Which of the following is most highly developed in human brains compared to other mammals?
B. cerebral cortex
What is most responsible for conscious thought?
frontal lobe
The part of the brain that controls basal processes is the?
hind brain and midbrain
The major cell signaling of the nervous system is the what?
neuron
Cells that form myelin sheaths on axons are?
Glia
The part of a neuron that is involved in sending outgoing signals is the?
axon
The part of a neuron that is involved in receiving incoming signals is the
dendrite
Initiation of an action potential involves what?
Na+ channel opening
Graded potentials
Sometimes involve membrane hyperpolarization, Sometimes involve membrane depolarization, Vary in amplitude according to the strength of a stimulus, and Determine whether threshold potential is reached for
intiating an action potential
In a resting neuron, the concentration of K+ ions is high inside the cell because why?
Of the energy provided by ATP, Ion-selective channels allow diffusion of K+, A negative charge inside the cell provides electrical attraction to the K+ ions, and The
cell membrane is impermeable to Na+ or Cl- ions.
what is involved in depolarizing a neuronal membrane during an action potential?
Opening Na+ channels
What is involved in repolarizing a neuronal membrane following an action potential?
Opening K+ channels
Action potentials are conducted in just one direction
on an axon because why?
Na+ channels are blocked during the refractory period
Myelination of axons is important because why?
it enhances the speed of neural impulse conductance
A neurotransmitter
is a signaling molecule that influences membrane potential on its target cell
Postsynaptic cells
Often contain neurotransmitter receptors
Presynaptic release of neurotransmitter
Occurs via exocytosis
A synapse
is a target for some psychoactive drugs and neruotoxins and transmits signals from a neuron to a receiving cell
Mechanosensors
Produce different frequency of action potentials depending on intensity of a stimulus and Contain stretch-induced ion channels that lead to membrane depolarization when cells are deformed
In sensory neurons
the amplitude of graded potentials is proportional to the intensity of the input stimulus and the frequency of action potentials is proportional to the intensity of the input stimulus
We detect tones because differnt sound frequencies do what?
vibrate different parts of the cochlea, which are detected by many mechansensors.
We dectect motion and postion becaue why?
hair sensory cells detect the direction of fluid movement in our ears
Folding of the mimosa (sensitive plant) leaves in response to touch is triggered by what?
action potential
A neurotoxin that stimulated acetocholine release would most likely cause what?
muscle cramping
Glucagon does what?
promotes fat breakdown
Insulin does what?
triggers glucose uptake from blood
The function of insulin and glucagon are examples of what?
hormonal maintainence of homeostasis
The function of the Thyroid hormone in amphibian morphogenesis is an example of what?
hormones coordinating activities in distant parts of an organism
The control of the pituitry secretions by the hypothalamus is an example of what?
integration of neural and hormonal systems
The proper sequence of events in amphibian metamorphosis is controlled by what?
differential sensitivity to increasing thyroid hormone concentration
The differencial responses to different tissues to thyroid hormone in amphibian metamorphosis might attribute to what?
Different cells express different transcription factors that regulate expression of different genes in response to thyroid hormone
Auxin does what?
Promotes initiation in peristems, inhibits lateral bud outgrowth, and is controlled by transporters
The promotion of leaf initiation at localized sites of
meristems is controlled by
localized patterns of auxin transport controlled by
PIN proteins
The hardness of vertebrates bones is due to what?
mineralization of the extracellular matrix
cross-bridges form between ____ and ___ during muscular contraction.
actin and myosin
Which of the following does NOT happen during a muscle contraction?
center
d. The sarcomere shortens
e. The myofibril and the muscle shorten
B. The thick and thin filaments shorten
What would happen to a myofibril if ATP were depleted from a muscle cell?
Myosin could not release from actin
When during a muscle contraction sequence is ATP hydrolyzed to provide power?
Reactivation of myosin heads
In a normal resting myofibril, what determines whether
a contraction will occur?
the exposure (availability) of myosin binding sites on the actin fibers
Calcium in skeletal muscles does what?
Regulates avalability of myosin binding sites on actin
How do neurons establish differential concentrations of ions inside and outside the cell?
Active transport
How is Ca2+ concentrated in the sarcoplasmic reticulum?
Active Transport
An action potential in a muscle cell
Triggers calcium release in the Sarcoplasmic reticulum
Muscle relaxation requires what?
ATP, calcium pumps, blocking myosin binding sites on actin filaments, and muscle cell membranes to be at resting potential
Neuromuscular junctions involve what?
an axon terminal, acetylcholine, and ligand grated ion channels
