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198 Cards in this Set
- Front
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functions of plasma membrane
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Provides binding sites or receptors for extracellular molecules
Provide specialized junctions for cell to cell adhesion/communication provide the attachment site for the cytoskeleton components - microtubules and microfilaments Provides anchor sites for enzymes |
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Peripheral proteins
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water soluble and weakly bound to the membrane and found mostly on the outside of membrane.
some may have contractile properties. |
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Integral Proteins
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insoluble in water and cannot be removed unless the lipid components are disrupted.
span the entire length. can move laterally but can't be pulled out. water insoluble. transmembrane seem to be organized to form channels or pores for the transport of small water soluble molecules and ions may be involved in transmitting signals from one side of the membrane to the other. |
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diffusion
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the movement of molecules because of random thermal molecular motion.
net diffusion always occurs from region of high concentration to low. |
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flux
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rate of diffusion
F= AxTx(C1-C2) / MWxD |
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Diffusion through the cell membrane
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molecules with few polar groups enter cells more rapidly than polar molecules.
lipid soluble substances (with few polar or ionized groups) will be dissolved in the membrane lipids and have a greater flux across membrane. oxygen, co2 and steroid hormones=non polar and diffuse rapidly SMALL charged ions/molecules may diffuse through the pores in membrane |
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pores in cell membrane
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diameter = 8 angstroms.
probably formed by the integral proteins small charged ions and molecules may diffuse through here |
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Mediated Transport Systems
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Involve the movement of Large POLAR molecules (sugars, amino acids, etc) by BINDING to specific proteins on the membrane surface which in some manner leads to their movement across the membrane.
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Protein binding sites
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carriers
may be a conformational change in carrier molecule to enable molecules to cross the membrane 2 classes: facilitated diffusion, active transport |
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facilitated diffusion
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binding of the molecules to carrier proteins to pass the cell membrane.
net movement of molecules from high to low concentration ex: glucose |
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active transport
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a form of carrier mediated transport in which molecules can be transported across membrane from regions of low to high concentration.
At the expense of energy provided by metabolism. Ex: sodium and potassium ions, amino acids |
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Mole
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a unit that indicates the number of molecules of a substance present.
the number of moles = weight in grams/molecular weight |
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avogadro's number
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6.02 x 10 to the 23rd
the number of molecules in a mole the same number for 1 mole of any substance, although the weight will differ |
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Molarity
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Moles/Liter
Solute concentration in a solution A 2M NaCl solution has twice the number of molecules as a 1M NaCl solution. |
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Isotonic
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any solution in which the cell volume remains the same because it is a soln that contains the same number of non-penetrating solute particles as the cell
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Hypertonic Solution
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a solution that contains a higher concentration of non-penetrating solute particles than the cell placed into it. Cells place in this solution will CRENATE (shrink) due to the diffusion of water of the cell.
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Hypotonic Solution
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A solution containing a lower concentration of non-penetrating solute molecules.
Cells placed in a hypotonic solution will swell and lyse if the concentration difference is large enough. water from the soln outside the cells will diffuse into the cell. |
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Three types of endocytoses
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pinocytosis
phagocytosis receptor mediated endocytosis ALL require Energy The vesicle formed by endocytosis is the PHAGOSOME |
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pinocytosis
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the invagination of the cell membrane to form narrow channels that pinch into vacuoles.
celllar uptake of extracellular fluid and dissolved molecules |
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phagocytosis
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the engulfing of LARGe macromolecules or cells such as bacteria
can be used to protect the body from invading mircrobes and to remove extracellular debris. white blood cells and liver Kupffer's cells exhibit phagocytosis. |
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receptor-mediated endocytosis
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involves interaction of very SPECIFIC molecules in the extracellular environment with specific membrane receptor proteins and this causes the membrane to invaginate, fuse, and pinch off to form a vesicle
ex: cholesterol attached to specific proteins is taken into cells by theis method. |
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Phagosome
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the vesicle formed by endocytosis.
They may: -pass through the cytoplasm and fuse with the opposite plasma membrane and release its contents to the extracellular space on the opposite side of the cell... OR -it may fuse with the membrane of a primary lysosome. this causes the enzymes in the lysosome to be released into the phagosome to break it down. |
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Residual Body
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A lysosome remaining after digestion has taken place and contains undigested material
the molecules that cannot be broken down by the enzymes remain in the lysosome/residual body. |
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primary lysosome
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one which has not fused with a phagosome.
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secondary lysosome
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those lysosomes which have fused with a phagosome and have active enzymes digesting the contents of the phagosome.
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Exocytosis
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the process by which the membrane of an intracellular vesicle fuses with the plasma membrane, vesicle opens nad the vesicle contents are liberated into the extracellular fluid.
Avoids molecules having to move through the membrane. Provides a way to replace the membrane that was removed by endocytosis and to add new membrane during cell growth Free calcium ions inside the cell are required for exocytosis to take place. Aids in the fusion of the vesicle membrane to plasma membrane |
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Exocytosis and ribosomes
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Proteins made on the ribosomes attached to rouch ER use exocytosis to be exported out of the cell.
