ANP midterm 2 Flashcards

Question

Sarcomeres

Answer 1

The repeating contractile units in striated muscle fibers, made of actin and myosin filaments.

Answer 2

Layers of connective tissue that surround and protect muscle fibers and groups of fibers.

Answer 3

Bundles of muscle fibers grouped together within a muscle.

Answer 4

Swellings along nerve fibers in smooth muscle that release neurotransmitters.

Answer 5

A type of nerve–muscle connection in smooth muscle where neurotransmitters spread over a wide area instead of one specific spot.

Answer 6

Smooth muscle found in the walls of internal organs, acting as a single unit.

Answer 7

Channels between cells that allow ions and signals to pass directly from one cell to another. IN HEART: pores - Allows electrical current to spread throughout heart, important for heart to contract as a single unit

Answer 8

A group of cells that function together as one coordinated unit.

Answer 9

A change in a cell’s electrical charge that makes it more positive and can trigger muscle contraction.

Answer 10

A network of protein filaments inside cells that give shape, structure, and help with movement.

Answer 11

The cell membrane of a muscle cell.

Answer 12

Structures in smooth muscle that anchor actin filaments and transmit contractile force.

Answer 13

Strong junctions that hold adjacent cells together to prevent them from pulling apart. - Have signaling molecules

Answer 14

Cell connections that attach actin filaments from one cell to another for stability.

Answer 15

Small pouches in the smooth muscle cell membrane that increase surface area and help transmit signals.

Answer 16

Extensions of the muscle cell membrane that carry electrical signals deep into the cell (found in skeletal and cardiac muscle).

Answer 17

Describes ion channels that open or close in response to changes in electrical voltage across the membrane.

Answer 18

An enzyme that adds phosphate groups to other proteins to change their activity.

Answer 19

Small changes in membrane potential that vary in strength and can lead to action potentials if strong enough.

Answer 20

Refers to receptors that use a G-protein inside the cell to relay signals from hormones or neurotransmitters.

Answer 21

The projecting heads of myosin molecules that attach to actin filaments during muscle contraction.

Answer 22

The protein threads (actin and myosin) that slide past each other to produce muscle contraction.

Answer 23

- It is found in walls of most hollow organs like the stomach, intestines, urinary bladder, uterus, walls of passageways of circulatory system like arteries and veins (NOT capillaries) - It tracks on the respiratory, urinary, and reproductive system - Heart is the main exception because it has cardiac muscle - Most muscles contain two layers or sheets of tightly packed smooth muscle fibers, which are oriented at right angles to each other - The outer layer is longitudinal, where the fibers run parallel to the long axis of the organ, and contraction shortens the organ along its length - Inner layer is circular, and the fibers run around the circumference of the organ. The contraction of these fibers constricts the lumen - alternating the contraction and relaxation of the inner and outer smooth in the gi tract mixes and squeezes substances through the lumen. - There are exception to this pattern: - the stomach, for example, has 3 layers of smooth muscle - the ureter has opposite orientation of smooth muscle from the gi tract. An inner longitudinal and outer circular

Answer 24

- Smooth muscle has spindle shaped cells that are shorter and thinner - Smooth muscle has one single central nucleus unlike skeletal that has multiple nuclei in fiber in periphery of cell - Smooth and skeletal muscle have thin and thick filaments -Filaments in smooth muscle aren't rearranged into sarcomeres and don't produce visible striations Smooth muscle is under involuntary control - Smooth muscle doesn't have epimysium or perimysium, but it does have an endomysium that is made from its cells - The ECM surrounds the smooth muscle cells

Answer 25

- It is controlled by autonomic nervous system, so it is involuntary (peripheral nervous system) - Has varicosities: the axons that enter the tissue contain swellings, which release neurotransmitters along a significant length of the axon when the neuron is stimulated. When neurotransmitters are travelling, they diffuse through where they are supposed to go. - Has diffuse junctions, which are the spaces between axons and tissues

