Lab Exam 1 Notes Contd Flashcards
the contraction of skeletal and cardiac muscle fibers can be considered in terms of 3 events – … of the muscle cell, …., and shortening of the muscle cell due to … within it
electrical excitation; excitation contraction coupling; sliding of the myofilaments
because the plasma membrane is more permeable to … than to …, the cell’s resting membrane potential is more negative inside than outside
K+; Na+
the resting membrane potential is of particular interest in excitable cells, like muscle cells and neurons, because changes in that voltage underlie their ability to … (to … and/or …)
do work; contract; issue electrical signals
when a muscle cell is stimulated, the sarcolemma becomes temporarily more permeable to sodium ions, which enters the cell. this sudden influx of sodium ions alters the membrane potential, such that the cell interior becomes less negatively charged – ….
depolarization
when depolarization reaches a certain level and the sarcolemma momentarily changes its polarity, a depolarization wave travels along the sarcolemma. even as the influx of sodium occurs, the sarcolemma becomes becomes less permeable to sodium and more permeable to potassium, which moves out of the cell –
repolarization
the … is the period of time when sodium permeability of the sarcolemma is rapidly changing and maximal, and the following period when sodium permeability becomes restricted. during this period there is no possibility of generating another action potential
absolute refractory period
as sodium permeability is gradually restored to resting levels during repolarization, an especially strong stimulus to the muscle cell may provoke another action potential –> …
repolarization restores the muscle cell’s normal excitability
relative refractory period
if the muscle cell is stimulated to contract rapidly repeatedly, the changes in sodium and potassium concs near the membrane begin to reduce its ability to respond. the … must become more active to reestablish the ionic concs of the resting state
sodium-potassium pump
Propagation of the action potential along the sarcolemma causes the release of …. from storage in the … within the muscle cell.
calcium ions (Ca2+); sarcoplasmic reticulum;
When the calcium ions bind to the regulatory protein… on the actin myofilaments, they act as an ionic trigger that initiates …, and the actin and myosin filaments slide past each other. Once the action potential ends, the calcium ions are almost immediately transported back into the sarcoplasmic reticulum. Instantly the muscle cell relaxes.
troponin; contraction;
Muscle cell contraction is initiated by generation and transmission of an …along the sarcolemma. This electrical event is coupled to the sliding of the …—contraction—by the release of calcium ions (Ca2+).
action potential ; myofilaments;
generally there is … with ATP alone. There is … with the salt solutions alone. … occurs in the presence of ATP and the proper concs of potassium and magnesium ions
little or no contraction; no contraction; maximum contraction
a single contraction of skeletal muscle is called a …
a tracing of this shows three distinct phases: latent, contraction, and relaxation
muscle twitch
the … is the interval from stimulus application until the muscle begins to shorten. although no activity is indicated on the tracing during this phase, … is occurring within the muscle
latent period; excitation-contraction coupling;
during the …, the muscle fibers shorten; the tracing shows an increasingly higher needle deflection and the tracing peaks
period of contraction
during the .., represented by a downward curve of the tracing, the muscle fibers relax and lengthen
period of relaxation
If a muscle is stimulated with a rapid series of stimuli of the same intensity before it has had a chance to relax completely, the response to the second and subsequent stimuli will be greater than to the first stimulus. This phenomenon, called …, or …, occurs because the muscle is already in a … state when subsequent stimuli are delivered.
wave summation; temporal summation; partially contracted;
voltage that produces the maximal strength of contraction, and is the weakest stimulus at which all muscle cells are being stimulated: …
maximal stimulus
Stimulation of a muscle at an even higher frequency will produce a “fusion” (complete tetanization) of the summated twitches. In effect, a single sustained contraction is achieved in which no evidence of relaxation can be seen. …, or …, demonstrates the … generated by a skeletal muscle
Fused tetanus; complete tetanus; maximum force
… is a reversible physiological condition in which a muscle is unable to contract even thought it is being stimulated. it can occur with short-duration maximal contraction or long-duration submaximal contraction
muscle fatigue
several factors contribute to muscle fatigue, most of which affect …
one theory involves the buildup of … from ATP and creatine phosphate breakdown, which may block …
another theory suggests that … in the T tubules may block ca release from the SR and alter the membrane potential of the muscle fiber
excitation-contraction coupling; Pi; calcium release from the SR; potassium accumulation
When the fibers of a skeletal muscle are slightly stretched by a weight or tension, the muscle responds by …and thus is capable of doing more work. When the actin and myosin barely overlap, sliding can occur along nearly the entire length of the actin filaments. If the load is increased beyond the optimum, the latent period becomes longer, contractile force decreases, and… (fatigue) occurs more quickly. With excessive stretching, the muscle is unable to develop any active tension and no contraction occurs. Since the filaments no longer overlap at all with this degree of stretching, the sliding force cannot be generated.
