Chapter 3 - Biological Foundations of Behavior Flashcards
What is retinal and its purpose in polarizing photoreceptors?
It is a molecule derived from vitamin A in rods and cones that changes to an all-trans form when a photon of light is absorbed. The new form triggers the closing of Na+ channels, hyperpolarizing the cells.
Define presbyopia.
the inability to focus because of the loss of lens flexibility (with aging)
What are astrocytes?
glial cells in the CNS that regulate development and neurotransmitter levels
Which lobe is involved in touch and taste sensations?
parietal lobe
What are two major functions of the medulla?
It regulates vital autonomic functions and respiratory rhythmicity.
Which photoreceptors are responsible for color vision and acuity?
cones
What is spatial summation?
EPSPs (excitatory) and IPSPs (inhibitory) from all synapses at a postsynaptic membrane are summed, and based on that total will cause depolarization or hyperpolarization.
What is visual parallel processing?
Many aspects of a visual stimulus (form, motion, color, and depth) are processed simultaneously.
What are interoreceptors?
They detect stimuli from the internal environment of the body.
Which lobe is involved in voluntary movement, reasoning skills, and problem solving?
frontal lobe
With what kind of lens would farsightedness be corrected?
convex (converging)
What is temporal summation?
A presynaptic neuron fires action potential so frequently that EPSPs (excitatory) or IPSPs (inhibitory) have an additive effect and can cause depolarization or hyperpolarization in the postsynaptic cell.
What is the blood supply called in the endocrine control center of the brain?
hypothalamic-pituitary portal system
What is the endocrine control center in the brain?
hypothalamus-pituitary control axis
What is the adenohypophysis?
anterior pituitary
How is sound volume measured?
by the amplitude of its waves (larger waves cause more frequent action potentials)
What is gestalt theory and its relation to perception??
The whole exceeds the sum of its parts. Humans perceive an object, rather than all the little parts that make up the object.
Since neuronal repolarization actually hyperpolarizes, how does the membrane get back to resting potential?
After hyperpolarization, voltage-gated K+ channels close. K+ leak channels and the Na+/K+ ATPase pump continue to function.
Where are steroid hormones syntheszed and from what?
in the smooth ER from cholesterol
What is the neurohypophysis?
posterior pituitary
What is negative feedback?
inhibitory feedback (the presence of something inhibits the action the caused it)
What is a bipolar neuron?
a neuron that has only one dendrite
Where are peptide hormones synthesized and from what?
in the rough ER from amino acids
What is a chemical synapse?
An action potential is converted into a chemical signal
What are exteroreceptors?
They detect stimuli from the external environment.
How are steroid hormones stored?
They are not stored; they are made when needed.
How do action potentials propagate when a photon of light is absorbed?
Photoreceptors become hyperpolarized and stop releasing glutamate (which is inhibiting to bipolar cells). Bipolar cells and ganglion cells can then depolarize.
What is signal detection theory?
Predicts how and when someone will detect a sensory stimulus amidst other sensory stimuli in the background.
What is the difference threshold of a stimulus?
Difference threshold is the minimum noticeable difference between any two sensory stimuli 50% of the time.
What is the important physical property of peptide and amino acid derivative hormones?
They are hydrophilic and must bind to a receptor on the cell surface.
What are tonic receptors?
They fire action potentials as long as a stimulus continues. They may also adapt over time.
Define top-down processing.
brain applies experience and expectations to interpret sensory information
What are nociceptors?
They detect chemical signs of tissue damage as pain.
Define emmetropia.
Normal vision
With what kind of lens would nearsightedness be corrected?
concave (diverging)
What are mechanoreceptors?
They detect mechanical disturbances (pressure, vibrations, gravity changes).
What two gradients make up an ionic equilibrium potential in neuronal cells?
1) chemical gradients (concentration)
2) electrical gradients (positive versus negative charges)
What are tropic hormones?
hormones that regulate hormones
Define bottom-up processing.
sensory receptors ► complex integration of information in the brain
What determines if a postsynaptic membrane becomes depolarized (excited) or hyperpolarized (inhibited)?
postsynaptic membrane receptors for neurotransmitters and their associated ion channels: a neurotransmitter can have different effects based on the receptor it binds
What are the four properties of a stimulus that must be communicated to the CNS from a receptor?
1) Modality: what kind of stimulus
2) Location: overlapping receptive fields
3) Intensity: frequency of action potentials
4) Duration: length of time action potentials fire
What are electromagnetic receptors and what is an example in humans?
They detect electromagnetic waves. Humans have rods and cones in their retinas.