Answer 26

- Smooth muscle varies by muscle fibers, type of innervation, and responsiveness to various stimuli Unitary - A single unit - all visceral organs except the heart - electrically coupled by gap junctions, cells act in uniformed fashion, syncytium - Respond to various chemical stimuli - Self-excitable - Pacemaker cells display spontaneous activity, depolarize in absence of external stimuli - Neural and chemical stimuli affect rate of intensity of unitary contraction - Pacemaker cells contract by contractile cells to contract in unison by electrical coupling by gap junctions - Pacemaker cells are always active because their membrane potential changes in cyclical manner - Two types of spontaneous depolarization that give rise to action potentials by different mechanisms: Pacemaker potentials and Slow wave potentials - Both serve as the basis for the rhythmic digestive processes in gi tract Multi-unit - Lines large airways of the lungs, large arteries, erector pili muscles, and iris of eye - Has few gap junctions, fibers act independently - Because of this and that it is innervated, forms different motor units that can be recruited when needed for strength of contractions - Skeletal is controlled by somatic nervous system and while multi-unit smooth is controlled by autonomic nervous system, hormones, and other stimuli Spontaneous depolarizations are rare - More similarities to skeletal muscle than unitary - Iris of the eye has two layers of smooth muscle. One is oriented in a circle, and the other is oriented radially. Function is to limit amount of light that passes through lens to retina. To make it opaque, coated with pigment called melanin, which makes the eyes brown - Mutation turned off pigmentation in front of iris, which makes light reach the fibers of stromal cells, reflect light back as blue - Green and gray eyes are in between colours

Answer 27

- It is one of the three cytoskeletal systems in smooth muscle - it is composed of non-contractile proteins like desmin and vimentin, which form lattice like framework that transmits the tension through fiber to sarcolemma - Has dense bodies, which are analogous to the zedness of skeletal muscle fiber. They are scattered throughout the cytoplasm, and connect the intermediate filaments to each other and to thin filaments. It also indirectly fastens them to the sarcolemma at regular intervals via adherence junctions and desmosomes - Adherence junctions are scattered around the dense plaques that encircle smooth muscle cells with rib like pattern - When the complexes of actin and myosin contract, the force is transduced to the sarcolemma though intermediate filaments for dense plaques. These alternate with regions of membrane which contains lots of caveolae - Caveolae contain many calcium channels to allow rapid influx of extracellular calcium

Answer 28

- They have thin bodies that are rich in alpha actinin - These connect intermediate filaments, as anchors, to the thin filaments, which make force and transmit the force to plasma membrane - In contracted muscle fiber, the thin and thick filaments overlap, so the force that was generated is transferred through the whole fiber - This is regulated by changes in the intracellular calcium concentrations. Since smooth muscle has excitable cells, changes in the membrane potential triggers the increase in calcium and calcium formation of cross bridges with myosin and actin (like in skeletal muscle) - smooth muscle has less developed sarcoplasmic reticulum to store calcium than skeletal muscle, so it doesn't have t-tubules - increases of intracellular calcium concentration are mediated by calcium influx through voltage-gated calcium channels that are concentrated with cavioli - Calcium influx causes calcium release from sarcoplasmic reticulum by calcium-induced calcium release (c i c r)

Answer 29

- It is regulates primarily by cytoplasmic free calcium concentration - The stimuli that induced smooth muscle contraction triggers increase in sarcoplasmic free calcium - At the elevated calcium concentration, calcium binds to calmodulin, which is a ubiquitous and multifunctional calcium binding protein. Calcium +calmodulin makes a conformational change in protein, which exposes binding sites for target proteins - The enzyme myosin light chain kinase, also called mlck, can interact with calmodulin, which results in activation of kinase, catalyzing phosphorylation of myosin on each of two light chains. This triggers a cycling of myosin cross bridges along actin filaments and development of force

Answer 30

The removal of calcium from cytoplasm, where calmodulin dissociates from myosin-like chain kinase, which regenerates the inactive kinase. Myosin is dephosphorylated by myosin light chain phosphatases, where it also dissociates and is detached from actin filaments, then muscle relaxes

Answer 31

- Skeletal muscle fibers are stimulated exclusively by the nervous system - smooth muscle fibers are stimulated by multiple types of signals, such as nervous signals, hormonal stimulation, stretch, and other ways - this is because smooth muscle's membrane contains many types of receptors that initiates contractile process - Smooth muscle also has receptors that inhibit contraction, which is different from skeletal muscle

