Biological Foundations of Behaviour Part II Flashcards
exteroceptors
sensory receptors that detect stimuli from the outside world
interoceptors
receptors that respond to internal stimuli
mechanoreceptors
respond to mechanical disturbances (ex. Pacinian corpuscles, auditory hair cell, vestibular hair cell)
chemoreceptors
respond to particular chemicals (ex. olfactory receptors, gustatory receptors)
nociceptors
pain receptors, stimulated by tissue injury, consists of a free nerve ending
referred pain
the illusion of pain on the skin created by nociceptors when their nerves cross paths with somatic afferents from the skin
thermoreceptors
stimulated by changes in temperature
electromagnetic receptors
stimulated by electromagnetic waves (photoreceptors)
what are four properties of sensory information that need to be communicated to the CNS?
1) modality (type of stimulus-based on which receptor is firing)
2) location (communicated by the receptive field of the sensory receptor sending the signal)
3) intensity (frequency of action potentials)
4) duration
tonic receptors
fire action potentials as long as the stimulus continues (subject to adaptation, frequency of action potentials decrease as stimulus continues at the same level)
phasic receptors
only fire action potentials when the stimulus beings, do not explicitly communicate the duration of the stimulus
adaptation
decrease in firing frequency when the intensity of a stimulus remains constant
which receptors do not adapt under any circumstances?
nociceptors
proprioception
awareness of the self (body position), aka: kinesthetic sense, ex. muscle spindle, Golgi tendon organs, joint capsul receptors
pitch
(frequency of sound), distinguished by which regions of the basilar membrane vibrate, stimulating different auditory neurons
where do low frequency wavelengths vibrate the basilar membrane?
near the apex of the cochlear duct, farthest away from the oval window
where do high frequency wavelengths vibrate the basilar membrane?
at the base of the cochlea, near the oval window
loudness
distinguished by amplitude of vibration, larger vibrations cause more frequent action potentials in auditory neurons
auditory cortex
located in the temporal lobe of the brain, processes sound
what does the vestibular complex consist of?
3 semicircular canals, the utricle, the saccule, and the ampullae
what does the vestibular complex monitor?
static equilibrium and linear acceleration to contribute to balance
rods and contes contain photopigments called opsin which is bound to one molecule and contains one molecule of retinal, what is its conformation in the dark?
several trans double bonds and one cis double bond: keeps sodium channels open, cell remains depolarized, release glutamate to bipolar cells (inhibitory), prevents optic nerves from depolarizing
what is the conformation of retinal upon absorption of light?
all-trans: closes sodium channel, cell is hyperpolarized, does not release glutamate to bipolar cells, bipolar cells depolarize, optical nerve signals to CNS
emmetropia
normal vision
myopia
nearsightedness, caused by too much refraction (short focal length) or abnormally long eyeball, corrected by concave lens
hyperopia
farsightedness, caused by too little refraction (long focal length) or an abnormally short eyeball, corrected by convex lens
feature-detection theory
visual cortex fires in response to very specific information, this info is then passed on to other neurons that begin to assimilate these distinct features into more complex objects
parallel processing
many aspects of a visual stimulus are processed simultaneously instead of in a step-by-step fashion
depth perception
the ability to see objects in three dimensions, determined by binocular and monocular cues
binocular cues
depth cues based on information received from both eyes, most important for perceiving depth when objects are close to us in our visual field
retinal disparity
a binocular cue whereby the brain compares the images project onto the two retinas in order to perceive distance
converge
binocular cue that describes the extent to which the eyes turn inward when looking at at object
monocular cues
depth cues that depend on information that is available to either eye alone and are important for judging distances of objects that are far from us since the retinal disparity is only slight
what are some monocular cues?
