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MCAT Biology #2
Nerve and Muscle
| Term | Definition |
|---|---|
| Microvilli | projections on the luminal side of simple epithelial cells that increase the total absorptive area of the cell |
| Cilium (pl. cilia) | appendages projecting outward on the apical surfaces of simple epithelial cells |
| Tight junctions | cell junction that prevents transport of proteins molecules and also holds neighboring cells together |
| Desmosomes | cell junction that helps to resist shearing forces |
| Basal lamina | or “basement membrane.” Helps anchor cells in place |
| Gap junction | cell junction that allows for a means for water-soluble molecules to pass from the cytoplasm of one cell to the cytoplasm of another cell |
| Exocrine glands | if a cell secretes a substance into the lumen by way of a duct |
| Endocrine glands | if a cell secretes a substance into the blood |
| Stratified squamous epithelium | cells that usually have a protective function |
| Keratin | a fibrous protein in skin cells |
| Epidermis | composed of stratified epithelia cells that act to protect the deeper layers of the skin |
| Dermis | the layer of skin underneath the epidermis |
| Erector muscles | muscles that surround the hair follicles that can straighten the hair shaft |
| Subcutaneous tissue | the layer of skin beneath the dermis where adipose deposits |
| Connective tissue | tissue that supports, connects, or separates different types of tissues and organs in the body |
| Fibroblasts | cells that secrete many of the proteins that make up structural connective tissue |
| Collagen | triple-stranded, insoluble, fibrous protein that is highly stranded which makes it strong yet flexible. |
| Reticulin | thin fiber found in the spleen and lymph nodes |
| Elastin | highly cross-linked protein found associated with organs that require some degree of elasticity |
| Cartilage | structural connective tissue found where there are a certain amount of stress placed on the body |
| Chondrocyte | a specialized fibroblast cell that secretes cartilage |
| Bone | structural connective tissue composed of 1/3 collagen, 2/3 calcium phosphate and calcium carbonate |
| Osteoblasts | specialized fibroblast cells that secrete bone collagen |
| Mast cells | connective tissue that release histamines in response to an allergic reaction, infection or injury |
| Histamine | causes an increase in blood flow to a region |
| Sensory neuron | an afferent neuron that directs signals from external stimuli to central nervous system |
| Motor neuron | efferent neurons that direct signals from the central nervous system to the muscles |
| Nerve cell body | part of the neuron involved in integration of information |
| Nerve dendrite | part of neuron involved in receiving and transmitting information towards the cell body |
| Nerve axon | part of neuron involved in conducting information away from the cell body |
| Bouton terminal | the end of the axon, also called the synaptic bulb |
| Nernst equation | (look for formula elsewhere) |
| Depolarization | due to influx of sodium ions, the membrane potential becomes more positive. A strong enough event will trigger an action potential |
| Threshold potential | a specific minimum value characteristic of the cell, which when passed, triggers an action potential |
| Ionophores | ion channels |
| Refractory period | a brief period of time after sodium channels open for depolarization in which the channels are close and cannot be open |
| Repolarization | due to the efflux of potassium ions, the membrane potential is restored by becoming more negative |
| Hyperpolarization | due to the excess efflux of potassium ions. Occurs right before cell membrane equilibrates |
| Central nervous system | brain and spinal cord |
| Peripheral nervous system | nerves outside of the brain and spinal cord |
| Oligodendrocytes | glial cells in the central nervous system |
| Schwann cells | glial cells in the peripheral nervous system |
| Glial cells | a specialized type of cell that attaches itself to a section of an unmyelinated axon that rotates around it to form a myelin sheath |
| Salutatory conduction | the impulse transmission of the action potential that seems to jump from node to node along the axon |
| Synapse | a nerve axon impinging on or forming a junction with another axon, a dendrite, or another type of cell body |
| Excitatory postsynaptic potentials (EPSPs) | synaptic junctions in which an action potential is generated in the receiving post synaptic membrane |
| Inhibitory postsynaptic potentials (IPSPs) | synaptic junctions in which hyperpolarization is triggered in the receiving post synaptic membrane, which prevents action potential generation |
| Tendons | connective tissue that connects muscles to bones |
| Sarcomere | the contractile unit in muscle myofibrils, bound by a central structure called the Z-line |
| A-band in muscle | the region in the sarcomere where the myosin and actin filaments overlap |
| I-band in muscle | the region in the sarcomere where there is only actin filament |
| Myosin heads | projections on the myosin filaments that allow for binding onto actin filaments |