Answer 32

- In some types of smooth muscle, neurotransmitter binding generates an action potential, leading to a rise in cytoplasmic calcium levels and cousin contraction - Other types of smooth muscle respond to neural stimulated with only graded potentials - A neurotransmitter can excite or inhibit a particular group of smooth muscle cells, depending on the types of receptors that it has. - aCh is a neurotransmitter at the neuromuscular junction, which causes skeletal muscle to contract. In smooth muscle, when aCh binds to it in bronchitis of the lungs, it causes a strong contraction that constricts the bronchioles. Norepinephrine binding to the same cells is inhibitory, which causes bronchial relaxation and dilation. Norepinephrine on smooth muscle of blood vessels causes contraction and constriction of the vessels - Some types of smooth muscle are not innervated, but they are depolarized spontaneously or depolarize in response to hormones that bind g-protein-coupled receptors - Other chemical stimuli cause smooth muscle to contract or relax by enhancing calcium entry into the cytoplasm (histamine, excess CO2, low pH, lack of oxygen) - Some smooth muscle responds to both neural and chemical stimuli

Answer 33

- Many instances where contraction happens, it occurs with the absence of nerves. So it is not the activation of neural reflex (like in skeletal muscle) - Contraction most likely results from membrane depolarization or from opening of stretch activated calcium channels - This response explains why organs like stomach, bladder, and small arterioles contract to oppose distention - Some smooth muscle of mostly likely larger blood vessels can quickly stretched and this is followed by a temporary increase in wall tension. This increase is quickly followed by a relaxation toward original wall tension (stress relaxation). - Reverse stretch relaxation: occurs when muscle is allowed to shorten. External stress is removed and the tension temporarily decreases. The decrease is followed quickly by muscle contraction toward original wall tension. - These actions help to accommodate different blood volumes while maintaining pressure

Answer 34

- for long periods of time - This sustained phase has been attributed to certain myosin bridges (latch bridges), which cycle very slowly. This slows the progression to the stage where the phosphorylated myosin detaches from actin, which maintains force at low energy costs. - Tonically active smooth muscle: in some smooth muscle cells, the phosphorylation of the myosin light chain is maintained at low level in the absence of external stimuli (no receptor or mechanical activation).

Answer 35

- slower in smooth muscle than skeletal muscle - Leads to slower cross bridges cycling speed and more extended period of contraction, maybe even greater force of contraction, and more of a long period of contraction

Answer 36

- No sarcomeres - Myofilaments are arranged diagonally within fiber - Fewer thick filaments, and each has thin filaments. Skeletal has more thick filaments but only 2 thin per thick filament. - Skeletal muscle has myosin heads that protrude in a hexagon pattern around circumference of thick fiber (60 degrees to each other) - Smooth muscle protrudes 180 degrees to each other, oriented in opposite directions on either side of thick filaments - Thin filaments are on opposite side of thick filaments, move in opposite directions - Myosin heads are found along entire length of thick filament - Cross bridge

Answer 37

Network of non-contractile (autorhythmic) cells SA node, pacemaker is where pacemaker cells are in. After being depolarized, signals go from the atria to the AV node (at the junction between atria and ventricles). The AV node has pacemaker cells that can work in the absence of the SA node. There’s a pause when going from SA to the AV node where the heart contracts. Then, goes to atrioventricular bundle, then bundle branches Opening of sodium channels and closing of potassium channels causes the pacemaker potential to increase. Eventually this will reach a threshold where an action potential will occur and there will be an influx of calcium through open calcium channels

Answer 38

Maintained via homeostatic processes to sustain cell function Testosterone levels and blood hematocrit are not homeostatically regulated

Answer 39

Variables that can be changed by the body but sensors do not exist Can be modulated to achieve regulation (heart rate by autonomic nervous system for pressure, so non regulated variable)

Answer 40

Helps to control muscle movement but is not homeostatic bc doesn’t help maintain internal environment

Answer 41

Not all negative feedback systems are homeostatic Needs a sensor, control center, and an effector These can be near or far from each other, even in the same cell Sensor- measures the value of a regulated variable. Often are neurons that change their firing rate. Constantly active. Generate an output whose value is proportional of the stimulus, which is a change in the value of a measured variable What can’t be measured can’t be regulated Control center- has a error detector and integrator Error detector- receives signal from sensor. Continuously determines the difference between the signal from the sensor and the setpoint variable (normal range of regulated variable) Integrator- that value between the sensor and setpoint variable is used to calculate change in signals going to effector Control center is usually part of endocrine or nervous system It’s possible for set point to change