1. Proteins move down the ER to the free end. 2. the ER will pinch off vesicles containing the proteins. 3. The vesicles migrate to the Golgi 4. Proteins will be concentrated by the removal of fluid. 5. Carbs will be added to the proteins forming glycoproteins. different types of proteins are separated according to f(x) and destination. 6. Small vesicles containing the proteins will be pinched off the Golgi, forming ZYMOGEN or SECRETORY GRANULES. 7. The secretory granules can then export their contents to the extracellular fluid of the cell by exocytosis. |
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Zymogen
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Secretory granules that contain proteins that were originally made by the ribosomes on the rouch ER, then sent to the Golgi, modified, then pinched off from the Golgi.
They can then export their contents to the extracellular fluid of the cell by EXOCYTOSIS. |
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Desmosomes or adhering junctions
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2 opposing membranes separated by a space of about 2 nm.
There are bundles of immature Keratin fibers (tonofilaments) embedded in glycoprotein deposits between the cells. Fibers extend from the inner surface of hte desmosome into the cytoplasm. Function: is to hold adjacent cells together in areas that are subjected to considerable STRETCHING. Found between stratified squamous epithelial cells in the skin. |
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Tonofilaments
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Immature Keratin fibers found between cells in Desmosomes.
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Tight Junctions
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Location: between epithelial cells that separate 2 compartments which have different chemical compositions.
Ex: intestinal epithelial Cell membranes of adjacent cells are fused so there is no space between the opposing cells. They extend around the entire perimeter of the cell, making a tight seal between it and adjacent cells. Function: holding cells together and in sealing the passageway between adjacent cells |
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Gap Junctions
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There is a direct channel linking the cytoplasms of the 2 cells
Channels are small (about 1.5 nm in diameter) Only small ions like Na and K and small molecules pass between the cells. Location/Ex: found between cardiac and smooth muscle cells. Function: Play an important role in the transmission of electrical activity between adjacent cells. Important for nervous system link the cytoplasms of 2 cells |
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Ameboid Motion
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Achieved by Cytoplasmic streaming
Chemotactic stimulus Myxomyosin contract in presence of Calcium and ATP energy Causes cytoplasm to stream Forming Pseudopodium, which attach to a substrate and pull the cell along. EX: white blood cells, tissue macrophages, microglial, embryonic |
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Myxomyosin
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contractile proteins
contract in the presence of calcium and energy from ATP cause cytoplasm to stream --> form pseudopodium, which attach to subrstrate and pull the cell along |
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Cilia
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Human: located in respiratory system (trachea & bronchi) and the female genital tracts (fallopian tubes)
In order to move, cilia require Energy from ATP, magnesium and calcium |
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Axoneme
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The 9-2-2 arrangement of microtubules linked together by protein cross-linkages, forming CILIA.
In order to move, cilia require Energy from ATP, magnesium and calcium |
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Flagella (in humans)
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only found in sperm cells!
9-2-2 |
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Extracellular Fluid
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surrounds body cells
Accounts for 1/3 of total body water (14 Liters) Composed of: Interstitial Fluid and Plasma The Solute concentrations in the interstitial fluid and the plasma are virtually identical except for the protein. |
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Interstitial Fluid
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Comprises 80% of the extracellular fluid (11 Liters)
lies BETWEEN cells and tissues |
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Plasma
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Makes up 20% of the extracellular fluid (3L)
Contained within blood vessels. |
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Intracellular Fluid
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fluid inside the cells
Accounts for 2/3 the total body water (28L) |
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WATER in humans
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accounts for 60% of normal body weight
42 Liters |
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Nissl Bodies
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Rough ER found within the Cell body of a Neuron
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Cell Body/Soma/Perikaryon
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enlarged portion of the neuron which contains the nucleus and serves as the center of the neuron where macromolecules are produced
contains Nissl bodies which are rough ER Groups of cell bodies in CNS = Nuclei Groups of cell bodies in PNS = ganglia |
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SOmatic motor neurons
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innervate skeletal muscles
voluntary |
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autonomic motor neurons
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innervate smooth and cardiac muscle and glands.
divided into sympathetic and parasympathetic |
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Bipolar Neurons
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have 2 processes, - 1 dendrite, 1 axon
found in the retina sensory ONLY |
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Multipolar neurons
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have several dendrites and one axon
ex: motor neurons and association neurons |
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Pseudounipolar neurons
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has a single short process that divides like a T
1 end of the process receives sensory stimuli from the receptors (dendritic branches of the axon - not really a dendrite!) and the other end delivers impulses to the CNS (axon). the cell bodies are located outside the CNS in the DORSAL ROOT GANGLIA of the spinal and cranial nerves Ex:Somatosensory Neurons - sensations from skin, underlying tendons and ligaments; such as : touch, pressure, temperature and pain |
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Nerve
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a collection of axons outside the CNS
most nerves are composed of both afferent and efferent fibers and are called mixed nerves some cranial nerves = only afferent fibers |
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Neuroglia
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schwann cells
oligodendrocytes microglia astrocytes ependymal cells satellite cells |
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Schwann cells
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form myelin sheaths around peripheral axons
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Oligodendrocytes
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form myelin sheaths around axons of the CNS
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Microglia
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phagocytic cells that migrate through the CNS and remove foreign and degenerated material.
