3A Flashcards
CNS is made up of the
brain + spinal cord
forebrain
cerebrum
lateralization of cortical functions (2)
language: production + comprehension = left hemisphere
Emotion: left = positive; right = negative
Frontal lobe (3)
motor, prefrontal, Broca’s area
Parietal lobe (2)
somatosensory cortex, spatial manipulation
Occipital lobe (2)
vision, “striate cortex”
Temporal lobe/cortex (2)
sound, Wernicke’s area
Brainstem (4)
reticular formation, long tracts, cranial nerves midbrain pons (hindbrain), medulla (hindbrain)
cerebellum
hindbrain–movement and balance
White matter
axons encased in myelin sheaths (deeper) [myelinated fiber tracts]
Grey matter
unmyelinated cell bodies + dendrites (soma)[bundles of neuron bodies]
Forebrain (aka _______) becomes ____
Forebrain (aka Prosencephalon) becomes cerebrum
afferent
Sensory input
Nerve impulses conveyed to the CNS
efferent
Motor output
Nerve impulses from CNS to effector organs
sympathetic nervous system
controls the body’s automatic response to danger, increasing the heart rate, dilating the blood vessels, slowing digestion, and moving blood flow to the heart, muscles, and brain.
• Sympathetic: far from effectors (because need distance to generate strong, coordinated signal needed for flight or flight); uses epinephrine/norepinephrine
parasympathetic nervous system
works in opposition to the sympathetic; during periods of rest, it slows the heart rate, lowers the blood pressure, stimulates digestion, and moves blood flow back to the skin.
- Parasympathetic: close to effectors, give more uncoordinated signals; uses acetylcholine
- Both innervate the same organs, have opposing influences on the same organs, their signals compete with each other = antagonistic control
NT released from the postganglionic synapse
acetylcholine or nitric oxide
Monosynaptic reflex arc
consists of only 2 neurons (1 sensory, 1 motor)
presence of a direct single synapse. No interneuron is present.
Polysynaptic reflex arc
1 or more interneurons connect afferent (sensory) and efferent (motor) signals; causes the stimulation of sensory, association, and motor neurons
Positive feedback loops
unstable systems; a change in a given direction causes an additional change in the same direction (ie uterine contractions → oxytocin release → more contractions)
Negative feedback loops
stable systems; a change in a given direction causes a change in the opposite direction
(ie a ↓ in BP → ↑ in antidiuretic hormone → ↑ BP)
Synaptic transmission
chemical activity that is involved in the transmission of the impulse via release, diffusion, receptor binding of NT molecules which are essential for the impulse to be forwarded to the postsynaptic neuron.
Presynaptic Neuron (4)
- Voltage-gated calcium channels open
- Influx of calcium
- Exocytosis of secretory vesicle
- Release of NT into synaptic cleft
Postsynaptic Neuron (3)
- NT binds to ligand-gated ion channel
- Ions enter postsynaptic cell
- Membrane polarization is increased or decreased
Postganglionic neurons in sympathetic nervous system use
epinephrine
All preganglionic neurons in autonomic and postganglionic neurons in parasympathetic nervous system use
acetylcholine
Depolarized
when the inside of the cell loses the negative potential
Hyperpolarized
when the cell drops to a more negative potential after peaking at +40 mV in an action potential
Resting potential
At the resting membrane potential, all voltage-gated Na⁺ channels and most voltage-gated K⁺ channels are closed. The Na⁺/K⁺ channels are closed. The Na⁺/K⁺ transporter pumps K⁺ transporter pumps K⁺ ions into the cell and Na⁺ ions out.
Spatial summation
the effects of impulses received at different places on the neuron add up so that the neuron may fire when such impulses are received together, even if each impulse on its own would not be sufficient to cause firing.
Temporal summation
the effects of impulses received at the same place can add up if the impulses are received in close temporal succession.
