Definitions Flashcards
myotatic reflex (stretch reflex)
monosynaptic reflex starting from the muscle spindle and causing contraction of the muscle on stretching
homunculus
drawing indicating the representation of different body parts on the somatosensory cortex proportionally to the number of receptors, thus causing distortion of the image
Renshaw neuron
inhibitory neuron in the spinal cord excited by a collateral of the alpha motoneuron and providing negative feedback to the motoneuron
peristalsis
wormlike movement by which the alimentary canal or other tubular organs having both longitudinal and circular muscle fibers propel their contents
glaucoma
eye disease caused by an excessive intraocular pressure due to a disturbance in the production and reabsorption of the aqueous humor
anabolism
a part of the intermediary metabolism, syntheses of materials, building up the organism’s own materials
kinocilium
long process on the apical surface of the hair cells showing cilium structure in cross section
juxtaglomerular apparatus (JGA)
cell-group located in the angular area of the glomerulus and the tubules in the nephrons that produces renin (to regulate ionic milieu and fluid balance through the renin-angiotensin system)
erection
the solidification of the penis by being filled up with blood before a sexual act
diabetes insipidus
a condition caused by the lack or decreased production of the antidiuretic hormone (ADH or vasopressin); symptoms are excessive urination and extreme thirst
Purkinje neuron
GABAergic inhibitory neuron providing the main output of the cerebellum
cretinism
retarded mental and physical state (dwarfism) caused by a low level of thyroid hormones during development
calcitriol
hormone prepared from D2 and D3; increases calcium absorption in the gut and calcium mobilization in the bone, thus increases calcium level in the blood
fenestra ovale
membrane covered opening between the cochlea and the middle ear, stapes transmit movement of the tympanic membrane to the perilymph through this opening
chief cells
pepsinogen producing cells in the stomach
polydipsia
excessive thirst and water consumption
ejaculation
the forceful removal (ejection) of the sebum through the urethra in the males
gametogenesis
production of reproductive cells (gametes) in the reproductive organs (oogenesis, spermatogenesis)
intrinsic factor
protein secreted in the stomach, needed for the absorption of B12 vitamin (extrinsic factor)
renin
peptid hormone (protease) released by the juxtaglomerular apparatus, transforms angiotensinogen into angiotensin I
ANP
atrial natriuretic peptide, secreted in the atrium of the heart, it increases Na+ and urine discharge decreasing blood volume
osteoclast
phagocyte digesting bone tissue allowing remodeling of bone
orgasm
the highest point of sexual excitement, marked by strong feelings of pleasure and marked normally by ejaculation of semen by the male and by vaginal contractions within the female
P ganglion cell
ganglion cell projecting to the parvocellular layer of the corpus geniculatum laterale
semen
a mixture of sperm cells and of excretes of different reproductive glands (prostate, vesicula seminalis) which is ejaculated during the sexual intercourse
clearance
a functional measure of the kidney function, the plasma volume that is (theoretically) fully cleared of a certain material per a unit of time in the kidneys
secretin
produced in the small intestine in response to acid, it increases HCO3- production in the pancreas and inhibits emptying of the stomach
umami
the fifth basic taste evoked by peptides, amino acids and most importantly glutamate in the food
inverse myotatic reflex (tendon reflex)
bisynaptic reflex starting from the tendon organ; it protects the muscle and tendon by relaxing the muscle, when extreme tension develops
ADH
antidiuretic hormone, hypothalamic hormone, released from the neurohypophysis, increases water permeability in the collecting duct, thus decreasing urine volume
glucogenic amino-acids
