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123 Cards in this Set
- Front
- Back
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Eletrical Transmission |
gap junctions connect cells using connexons which allow ions of the action potential to conduct directly into the effector neuron - faster than chemical - bidirectional - excitatory |
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Chemical Transmission |
signals sent through neurons through neurotransmitters that bind to receptors on post-synaptic membrane - plastic - unidirectional - excitatory or inhibitory |
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Describe neurotransmitter release |
1) action potential arrives 2) Ca2+ triggers vesicle fusion into cleft 3) neurotransmitter binds |
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Ionotropic Receptors |
- fast - ligand-gated ion channel receptors - increase permeability |
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Metabotropic Receptors |
- slow - g-coupled protein receptors - activate signaling cascade |
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Excitatory post-synaptic potential (EPSP)
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- depolarization - ion channels: Na+ and Ca2+ - neurotransmitters: acetylcholine (muscles) and glutamine (neurons) |
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Inhibitory post-synaptic potential (IPSP) |
- hyperpolarization or anything below threshold - ion channels: K+ and Cl- - neurotransmitters: glycine and GABA * ACh is inhibitory in the heart |
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Spatial Summation |
- the closer to the hillock the stronger the potential - when multiple post-synaptic potentials go off, they are added together |
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Temporal Summation |
- when one synapse is fired multiple times, the post-synaptic potentials will add up |
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Name 4 ways that transmission is terminated |
1) ion channel inactivation 2) enzymatic decay of neurotransmitter 3) uptake by presynaptic or nearby cell 4) endocytic internalization |
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Acetylcholine |
* body/heart - nicotinic/muscarinic receptor - ionotropic/metabotropic - excitatory/inhibitory - amine |
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Glutamate |
- AMPA receptor - ionotropic - excitatory |
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GABA |
- GABAA/GABAB receptors - ionotropic/metabotropic - inhibitory |
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Glycine |
- ionotropic - inhibitory |
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Agonist |
ligand that binds for another molecule and causes and effect - ex: morphine, codine, heroin |
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Antagonist |
ligand that binds for another molecule with no effect - ex: Narcan (given to people overdosing on opioids) |
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Neuromuscular juction |
- larger than neuron-neuron - EPSP is larger - no IPSP in vertebrates
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Ionotropic Receptors |
- ligand-gated - open ion channel - not a second messenger - direct gating of ion channels - fast PSP |
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Metabotropic Receptors |
- g-protein coupled - activate g-protein, cascade - usually second messenger - indirect or no gating of ion channels - slow PSP |
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Synaptic plasticity |
- ability to change synaptic strength over time - ex: habituation and sensitization |
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Conditioning |
- using eletrical and tactile stimuli together to be able to elicit a response when using one or the other - the response is mediated by long term potential (Ca2+ enters cell) - neurons that fire together wire together |
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Long-Term Memories |
- caused by structural changes in synapse or gene expression (protein synthesis) - also related to LTP (increases size of dendritic spines) |
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Receptor Cells |
specialized cells that transmit a graded response to an afferent neuron |
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What does receptor potential amplitude vary with? |
stimulus strength |
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Action potential frequency varies with what? |
potential amplitude |
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Describe sensory adaptation |
prolonged sensory signals result in decreased neural responses (fast) |
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Labeled lines |
sensory signals are distinguished by which axons carry the signal, but the signal is the same (action potentials) |
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Chemoreception |
- simplest type - taste: direct contact - smell: at a distance - mediated by neurotransmitter release |
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Taste |
- chemoreception by direct contact - each taste bud is made up of several chemoreceptive cells, but each cell can taste only one flavor - flavors: salty, sour, bitter, sweet, umami (MSG), fat |
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Tasting Salt |
Na+ flows into taste cells and depolarizes membrane |
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Tasting Sour |
1) H+ ion closes K+ channel 2) Na+ becomes more permeable and depolarizes membrane |
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Tasting bitter, sweet and umami |
sensing transduced through metabotropic receptors (g-coupled secondary messenger) |
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Smell |
- chemoreception at a distance
- normally senses airborne chemicals - receptors very similar to taste receptors - detects food, predators, competitors, and potential mates |
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Smelling airborne chemicals |