Excitatory synapse
receptor binding causes postsynaptic potential to be more positive (depolarization) = if it gets above threshold, action potential results
Inhibitory synapse
receptor binding causes postsynaptic potential to be more negative (hyperpolarization) = makes it more difficult to reach threshold
Glial cells
guides developing neurons to their destinations; buffers ions & chemicals that would otherwise harm neurons; provides myelin sheaths around axons
Astrocytes
makes contact w/ both capillaries & neurons in the CNS to provide nutrients and other substances to neurons
Microglial cells
monitors and maintains the health of neurons by detecting injuries to the neuron
Ependymal cells
involved in the production of CSF which serves as a cushion for the brain
Oligodendrocytes
line up along the nerve fibers in the CNS; wraps their process tightly around the fibers producing the insulating myelin sheath
Schwann cells
myelinates the axons of the PNS
Satellite cells
highly sensitive to injury & inflammation; contributes to pathological states like chronic pain
Nernst equation
concentration cell
a voltaic cell that has the same electrodes but different [electrolytes] on either side of the cell joined by a salt bridge. This difference in concentration is enough for a voltage to be generated
Electrons always flow from the
Anode to the Cathode. {Mnemonic: A to C in alphabetical order}
Oxidation (at the ___)
Oxidation (at the anode) produces electrons (and cations) and shoots out electrons toward the cathode. The cathode receives those electrons and uses them for reduction.
Ligand-gated ion channels
form a pore through the plasma membrane that opens when a signaling molecule binds; allows ions to flow into or out of the cell
voltage-gated ion channels
open in response to a change in membrane potential.
Receptor enzymes or enzyme-linked receptors
cell-surface receptors with intracellular domains that are associated with an enzyme.
G-protein-coupled receptors
transmembrane proteins that act as molecular switches by converting between on and off states to convert an extracellular signal into an intracellular signal.
Cell-surface receptors
transmembrane receptors, are cell surface, membrane-anchored, or integral proteins that bind to external ligand molecules.
Cell-surface receptors/cell-specific proteins or markers
specific to individual cell types. Each cell-surface receptor has three main components: an external ligand-binding domain (extracellular domain), a hydrophobic membrane-spanning region, and an intracellular domain inside the cell. The size and extent of each of these domains vary widely, depending on the type of receptor. Cell-surface receptors are involved in most of the signalling in multicellular organisms.
fatty acid chain of lipids— saturated vs unsaturated
saturated which contain only single bonds b/t the carbons, and unsaturated, which contain a double bond between two carbons in the chain. Unsaturated fatty acids contain either cis or trans double bonds
Steroids
a type of lipid, are composed of four fused carbon rings. Many steroids contain an -OH functional group attached at a site. Cholesterol = the most common steroid.
Terpenes
hydrocarbons that consist of isoprene units.
Isoprene units contain five carbon atoms attached to eight hydrogen atoms (C₅H₈).
Terpenoids
oxygenated derivatives from terpenes and their isoprene units consist of five-carbon units attached to an oxygen-containing group.
Hormones
chemical messenger molecules that help to regulate the physiological process of the body along with the nervous system. They are released by endocrine glands in the blood. The hormones travel via the blood to reach the specific target cell, tissues and organs and show their effects to regulate certain physiological processes of the body.
Endocrine glands secrete hormones into
surrounding tissue fluids (hormone, no duct, acts long distances)
The exocrine system secretes
substances out of ducts (ie the salivary and sweat glands; sebaceous, ceruminous, mammary, lacrimal, and mucous glands) (non-hormone secretions into ducts)
Autocrine
they secrete chemicals to act in short distances and on themselves
Paracrine
they secrete hormones that work over short distances but on other organs.
Juxtacrine
requires cells to be in close contact w/ each other; more local than paracrine signaling
Merocrine cell
cell releases its secretions through exocytosis
Holocrine secretion
plasma membrane rupture, destroying the cell and releasing its product from the cytoplasm into the lumen (ie sebaceous glands
hypothalamus and its hormones
its an endocrine organ located in the brain. The hypothalamus synthesizes hormones such as ADH and oxytocin. The hypothalamus also synthesizes and secretes regulatory hormones that control the endocrine cells in the anterior pituitary gland such as Gonadotropin-Releasing Hormone, Thyrotropin Releasing Hormone, Growth Hormone Releasing Hormone and somatostatin.
pituitary gland
“master gland,” is located at the base of the brain. The pituitary has two distinct regions: the anterior pituitary and the posterior pituitary.
anterior pituitary hormones
seven hormones: growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), melanin-stimulating hormone (MSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). Anterior pituitary hormones are sometimes referred to as tropic hormones because they control the functioning of other organs. While these hormones are produced by the anterior pituitary, their production is controlled by regulatory hormones produced by the hypothalamus.
posterior pituitary hormones
The antidiuretic hormone (ADH) (or vasopressin) and oxytocin are produced by neurons in the hypothalamus and transported to the posterior pituitary. They are released into the circulatory system via neural signalling from the hypothalamus. These hormones are considered to be posterior pituitary hormones even though they are produced by the hypothalamus since that is where they are released into the circulatory system.
thyroid gland
one of the largest endocrine glands in the body, is located in the neck, just below the larynx and in front of the trachea. The thyroid gland produces the hormones T3 (triiodothyronine) and T4 (thyroxine) which increase the metabolic activity of the body‘s cells.
parathyroid glands
small endocrine glands that produce parathyroid hormone.