amino-acids that can enter into the sugar-metabolic pathways
extrafusal fiber
muscle fibers outside the muscle spindle
osteocyte
bone cell, osteoblasts are transformed into osteocytes; they are located in small cavities within the bone tissue and keep contact with each other through cytoplasmic processes
hyper- and hypothyreosis
over- or underproduction of the thyroid hormones in the thyroid gland, and its symptoms
endopeptidase
protease that cuts internal peptide bonds in a peptid chain
T3
triiodothyronine, the most effective hormone of the thyroid gland
portal circulation
capillaries in one organ are collected into larger vessels (veins), enter the other organ through a narrow entrance (port) and form a second capillary bed to release substances carried from the first organ (e.g. gastrointestinal tract - liver, hypothalamus - hypophysis)
aldosterone
steroid hormone of the adrenal gland, increases Na+ reabsorption in the kidney and at other places
polyuria
the excretion of an abnormally large quantity of urine
macrosmatic
animal with superior olfactory abilities
corticosteroids
steroid hormones produced by the adrenal cortex (glucocorticoids, mineralocorticoids, androgens)
tubular maximum
a rate limit of transport proteins (maximal transport capacity) in the kidney tubules above which only a portion of the given material is reabsorbed (e.g. glucose in the proximal tubule)
lipases
enzymes in the pancreatic juice that digest lipids (fat)
mineralization
(calcification) osteoid tissue becomes bone tissue by the precipitation of calcium salts
podocyte
epithelial cell type in the Bowman’s capsule attached to the basal membrane of the glomerulus, filtrate passes between its foot like processes into the tubules of the nephron
climacteric
(ending) cessation and termination of the female reproductive activity; a natural physiological procedure
calcitonin
hormone produced by C cells in the thyroid gland; inhibits osteoclast activity, thus decreases calcium level in the blood
blind spot (optic disc)
the spot on the retina, where the axons of the ganglion cells and blood vessels penetrate the wall of the eyeball; no receptor cells are found here
indirect calorimetry
estimation of the heat produced by an organism by measuring oxygen consumption and respiratory differences of oxygen and carbon dioxide in the inspired and expired air
Sertoli-cells
cells in the wall of the tubules in the testis with a crucial role in the maturation of sperm cells
alkalosis
higher than normal pH level, i.e. accumulation of base in the body
Langerhans’ islets
hormone producing (endocrine) cell-groups of the pancreas
muscle tone
continuous, slight contraction of the skeletal muscles important in the maintenance of the posture
cardiac sphincter
ring of muscles separating the esophagus from the stomach
amylases
enzymes that digest carbohydrates (in the saliva or pancreatic juice)
absorption
transport of the digested nutrients (amino-acids, sugars, fatty-acids) from the lumen of the intestine to the blood vessels across the intestinal wall
receptive field
part of the environment or body (visual field, skin, etc.) from which the activity of the examined element of the sensory system can be changed // particular region of sensory space (visual field, skin, etc.) in which a stimulus will modify the firing of the sensory neuron
neurohemal-organ
organs of neuronal origin in that store hormones (usually secreted by other neurons (e.g. neurohypophysis)
lipogenesis
synthesis of neutral fat from fatty-acids and glycerol
lipoprotein lipase
enzyme in the capillary wall catalyzing cleavage of fatty acids from lipids in lipoproteins (LDL, VLDL, etc.)
vomeronasal organ
auxiliary olfactory organ in many animals opening into the nasal or buccal cavity and detecting mainly pheromones
diuresis
discharge of urine from the urinary bladder
stimulus adaptation
the process in which the effect of the stimulus on the receptor decreases in time
fatty-acid synthesis
enzymatic production of long-chained fatty-acids from acetyl-Coenzyme-A (requires NADPH).