Like an immune system for the CNS Can divide mitotically, can get out of control and cause tumors ! =( |
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Astrocytes
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"nurse" cells
Regulate the external environment of neurons in the CNS the most abudant of the neuroglia cells in the CNA Break down the neurotransmitters glutamic acid and gamma-aminobutyric acid, releasing glutamine which can be available to neurons for the resynthesis of the neurotransmitters. Establish the Blood brain barrier Convert glucose to lactose so that the brain can use it for energy |
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Ependymal Cells
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Line the ventricles of the brain and central canal of the spinal cord
Work with capillary beds to produce CSF, they transport CSF to these capillary beds |
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Satellite Cells
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Support neuron cell bodies within the ganglia of the PNS
Bundled around dorsal root ganglia |
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Sheath of Schwann
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Surround all axons in the PNS
living cells The outer surface of this layer of cells is encased in a glycoprotein basement membrane, often called the neurilemma not present in CNS |
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Myelin Sheath
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Composed of successive wrappings of the cell membrane of Schwann cells or oligodendrocytes around the axon.
The cytoplasm becomes squeezed to the outer region of the cell Each cell only wraps about 1 mm of axon leaving gaps of exposed axon between the adjacent cells called Nodes of Ranvier Schwann cells form myelin in the PNS, which is surrounded by the sheath of Shwann and Neurilemma Oligodendrocytes form myelin in the CNS |
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Blood Brain Barrier
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The perivascular feet of the astrocytes surround the brain capillaries, joining the endothelial cells with tight junctions
The transport of molecules is regulated by the endothelial cells. |
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resting membrane potential
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the charge difference in a neuron across the cell membrane
the inside of the cell is negatively charged in comparision to the outside (-65mV) |
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Na+/K+ Active Transport Pump
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pumps 3 Na+ ions out for every 2 K+ ions into the cell whcih helps to maintain the concentration difference of K+ and Na+ on both sides of the membrane
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Catecholamines
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Ring structure
Occur in a cascading sequence: Tyrosine(amino acid) --> L Dopa --> Dopamine --> Norephinephrine (neurotransmitter and hormone --> Epinephrine Use a secondary messenger: Cyclic AMP 1.bind to postsynaptic membrane 2. G Protein dissociates and subunit diffuses through membrane. 3.activate Adenylate Cyclase 4. Converts ATP --> cyclic AMP +2PO4 in cytoplasm 5. cyclic AMP activates protein kinase 6. Kinase phosphorylates gates for Na+ or K+, causing it to open |
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Monoamine Oxidase
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Perform enzymatic degradation of Catecholamines after their re-uptake into the presynaptic neuron endings
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Catecholamine-O-Methyltransferase (COMT)
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Perform enzymatic degradation of Catecholamines after their re-uptake into the prostsynaptic neuron endings
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Afferent Sensory Nerves
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Bring info towards the CNS
CN 1,2,5,7,8,9,10 all 31 pairs of spinal nerves |
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Somatic Efferent Nerves
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Innervate Skeletal Muscle, making them contract voluntarily
CN 3,4,5,6,7,9,10, 11, 12 all 31 pairs of spinal nerves ALWAYS excitatory - contraction Neurotransmitter is acetylcholine |
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Autonomic Efferent Nerves
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Sympathetic nerves: T1-L2
Parasympathetic nerves: CN 3, 7, 9, 10 Sacral 2,3,4 Nerve fibers synapse once in ganglia after they LEAVE CNS. Innervate smooth or cardiac muscles and glands Can lead to excitation or inhibition of the effector. Neurotransmitter is acetylcholine or norepinephrine. |
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Sympathetic nerves
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A type of Autonomic Efferent Nerve.
Leave the CNS at T1-L2 Ganglia lie close to the spinal cord; preganglionic fiber synapses here. Preganglionic fiber is short and uses neurotransmitter Acetylcholine. (always an excitatory effect on post-ganglionic neuron.) Postganglionic fiber is long and goes to the effector organ; most nerves use norepinephrine as neurotransmitter. Postganglionic fibers cause Adrenergic Stimulation. Involved in stressful or emotional situations (rage or fear). |
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Parasympathetic Nerves
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A type of Autonomic Efferent Nerve.
Leave the CNS from the brain (CN 3,7,9,10) Ganglia lie close to or in the walls of the effectors Preganglionic fiber is long and uses acetylcholine (goes almost all the way to effector organ!) Postganglionic fiber is short and synapses on the effector organ, uses acetylcholine. Most active during recovery or rest. Dominant system in body. Vagus Nerve dominates this system. |
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Adrenergic Stimulation
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Stimulation from the Postganglionic fibers from the Sympathetic Nervous System:
Epinephrine/adrenaline (hormone) in blood Norepinephrine/noradrenaline (neurogransmitters from postganglionic fibers) Has BOTH excitatory and inhibitory effects: heart: stimulated, contracts smooth muscle of bronchioles, inhibited, bronchodilation. Different responses are a result of the differences in membrane receptor proteins. Alpha and Beta receptors |
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Alpha Adrenergic receptors
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2 Subtypes: alpha 1 and alpha 2
Both cause contraction of the smooth muscles of the blood vessels, vasoconstriction. |
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Alpha 1 receptor
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Subtype of Adrenergic Receptor
Stimulated by norepinephrine or epinephrine. Respond to Norepinephrine by increasing the amount of Ca+ inside the cell. Causes contraction of the smooth muscles of the blood vessels/vasoconstriction. Stimulated by the drug Phenylephrine (found in nasal spray), causing vasoconstriction in nasal mucosa relieving the running nose/preventing leakage from the capillaries. |
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Alpha 2 receptors
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Subtype of Alpha Adrenergic Receptors.