Answer 42

Blood pressure, heart and breathing rate, digestion, metabolism, body temperature, balance of water and electrolytes, production of body fluids, urination, defecation, sexual response All of these occur without conscious effort, autonomous Part of motor (efferent) pathway of PNS Part of motor (efferent) pathway of PNS Motor neurons innervate cardiac muscle, smooth muscle, and glands Uses two-neuron chain to reach effectors First start at CNS, where pre-ganglionic neuron cell bodies relied in the lateral horn of the brain stem Lightly myelinated preganglionic axons exit CNS by spinal/cranial nerves and extend to autonomic ganglia in PNS, where they synapse on the cell bodies of the second order of neurons, releasing aCh. This is stimulatory at the synapses Non myelinated axons of the second order of neurons travel from ganglia to target effector organs Exception: adrenal medulla, which is stimulated by a preganglionic (first order) neuron that releases aCh. Cells of adrenal medulla have the same embryonic origin as neural tissue, which functions as modified postganglionic neurons Instead of releasing NT at the synapse within an effector tissue, the secretory products of adrenal medulla are picked up by blood and travel throughout the body to all effector tissues of the sympathetic tissue Autonomic postganglionic fibers release two neurotransmitters, norepinephrine (secreted by sympathetic fibers) and aCh (secreted by parasympathetic fibers) Depending on NT and type of receptor of target organ, effect might be excitatory or inhibitory. Autonomic nervous system differs from somatic nervous system since it can stimulate or inhibit its effectors

Answer 43

Effectors are targets that motor neurons innervate Efferent pathways and ganglia Target organ responses to NTs

Answer 44

Skeletal muscle Cell bodies lie in central horn of spinal horn, which is in CNS A single and thick myelinated axon travels out of CNS to PNS via spinal/cranial nerves and continues uninterrupted to target, which is skeletal muscle Nerve terminals of somatic motor neurons release aCh, which always stimulates skeletal muscle to contract

Answer 45

Tonically active: provide some degree to nervous input to given tissue at all times. The frequency of action potentials in both systems can increase or decrease. Tissue activity can be enhanced/inhibited. This helps the autonomic nervous system to help regulate a tissue’s function. Without it, nervous input in a tissue can only increase. Dynamic antagonistic interaction: when one system is working in a visceral organ, the other’s work decreases. Both systems are present in the same organs but do opposite work of each other. In some cases, both systems may have a cooperative effect Sympathetic system Strenuous and physical activity Well oxygenated nutrient-rich blood must go to working skeletal muscles, so changes in organ and tissue function in body are coordinated Heart rate and myocardial contractility = increase so heart pumps more blood per minute Sympathetic stimulation of vascular smooth muscle causes widespread vasoconstriction in organs of the gastrointestinal system and kidneys. This redirects blood away from metabolically inactive tissues and towards contracting muscles Bronchodialation in lungs facilitates air in and out of lungs so that there is maximization of oxygen coming in and carbon dioxide out Increase in glycogenolysis (glycogen to glucose) and gluconeogenesis (formation of new glucose from non-cardbohydrate sources in liver) increase concentration of glucose in blood. Important for the brain because it's the only nutrient there that can be used for metabolic energy. Lipolysis in adipose tissue increases concentration of fatty acids in blood, which are used by skeletal muscle to form metabolic energy for contraction Sweating helps to thermoregulate during increased physical activity and heat production Pupil dilates and there's more light coming into retina, lens adapts for distance vision Parasympathetic system Appropriate when body is resting Decreases heart rate to conserve energy under resting conditions Salivary secretion = enhanced to facilitate swallowing of food, gastric motility, and secretion, in order to ingest food. Intestinal motility and secretion = stimulated to continue processing and facilitate absorption of nutrients Exocrine and endocrine secretion from pancreas = promoted. Enzymes released from exocrine glands of pancreas help with chemical breakdown of food in intestines. Insulin released from pancreatic islets promote the storage of nutrient molecules in the tissues once absorbed into body Contraction of urinary bladder = promoted to cause urination Contraction of pupil in eye, lens adapts to near vision. While the sympathetic system has more control for blood vessels, the parasympathetic has more control over heart and smooth muscle of digestive/urinary tract organs. These organs exhibit parasympathetic tone, meaning they work to slow heart and continue normal activity of the urinary/digestive tracts Sympathetic division can override this when there’s too much stress Parasympathetic fibers activate most glands except for adrenal/sweat glands of skin