ultrafiltration
filtration in the glomeruli of the kidneys in which water and small organic and inorganic compounds pass the membranes from the plasma to the proximal tubule whereas colloid particles and cells remain unfiltered
melanopsin
photopigment contained by the W ganglion cells
villus, villi
small, finger-like, vascular processes found densely packed on the inner wall of the gut increasing the absorptive surface
hair cell
secondary sensory cell in the inner ear
direct calorimetry
measurement of heat actually produced by an organism confined in a sealed chamber or calorimeter
decerebrate rigidity
increase of the muscle tone caused by the transsection of the brain stem above the Deiter’s nucleus
thyroglobulin
precursor of the thyroid hormones in the acinus of the thyroid gland; a large, iodine containing protein molecule
hermaphroditism
mixed male and female characteristics within the same person
exogenous hyperglycemia
blood sugar level increases abnormally following carbohydrate consumption
Huntington’s chorea
genetic neurological disorder leading to loss of GABAergic and cholinergic cells in the neostriatum leading to jerky, random, uncontrollable movements
adrenarche
the adrenal cortex starts to produce androgen hormones at the age of 5-8, causing
catabolism
part of the intermediary metabolism, breaking down the absorbed compounds (usually for producing or storing of energy)
nephron
functional and anatomical unit of the kidneys; its parts are the glomerulus, proximal- and distal tubules, Henle’s loop and collecting duct
reabsorption
backward transport of some ultrafiltrated materials from the tubules to the blood vessels in the kidneys
conjunctiva
very sensitive epithelial membrane covering the sclera and lining the inside of the eyelids
RBF
(renal blood flow), the amount of blood flowing through the kidneys per unit of time
microsmatic
animal with inferior olfactory abilities (i.e. humans)
obligate reabsorption
the compulsory reabsorption under any circumstances of a portion of some materials (e.g. water, sodium, glucose) in the proximal tubule of the nephron
HDL
high density lipoprotein – lipoprotein in the blood containing “good” cholesterol
respiratory quotient
the carbon dioxide output divided by the oxygen uptake
segmentation in small intestine
circular muscles in the small intestine contract and relax separating the chyme into smaller pieces
juxtamedullary nephron
nephron located close to the corticomedullary border in the kidney, with long Henle’s loop descending deep in the renal medulla
lipolysis
breaking down neutral fats into fatty-acids and glycerol
reproductive cycle (or menstrual cycle)
regularly recurring changes in the sexual hormones and reproductive organs in females
hemidecussation
partial crossing of optic fibers in the chiasma opticum ensuring that information collected from the same part of the visual field by the two retinas is analyzed in the same hemisphere
circular folds
structures in the small intestine increasing surface and slowing down the movement of chyme
releasing hormones and factors
hormones or hormone-like compounds produced by the parvocellular region of the hypothalamus (hypophysiotropic area) that facilitate adenohypophysis (anterior pituitary) hormone production and release
gonadotropins or gonadotropins
hormones that regulate reproductive functions and production of sexual hormones (e.g. FSH, LH-ICSH, prolactin).
glomerulus
the functional unit of the kidneys consisting of the Bowman-capsule and of a coiled capillary system
intrafusal fiber
modified muscle fiber in the muscle spindle
cortical nephron
the most frequent nephron type located in the cortex of the kidney with short Henle’s loop
NAD- (and NADH)
co-enzyme that binds hydrogen in the glycolysis and in the citric-acid cycle and carries it to the oxidative phosphorylation
transducin
G-protein in rods and cones, activated by the photopigment during light detection
rhodopsin
photopigment of the rods
iris
circular, pigmented membrane behind the cornea, perforated by the pupil; its contraction regulates the amount of light passing into the eye
reflux
backward flow of stomach content into the esophagus due mainly to weakness of the cardiac sphincter
pyloric sphincter
ring of muscles separating the stomach from the duodenum
adenohypophysis
the frontal, glandular portion of the hypophysis (anterior pituitary) that produces trophormones