- airborne chemicals dissolve in the mucus layer - receptor molecules sense chemicals which can cause transduction - receptor cells have thin unmyelinated axons straight into brain - cells depolarized by (metabotropic) activation of Ca2+ dependant Cl-channels |
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Rods |
- more sensitive and used in dim light 1) light changes the confirmation of the rhodopsin receptor, located on intracellular disk membranes 2) g-protein activates 3) secondary messenger is degraded 4) Na+ channels deactivate and hyperpolarize cell |
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Cones |
used in bright light to produce colors |
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Dark current (seeing under dark conditions) |
- under dark conditions, cGMP-gated Na+ channels are always open and flowing - leads to graded response |
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Seeing under light conditions |
cGMP is enzymatically degraded, closing cGMP-gated Na+channels |
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Color Vision |
- the result of having having three different cone pigments (blue, green, red) - perception of color results from the ration of the colors |
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Mechanoreception |
stretch-gated ion channels activate due to cytoskeletal tension |
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Vestibular organs |
- used for reception of equilibrium - ex: statocyts (snails), acoustico-lateralis system (vertebrates) |
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Hearing |
sound waves cause vibration in the tympanic membrane, which are conducted to auditory ossicles of the middle ear |
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Common themes in the senses |
1) stimulation is usually graded not all-or-none 2) sensory cells can habituate 3) each cell can only transduce one message 4) receptors are membrane bound proteins |
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Order the senses in most to least number of chemosensors |
1) olfactory (~1000) 2) taste (~4-10) 3) photo (~4) 4) mechanoreceptors (~1). |
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Neurons |
what nervous systems of all animals are based on |
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Reflex arcs |
1) stimuli 2) sensory neurons 3) centran nervous system 4) motor neurons 5) effectors; movement |
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Centralization |
neurons tend to be gathered in a central nervous system (CNS) |
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Relative size |
size of each brain region is related to the relative importance of that region’s sensory input or motor output |
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Nerve net |
- simplest form of a nervous system
- no central organizing structure |
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Central Nervous System (CNS) |
- brain, spinal cord and all the neurons, ganglia, synapses, and tracts within - accompanied by bilateral symmetry and cephalization |
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Segmentation |
- many local responses are contained completely within repeated segments - each segment associated with ganglia (peripheral neural hubs) |
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Gray matter |
- consists of cell bodies, synapses, and unmyelinated neural processes - less axons, more synapses |
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White matter |
myelinated axon bundles |
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Peripheral Nervous System (PNS) |
composed of peripheral nerves, ganglia, neurons, and synapses located outside of brain and spinal cord |
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Nerves |
-bundles of peripheral axons - tract: nerve within CNS |
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Which two major outgrowths become more pronounced in higher vertebrates? |
1) cerebrum (forebrain) 2) cerebellum (hindbrain) |
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Sympathetic effect |
- controls "fight or flight" response (stress) - inhibits digestion - increases rate and force of heartbeat - constricts vessels - increases blood pressure - opens airways - stimulates secretion of epinephrine |
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Parasympathetic effect |
- controls "rest and digest" functions - dominates at rest - stimulates digestion - slows heartbeat - dilates blood vessels - decreases blood pressure - constricts airways - contracts urinary blatter |
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Acetylcholine in the ANS |
receptors are nicotinic on all postganglionic nerves (i.e. the first synapse) and muscarinic on the effector organs stimulated by the parasympathetic system (i.e. the second synapse)
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Norepinephrine in the ANS |
the neurotransmitter at the effector organs for the sympathetic system |
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Nicotinic ACh Receptors |
- ionotropic receptors - permeable to Na+,K+, & Ca2+ - functionally similar in action to the muscle nicotinic receptors at the NMJ |
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Muscarinic ACh Receptors |
- g-protein mediated metabotropic receptors that activate secondary messenger systems
- located only at post-ganglionic synapses of parasympathetic division |
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Catecholamines |
1) dopamine 2) epinephrine 3) norepinephrine * target adrenergic receptors * release stimulated by sympathetic divison |
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Adrenergic Alpha Receptors |
- Alpha 1: vasoconstriction (arteriole smooth muscle) and glucogenesis (liver) - Alpha-2: inhibition of insulin release (pancreas) |
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Adrenergic Beta Receptors |
- Beta-1: increase in heart rate and contractile force - Beta 2: smooth muscle (dilation of bronchioles, relaxation of uterus, GI tract) |