contracting more forcibly; relaxation;
A single skeletal muscle consists of numerous elongated skeletal muscle cells, also called skeletal muscle …. These muscle cells are excited by motor neurons of the central nervous system whose axons terminate at the muscle. an axon of a motor neuron branches profusely at the muscle. each branch produces multiple …, each of which innervates a single fiber
fibers; axon terminals
the most important organizational concept in the physiology of muscle contraction is the …, a single motor neuron and all of the cells within a muscle that it activates
motor unit
a muscle consists of multiple motor units and the gradual and coordinated activation of these motor units results in … of the whole muscle
graded contraction
the nervous system controls muscle contraction by two mechanisms:
…: the gradual activation of more and more motor units
…: an increase in the frequency of nerve impulses for each active motor unit
recruitment (multiple motor unit summation);
temporal (wave) summation
…: constant state of slight excitation of a muscle while it is in the relaxed state. even while “at rest,” a small number of motor units to a skeletal muscle remain slightly active to prepare the muscle for possible contraction
tonus
graded muscle contractions, which represent increasing levels of force generated by a muscle, depend upon:
- the gradual …
- increasing the … for each active motor unit. this permits a range of forces to be generated by any given muscle or group of muscles, all the way up to the …
activation of more motor units;
frequency of motor neuron action potentials; maximum force
the … is the second major control system of the body, and acting with the nervous system, it helps coordinate and integrate the activity of the body
endocrine system
the endocrine system uses chemical messengers, or …, which enter the blood to be transported throughout the body
hormones
organs that respond to a particular hormone are referred to as the … of that hormone. the ability of the target tissue to respond depends on the ability of the hormone to bind with … occurring on the cells’ plasma membrane or within the cells
target organs; specific receptors
endocrine glands release their hormones directly into the …, from which the hormones enter the blood or lymph
the exocrine glands release their products at the … or upon an … via ducts
extracellular fluid; body’s surface; epithelial membrane
the pituitary gland, or …, is located in the sella turcica of the sphenoid bone. it consists largely of two functional lobes, the …, or …, and the …, consisting of the … and the …. – the stalk that attaches the pituitary gland to the hypothalamus
hypophysis;
adenohypophysis; anterior pituitary;
neurohypophysis; posterior pituitary; infundibulum
the anterior pituitary produces and secretes a number of hormones, four of which are …,
tropic hormones
the target organ of a tropic hormone is another …, which secretes its hormone in response to stimulation
endocrine gland
because the anterior pituitary controls the activity of many other endocrine glands, it has been called the …
however, because … or … hormones from neurons of the ventral hypothalamus control anterior pituitary cells, the hypothalamus has superseded the anterior pituitary as the major controller of endocrine glands
master endocrine gland; releasing; inhibiting
(anterior pituitary tropic hormones) … and … - regulate gamete production and hormonal activity of the gonads (ovaries and testes0
gonadotropins-follicle-stimulating hormone (FSH); luteinizing hormone (LH)
(anterior pituitary tropic hormones) … regulates the endocrine activity of the adrenal cortex
adrenocorticotropic hormone
(anterior pituitary tropic hormones) … or … influences the growth and activity of the thyroid gland
thyroid-stimulating hormone; thyrotropin
other important hormones produced by the anterior pituitary are not directly involved in the regulation of other endocrine glands of the body:
… – general metabolic hormone that plays an important role in determining body size – hyposecretion results in dwarfism in children and hypersecretion causes gigantism in children and … (overgrowth of bones in hands, feet, and face) in adults
growth hormone; acromegaly;
other important hormones produced by the anterior pituitary are not directly involved in the regulation of other endocrine glands of the body:
… stimulates milk production by the breasts. the role of the hormone in males is not well understood
prolactin (PRL)
the … hormones control production and secretion of the tropic hormones, GH, and PRL
ventral hypothalamic
the hypothalamic hormones reach the cells of the anterior pituitary through the …, a complex vascular arrangement of two capillary beds that are connected by the hypophyseal portal veins
hypophyseal portal system
the posterior pituitary is not an endocrine gland because it does not …
synthesize the hormones it releases
the posterior pituitary acts as a storage area for two neurohormones that are released in response to nerve impulses from neurons in the hypothalamus:
…: stimulates powerful uterine contractions during birth and also causes milk ejection in the lactating mother
…: causes the tubules of the kidneys to reabsorb more water from the urinary filtrate, reducing urine output and conserving body water
oxytocin; antidiuretic hormone
hyposecretion of ADH results in dehydration from excessive urine output, a condition called … Individuals with this condition experience an insatiable thirst. hypersecretion results in edema, headache, and disorientation
diabetes insipidus
the pineal gland is a small cone-shaped gland located in the roof of the third ventricle of the brain. its major endocrine product is …, which exhibits a diurnal cycle. it peaks at night, making us drowsy, and is lowest around noon
melatonin
The endocrine role of the pineal gland in humans is still controversial, but it is known to play a role in mating and migratory behavior of other animals. In humans, melatonin appears to exert some inhibitory effect on the reproductive system that prevents … Changing levels of melatonin may also affect biological rhythms associated with body temperature, sleep, and appetite.