| Power stroke | the step in which actin filaments move relative to myosin filaments |
| Tropomyosin | a coiled protein that typically covers up the binding sites for myosin head groups, which needs ATP to move |
| Actin-based regulation of muscle contraction | regulation of muscle via tropomyosin |
| Troponin | multi-subunit binding protein that, when calcium ions bind to it, will cause tropomyosin to shift position |
| Sarcoplasmic reticulum | a modified version of the endoplasmic reticulum which sequesters calcium in muscles. |
| Transverse tubules (t-tubules) | follow the Z-line of myofibrils and which conducts action potentials through the muscles and somehow stimulates the release of calcium ions |
| Motor unit | a motor neuron and the muscle fibers tha tit innervates |
| Associative neurons | neurons that are able to combine or integrate all incoming sensory information and direct an appropriate response |
| Ganglion | a grouping of nerve cells outside the CNS |
| Nucleus | a grouping of nerve cell bodies inside the CNS |
| Prosencephalon (forebrain) | consisting of the telencephalon (cerebrum), corpus callosum, and the diencephalon |
| Telencephalon (cerebrum) | divided into the right and left cerebral hemispheres, joined by the corpus callosum; the hemispheres are further divided into frontal, parietal, occipital, and temporal lobes |
| Frontal lobe | part of cerebrum associated with movement and personality |
| Parietal lobe | part of the cerebrum associated with touch and stretch sensation |
| Occipital lobe | part of cerebrum associated with vision |
| Temporal lobe | part of cerebrum associated with hearing |
| Cerebral cortex | outermost layer of the cerebrum that consists of grey matter covering white matter (situation reversed in spinal cord) |
| Grey matter | nerve cell bodies and their dendrites |
| White matter | myelinated axons of the nerve cells |
| Central sulcus | prominent groove on the cerebral cortex that separates the frontal lobes and the parietal lobes |
| Moto cortex | controls the movement of individual muscles |
| Somatic sensory cortex | detects sensations in various parts of the body |
| Homunculus | a schematic model of a human being mapped out onto the sensory cortex |
| Premotor cortex | an association area that have neuronal connections with the thalamus and cerebellum |
| Thalamus | a relay station for much of the visual and auditory information that we receive from our environment |
| Hypothalamus | part of the diencephalon that regulates the hormones released from the pituitary gland |
| Pituitary gland | the master endocrine gland located in a structure called the sella turcica in the sphenoid bone |
| Mesencephalon (midbrain) | sits on top of the brainstem and is the smallest component of the brainstem – deals with eye movement, esp. muscles |
| Rhombecephalon (hindbrain) | consists of most of the brain stem |
| Metencephalon | consists of pons and the cerebellum |
| Pons | relay station to the cerebellum, much like the thalamus is to the cerebrum |
| Cerebellum | for fine motor control |
| Myelencephalon | area of the brain that gives rise to the medulla oblongata |
| Medulla oblongata | regulates cardiac activity and respiration |
| Reticular formation | an activating system designed to alert the brain, and can also inhibit motor and sensory impulses and can also induce sleep |
| Extensor muscle | a muscle that extends a joint upon contraction |
| Monosynaptic reflex arc | a reflex arc with only one synapse event |
| Interneuron | a neuron that connects other neurons |
| Flexor | muscle that bends a joint upon contraction |
| Polysynaptic reflex arc | a reflex arc that involved multiple synapse events |
| Parasympathetic division (PNS) | tends to increase digestion rate, lower heart rate, lower blood pressure, constricts pupils, and conserves energy |
| Cholinergic nerve fibers | nerve fibers that release acetylcholine at the synaptic cleft |
| Vagus nerve | the tenth cranial nerve that innervates a lot of visceral organs |
| Sympathetic division (PNS) | tends to increase heart rate, elevates blood pressure, dilates pupils, decreases digestion |
| Adrenergic nerve fibers | nerve fibers that release norepinephrine or epinephrine |
| Mechanoreceptors | senses pressure, hearing, balance, blood pressure |
| Nocireceptors | senses pain |
| Thermoreceptors | senses temperature |
| Chemoreceptors | senses a variety of chemicals. Taste and smell fall under this |
| Photoreceptors | senses light |
| Receptor potential | change in membrane potential induced by reception of sensory information |
| Sensory adaptation | sensors getting used to a stimulus |
| Receptive field | the branching of the end of a neuron |
| Lateral inhibition | when one nerve is stimulated, the axon branches in the end, and will involve an inhibitory synapse event. |
| 1st order neurons | nerves from the receptive fields to the spinal cord |
| 2nd order neurons | nerves from the spinal cord to the thalamus |
| 3rd order neurons | nerves from the thalamus to the cerebral hemispheres |
Created by:
ruiyuwu1998
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