Answer 46

Increase heart rate, cause fecal/urinary retention

Answer 47

Adrenal medulla, sweat glands, erector pili muscles of skin, kidneys, most blood vessels

Answer 48

Sympathetic division mediates reflexes that regulate body temperature. Heat to skin causes blood vessels to dilate. When the body temperature rises, sympathetic nerves dilate the skin’s blood vessels, which helps heat to escape and activates sweat glands to cool the body. When cold weather = heat loss, blood vessels constrict Renin angiotensin system: sympathetic impulses stimulate kidneys to release renin, which helps to make potent blood pressure increasing hormones. This hormone system helps to regulate blood pressure, fluid/electrolyte balance, and systemic vascular resistance. Can promote many metabolic effects that are not reversed by parasympathetic activity. This is because of neural stimulation and release of adrenal medullary hormones. For example: metabolic rate of body cells raises glucose levels and mobilizes fat for use as fuels. Medullary hormones also cause skeletal muscle to contract more strongly and quickly Preganglionic axons branch a lot as they enter the sympathetic trunk. Synapse with postganglionic neurons at many levels, so when sympathetic division is activated, responds in a diffuse/interconnected way. Parts of sympathetic can be activated individually. Just because the eye dilates because of light, it doesn’t mean the heart rate also must beat faster Activation of sympathetic can produce more long lasting effects than parasympathetic Adrenal medullary cells secrete epinephrine and norepinephrine into blood when sympathetic division is working. These help with the effects of the sympathetic nervous system to last longer. Last for a couple minutes and then get destroyed by liver While the effects of the sympathetic system may be short, the hormonal effects last a long time.

Answer 49

One preganglionic neuron synapses with one, or at most, a few of postganglionic neurons. All sympathetic fibers release aCh, which is quickly hydrolyzed/destroyed by aCh esterase. Because of this, parasympathetic division has short-lived but highly localized control over its effectors Preganglionic axons branch profusely

Answer 50

Hypothalamus Main integration center for autonomic nervous system. Anterior hypothalamus direct parasympathetic functions and posterior direct sympathetic functions Exert effects both directly and indirectly, via relays through reticular formation, which influences preganglionic motor neurons in brain stem and spinal cord Coordinates heart activities, blood pressure, body temp, water balance, and endocrine activities Also mediates reactions to fear and other emotions by association with limbic system (system for emotions;/behaviour responses) Limbic lobe involved in emotional responses and memory function, like hippocampus, amygdala, and cingulate gyrus Since the hypothalamus and limbic lobe are closely connected, the lobe influences the hypothalamus activity based on emotional state. When you’re scared, amygdala sends signals to hypothalamus along medial forebrain bundle, which stimulates sympathetic fight/flight Hypothalamus also stimulates release of stress hormones through control of the endocrine system by responding to amygdala input. Hypothalamus is the gatekeeper of emotional and visceral brain Cerebral cortex Brain stem reticular formation: loose collection of neuron cell bodies in pons, medulla, and midbrain in white matter. This exerts the most direct influence over autonomic functions. Certain motor centers, ventral lateral medulla, reflexively regulate heart rate and blood vessel diameter. Other medulla regions control gastrointestinal activities. Midbrain centers, motor nuclei, control muscles of pupil and lese focused. Spinal cord Urination, defecation, erection, ejaculation. Involuntary, but subject to conscious control and can be overridden by the brain.

Answer 51

A boost of sympathetic signaling by long-term stress enhances tone in smooth muscles, raises blood pressure Heart must work harder and artety walls will be worn out and torn Can be helped with beta blockers, which block

Answer 52

Sympathetic vasoconstrictor response to stress, decreases blood flow in stomach wall

ANP midterm 2 Flashcards

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