precocious sexual maturation.
The thyroid gland is composed of two lobes joined by a central mass, or…. It is located in the throat, just inferior to the larynx. It produces two major hormones, …and ….
isthmus; thyroid hormone; calcitonin;
thyroid hormone is actually two physiologically active hormones known as … and …
TH’s primary function is to control the rate of … and …
T4 (thyroxine); T3 (triiodothyronine); body metabolism; cellular oxidation
hyposecretion of TH leads to a condition of mental and physical sluggishness, which is called … in the adult. hypersecretion causes elevated metabolic rate, nervousness, weight loss, sweating, and irregular heartbeat
myxedema
calcitonin is released in response to … levels. although it decreases these levels by stimulating … in the bones, it is not involved in day-to-day control of Ca homeostasis
high blood calcium levels; calcium salt deposit
the parathyroid glands are found embedded in the posterior surface of the thyroid gland. typically, there are two small oval glands on each lobe, but there may be more and some may be located in other regions of the neck. they secrete …, the most important regulation of calcium balance of the blood
parathyroid hormone (PTH)
when blood calcium levels decrease below a certain critical level, the parathyroids release PTH, which cause release of calcium from … and prods the kidney to … and … from the filtrate
bone matrix; reabsorb more calcium and less phosphate
PTH also stimulates the kidneys to convert Vit D to its active D3 form …, which is required for the absorption of calcium from food
calcitriol
hyposecretion of PTH increases neural excitability and may lead to .., prolonged muscle spasms that can result in respiratory paralysis and death. hypersecretion results in loss of calcium from bones, causing deformation, softening, and spontaneous fractures
tetany
The thymus is a bilobed gland situated in the superior thorax, posterior to the sternum and anterior to the heart and lungs. Conspicuous in the infant, it begins to… at puberty, and by old age it is relatively inconspicuous.
atrophy
The thymus produces several different families of hormones including…, …, and…. These hormones are thought to be involved in the development of .. and the immune response. Their role is poorly understood; they appear to act locally as paracrines.
thymulin; thymosins; thymopoietins; T lymphocytes
The two adrenal, or suprarenal, glands are located atop or close to the kidneys. Anatomically, the adrenal medulla develops from neural crest tissue, and it is directly controlled by the.. nervous system. The medullary cells respond to this stimulation by releasing a hormone mix of… (80%) and… (20%), which act with the sympathetic nervous system to elicit the fight- or-flight response to stressors
sympathetic; epinephrine; norepinephrine
The adrenal cortex produces three major groups of steroid hormones, collectively called…
corticosteroids
The…, chiefly …, regulate water and electrolyte balance in the extracellular fluids, mainly by regulating sodium ion reabsorption by kidney tubules.
mineralocorticoids; aldosterone
The… include (cortisol [hydrocortisone], cortisone, and corticosterone), but only cortisol is secreted in significant amounts in humans. It enables the body to resist long-term stressors, primarily by increasing blood glucose levels.
glucocorticoids;
The…, or sex hormones, produced by the adre- nal cortex are chiefly … (male sex hormones), but some estrogens (female sex hormones) are also formed.
gonadocorticoids; androgens
The gonadocorticoids are produced throughout life
in relatively insignificant amounts; however, hyper- secretion of these hormones produces abnormal hairiness (…), and masculinization occurs
hirsutism
The pancreas, located partially behind the stomach in the abdomen, functions as both an endocrine and exocrine gland. It produces digestive enzymes as well as … and …, important hormones concerned with the regulation of blood sugar levels.
insulin; glucagon
Elevated blood glucose levels stimulate release of…, which decreases blood sugar levels, primarily by accelerating the transport of glucose into the body cells, where it is oxidized for energy or converted to glycogen or fat for storage.
