteries?
large blood vessels that carry blood away from the heart
what are veins?
large blood vessels that carry blood toward the heart
what is the lumen in an artery?
the space in the center that allows blood flow
what is vascular endothelium?
simple epithelium that surrounds the lumen
what allows arteries to stretch and withstand high pressure?
the elastic tissue and smooth muscle
what is microcirculation?
beds of small blood vessels made of arterioles, capillaries, and venules
what systems is microcirculation not found?
open systems
what are capillary beds?
web-like structure or capillary network where oxygen and nutrient exhange occurs
how does exchange occur in capillaries?
pores (gaps) between endothelial cells
what is vasoconstriction?
contraction of muscles to make the lumen smaller
what is vasodilation?
relaxation of muscles to make lumen larger
what is the order of bloodflow?
heart –> arteriole –> capillary –> venule –> heart
what types of animals have open circulatory systems?
arthropods and most mollusks
what are the components of blood?
respiratory pigments (iron in human hemoglobin), plasma, red blood cells, white blood cells, and platelets
what are respiratory pigments?
proteins that help carry oxygen
what is the human respiratory pigment?
iron in hemoglobin
what is another respiratory pigment in other animals?
copper in hemocyanin
what is blood plasma?
solution in blood with no blood cells- made of water and other materials
what do platelets do?
blood clotting
what type of protein is hemoglobin?
a tetramer
what does it mean that hemoglobin is a tetramer?
each hemoglobin molecule can hold 4 oxygen molecules
what is myocardium?
muscle tissue in the heart
what is cardiac output?
volume of blood pumped per minute
what is stroke volume?
volume of blood pumped per beat
what is the breathing-organ circuit?
blood vessels that carry blood to and from breathing organ
what is the cardiac cycle?
cycle where the heart contracts and relaxes
what is blood pressure?
point when the pressure in the blood exceeds the pressure in the animal’s environment
how is the heart’s elecrical activity monitored?
EKG, or electrocardiogram
what is systole?
during each repetition of the cardiac cycle, period of contraction of the heart chambers
what is diastole?
portion of the cardiac cycle when the heart muscle relaxes
in an EKG, what does the P wave correspond to?
depolarization of atria
in an EKG, what does the QRS complex correspond to?
depolarization of the ventricles
in an EKG, what does the T wave correspond to?
repolarization of the ventricles
what is the atrioventricular (AV) node?
area of the heart where the signal is conducted to after the atria begin to contract (passes on signal to ventricle)
how is systolic measured via blood pressure?
no blood flow heard through artery at all
how is diastolic measured via blood pressure?
max pressure that allows continuous flow
what is the cardiovascular system composed of?
blood vessels and heart
what is a simple type of circulatory system?
single circuit- heart, gills, body, heart
what is a more complex type of circulatory system?
double circuit- heart, lungs, heart, body, heart
what circulatory system has evolved to be most similar to humans?
birds
what are critical characteristics of the circulatory system?
mean blood pressure, total cross-sectional area of blood vessels, and linear velocity of blood flow
when does blood pressure drop in the cardiac cycle?
after leaving the heart
where is the surface area highest in the cardiac system?
capillaries
where is the velocity highest in the cardiac system?
arteries
what do parallel arrays of blood vessels do?
creates large differences of temperature from place to place
what are autoregulatory mechanisms?
each tissue controls its own blood flow
what does regional autoregulation do?
sets up a problematic positive feedback loop, which can be counteracted by systemic regulatory mechanisms
what is atherosclerosis?
buildup of lipids in vessels
what does clotting do?
helps maintain homeostasis after an injury
what are the ways that animals can eat?
predation, suspension feeding, and symbiosis
what is a fluid feeder?
animal that eats liquids that contain organic molecules
what is a suspension feeder?
animal that ingests small organisms in water (such as bacteria)
what is a deposit feeder?
animal that picks up or scrapes food particles
what is a bulk feeder?
animal that eats another animal whole or in large parts
what are some main minerals we need in our diets?
calcium, phosphorus, potassium, sodium
what do we need calcium for?
bones
what do we need phosphorus for?
nucleic acids and ATP
what do we need potassium for?
nervous system
what do we need sodium for?
nervous system
why do we need energy?
to do work and maintain self and organization
what type of energy doesn’t do any work?
heat
what is nutrition?
how animals ingest to meet their chemical substance and energy needs
what is an essential nutrient?
type of molecule that an animal requires but can’t make by itself
what are some types of essential nutrients?
amino acids, fatty acids, vitamins, essential minerals
what vitamins are water soluble?