relative size, interposition, relative clarity, texture gradient, relative height, relative motion, linear perspective, light and shadow
absolute threshold
the minimum stimulus intensity required to activate a sensory receptor 50% of the time (and thus detect the sensation)
difference threshold
the minimum noticeable difference between any two sensory stimuli, 50% of the time (aka just noticeable difference JND)
Weber’s law
two stimuli must differ by a constant proportion in order for their difference to be perceptible, the exact proportion varies by stimulus
signal detection theory
attempts to predict how and when someone will detect the presence of a given sensory stimulus amidst all of the other sensory stimuli in the background
Gestalt
refers to the idea that the whole exceeds the sum of its part; describes perceptual organization but not how this perception occurs
Gestalt Laws of Groupings
several laws meant to help explain how we tend to perceive things
law of proximity
things that are near each other seem to be grouped together
law of continuity
perceive smooth, continuous lines and forms rather than disjoined ones
law of closure
perceive things as a logical entity because brain will fill in the gaps in the information
gestalt law of common fate
objects moving in the same direction or moving in synchrony are perceived as a group or unit
law of connectedness
things that are joined or linked or grouped are perceived as connected
bottom-up processing
begins with the sensory receptors and works up to the complex integration of information occurring in the brain; more used when we have no or little experience with a stimulus
top-down processing
when the brain applies experience and expectations to interpret sensory information; more used when stimuli is familiar
hormone
a molecule which is secreted into the bloodstream by an endocrine gland, and which has its effects upon distant target cells possessing the appropriate receptor
endocrine gland
a ductless gland whose secretory products are picked up by capillaries supplying blood to the region
exocrine glands
secrete products into the external environment by way of ducts, which empty into the gastrointestinal lumen or to the external world
hormone receptor
a polypeptide that possesses a ligand-specific binding site
what determines tissue-specificity of hormone action?
whether the cells of a tissue have the appropriate receptor
autocrine
describes activity of some signalling molecules that are able to modify the activity of the cell which secreted them
what are the two classes of hormones?
hydrophilic hormones (peptides, amino acid derivatives that bind to receptors on the cell surface) and hydrophobic hormones (steroid hormones that bind to receptors in the cellular interior)
peptide hormones
synthesized in the rough ER, modified in the Golgi, stored in vesicles until needed (release by exocytosis), dissolve in plasma, the first messenger which must bind to a cell-surface receptor, initiates a second messenger cascade causing signal amplification and changing the activity of many enzymes in the cytoplasm
steroid hormones
synthesized from cholesterol in the smooth ER, diffuses into bloodstream as soon as made (not made if not needed), sticks to proteins in the plasma through hydrophobic interactions, diffuses through plasma membrane to bind with a receptor in the cytoplasm, steroid hormone-receptor complex acts as a sequence-specific regulator of transcription to change the amount/type of proteins in the cell
tropic hormones
hormones that regulate hormones
feedback regulation applies to:
tropic hormones as well as to direct regulators of physiological endpoints
negative feedback/feedback inhibition
the result of hormone secretion inhibits further secretion
which portion of the brain controls much of the endocrine system?
hypothalamus, controls by releasing tropic hormones (releasing and inhibiting factors/hormones) that regulate other tropic hormones
hypothalamic-pituitary control axis
the hypothalamus exerts control of the pituitary by secreting hormones into the bloodstream (a unique circular miniature circulatory system) to transport hypothalamic releasing and inhibiting factors to the anterior pituitary
hypothalamic-pituitary portal system
the blood supply between hypothalamus and pituitary: consists of two capillary beds in sequence that allows for direct communication between structures
hypophysis
another name for pituitary gland
anterior pituitary
adenohypophysis; normal endocrine gland, controlled by hypothalamic tropic hormones
posterior pituitary
neurohypophysis; composed of axons which descend from the hypothalamus
neuroendocrine cells
neurons which secrete hormones into the bloodstream, ex. the hypothalamic neurons that send axons down to the posterior pituitary
what are the hormones of the posterior pituitary?
ADH and oxytocin
