Diversity Exam 2: Animals

animal

multicellular, heterotrophic, internal digestion, movement and nervous systems

monophyletic

closest living relative to animals

choanoflagellates

cambrian explosion

large increase in diversity, seen in fossil record

~540 mya

establishment of basic body forms still seen today

land not yet colonized

punctuated equilibrium

evolution containing long intervals of relative stasis punctuated by short periods of rapid diversification

success of the cambrian explosion

increase in global O2

increase in ocean Ca2+

expansive continental shelf

evolution of hox genes (body plan changes)

extinction events

late oridivician: 85% all species, volcanism and anoxia

late devonian: 70% all species, ocean anoxia, global cooling flux

permian-triassic: 80% marine, 70% terrestrial, global warming, ocean acidification

triassic-jurassic: 70% all species, volcanism, global warming, ocean acidification

cretacous-paleogene: 75% all species, asteroid, bye all non avian dinosaurs

trends in animal evolution

centralization: of nervous system

cephalization: sensory organs concentrated towards anterior end

ordivician

modern spinal column, first fish

plants colonize land, then animals

fish evolution

early ordivician: first fish, armored plate evolution

late ordivician: bony jaws develop

two major lineages:

placoderms (bony fish ancestor)

acanthodians (shark ancestor)

devonian: shark and bony fish diversification, placoderms extinct by end of period, first lobe finned fishes evolve

end of triassic: bony fish diversify, extinction event

jurassic: body size increases, extinction event

cretaceous: closest ancestors of modern fish evolve

cretaceous-paleogene: radiation of bony fish

lobe finned fish

arose and diversified in devonian

first colonization of land end of devonian

led to evolution of tetrapods (amphibians, mammals, birds, crocs, squamates)

amphibians

early species fully aquatic, transition to terrestrial lifestyle

sarcopterygian ancestor (lungs, appendages with support away from body)

birds, crocs, reptiles diversification

first ancestors pennsylvanian period

sauropsid lineage

K-Pg extinction wiped our non avian dinosaurs

mammal diversification

first ancestors pennsylvanian period, synapsids

jurassic period: mammal lineage leading to modern
mammals forms

K-Pg extinction opened niches

homeostasis

maintaining a stable internal environment, requires energy

homeostasis parameters

temp, pH, blood glucose and pressure, heart and respiratory rates, behavioral feedback responses, [O2], [CO2], [Na+], [Ca+]

importance of thermoregulation

daily and seasonal temp variation can be extensive

temp affects rates of reactions (enzyme catalyzed and uncatalyzed rxns)

blood vessels and thermoregulation

vessels constrict or dilate based on temp

cold: vessels near surface constrict

warm: vessels near surface dilate

Q10 temp coefficient

measure of sensitivity of a reaction or physiological process to a change in temp (within a limited range)

can’t be extrapolated above/below the range

homeotherms

animals that keep a steady internal body temp

aka regulators

ex: birds, mammals

poikilotherms

animals that vary their body temp along with their environment

aka conformers

ex: frogs, lizards, fish

endotherm

animal gets heat primarily from internal sources (metabolism)

may or may not be successful at maintaining constant temp

ectotherm

animal obtains heat primarily from external sources

may have body temps higher or lower than external temp

thermoregulation small vs large body size

small: more behavioral options, move to microclimates

large: more structural and physiological, develop structures to help (adaptations)

microclimates

environments within a larger habitat that contain diff conditions

ex: shade, snow, roots, water depth

countercurrent heat exchange

in feet, cold and warm flow in opposite directions

surface and heat

larger surface = more heat lost

hibernation

state with low body temp and thermal conformity, most small mammals

heterotherms

homeothermic during summer, hibernate during winter

negative feedback regulation

stressor causes deviation from set point/range, physiology stabilizes system

positive feedback regulation

speeds up/amplifies process occurring

not typically involved in homeostasis

muscle function

convert energy from atp to mechanical movement

ex: move limbs, breathing, digestive movement, heart contraction

3 main types of muscles

skeletal, cardiac, smooth

skeletal muscles

attached by tendons to bones, packed with actin and myosin

troponin

cardiac muscles

shorter cells, branched, interlinked network

to decrease communication time

smooth muscles

actin and myosin arranged in loose network instead of bundles

locations: blood vessels, stomach, intestine, bladder, uterus

skeletal muscle anatomy

muscle fibers (cells) arranged into bundles (fascicles)

anchored to bone by tendon or directly fused on bone surface

voluntary locomotion, long cells with striations, adaptable

myofibrils

packaged into cells

contain myofilaments arranged into sarcomeres (actin and myosin)

sarcomere = contractile unit

t-tubules

cell membrane dips into cell

allow electric signal to travel deeper into the muscle cell

sarcoplasmic reticulum

modified smooth ER, calcium storage

myoglobin

oxygen storage within the cell

glycosomes

packets contain glycogen (sugar storage)

sarcomere structures

z line- boundaries of a sarcomere

m band/line - down middle of sarcomere

a band - dark band

i band - light band

h zone - no myosin heads (no actin)