B1-12, Folic acid, and C
what vitamins are fat soluble?
A, D, E, K
what does a vitamin B3 (Niacin) deficiency cause?
pellagra, skin disorders, diarrhea, mental disorders
what does a vitamin C deficiency cause?
scurvy, slow healing, poor bone health
what happens when we don’t get enough food?
the body starts to metabolize it’s own molecules (self-consumption), which starts in the blood plasma; the fluid in the body shifts, leading to edema, starvation, and death
what is a metabolic rate?
amount of energy the animal converts to heat each day
what type of animals have a high need for oxygen?
homeotherms
how can you measure the energy cost of exercise?
measure the rate of oxygen consumption to the rate of heat production
what is the difference between the metabolic rate in humans and birds?
in humans, the faster you move increases the metabolic rate; in birds, slow and fast speeds have higher metabolic rates, while medium speeds have a low metabolic rate
what is basal metabolic rate?
standardized measure of metabolic rate
what is the general trend in animals’ BMR?
smaller animals have a higher basal metabolic rate
what is a calorie?
the amount of heat required to raise the temp of 1 gram of water by 1 degree Celsius
what type of molecules can’t be absorbed?
proteins
what does the mouth do?
chews food and produces an enzyme to start digesting carbohydrates
what does the liver do?
stores glucose as glycogen and releases glucose as needed, and synthesizes bile salts
what do the sphincter muscles do?
keeps food from entering or leaving midgut or stomach, except when it relaxes
what does the hindgut (colon/large intestine) do?
reabsorbs large quantities of water and minerals; forms and stores feces
what does the rectum do?
stores and expels fully formed feces
what does the esophagus do?
muscles undergo waves of contraction to move food to the stomach
what does the stomach do?
serves as a place for food to accumulate during a meal, and secretes HCl and protein-digesting enzymes
what does the pancreas do?
synthesizes digestive enzymes responsible for carbohydrate, lipid, and protein digestion; alpha and beta cells secrete insulin and glucagon
what type of pancreatic cells secrete glucagon?
alpha cells
what type of pancreatic cells secrete insulin?
beta cells
what does the midgut do?
principal location of food digestion and absorption by means of pancreatic digestive enzymes and liver bile emulsifying lipids
what is digestion?
breakdown of ingested food molecules into smaller chemical components that an animal is capable of absorbing and distributing to the tissues of the body
what are the functions of the digestive system?
digestion, absorption of nutrients, storage, and elimination of wastes
what makes up the foregut?
mouth, esophagus, and stomach
what makes up the midgut?
small intestine
at makes up the hindgut?
large intestine, rectum
what type of animals have tube gut systems?
bilaterians
what do canine teeth do?
ripping and tearing
what do incisor teeth do?
cutting
what do premolar teeth do?
shearing
what do molar teeth do?
grinding
what is the difference in intestine length between herbivores and carnivores?
herbivores have long intestines to store large amounts of plant material, and carnivores have short intestines
what is division of labor?
cells are specialized for a particular function
True or False: glucose and amino acids require a carrier protein to enter the cell through the membrane.
True- they are cotransported through the cell with Na+ ions
how is food processed through the digestive system?
mouth- salivary enzymes, stomach- acid and mechanical churning, intestine- small molecules and water absorption
where do proteins begin to be broken down?
the stomach
where do carbohydrates begin to get broken down?
the mouth (salivary amylase), then lumen of small intestine
where do lipids begin to get broken down?
the mouth (lingual lipase), then lumen of small intestine
what does the rumen do?
allows for cellulose digestion because of symbiotic relationship with microbes
what is released when blood glucose gets too high?
insulin
what is released when blood glucose gets too low?
glucagon
what can happen if there is too much glucose?
kidney, retina, and brain damage
why is the lac operon not always on?
it is energy expensive and because lactose is relatively rare sugar in nature
what is the lac operon?
genes encoding enzymes and other proteins needed for lactose metabolism are found clustered together with common promoter and regulatory sequences in an operon
what conditions are required for the lac operon to be expressed in high amounts?
lactose must be present, and glucose must be low
what causes the feedforward response of the lac operon?
lactose is present
what causes the feedback response of the lac operon?
glucose is low (because it is the end product of lactose metabolism)
what is the cause of type 2 diabetes?
insulin resistance
how many genes are shown to cause higher incidence of type 2 diabetes?
38+
what proves that type 2 diabetes is not genetic?
when looking at Pima groups, those in the US have a much higher rate of type 2 diabetes than those in Mexico