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Adrenal Medulla |
- under sympathetic control - releases norepinephrine when activated |
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What do the CNS and Endocrine System do together? |
mediate an acute stress response to quickly enable short-term burst capabilities |
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4 types of transmission |
- neural: fast - endocrine: slow - neurosecratory: broadcast - paracrine: local |
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Pheromones |
chemical signaling between conspecific organisms |
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Hormones |
- chemical substances used by the neuroendocrine system to exert regulatory control over target cells - may be secreted by isolated cells or tissues or by organized endocrine glands - bind to receptor molecules expressed by target cells |
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What 2 things does the magnitude of a hormone's effect depend on? |
1) abundance of hormone 2) abundance of receptor |
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Steroid Hormones |
- cholesterol derivatives
- lipid soluble - secreted by gonads and adrenal cortex - target receptors are intracellular - synthesized as needed, not stored - ex: testosterone, cortisone, aldosterone |
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Peptide Hormones |
- peptide chains
- water soluble - secreted by many glands/organs - target receptors are extracellular - stored in secretory granules and released by exocytosis - ex: insulin |
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Amines |
- tyrosine (catecholamines) and tryptophan (melatonin) derivatives
- secreted by few glands/organs (e.g. adrenal medulla, thyroid). - ex: dopamine, epinephrine, melatonin |
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Endocrine Glands |
release hormones into bloodstream |
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Adrenal Cortex |
- secretes: 1) aldosterone: stimulates Na+ reabsorption and K+ secretion in kidneys 2) androgen: induce growth spurt at puberty 3) glucocorticoids: part of stress response - all steroids |
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Adrenal Medulla |
- secretes: epinephrine and norepinephrine: reinforce sympathetic response system - catecholamines |
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Two major classes of hormone secreting cells |
1) epithelial endocrine cells: usually stimulated by other hormones (adrenal cortex) 2) neurosecratory cells: stimulated by neural input (adrenal medulla ((inside))) |
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Anterior Pituitary Glad Secretes: |
-adenohypophysis (neurohormonal control from hypothalamus via portal system) 1) prolactin 2) growth hormone 3)adrenocorticotropic hormone (ACTH, corticotropin) 4) thyroid-stimulating hormone 5) follicle-stimulating hormone 6) lutenizing hormone |
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Anterior Pituitary Gland acts: |
- through capillaries and hypo-hypo portal vessels 1) on nonendocrine tissues: growth hormone; influence growth and metabolism of bone & muscle 2) on other endocrine glands: ACTH; stimulates production of adrogens and cortisol from adrenal cortex |
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Posterior Pituitary Gland |
- neurohypophysis (neural control from hypothalamus via neural synapses) 1) antidiuretic hormone (ADH): water retention in kidneys, vasodilation 2) oxytocin: contraction of uterus during birth, lactation, bonding |
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Pituitary Gland |
- located at the base of the hypothalamus
- secretes hormones that regulate much of homeostasis - tells other endocrine glands what to do |
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Anterior pituitary releasing hormones |
stimulate release of anterior pituitary hormones |
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Anterior pituitary inhibiting hormones |
inhibit release of anterior pituitary hormones |
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Tropic Hormones |
- released by anterior pituitary - stimulate release of other hormones - synthesized and secreted within its endocrine cells |
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Axis |
- sequence of endocrine control - ex: Anterior Pituitary > ACTH > Adrenal Cortex > Target tissue - ex: TSH > Thyroid gland > Thyroid hormones > Growth - ex: ACTH > Adrenal Cortex > Glucocorticoids > Stress response |
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Hypo-Pituitary-Adrenocortico Axis |
1) neural input 2) hypothalamus to portal system (secretes CRH) 3) anterior pituitary gland to general circulation (secretes ACTH) (more ADH) 4) adrenal cortex to target tissue (secretes glucocorticoids) - regulated by negative feedback |
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Insulin |
- peptide hormone secreted by beta cells - decreases blood glucose- promotes storage and uptake of nutrients - concentrated in cells that store glycogen - helps absorb amino acids too - inhibitory to glucagon and epinephrine |
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Epinephrine is synergistic to what |
glucagon |
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Early physiological effects of stress |
- heart rate up - ventilation up - vasoconstriction of regions like skin - glucagon up, insulin down - digestion down - fat catabolism up - glucose released from stores |
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Delayed physiological effects of stress |
- liver glucogenesis up - glucose up - protein catabolism up - amino acids up - fat catabolism up - free fatty acids and glycerol up - inhibition of TSH, GH, and gonadotropins |
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ADH |
- from pituitary gland - conservation of water - stimulates kidney to retain fluid by concentrating urine - stimulates aquaporin channels allowing water into the bloodstream |