insulin
Hyposecretion of insulin or some deficiency in the
insulin receptors leads to …, which is characterized by the inability of body cells to utilize glucose and the subsequent loss of glucose in the urine. Alterations of protein and fat metabolism also occur secondary to derangements in carbohydrate metabolism. Hypersecretion causes low blood sugar, or…. Symptoms include anxiety, nervousness, tremors, and weakness.
diabetes mellitus; hypoglycemia
..acts antagonistically to insulin. When blood glucose levels are low, it stimulates the liver, its primary target organ, to break down glycogen stores to glucose, to synthesize glucose by gluconeogenesis, and subsequently to release the glucose into the blood
Glucagon
the female gonads, or ovaries are located in the pelvic cavity and produce the female sex cells (ova) as well as two steroid hormone groups, the … and …
estrogens; progesterone
the endocrine and exocrine functions of the ovaries do not begin until the
onset of puberty
the … are responsible for the development of the secondary sex characteristics of the female at puberty (primarily maturation of the reproductive organs and development of the breasts) and act with … to bring about cyclic changes of the uterine lining that occur during the menstrual cycle
estrogens; progesteorne
the estrogens also help prepare the mammary glands for … During pregnancy … maintains the uterine musculature in a quiescent state and helps to prepare the breast tissue for lactation
lactation; progesterone
The paired oval testes of the male are suspended in a pouchlike sac, the scrotum, outside the pelvic cavity. In addition to the male sex cells (sperm), the testes produce the male sex hormone,…, which promotes the maturation of the reproductive system accessory structures, brings about the development of the male secondary sex characteristics, and is responsible for sexual drive, or libido. Both the endocrine and exocrine functions of the testes begin at….
testosterone; puberty
Stored T3 and T4 from the thyroid are attached to the protein colloidal mate- rial stored in the follicles as… and are released gradually to the blood.
thyroglobulin
… or … cells are responsible for calcitonin production
parafollicular; C cells
when the thyroid gland is actively secreting, the follicles appear … , and the colloidal material has a ruffled border. when the thyroid is hypoactive/inactive, the follicles are … and .., and the follicular epithelium appears to be squamouslike
small; large; plump
The …, which synthesize parathyroid hormone (PTH), are small and abundant, and arranged in thick branching cords. The function of the scattered, much larger… cells is unknown.
parathyroid cells; oxyphil
the … are the endocrine portions of the pancreas
pancreatic islets (islets of Langerhans)
the islets are scattered amid the more numerous …, which are cells that produce the exocrine secretion of digestive enzymes that is released into the duodenum through the pancreatic duct.
acinar cells
… cells: cluster at the periphery of the islets and produce glucagon
… cells: synthesize insulin
alpha; beta
… cells: produce growth hormone and prolactin
… cells: contain granules that are responsible for the production of the tropic hormones
acidophil; basophil
…: third cellular population of the anterior pituitary that don’t take up the stain and are not directly involved in hormone production
chromophobes
… of the adrenal gland: where most mineralocorticoid production occurs
zona glomerulosa
… of adrenal gland: produces glucocorticoids – thickest part of the cortex
zona fasciculata
…: innermost cortical zone; produces sex hormones and some glucocorticoids – cells here stain intensely and form a branching network
zona reticularis
the … or …cells of the CNS include astrocytes, oligodendrocytes, microglial cells, and ependymal cells
neuroglia; glial
the neuroglia found in the PNS include …, also called neurolemmocytes, and …
Schwann cells; satellite cells
neuroglia serve the needs of the delicate neurons by … and … them.
bracing; protecting
neuroglia also act as … (microglial cells), … the cytoplasmic extensions of the neurons (… and … cells), play a role in capillary-neuron exchanges, and control the chemical environment around neurons (…)
phagocytes; myelinate; oligodendrocytes; Schwann; astrocytes
… or nerve cells, are the basic functional units of nervous tissue – highly specialized to transmit messages from one part of the body to another in the form of nerve impulses
neurons
all neurons have a … from which slender processes extend – cell body is both the … of the neuron and part of its …
cell body; biosynthetic center; receptive region
neuron cell bodies make up the gray matter of the CNS, and form clusters there that are called … In the PNS, clusters of neuron cell bodies are called ..