Stimulated by norepinephrine or epinephrine. Response is to block cAMP production. (cyclic AMP) Cause contraction of the smooth muscles of the blood vessels, or vasoconstriction. |
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Beta Adrenergic Receptor
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1 of the 2 classes of Adrenergic Receptor Proteins.
Stimulated by epinephrine (hormone) or norepinephrine (postganglionic fibers of Sympathetic nervous system) 2 Subtypes: beta 1 and beta 2 Both beta subtypes produce their effects by stimulating the production of cAMP within the target cell. Stimulate the relaxation of smooth muscles in the digestive tract, bronchioles (bronchodilation), and uterus. Stimulate contraction of cardiac muscle; increases heart rate. Beta-blocking drugs such as propranolol reduce heart rate; inhibit beta receptors. |
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Chonlinergic Stimulation
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Somatic motor neurons, all preganglionic neurons, and all postganglionic parasympathetic neurons.
Release acetylocholine as a neurotransmitter. Somatic motor neurons and preganglionic autonomic nerves = Excitation of target cell ALWAYS Postganglionic parasympathetic fibers = USUALLY excitation, can be inhibition 2 subtypes: Muscarinic and Nicotinic |
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Muscarinic Receptors
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Subtype of a Cholinergic Receptor
Located on Smooth Muscle OR Cardiac muscle cells (innervated by postganglionic parasympathetic nerve fibers) USUALLY Excitatory, sometimes Inhibitory. Inhibits heart rate. Excites smooth muscle of iris, pupil constriction. Excites digestive tract, contraction/digestion. Stimulated by Muscarine from poisonous mushroom. Inhibited by drug Atropine: dilates the pupil, dries mucous membranes of the respiratory tract; prior to general anesthesia, and inhibits spasmodic lower digestive tract contractions. |
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Muscarinic Cardiac Receptors
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When ACH from the postganglionic parasympathetic fiber binds to these receptors:
Decreases the heart rate Inhibition. Autonomic parasympathetic pathway. Rest and Digest! |
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Muscarinic receptors on smooth muscle of the Iris
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When ACH from the postganglionic parasympathetic fiber binds to these:
the smooth muscle of the Iris (eye) will contract resulting in pupil constriction. Excitation. |
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Muscarinic Receptors of the Digestive Tract
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When ACH from the postganglionic parasympathetic fiber binds to these:
Digestive tract will contract, allowing digestion to occur. Excitation. |
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Nicotinic receptors
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A subtype of Cholinergic Receptors
Stimulated by Acetylcholine. Nicotine stimulates cholinergic transmission from preganglionic fibers of the autonomic ganglia and from the somatic efferent neurons at the neuromuscular junction. ALWAYS EXCITATORY. Located on the postganglionic neuron membranes and on the skeletal muscle membrane. Drugs that inhibit or block these cause paralysis. Curare is a drug used to relax skeletal muscle because it blocks Nicotinic receptors. |
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Patella Reflex
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Monosynaptic reflex
Functions through Spinal nerves L2, L3, and L4 Extension of leg |
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Achilles Reflex
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Ankle Jerk
Contraction of the triceps surae muscle, resulting in plantar flexion of foot. Functions through Spinal nerves S1 and S2 Hyporeflexia - hypothyroidism |
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Biceps Reflex
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Deep reflex.
Causes flexion of the forearm. Functions through spinal nerves C5 and C6. *****Sames nerves used in Brachioradialis Reflex!!! |
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Triceps Reflex
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deep reflex.
Extension of the forearm. Functions through Spinal nerves C7 and C8. |
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Brachioradialis Reflex
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Flexion and pronation of the brachioradialis.
Functions through Spinal nerves C5 and C6. ******Same nerves tested as biceps reflex!!! |
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Hoffman's Reflex
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A positive response is considered abnormal and is an example of hyperreflexia.
Individuals with injury to the pyramidal tract will respond with adduction and flexion of the thumb and a twitch-like flexion of the other fingers. |
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Cutaneous Receptor Variation
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Receptors for touch vary in density over various areas of the body surface.
Can measure the distance between dendrite receptors on the particular area of body being tested! |
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Conscious Activity
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Involves the brain on a higher level.