How much energy does the Na+/K+ ATPase pump consume in unmyelinated axons compared to myelinated axons?
It consumes much more in the unmyelinated axons, because it must establish a potential across the entire membrane. In myelinated axons, it only needs to establish potential at the nodes of Ranvier.
How do thyroid hormones carry out their function in a target cell?
They incorporate iodine into their structure, diffuse through the plasma membrane, bind to a cytoplasmic receptor, which alters gene expression in the nucleus.
Does the neuronal membrane have more K+ or Na+ leak channels?
It has more K+ leak channels, which establishes the resting potential.
What are chemoreceptors?
They detect particular chemicals.
Which photoreceptors are responsible for night vision?
rods
What is the major function of the cerebellum?
It regulates coordination and balance.
What is the threshold potential for an action potential?
~-50mV
What is the difference between absolute and relative refractory periods?
Absolute refractory periods cannot be depolarized because voltage-gated Na+ channels have been inactivated. Relative refractory periods can be depolarized with a strong enough stimulus, since it has hyperpolarized.
Which lobe is involved in visual sensation?
occipital lobe
What are bundles of neuronal cell bodies called in the CNS?
nuclei
What kind of cells make up the posterior pituitary?
neuroendocrine cells (their axons descend from the hypothalamus)
Define proprioception.
awareness of body position
How are peptide hormones stored?
in vesicles in the cell
Define myopia and its cause.
Nearsightedness: caused by over-curvature of the lens resulting in too short of a focal point
What is the absolute threshold of a stimulus?
Absolute threshold is the minimum stimulus intensity required to activate a sensory receptor 50% of the time. It varies by individual.
What is an autocrine activity?
A signaling molecule modifies the activity of the cell that secreted it.
How do steroid hormones carry out their function in a target cell?
They diffuse through the plasma membrane, bind to a cytoplasmic receptor, and get transported to the nucleus to alter gene expression.
What is an electrical synapse?
Action potentials are spread directly from cell to cell via gap junctions (smooth and cardiac muscle).
What is positive feedback?
The present of something amplifies the action that caused it.
What is the organ of Corti?
Within the cochlea, it is the final place of stimulus reception in the ear that converts sound vibrations to nerve impulses.
What are phasic receptors?
They fire action potentials only when a stimulus begins.
Which lobe is involved in auditory and olfactory sensations, short-term memory, launguage comprehension, and emotion?
temporal lobe
What are ependymal cells?
glial cells in the CNS that produce cerebrospinal fluid
Weber’s law of stimulus detection
Two stimuli must differ by a constant proportion in order for their difference to be perceptible.
What are bundles of neuronal cell bodies called in the PNS?
ganglia
What 3 structures make up the brainstem?
1) midbrain
2) pons
3) medulla
What is the role of kinesin in neurons?
It drives movement of vesicles and organelles along microtubules in axons toward the axon terminus.
What is meant by integrative function in the CNS?
processing sensory information in order to act on it
What are the ultimate organs of motor neurons called?
effectors (muscle and glands)
Sound waves propagate through what 3 mediums in your ear?
air ► bone ► cochlear liquid
How do polypeptide hormones carry out their function in a target cell?
they bind with receptors on the cell membrane and cause a second-messenger cascade to alter enzyme activity
What is the important physical property of steroid hormones?
They are hydrophobic and bind to receptors inside the cell.
What is feature detection theory?
Specific neurons in the brain detect particular visual features (lines, edges, angles, and movement).
What is the major function of the right cerebral hemisphere?
visual-spatial reasoning
Is epinephrine a neurotransmitter or hormone?
It is a hormone that acts like a neurotransmitter (rapid effects).
Define hyperopia and its cause.
Farsightedness: caused by a flat lens resulting in too long of a focal point
How is sound pitch measured?
by the frequency (different regions of the basilar membrane will be stimulated)
What is reciprocal inhibition?
Muscles on one side of a joint contract, while muscles on the other side relax to accommodate that contraction.
What is the purpose of the ciliary muscle?
It changes the curvature, and thus the refractive power of the lens
Which hormone type how rapid, but short-lived effects?
peptide hormones
Once the neuronal membrane has been depolarized, which channels open/close?
Voltage-gated Na+ channels inactive and voltage-gated K+ channels slowly open
What is the major function of the left cerebral hemisphere?
speech
What are microglia?
glial cells in the CNS that remove debris and dead cells
What is the purpose of the vestibular complex?
It monitors balance, movement, and position.
What are thermoreceptors?
They detect changes in temperature.
What is a multipolar neuron?
a neuron that has many dendrites