Parkinson’s disorder
movement disorder caused by the insufficient production and release of dopamine in the neostriatum by dopaminergic neurons in the substantia nigra pars compacta; it causes tremor and decreased initiation of movements
neurohypophysis
posterior lobe of the pituitary gland (hypophysis) that stores hormones secreted by hypothalamic neurons (a neurohemal organ)
incretins
intestinal hormones increasing insulin secretion
gluconeogenesis
a procedure in which the liver synthesizes de novo sugars from lactic acid and amino-acids (mainly from blood proteins)
receptor potential
membrane potential change of the sensory cell in response to the stimulus
spermatogenesis
formation and maturation of the sperms in the testes and accessory male reproductive organs
sclera
the outermost, white layer of the eyeball
citric-acid cycle (Szentgyörgyi-Krebs cycle)
final break-down of the two-carbonic compound acetyl-group that comes from either the glycolysis or the fatty-acid metabolism (beta-oxidation); the end-products are carbon-dioxide and reduced co-enzymes
epitop
characteristic part of the odor molecule that can be detected by a specific 7TM receptor on the apical surface of the olfactory sensory neuron
tip link
protein structure connecting the tips of the stereocilia; important for the deformation of the membrane and thus for the opening of the K+ channels during bending of the stereocilia
dermatome
strip-like part of the skin innervated by one spinal segment
stimulus threshold
minimal energy of stimulus that changes action potential frequency in the primary sensory neuron
T4
tetraiodothyronine, hormone of the thyroid gland
hypoglycemia
decreased blood-sugar level
calcification
(mineralization) osteoid tissue becomes bone tissue by the precipitation of calcium salts
parathormone
hormone of the parathyroid glands; increases calcium reabsorption in the kidneys and calcium mobilization in the bone, thus increases calcium level in the blood
Weber-Fechner’s law
exponential equation showing the relationship between stimulus and response in sensory systems
fermentation
anaerobic enzymatic conversion of organic compounds, especially carbohydrates, to simpler compounds usually by bacteria (e.g. fermentation of cellulose in the alimentary canal)
LDL
low density lipoprotein – lipoprotein in the blood containing “bad” cholesterol
RPF
(renal plasma flow), the amount of blood plasma flowing through the kidneys per unit of time
musculus ciliaris
the lens is attached to the ciliary body (ciliary muscles) in the eye, its contraction is needed for accommodation
endogenous hyperglycemia
blood sugar level is abnormally high without carbohydrate consumption
digestion
chemical break-down of the nutritive macromolecular polymers (proteins, carbohydrates, lipids, nucleic acids) into oligomers, dimers and finally monomers.
ketogenic amino-acids
amino-acids with ketone-like derivatives that cannot enter into the sugar-metabolism
hypophysiotropic area
parvocellular region of the hypothalamus that regulates the function of the adenohypophysis; releasing and inhibiting factors (hormones) are produced here
diuretics
drugs that increase the amount of urine and urination
ergocalciferol
vitamin D2, precursor of calcitriol, a dietary supplement found in certain fish oils and fungi
mass peristalsis
a fast and powerful peristaltic wave in the large intestine initiated by the sudden distension of the (usually empty) duodenum (frequently results in defecation)
optical illusion
distortion of visual perception at the cortical level caused by previous experiences
basal ganglia
collective name for the neostriatum, pallidum, substantia nigra and subthalamic nucleus, subcortical nuclei involved in motor control
osteoporosis
weakening of the bones due to a loss of minerals (calcium) and organic components
tubule (proximal, distal)
small tubes leading from the glomerulus to the collecting duct in the nephron
final common pathway
skeletal muscles can only be reached through the spinal or brainstem motoneuron
color blindness
disturbance of color vision caused in most cases by a mutation in the genes coding for the photopigments; the most common form is the red/green color blindness
ketoacidosis
acidosis caused by the increased production of acidic ketone bodies (e.g. in diabetes mellitus)
M ganglion cell
ganglion cell projecting to the magnocellular layer of the corpus geniculatum laterale