nulei; ganglia
two prominent structures are found in the cytoplasm of the neuron: one is cytoskeletal elements called …, which provide support for the cell and a means to transport substances throughout the neuron
neurofibrils;
the second prominent structure found in the cytoplasm of the neuron is the the … (also known as …) an elaborate type of RER involved in the metabolic activities of the cell
chromatophilic substance; Nissl bodies
neurons have two types of processes:
… are receptive regions that bear receptors for neurotransmitters released by the axon terminals of other neurons
…, also called nerve fibers, form the impulse generating and conducting region of the neuron
dendrites; axons
in the CNS, bundles of axons are called …
in the pNS, bundles of axons are called …
tracts; nerves
neurons may have many dendrites, but they have only a single axon. the axon may branch, forming one or more processes called …
axon collaterals
in general, a neuron is excited by other neurons when their axons release neurotransmitters close to its dendrites or cell body. the electrical signal produced travels across the cell body and if it is great enough, it elicits a regenerative electrical signal, an …. or … that travels down the axon
impulse; action potential
the axon in motor neurons begins just distal to a slightly enlarged cell body structure called the …
axon hillock
the point at which the axon hillock narrows to axon diameter is referred to as the …
initial segment
the axon ends in many small structures called …, or …, which form … with neurons or effector cells
axon terminals; terminal boutons; synapses
axon terminals store the neurotransmitter chemical in tiny … each axon terminal of the presynaptic neuron is separated from the cell body/dendrites of the next, or postsynaptic, neuron by a tiny gap called the …
vesicles; synaptic cleft
when neurotransmitters diffuse across the synaptic cleft to bind to membrane receptors on the postsynaptic neuron, an electrical current is initiated - a …
synaptic potential
specialized synapses between neurons and skeletal muscles are called
neuromuscular junctions
most long nerve fibers are covered with a fatty material called myelin and are referred to as ..
myelinated fibers
axons in the PNS are typically heavily myelinated by special supporting cells called …, which wrap themselves tightly around the axon in jelly roll fashion
schwann cells
the schwann cell nucleus and the bulk of its cytoplasm end up just beneath the outermost portion of its plasma membrane. this peripheral part of the schwann cell and its exposed plasma membrane is referred to as the …
outer collar of perinuclear cytoplasm
since the myelins heath is formed by many individual schwann cells, it is a discontinuous sheath. the gaps or indentations in the sheath are called … or …
myelin sheath gaps; nodes of Ranvier
within the CNS, myelination is accomplished by neuroglia called … because of its chemical composition, myelin electrically insulates the fibers and greatly increases the transmission speed of nerve impulses
oligodendrocytes
in … neurons, one very short process, which divides into … and … processes, extends from the cell body
unipolar; peripoheral; central
in unipolar neurons, functionally, only the most distal parts of the … act as receptive endings; the rest acts as an axon along with the …
peripheral process; central process
unipolar neurons are also called … because they are derived from bipolar neurons; nearly all neurons that conduct impulses … are unipolar
pseudounipolar neurons; toward the CNS
… neurons have two processes attached to the cell body– rare type, found only as part of the receptor apparatus of the eye, ear, and olfactory mucosa
bipolar;
many processes issue from the cell body of …, all classified as dendrites except for a single axon. most neurons in the brain and spinal cord and those whose axons carry impulses … fall into this last category
multipolar neurons; away from the CNS
In general, neurons carrying impulses from sensory receptors in the internal organs (viscera), the skin, skeletal muscles, joints, or special sensory organs are termed…, or …, neurons
sensory; afferent
the cell bodies of sensory neurons are always found in a … outside the CNS, and these neurons are typically …
ganglion; unipolar
neurons carrying impulses from the CNS to the viscera and/or body muscles and glands are termed …, or …, neurons; these are most often …, and their cell bodies are almost always located in the …
motor; efferent; multipolar; CNS
the third functional category of neurons is … or …. neurons, which are situated between and contribute to pathways that connect sensory and motor neurons. their cell bodies are always located within the …, and they are … neurons structurally
interneurons; association neurons; CNS; multipolar
A nerve is a bundle of axons found in the PNS. Wrapped in connective tissue coverings, nerves extend to and/or from the… and … or structures of the …such as skeletal muscles, glands, and skin.
CNS; visceral organs; body periphery
… nerves conduct impulses only toward the CNS. a few of the … nerves are of this type purely
sensory (afferent); cranial
… nerves carry impulses only away from the CNS. the … are of this type
motor (efferent); ventral roots of the spinal cord
nerves carrying both sensory and motor fibers are called …; most nerves of the body, including all … nerves, are of this type
mixed nerves; spinal
within a nerve, each axon is surrounded by a delicate connective tissue sheath called an …, which insulates it from the other neuron processes adjacent to it. this is not the myelin sheath, rather it is an additional sheath that surrounds the myelin sheath
endoneurium
groups of axons are bound by a coarser connective tissue, called the …, to form bundles of fibers called …, which are all bound together by a white fibrous connective tissue sheath called the …, forming the cordlike nerve
perineurium; fascicles; epineurium