Adrenal glands
a pair of ductless glands located above the kidneys. The adrenal glands produce glucocorticoids and androgens, which are sex hormones that promote masculinity. Androgens are produced in small amounts by the adrenal cortex in both males and females. They do not affect sexual characteristics and may supplement sex hormones released from the gonads. The adrenal medulla contains large, irregularly-shaped cells that are closely associated with blood vessels. The adrenal glands also produce epinephrine (adrenaline) and norepinephrine (noradrenaline) in response to stress
pancreas
located between the stomach and the proximal portion of the small intestine. It contains both exocrine cells that excrete digestive enzymes and endocrine cells that release hormones. As an endocrine gland, the pancreas produces several important hormones, such as insulin and glucagon in the islets of Langerhans, which are secreted into the bloodstream to regulate blood sugar levels
pineal gland
small endocrine gland in the brain. It is located near the center of the brain, between the two hemispheres. The main hormone produced and secreted by the pineal gland is melatonin.
gonads
additional types of endocrine glands. They are the sex organs and include the male testes and female ovaries. Their main role is the production of steroid hormones. The testes produce androgens, which allow for the development of secondary sex characteristics and the production of sperm cells. The ovaries produce hormones, such as estrogen and progesterone, which cause secondary sex characteristics and prepare the body for childbirth..
Insulin
peptide hormone from the β-cells of pancreas; responds to ↑BGL; reduces BGL by promoting transport of glucose into cells via insulin receptors which activate membranebound glucose transporters & ↑ the transport of amino acids into the cell
Glucagon
peptide hormone from the α-cells of the pancreas; responds to ↓ BGL and ↑ BGL by promoting glycogenolysis and glucogenesis
Cortisol
(glucocorticoid) = released by the adrenal cortex; associated w/ long-term responses to stress and ↑ BGL
Epinephrine— released by the ____; role in _____; raises ____ under ____
Epinephrine = released by the adrenal medulla; role in fight-or-flight response; raises BGL under intense physical stress
Calcitonin
released by the C cells of the thyroid; inhibits osteoclast activity
Vitamin D
regulation of serum Ca²⁺ and phosphate levels
Cholecalciferol
inactive vitamin D₃ = processed to form calcitriol, the biologically active form that affects Ca²⁺ and phosphate levels; it has a similar function to PTH— both ↑ serum calcium levels, but calcitriol do so by promoting the absorption of Ca²⁺ from the GI tract
Aldosterone
mineralocorticoid (steroid hormone)
‣ ↑ Na⁺ absorption in the distal convoluted tubule and collecting duct of the nephron
‣ It ↑ K⁺ and H ion excretion in the urine
‣ Effects focus on solutes
‣ Has no effect on osmolarity b/c Na⁺ absorption is what drives H₂O absorption
‣ Released by the adrenal cortex; responds to low BP; regulated by the renin-angiotensin-aldosterone system
‣ It restores blood pressure
ADH
= vasopressin = peptide hormone
‣ It ↑ the permeability of the collecting duct to water, thereby ↑ H₂O absorption
‣ It ↓ blood osmolarity by ↑ the amount of water present w/o ∆ solute levels
‣ Released by the posterior pituitary gland in response to low BP and high blood osmolarity (both indications of dehydration).
Atrial natriuretic peptide
opposite of aldosterone; responds to excess blood volume- it ↓ Na⁺ reabsorption in the distal convoluted tubule and the collecting duct; ↑ the glomerular filtration rate & inhibits aldosterone release
Cortisol
a glucocorticoid released from the adrenal cortex; 2 main effects: (1)↑ BGL by stimulating gluconeogenesis and acts as an insulin antagonist, facilitating insulin resistance; (2) ↓ inflammation by inhibiting certain inflammatory immune responses
Norepinephrine
(1) is an NT when used to relay signals b/t neurons in the SNS; (2) is a hormone when released into the blood to induce systemic effects in other organ systems
LH
secreted in response to low sex hormones (estrogen & testosterone). LH stimulates estrogen release in the luteal surge in the menstrual cycle → ovulation; also is released in response to gonadotropin-releasing hormone (GnRH) release
Progesterone
prepares the uterus for implantation & maintains it throughout pregnancy
LH
secreted in response to low sex hormones (estrogen & testosterone). LH stimulates estrogen release in the luteal surge in the menstrual cycle → ovulation; also is released in response to gonadotropin-releasing hormone (GnRH) release
Follicle stimulating hormone (FSH)
promotes ovarian follicle growth in females & spermatogenesis in males
Human chorionic gonadotropin (hCG)
maintains the corpus lute; induces it to secrete progesterone
Prolactin
acts on the mammary glands for milk production; it’s released in response to ↓ dopamine levels that occurs s/p placental expulsion in childbirth. Dopamine secretion is also ↓ in response to infant suckling.