topography
the spatial arrangement of the sensory cells is mapped throughout the sensory system
glycolysis
break-down procedure of 6-C sugars into acetyl (-Coenzyme-A)-group
pentose-phosphate cycle
an alternative route to the glycolysis in which 5 C-atom sugars (e.g. ribose, etc.) are formed; NADPH, a co-enzyme necessary for fatty-acid synthesis is also produced here
menopause
termination of the female reproductive activity; result of a natural physiological procedure
exteroceptor
receptor receiving stimuli from outside the body
deep cerebellar nucleus
most of the cerebellar Purkinje cells project through these nuclei to other parts of the brain
gastrin
hormone produced in the stomach, increases HCl secretion
choroid
the middle, vascularized layer of the eyeball, including the iris and the ciliary body (ciliary muscles)
puberty
the period of human development during which physical growth and sexual maturation occurs
cholecalciferol
vitamin D3 (hormone), precursor of calcitriol, synthesized in the skin upon UV irradiation
acidosis
lower than normal pH level, i.e. accumulation of acid in the body
proteases
enzymes digesting proteins and polypeptides
fovea centralis
a depression in the center of the macula of the retina, the area of the most acute vision, where only cones are present
spinocerebellum (paleocerebellum)
consists of the vermis and the intermediate part of the hemispheres, it monitors the execution of motor commands issued by the cortex
opsin
protein part of the photopigment
horizontal cell
inhibitory interneuron in the retina connecting receptor cells
scotopic vision
monochromatic vision produced through the rods in low light
photopic vision
chromatic vision produced through the cones under well-lit conditions
white muscle fiber
muscle fiber characterized by few mitochondria, low myoglobin content, quick fatigue, but very fast contraction
red muscle fiber
muscle fiber characterized by good blood supply, many mitochondria, high myoglobin content and slow fatigue
emission
the release of the semen from it stores (vesicula seminalis) to the urethra before ejaculation
bilirubin
yellowish bile pigment produced by breakdown of heme
dark current
continuous inflow of Na+ and Ca++ into rods and cones in dark through cGMP-regulated channels, causing hypopolarization and glutamate release
rachitis (rickets)
malformation (weakness) of bones caused by the lack of vitamin-D that leads to a decreased absorption of calcium from the gut during development
Addison’s disease
caused by the insufficiency of the adrenal cortex most frequently due to an autoimmune process; it leads to extreme weakness, darkening of the skin and increased discharge of urine
presbiopia
in elderly people the lens looses its flexibility, thus accommodation is no longer possible for short distances; corrected by reading glasses
interoceptor
receptor receiving stimuli from outside the body
cerebrocerebellum (neocerebellum)
the newest part of the cerebellum, consists of the lateral part of the hemispheres, its role is in the learning, starting and stopping movements
somatotopy
topography in the somatosensory and motor system
nucleases
enzymes digesting nucleic-acids (e.g. DNA, RNA)
goblet cells
cells in the stomach producing mucus and NaHCO3
lactose intolerance
lactose contained by milk and some diary products is not metabolized in the gut due to the lack of the enzyme lactase
glucocorticoids
hormones produced by the adrenal cortex regulating sugar- and protein-metabolism (cortisol, hydrocortisone)
osteoid tissue
organic part of the bone matrix made up by fibers and other components, its mineralization finishes bone formation
taste bud
structure serving the sense of taste, it contains sensory and supporting cells
oxidative phosphorylation
final phase of the energy metabolism in the mitochondrion; hydrogen is moved from reduced co-enzymes (FADH2, NADH) to oxygen forming water, while released energy is stored in the form of ATP
annulospiral ending
terminal of the Ia fiber on the intrafusal fiber
Leydig-cells
interstitial cells producing testosterone in the testes
enteropeptidase
enzyme secreted by the duodenum; transforms trypsinogen into trypsin
telereceptor
the source of the stimulus is distant from the receptor
stereocilium
processes on the apical surface of the hair cells filled with actin filaments and bearing mechanosensitive K+ channels at the tip