Demonstrated by the use of "time sticks" to measure reaction time. Slower than the reflex due to decision making, and |
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Insula
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internal lobe of the brain
involved in: memory, sensory (primarily pain), visceral information (coordination of internal activities) |
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Red Nucleus
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Maintains connections with the cerebrum and the cerebellum and is involved in Motor Coordination
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Substantia Nigra
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Involved in motor coordination
Degenerated in people with Parkinsons Part of the Midbrain |
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Pons
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Contains 2 respiratory control centers
apneustic pneumotaxic Part of the Metencephalon part of reticular activating system |
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Cerebellum
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participates in the coordination of movement.
muscle coordination equilibrium or balance |
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Medulla Oblongata
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Makes up the Myelencephalon
All descending and ascending fiber tracts that provide communication between spinal cord and brain must pass through medulla Contains the vital centers: Vasomotor center - controls the autonomic innervation of blood vessels, regulation blood pressure. Cardioinhibitory Center - controls the parasympathetic innervation of the heart. Respiratory Center - Controls breathing; works together with the respiratory centers in the Pons Part of Reticular Activating System |
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Reticular Formation
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A complex network of nuclei and nerve fibers with the medulla oblongata, pons, midbrain, thalamus and hypothalamus that functions as the Reticular Activating System
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Reticular Activating System
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Reticular Formation.
Functions in the nonspecific arousal of the cerebral cortex to incoming sensory info. Helps to maintain a state of alert consciousness. Measured with EEG |
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EEG
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alpha waves: awake but relaxed with eyes closed.
beta waves: visual stimuli and mental activity. theta: common only in newborns. delta waves: sleep in the adult and in an awake infant. |
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Basal Nuclei
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A group of nuclei located in the Cerebrum that are involved in motor coordination along with the Cerebellum and midbrain.
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Limbic System
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A group of nuclei located in the Cerebrum that are involved in emotions, long-term memories and the sense of smell (olfaction).
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Funiculi
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6 Ascending and descending fiber tracts which make up the white matter surrounding the gray matter of the spinal cord.
Ascending fiber tracts convey sensory info from the cutaneous receptors, proprioceptors and visceral receptors. Most of the sensory info that originates in the right side of the body crosses over to reach the left side of the brain and vice versa. |
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GABA
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Inhibitory Neurotransmitter
Prevents you from making extra movements in skeletal muscles. Allows you to hold your arm out and be steady. Parkinsons : patients lack GABA and Dopamine. |
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Glutamic Acid
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Excitatory Neurotransmitter
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Aspartic Acid
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Excitatory Neurotransmitter
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Glycine
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Inhibitory Neurotransmitter
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Endorphin
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Neurotransmitter involved in blocking the transmission of pain
Secreted in increasing amounts while under stress. Cause the relaxed feeling after a workout |
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SSRIs
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Serotonin Specific Reuptake Inhibitors
Depression medication; depressed patients lacking in Serotonin Mimic Serotonin and remain in receptors so the cell can be stimulated longer than normal. Problem: after time, the body adjusts to the continual stimulation and compensates by exocytosing some of its receptors for Serotonin; with less receptor proteins available, the body is even less able to respond to the neurotransmitter, causing further Depression. =( |
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Nitric Oxide
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gas neurotransmitter used in Viagra
Dilates all the blood vessels in the body, allowing increased blood flow and an Erection. PROBLEM: dilation of all blood vessels is bad for people who have an existing heart problem. The blood pressure can drop too low and be lethal!!! |
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Chemoreceptors
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sense chemical stimuli in the environment or the blood
Ex: taste buds, olfactory epithelium, the aortic and carotid bodies |
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Photoreceptors
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sense different wave lengths of light
Ex: rods and cones in the retina |
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Cutaneous Receptors
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Touch and pressure receptors, warm and cold receptors and pain receptors.
Thermoreceptors Mechanoreceptors Nocioreceptors |
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Mechanoreceptors
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Type of Cutaneous Receptor
Stimulated by mechanical deformation of the hair processes of the receptor cells. Ex: Pacinian corpuscles for deep pressure Meissners corpuscles for light touch Hair cells of the organ of Corti within the ear |
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Nocireceptors
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Pain receptors
Stimulated by tissue damage |
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Phasic receptors
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receptors which respond with a burst of activity when a stimulus is first applied, but then quickly decrease their firing rate, adapting to the stimulus.
Ex: Odor, touch and temperature adapt rapidly |
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Tonic receptors
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Receptors that produce a relatively constant rate of firing as long as the stimulus is maintained.
Sensations of pain adapt little if at all. |
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Taste receptors
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taste buds
Exteroceptors: respond to chemical changes in the external environment Have microvilli at their apical surface that are exposed to the external environment through a pore in the surface of the taste bud. Molecules dissolved in saliva interact with receptor molecules in the microvilli of cells. |
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Exteroreceptors
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Respond to chemical changes in the external environment.
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Innervation of the tongue
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taste buds in the posterior 1/3 of tongue: innervated by the Glossopharyngeal Nerve (CN IX)
taste buds in the anterior 2/3 of tongue: Facial Nerve (CN VII) |
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Taste sensations and gustatory cells
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5 different tastes: sweet, sour, salty, bitter and Umami
Due to the 5 different types of gustatory cells found inside the taste buds. Each type is specialized to respond to one of the 5 sense modalitites |
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Olfaction
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Olfactory receptors are the dendritic endings of the olfactory nerve (CN 1)
The sense of olfaction is transmitted directly to the olfactory bulb of the cerebral cortex. Many thousands of different odors can be distinguished. The molecular basis of olfaction is still incompletely understood. Involves G-Proteins |
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Olfactory receptors
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The dendritic endings of the olfactory nerve (CN 1)
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Sense of Equilibrium
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Provides orientation with respect to gravity.