Tropic hormones
= regulates other hormones
◦ Many crucial tropic hormones are released by the anterior pituitary gland:
‣ TSH ‣ ACTH ‣ LH ‣ FSH
◦ Tropic hormones can themselves be regulated by other tropic hormones.
HCG
human chorionic gonadotropin = stimulates progesterone release to maintain the uterus throughout the 1st trimester of pregnancy
lipid hormones
derived from cholesterol, so they are structurally similar to it. The primary class of lipid hormones in humans is the steroid hormones. Examples of steroid hormones include estradiol= an estrogen/female sex hormone, and testosterone= an androgen/male sex hormone. Other steroid hormones include aldosterone and cortisol, which are released by the adrenal glands along with some other types of androgens. Steroid hormones are insoluble in water; transport proteins carry them in the blood. As a result, they remain in circulation longer than peptide hormones.
amino acid-derived hormones
relatively small molecules derived from the amino acids tyrosine and tryptophan. Examples of amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland. The pineal gland in the brain makes and secretes melatonin, which regulates sleep cycles.
peptide hormones
polypeptide chain (chain of amino acids). The peptide hormones family includes molecules that are short polypeptide chains, such as antidiuretic hormone (ADH) and oxytocin produced in the brain and released into the blood in the posterior pituitary gland. This class also includes small proteins, such as growth hormones produced by the pituitary, and large glycoproteins, such as follicle-stimulating hormone produced by the pituitary.
Glucocorticoids
a set of steroid hormones that are synthesized in the adrenal cortex and regulate glucose metabolism. Cortisol is the most important glucocorticoid hormone.
Lipid-soluble hormones
diffuse across the lipid bilayer membranes of the endocrine cell.
◦ Once outside the cell, they bind to transport proteins that keep them soluble in the bloodstream.
◦ At the target cell, the hormones are released from the carrier protein and diffuse across the lipid bilayer of the plasma membrane of the target cells.
◦ Then they adhere to intracellular receptors residing in the cytoplasm or in the nucleus.
Water soluble hormones
◦ Can’t cross plasma membrane
◦ Binds to membrane receptors on the outside of cells
◦ Secondary messengers then relay the signal inside the cell
Lipid soluble hormones
◦ Able to cross the plasma membrane
◦ Directly activates genes
Phospholipid pathway:
- Amino acid hormone binds membrane receptor
- G protein activated
- Phospholipase C activated
- Membrane phospholipid split into DAG and IP3
- DAG triggers protein kinase cascade
- IP3 release Ca²⁺ from the ER
cAMP pathway:
- Amino acid hormone binds membrane receptor
- G protein activated
- Adenylate cyclase activated
- cAMP made
- Protein kinase cascade
• Tropic hormones → target cells → other hormones
Steroid pathway:
- Steroid hormone (and thyroid hormone even though it’s amino acid based) goes inside the cell
- Hormone binds receptor inside the cell (cytoplasm or nucleus)
- Hormone-receptor complex (transcription factor) turns certain genes on inside the nucleus
• Nontropic hormones → target cells —. Physiological effects
3 mechanisms by which endocrine glands are stimulated to synthesize and release hormones:
◦ Humoral stimuli: control of hormone release in response to changes in extracellular fluids such as blood or the ion concentration in the blood. Ie- a rise in blood glucose levels triggers the pancreatic release of insulin. Insulin causes blood glucose levels to drop, which signals the pancreas to stop producing insulin in a negative feedback loop.
◦ Hormonal stimuli: the release of a hormone in response to another hormone. A number of endocrine glands release hormones when stimulated by hormones released by other endocrine glands.
◦ Neural stimuli: when the nervous system directly stimulates endocrine glands to release hormones. Ie- In a short-term stress response, the sympathetic nervous system directly stimulates the adrenal medulla to release the hormones epinephrine & norepinephrine in response to stress.
Second messengers
