Glossary of MCAT Biology Lecture 4
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- nuclear envelope
- double phospholipid bilayer
- area in nucleus where rRNA transcribed, subunits of ribosomes constructed
- membrane surrounds and takes in matter inside vesicles. Types include phagocytosis, pinocytosis, receptor mediated endocytosis
- rough endoplasmic reticulum
- covered with ribosomes, translated proteins injected into ER lumen... proceed to Golgi.
- Golgi apparatus
- Recieves proteins from ER in vesicles, organizes and concentrates proteins, based on their signal sequence.
- Originate in Golgi, vesicles filled with enzymes that break down macromolecules. "Recycle"
- secretory vesicles
- protein filled vesicles from Golgi that are ejected from cell... ejected via exocytosis, so help build membrane.
- smooth endoplasmic reticulum
- hydrolizes glucose 6-phospate to glucose, produces triglycerides->fat droplets, &steroids. Oxidizes & detoxes foreign substances, incl toxins pollutants etc.
- cells containing mainly fat droplets, used for energy storage and temperature regulation.
- vesicles associated with smooth ER. Self-replicating. Produce and breakdown hydrogen peroxide, regulate oxygen, lipid synthesis etc. Not necessary for most cells.
- Larger than microfilaments. Made from tubulin polymer.
- Smaller than microtubules. Made from polymerized actin. Produce contracting force in muscle, also make cytoplastmic streaming in amoebas.
- Eukaryotic flagella and cilia composition
- "axoneme", 9 pairs of microtubules around two lone pairs of MTs, 9+2. Dynein bridges connect pairs. Cilia whip, flagella wiggle.
- prokaryotic flagella
- thin strand of protein flagellin. Motion is rotatation.
- mitotic spindle is made from...?
- tight junctions
- water tight seal around cell, fluid barrier. Restrict membrane protein motion. Helps keep material inside organs by forming epithelial layer.
- cell spot weld, joining two cells at a single point. Do not prevent fluid flow, found in tissue under physical stress.
- gap junctions
- tunnels connecting cells, let small molecules move between cells.
- endosymbiont theory
- theory that mitochondrea were bacteria that became incorporated into eukaryotes.
- Parts of mitochondria
- Outer membrane, intermembrane space, crista, inner membrane, mitochondrial matrix.
- extracellular matrix
- secreted by cell, surrounds cell. Examples are bone, blood, etc.
- four different tissue types
- epithelial, muscle, connective, nervous. (Ex. skin, muscle, blood, neurons)
- Neuronal communication
- Nervous System, rapid direct and specific.
- Hormonal communication
- Endocrine system, slower spread throughout body, affects many cells and tissues in diff ways.
- Paracine System
- Local mediators released into interstitial acting on nearby cells.
- neuron anatomy and process
- dendrites receive signal. axon hillock is disrupted, generates action potential. action potential travels down axon to synapse. synapse passes to another cell.
- resting potential
- potential established by Na+/K+ pump, expels 3Na+ and lets 2K+ in. Makes interior of membrane negative.
- action potential
- disturbance in membrane potential, away from resting potential.
- voltage gated sodium channels, and voltage gated potassium channels.
- change in voltage opens channel, allows sodium or potassium through. Sodium channels faster than potassium.
- Steps in action potential.
- 1. Membrane at rest, Na+, K+ channels closed.
2. Sodium channels open, depolarize cell.
3. Potassium channels open as Sodium channels start to inactivate.
4. Sodium channels inactivated, potassium opened repolarize.
5. Potassium closes, membrane equilibrates.
- Complete depolarization. Threshold stimulus exceeded, but always same size potential.
- electrical synapse
- Neuron interface, composed of gap junctions to transfer signal. Very fast but rare.
- chemical synapse messenger. Must be removed from synaptic cleft or will re-trigger neuron. Acetylcholine is an example of neurotransmitter.
- second messenger system
- exterior signal activates molecule inside a cell, which causes some change to occur... ex. activating gene transcription.
- chemical synapse
- Interface between neurons. Unidirectional, releases chemicals into synaptic cleft, receptors on other neuron receieve and create new signal. Slowest point of nervous signal transfer.
- nodes of Ranvier
- gaps between myelin
- electrically insulating sheats produced by Schwann cells. Exists in white matter, not in grey matter. Only in vertebrates.
- Neuron Types
- Sensory - recieves signals from receptor cell exposed to environment
Interneurons - neuron to neuron transfer
Motor - carry signals to muscle or gland (effecor).
Sensory neurons dorsally located on spine, motor neurons ventral.
- central nervous system (CNS)
- brain and spinal cord, integrates signals between sensory and motor neurons.
- peripheral nervous system (PNS)
- connects CNS to peripheral parts of body. Divided into somatic and autonomic nervous systems (ANS).
- somatic nervous system
- response to external env. innervates skeletal muscle, voluntary. Uses acetylcholine.
- autonomic nervous system
- recieves signals from organs. conducts signals to smooth muscle, cardiac muscle and glands. Divided into sympathetic and parasympathetic. (Fight or flight, rest and digest).
- specific neurotransmitters
- acetylcholine - somatic and parasympathetic NS
epinephrine, norepinephrine (adrenaline, noradrenaline) - sympathetic NS
- lower brain parts and function
- medulla, hypothalamus, thalamus, cerebellum. Subconscious activities, salivation, emotions, reactions to pain/pleasure, balance.
- higher brain
- cerebrum or cerebral cortex, - memories and thought processes
- sensory receptors
- transduce physical stimulus to neural signals.
- lights hits first, is bent.
- spherical, except that ciliary muscle stretches it thin. This changes focal length.
- images projected onto... consists of rods and cones, rods for light intensity, cones for frequency.
- color part around pupil, pupil dialated by sympathetic NS, contrafcted by parasympathetic.
- parts of middle ear
- tympanic membrane
3 bones - malleus, incus, stapes
transfers wave to inner ear.
- parts of inner ear
- cochlea, sound wave moves through.
haircells in organ of corti transduce into neural signals.
Semicircular canals also present.. for balance.
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