Involves the vestibular apparatus, which has 2 parts: the otolith organs (utricle and saccule) the semicircular canals When the stereocilia are bent in the direction of the kinocilium, the cell membrane becomes depolarized which causes the release of neurotransmitter which stimulates the dendrites of sensory neurons of the 8th cranial nerve (vestibular branch). When the sterocilia are bent away from the kinocilium, the hair cell membrane hyperpolarizes, releases less neurotransmitter and thus inhibits the sensory neuron. |
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Vestibular Apparatus
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located within the membraneous labyrinth, which is filled with fluid called Endolymph.
Utricle and Saccule provide info about linear acceleration Semicircular Canals provide a sense of rotational or angular acceleration |
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Membraneous Labyrinth
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tubular structure filled with fluid called Endolymph
Where the Vestibular Apparatus is located |
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Endolymph
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Similar in composition to intracellular fluid.
Fills the membraneous labyrinth. |
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Semicircular Canals
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provide a sense of rotational or angular acceleration
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Hair Cells
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Receptors for equilibrium
Modified epithelial cells that contain 20-50 hairlike extensions. Extensions contain protein filaments known as stereocilia. The larger extension has the structure of a true cilium and is known as a kinocilium. When the stereocilia are bent in the direction of the kinocilium, the cell membrane becomes depolarized release of neurotransmitter. When the sterocilia are bent away from the kinocilium, the hair cell membrane hyperpolarizes, releases less neurotransmitter and thus inhibits the sensory neuron. |
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Sterocilia
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protein filaments that look like hairlike extensions on the hair cells of the inner ear.
The larger extension has the structure of a true cilium and is called a kinocilium. |
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Utricle and Saccule
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The hair cells of the Utricle and Saccule protrude into the endolymph-filled membranous labyrinth, embedded within a gelatinous otolith membrane.
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Utricle
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Most sensitive to horizontal acceleration.
When a car accelerates, the otolith membrane lags behind the hair cells, pushing the hairs of the utricle backwards. |
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Saccule
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The most sensitive to vertical acceleration. When a person descends rapidly in an elevator, inertia of the otolith membrane causes the hairs of the saccule to be pushed upward.
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Otoliths
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calcium carbonate crystals (Statoconia) which increase the mass of the membrane resulting in HIGHER INERTIA (resistance to change).
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Vertigo
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The loss of equilibrium due to the spinning motion of the body
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Vestibular Nystagmus
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movement of eyes following the spinning of body and stopping
The eyes slowly drift in the direction of the spin and then are jerked back to the midline position rapidly, producing involuntary oscillations. |
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Semicircular Canals
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3 canals:
One of the two parts of the vestibular apparatus Superior/anterior - stimulated by Yes movements of the head Posterior - stimulated by side to side head movements Lateral - stimulated by No movements of the head Involved in rotational or angular acceleration, which helps us to maintain balance when turning the head, spinning or tumbling Filled with the fluid Endolymph Head movement --> Cupula pushed in 1 direction --> Stimulation of hair cells --> Activates Sensory neurons of Vestibular Nerve --> goes to the Cerebellum --> goes to the Vestibular Nerve in Medulla --> Vestibular nuclei sends fbers to the Oculomotor center in the brain stem to control eye moevemetns and to the spinal cord to stimulate limb movement. |
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Ampulla
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Located at the base of each canal of the Semicircular Canals of the inner ear.
Where the sensory hair cells are located. |
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Cupula
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A gelatinous membrane in which the sensory hairs are embedded.
Gets pushed in one direction or another by movements of the endolymph. As the head rotates to the right, the endolymph causes the cupula to be bent toward the left, stimulating the cells. Stimulation of the hair cells activates the sensory neurons of the vestibular nerve (CN 8), which goes to the cerebellum, and then to the vestibular nuclei in the medulla. |
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Vestibular Nuclei
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Located in the medulla
Receive stimulation from the 8th cranial nerve (vestibular) Sends fibers to the oculomotor center in the brain stem to control eye movements and to the spinal cord which stimulates movements of the head, neck and limbs. |
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Pinna/auricle
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Part of the outer ear
Functions to collect sound waves |
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Outer ear
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Consists of the
pinna/auricle external auditory meatus |
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External Auditory Meatus
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Funnels sound waves onto the tympanic membrane
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Middle Ear
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Consists of the :
tympanic membrane ear ossicles (malleus, incus, stapes) Eustachian tube |
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Eustachian tube
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functions to equalize the pressure in the middle ear with the pressure in the outer ear.
Located in the middle ear Connects with middle ear with the nasopharynx. |
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Inner ear
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Consists of:
semicircular canals utricle and saccule cochlea On the wall between the middle and inner ear are 2 openings covered by membranes: fenestra vestibuli and fenestra rotunda |
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Cochlea
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functions in hearing
located in inner ear Consists of 3 chambers: 1) scala vestibuli (perilymph) 2) scala tympani (perilympth) 3) scala media (endolymph) Reissner's membrane/vestibular membrane separates the scala vestibuli from scala media. Basilar membrane separates the scala media from the scala tympani Organ of Corti sits on the basilar membrane Overhanging the hair cells is the tectorial membrane |
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Fenestra vestibuli
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Oval window
An opening covered with a membrane, which separates the middle and inner ear. Connects with the scala vestibuli of the cochlea and the stapes moves into and out of the fenestra vestibuli |
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Fenestra rotunda
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Round window
An opening covered with a membrane, which separates the middle and inner ear. Connects with the scala tympani. |
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Reissner's membrane/vestibular membrane
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separates the scala vestibuli from scala media.