z line

boundaries of a sarcomere

z = end of alphabet

m band/line

down middle of sarcomere

m = middle

a band/line

dark band

dArk

i band

light band

LIght

h zone

no myosin heads (no actin)

no Heads

titin

anchors myosin, elastic property, connects ends of filaments to z line

sliding filament theory

myosin pulling actin towards the middle

Ca released by SR, binds to troponin, twists tropomyosin, uncovers myosin binding site

myosin

chains twisted together, heads and tails

actin

two chains twisted, myosin head binding sites

interactions:

troponin = calcium receptor, unwinds+reveals binding sites

tropomyosin = twists so blocks binding sites at rest

innervate

to provide neural input

neuromuscular junction

synapse where a motor neuron axon makes contact w a muscle fiber

excitation

nerve impulse arrives at a neuromuscular junction, initiates an action potential

excitation-contraction coupling

electrical excitation of membrane leads to contractive activity by proteins

initiation of contraction

motor neuron is stimulated, sends signals towards muscle fibers

ACh released, diffuses acrpss hap

creates action potential in muscle fiber (across membrane)

ap spreads away from junction

cross bridge cycle

atp binds to myosin

atp hydrolysis (adp+p = activated conformation)

myosin head binds to active site

adp + p removed = power stroke

ending cross bridge cycle

ca ions transported back into SR, troponin twists tropomyosin, resting conformation

exoskeleton muscles

pull on interior surface

apodeme

part of exoskeleton projects inside body (what muscles attach to)

invertebrate muscles

asynchronous flight muscles, each excitation causes many contractions

catch muscle: adductor muscles able to sustain contraction forces closing the shell

hydrostatic skeleton

due to high fluid pressure inside

atp production

immediate (small amount stored in muscle)

glycolytic (glycolysis)

oxidative (citric acid cycle and ETC)

skeletal fiber types

slow oxidative

fast oxidative

fast glycolytic

slow oxidative

• slow myosin ATPase
• resists fatigue, high endurance
• thin (= little power)
• many capillaries
• red

fast oxidative

• fast myosin ATPase
• moderate sprinting/exercise
• thicker
• many capillaries
• red

fast glycolytic

• fast myosin ATPase
• anaerobic glycolysis
• depends on glycogen (short lived)
• intense, powerful movements
• large fibers
• few capillaries
• white/pale color

nervous systems basic functions

sensory input (receptors)

integration (thoughts, memories, decisions, sensation)

moros output (effector organs)

structure of a neuron

myelin

insulates, increases speed of transduction

neuron cell body

organelles, neurotransmitter synthesis

dendrites

receptive, high surface area

axon

variable size, conduction region, axon terminals

axon terminals

secretory region (secrete neurotransmitters)

excite or inhibit

resting membrane potential

living cells, ions separated against gradients

energy needed to separate

if separated = potential energy

voltage vs current

potential energy stored

flow of charge between points, released potential energy

negative potential established

Na/K pump:

3 Na out, high Na outside

2 K in, high K inside

differences in permeability: leak channels

100x more K leak channels than Na

gated channels

require specific signals (ligand, voltage)

voltage gated Na: activation and inactivation gates

graded potential

short distance signaling, variable strength, small region of membrane

current decreases with distance, stimulus opens ligand-gated channels

excitatory or inhibitory

initiate action potentials

converse at summation/trigger zone

action potential

long distance signaling, constant strength

if summation potential strong enough

change in membrane potential

volate gated channels

inside of cell = more pos

doesn’t weaken with distance, all or nothing

action potential steps

resting state

depolarization

repolarization

hyperpolarization

myelinated fibers

prevent Na leaking, separates ionic attraction across membrane, increases conduction velocity

gaps between cells allows space for channel exchange

lipids = electric insulation

action potential graph

receptor cells transform stimuli into electric signals

transduction- conversion of energy from one form to another

1st step in receptor cells

graded potentials

potential is stronger with increased stimulation

2nd step in receptor cells

transmission: action potentials generated in nerves

stimulus energy relayed to integrative parts of nervous system for interpretation

2 types of receptor proteins

ionotropic: receptor protein is the ion channel

metabotropic: receptor protein relays signal through G protein mechanism to a channel, secondary messenger

receptor membrane proteins have high surface area = high sensitivity and response to stimuli

stretch receptors

mechanoreceptors, usually ionotropic

can be single neurons in simple systems, muscle spindle in skeletal muscle

further stretch = higher action potential

olfaction

metabotropic receptors

diversity of g protein couples receptor proteins (GPCRs) - one type per cell

oderants

chemicals detected by smell (chemoreceptors)

auditory systems

mechanoreceptors

sound waves > electric signals

high req waves → high pitch

low freq waves → bass/low pitch

human ear anatomy

external auditory canal- tympanic membrane (eardrum)

middle ear ossicles- oval window

diff pitches cause diff regions of basilar membrane to move

organ of corti- hair cells w stereocili, contact tectorial membrane

stereocilia move-neurotransmitters release onto neuron which generates ap - cochlear nerve - brain