myxedema
accumulation of mucopolysaccharides in the skin causing edema in patients with hypothyroidism
diabetes mellitus
disease due to the lack or ineffectiveness of the insulin hormone; symptoms are sugar in the urine, excess urination and overdrinking, acetone in the saliva, metabolic disturbances, sometimes coma
facultative reabsorption
controlled reuptake of certain elements of the primary urine (ultrafiltrate) in the distal kidney tubules and collecting duct according to the need of the organism
motor unit
collection of muscle fibers innervated by the same motoneuron
trop hormones
pituitary (adenohypophysis) hormones that stimulate production and release of other hormones from other glands (e.g. TSH, ACTH, FSH)
Cori-cycle
a procedure in which the lactic-acid produced in the muscles under anaerobic conditions is rebuilt to sugar in the liver on the expense of the break-down of its 1/3 amount
amacrine cell
interneuron in the retina establishing horizontal connections mostly close to the ganglion cells
CCK
cholecystokinin produced in the small intestine in response to lipids and proteins, it induces emptying of the gallbladder, increases enzyme production in the pancreas and inhibits emptying of the stomach
Henle’s loop
a tubule connecting the proximal and the distal tubules in the kidneys
cis-retinal
organic compound derived from vitamin A; in visual pigments it absorbs the energy of photons
proprioceptor
receptor detecting the position of the body and the state of the muscles, tendons and joints
mineralocorticoids
hormones produced by the adrenal cortex that regulate sodium/potassium (Na+/K+) ratio (aldosterone, DOC)
regurgitation
in ruminants chyme reenters the buccal cavity without vomiting
remodeling
the continuous degradation and rebuilding of the bone tissue
fenestra rotunda
membrane covered opening between the cochlea and the middle ear, it lets the perilymph move when the stapes pushes the membrane at the fenestra ovale
fenestra rotunda
membrane covered opening between the cochlea and the middle ear, it lets the perilymph move when the stapes pushes the membrane at the fenestra ovale
endolymph
fluid in the membranous labyrinth of the inner ear, produced by secretion, characterized by high K+ levels
inhibiting hormones and factors
hormones produced by the parvocellular (small cell) region of the hypothalamus that regulate adenohypophysis functions
perilymph
fluid in the perilymphatic space of the inner ear, produced by filtration, thus its composition is the same as that of other extracellular fluids
menstruation
removal of the uterine endometrium accompanied by bleeding at the end of the menstrual cycle
osteoblast
bone forming progenitor cell
cataract
eye disease caused by an opacity of the lens
Cushing’s symptoms
caused by high levels of cortisol in the blood frequently due to steroid medication; it leads to disproportional fat deposition on the trunk, neck and face
GIP
glucose-dependent insulinotropic hormone, produced in the small intestine in response to carbohydrates, it induces insulin secretion and inhibits emptying of the stomach
organ of Corti
the organ of hearing in the inner ear
Chinese restaurant syndrome
temporary, inconvenient symptoms caused by overdosing the taste enhancing, but also neuroexcitatory monosodium glutamate (MSG)
urea
nitrogen containing compound actively eliminated by the kidneys; the main way to eliminate excess nitrogen
ovulation
ejection of the matured oocyte (ovum) from the follicle in the ovary
GFR
(glomerular filtration rate) the amount of fluid filtrated per unit of time in the glomeruli of the kidneys
zona pellucida
protective layer around the ovum
parietal cells
HCl producing cells in the stomach
contact receptor
the source of the stimulus has to be in contact with the receptor to elicit a response
exopeptidase
protease that cuts amino acids from the end of peptide chains
digastric stomach
stomach possessing both fermentative and digesting parts
vestibulocerebellum (archicerebellum)
the most ancient part of the cerebellum (flocculonodular lobe), its input comes from the vestibular organ, and its main function is to keep posture and balance
cornea
frontal, transparent part of the sclera with the highest refracting power
gonads
organs producing reproductive cells (gametes) (testis, ovary)
motoneuron pool
collection of motoneurons innervating muscle units in the same muscle