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Ampulla
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the base of each semicircular canal, where the sensory hair cells are located.
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Cupula
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A gelatinous membrane above each semicircular canal, in which the sensory hairs are embedded
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Transmission of stimulation in the Semicircular Canals
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1. Cupula is pushed in 1 direction by the movement of the endolymph.
2. Cells are stimulated. 3. Activation of the sensory neurons of the vestibular nerve ( CN 8) 4. These fibers transmit impulses to the cerebellum and the vestibular nuclei of the medulla oblongata. 5. Vestibular nuclei send fibers to the oculomotor center of brain stem and spinal cord. 6. Neurons in oculomotor center control eye movements and neurons in spinal cord stimulate movements of head, neck and limbs. |
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Reissner's membrane/vestibular membrane
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Separates the scala vestibuli from the scala media.
Wave action in the scala vestibuli causes this membrane to vibrate, increasing the pressure of the endolypmph in the scala media. |
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Organ of Corti
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hair cell receptors sitting on the basilar membrane
the hair cells connect with the sensory fibers of the cochlear branch of the 8th cranial nerve |
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Tectorial membrane
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overhangs the hair cells in the Organ of Corti
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Tympanic Membrane
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When the sound waves strike this membrane, it starts to vibrate.
It vibrates slowly in response to low frequency sounds and rapidly in response to high frequency sounds. |
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cochlea
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High pitched tones are detected near the base of the cochlea, near the fenestra vestibuli.
Low pitched sounds are detected near the apex of the cochlea |
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Frequency
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The distance between crests of sound waves
Measured in hertz, which is cycles per second (cps) |
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pitch
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Related to the frequency of sound
The greater the frequency of the sound, the higher the pitch. |
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Amplitude of sound
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The intensity or loudness of sound is directly related to its amplitude.
Intensity is measured in decibels (db) Every 10 decibels indicates a ten-fold increase in sound intensity. |
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Fibrous Tunic
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outer layer of eyeball
Includes: sclera and cornea |
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Sclera
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The outer layer of eye
consists of dense connective tissue functions in providing shape to the eyeball protects the eyeball |
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cornea
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Its curvature refracts light, changes light's direction towards pupil.
Is the anterior continuation of the sclera is transparent does 2/3 of the focusing for the eye |
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Neural Pathway for Hearing
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Hair cells of organ of corti move up against Tectorial membrane
Graded Potentials are initiated Leads to Action Potentials Cochlear branch of Vestibulocochlear Nerve stimulated Potentials passed to Inferior Colliculus Passed to Medial Geniculate Nucleus of Thalamus Temporal Lobe of Cerebral Cortex |
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Vascular Tunic
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Middle layer of eyeball
Includes: choroid ciliary body iris |
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Choroid
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Part of the Vascular tunic/middle layer of eyeball
Supplies blood to eyeball |
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Ciliary Body
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Part of the Vascular tunic/middle layer of eyeball
Consists of smooth muscle and glandular epithelium Supports the lens through suspensory ligaments and determines the lens' shape Secretes aqueous humr. |
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Iris
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2 sets of muscle, works like an aperture on a camera
Part of the vascular tunic of the eye (middle layer) Consists of pigment cells and smooth muscle Regulates the diameter of the pupil and thus the amount of light that enters the eye |
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Nervous Tunic
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The inner layer of eyeball
Includes the Retina, Fovea centralis, and Optic Disc |
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Retina
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Part of the Nervous Tunic (inner layer of eye)
Contains photoreceptors, bipolar neurons, and ganglion neurons Functions in photoreception and trasnsmits impulses Fovea centralis is the area of the retina where there is a high concentration of cones Optic disc/blind spot contains no photoreceptors and is the region where optic nerve exits the eye |
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Lens
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Refracts light
is composed of tightly arranged protein fibers does 1/3 of the focusing for the eye can change its shape with use of suspensory ligaments is located between posterior and vitreous chambers |
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Anterior Chamber
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located between the cornea and the iris
contains aqueous humor within the anterior chamber is the canal of Schlemm which drains the aqueous humor and returns the fluid to the venous blood |
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Posterior chamber
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located between the Iris and the lens and contains aqueous humor
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Vitreous Chamber
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located behind the lens and contains vitreous humor
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Visual Pathways to the brain
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1. Photoreceptors (rods and cones) stimulated by light.
2. they synapse with the bipolar neurons 3. Synapse with ganglion neurons 4. Axons of ganglion neurons form the optic nerves. 5. Nerve fibers from the nasal half of each retina cross at the optic chiasma. 6. Nerve fibers from the temporal half of each retina do not cross at the optic chiasma. ***Fibers are now the Optic Tract 7. Some fibers synapse with Superior Colliculi for visual reflexes 8.. Most fibers synapse with neurons in the visual centers of the lateral geniculate body of the thalamus. 9. Impulses are relayed to occipital lobes of the cerebrum and integrated. 10. The right lobe receives impulses from the left side of the visual field and vice versa. |
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Light rays for the left side of visual field
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Fall on the temporal half of the right side retina and the nasal half of the left retina
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Light rays from the right side of the visual field
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Fall on the temporal half of the left retina and the nasal half of the right retina.