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Aldosterone |
- from adrenal cortex - keeps water's concentration gradient towards bloodstream - stimulates kidney to retain Na+ which leads to retention of fluid - when blood pressure is low, renin is secreted leading to aldosterone secretion - increases Na+-K+ pump activity to conserve Na+ |
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Glucagon |
- peptide hormone secreted by alpha cells - promotes glucose release from storage (liver) |
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Why are insulin and glucagon secreted together? |
- to maintain normal blood glucose (homeostasis) |
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Diabetes |
- insulin failure (beta cells) - Type 1: body doesn't produce insulin (genetic) - Type 2: body produces insulin but becomes resistant (environmental/diet) |
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Other hormones that regulate nutrient levels: Cortisol |
- promotes glucogenesis in liver (glucose up) - steroid hormone from adrenal cortex - secreted in response to HPA activity (stress) - synergistic with epinephrine, inhibitory to insulin |
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Other hormones that regulate nutrient levels: Epinephrine |
- promotes glucogenesis in liver (glucose up) - catecholamine from adrenal medulla - secreted in response to sympathetic stimulation (stress, exercise) -synergistic with cortisol, inhibitory to insulin |
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Injecting a newt with Corticosterone does what |
inhibits the clasping motor response |
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Injecting a vol with ADH or Oxytocin does what |
makes it become monogamous with first member of opposite sex that it sees |
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Asexual reproduction limits what? |
the # of an individuals own alleles being passed down |
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Sexual production increases what? |
diversity |
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Environmental influences on reproduction |
- nutrient availability - social status/activity - physical environment (temp-dependant sex determination, seasonal reproduction) |
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Estrous cycle |
- non spontaneous - animal goes into "heat" during ovulation - no menstruation |
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Menstrual cycle |
- spontaneous, happens sometimes - shedding of uterine lining after each cycle that does not result in pregnancy |
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Induced ovulation |
- ovulation in response to copulation 1) copulation stimulates impulses from cervix to brain 2) hypothalamus releases gonadotropin releasing 3) anterior pituitary secretes LH into blood 4) ovarian tissues respond to LH by stimulating ovulation |
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Oocyte |
female gamete |
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Spontaneous Ovulation Cycle |
period starts 3-7 days: menses 11-21 days: follicular phase ovulation fertile period 6 days 12-16 days: luteal phase period starts |
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During ovulation, what helps the follicle maature |
the hypothalamus 1) GnRH 2) LH 3) FSH 4) Estrogen |
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Uterine Ovulation Phases |
day 0-5: menstrual day 6-14: proliferative day 15-28: secretory |
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Ovarian Ovulation Phases |
day 0-13: follicular day 14: ovulation (triggered by LH surge) day 15-28: luteal |
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Corpus luteum |
- the ruptured follicle - acts as temporary endocrine gland to aid with process |
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Ovarian hormones |
- estrogen (spike just before ovulation): accelerates maturation of follicle - inhibin (spike just before ovulation) - progesterone (spike after ovulation): produced by luteum in women and adrenal cortex in both sexes, prepares genital tract for pregnancy, required for vascularization |
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Endometrium |
- lining of uterus - thickens and becomes vascularized before and after ovulation - lining shed during menstrual phase if pregnancy doesn't occur |
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Spermatogonia |
stem cells that produce immature sperm |
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Testosterone |
- synthesized in testes and adrenal cortes in males and ovaries and adrenal cortex in females - GnRH-LH axis - negative feedback - stimulates spermatogenesis and sexual dimorphogenesis |
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Fertilization |
- fusion of egg and sperm - occurs within upper third of oviduct near ovary |
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Fertilization timeline |
1) ovulation 2) fertilization (in tube near ovary) 3) development 4) implantation (uterus) |
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Acrosomal reaction |
release of enzymes by sperm to dissolve zona pellucida and block other sperm |
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Chorionic gonadotropin |
rescues the corpus luteum/progesterone from degeneration |
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Late pregnancy |
- high blood estrogen leads myometrium to produce connexons and oxytocin receptors - uterus cells can now respond to oxytocin in concert |
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Birth |
- positive feedback mechanism 1) baby drops lower (mechanical stimulation) 2) stretch of cervix releases oxytocin into blood from posterior pituitary 3) oxytocin causes contractions 4) contractions drop fetus lower |
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Lactation |
- hypothalamic stimulation leads to secretion of prolactin (anterior) and oxytocin (posterior) - increased blood prolactin leads to milk production - increased blood oxytocin stimulates milk ejection |