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Accommodation
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The ability of the lens of the eye to adjust its curvature so that an image of an object is focused on the retina at different distances.
Results from contraction of the ciliary muscles which are attached to the suspensory ligament which in turn is attached to the lens. Ciliary Muscle is a sphincter, so contraction = tightens, inner circle gets smaller allowing the lens to be fat and round (convex); suspensory ligaments are loose |
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Viewing an object less than 20 feet away
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Ciliary muscle contracts
suspensory ligaments are loose Lens is fat and round - CONVEX Causes light to rays converge |
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Viewing an object more than 20 feet away
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Ciliary muscle relaxes
suspensory ligaments are taut lens is concave and almost flat. Causes light rays to diverge |
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Pupillary Light Reflex
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Pupils constrict when a light is shined into eye.
Cuts down the amount of light entering the eyes, protects the retina from excessive stimulation, increases the depth of focus, and improves the sharpness of retinal images. Light hits retina: 1. Photoreceptors are stimulated 2. which is passed on the optic nerve. 3. then to the pretectal nucleus in the midbrain of the same side, 4. then to the Edinger-Westphal nucleus of the CN 3 of both sides, 5. then to efferent parasympathetic fibers in CN 3 6. Contraction of circular muscles of the iris 7. Pupil constriction |
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bleaching reaction
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In response to absorbed bright light, rhodopsin 11-cis-retinine-opsin dissociates into its 2 components:
all trans retinine (pigment) + Opsin (protein) rods are refractory when they are all-trans retinene must recycle retinines when darkness is restored |
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Cones
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Retinine + Photopsin
3 types: blue green red different cones have a different protein each type of cone absorbs light maximally at different wavelengths of light, not just the optimal wavelengths, and there is overlap of the ranges of wavelength between cones. |
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Myopia
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Nearsightedness
Caused by an elogated eyeball so the focus of the image falls in front of the retina instead of on the retina. corrected by concave lenses, which push the focus back onto the retina concave lens = causes light to diverge so it focuses further back as you age, lens is streched anterior-posterior |
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Basilar membrane
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Basilar membrane separates the scala media from the scala tympani
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Hyperopia
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Farsightedness
caused by an eyeball that is too short, so the focus of the image falls in back of the retina instead of on the retina corrected by convex lenses that push the focus forward onto the retina. convex lenses cause the light to converge. |
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Protanopia
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red color blindness
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Deuteranopia
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green color blindness
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tritanopia
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blue color blindness
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Glaucoma
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results from inadequate drainage of the aqueous humor, resulting in increased intraocular pressure which can cause serious damage to the retina.
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Near Point of Vision
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The closest distance one can see an object in sharp focus.
When focusing on objects close to the eye, the lens becomes more convex as the ciliary muscle is contracted and the suspensory ligament attached to the lens becomes loose. With age, lens loses elasticity and can not accomodate as well; so the near point will get farther away from the eye. |
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Stereopsis
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Binocular Vision
The eyes visual fields overlap considerably. There is 2 eyed vision at the overlap area, causing 3 dimensional vision, or stereopsis. The brain fuses the slightly different images to give us DEPTH PERCEPTION EXPERIMENT: dropping pencil into test tube with one eye closed. Predators have overlap also, eyes in front of head; allows depth perception for hunting. |
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Visual Acuity
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The ability to differentiate at a distance of 20 feet, 2 points that are one millimeter apart.
Determined by Snellen Eye Chart Tests for farsightedness (hyperopia)/short eyeball....need convex lenses |
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20/20
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Visual acuity measurement determined by Snellen Eye Chart.
first number = the distance that the person stands from the chart (20 ft) second number = the distance that a person with normal vision stands from the chart. 20/20 = normal vision 20/15 = better than normal vision. standing 20 ft away, they can see letters on the chart that a person with normal vision would be able to see at 15 ft 20/100 = worse than normal vision |
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Ishihara's Plates
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Book that tests for colorblindness
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Conduction Deafness
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May result from damage to the tympanic membrane or ear ossicles.
"Middle Ear" deafness May be corrected with surgery or hearing aids |
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Nerve deafness
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May result from damage to the cochlea or the cochlear nerve.
Nerve deafness cannot be corrected. |
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Rinne Test
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Strike a tuning fork and place against mastoid process.
Tests for Conduction Deafness: if you have conduction deafness, you will not be able to hear the sound when fork is in front of your ear, but you will hear it when it is placed against your mastoid process, because this allows sound to bypass the Middle Ear: |
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Weber Test
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Hearing test, place tuning fork in the middle of forehead
If: Normal hearing in both ears = hear the sound with equal intensity in BOTH ears Conduction deafness in one ear = hear the sound more loudly in the deaf ear than the normal ear. Nerve deafness in one ear = would hear the sound more loudly in the normal than in the deaf one. |
