Final Comprehensive Flashcards
3 types of muscle, where and characteristics
- Skeletal Muscle- Attached to skeleton- voluntary- have strations-does not undergo mitosis during immaturity
- Cardiac Muscle- only in heart-involuntary-striated, no mitosis during maturity
- Smooth muscle- in walls of hollow visceral organs-involuntary-no striations- does undergo mitosis during maturity
4 functions of muscles
- provide movement
- maintain posture/ body position
- stabilize
- generate heat
myosin
- responsible for actin based motility- thick filament
- head has filamentous actin and uses ATP hydrolysis to generate force and to “walk” along the filament
- contractions depend on myosin and actin
actin
- thin filaments- protein
- binding sites for myosin found on actin (inhibitor- tropomyosin)
- make up myofilament with myosin
crossbridge
the globular heads of myosin link thick & thin filaments together, forming crossbridges
- these crossbridges act as motors to generate tension developed by a contracting muscle cell
tropomyosin
-rod-shaped protein(polypeptide) that helps stabilize actin and in relaxed muscles, blocks the binding site for myosin on actin
troponin
-initiated by AP, this is the protein Ca2+ binds to , to change the shape of tropomyosin, exposing binding site for myosin on the thin filaments(actin)
sarcoplasmic reticulum
-GOING TO REGULATE THE INTRACELLULAR LEVELS OF CALCIUM
T-tubules
- at the A-band/ I-band junction, the sarcolemma protrudes into the cell, making an elongated tube (T-transverse)
- they run between terminal cisternae of the SR forming triads
sliding filament model of contraction
-during contraction, your thin filaments slide past the thick ones, making actin and myosin filaments overlap more
acetylcholine ACh
- neurotransmitter found in small membraneous sacs ( synaptic vesicles) that are located at axon terminal
- 6 seconds of exercise Short term
- ATP stored in muscles is used first
- 10 seconds of exercise short term
- ATP is formed form creatine phosphate and ADP
- creatine phosphate is high energy molecule stored in muscle
- creatine phosphate + ADP= (cat. creatine kinase) creatine + ATP
- stored ATP + CP provides for 14-16 seconds of muscle contraction
- 30-40 seconds to end of short term exercise
-glycogen stored in muscles is broken down to glucose, which is oxidized to generate ATP
4.Hours of exercise-long term
- ATP is generated by breakdown of several nutrient energy fuels by aerobic pathway
- Glucose + oxygen = CO2 + water + ATP
- aerobic provides lots of ATP but its slow and requires O2
slow oxidative fibers
- slow to contract
- aerobic respiration
- resistant to fatigue
- LOW POWER
- endurance type: marathon, maintaining posture
fast glycolytic fibers
- contract rapidly
- anaerobic respiration
- tire quickly
- contract powerfully
- good for short-term, intense or powerful movements, weight lifting , hitting baseball
fast oxidative fiber
- contracts rapidly
- aerobic respiration
- moderate fatigue
- moderate power
- good for walking, sprinting
what is muscular dystrophy?
- Duchenne muscular dystrophy-sex-linked recessive disease
- diagnosed at early childhood and only live into 20s
a. DMD is caused by lack of protein DYSTROPHIN, that links the cytoskeleton to the extracellular matrix and helps stabilize the sarcolemma
b. the sarcolemma tears, allowing excess calcium to enter, damaging the fibers - eventually apoptosis occurs and muscle mass is lost
c. there is no cure for DMD, but animal testing is underway for processes which will allow the body to produce dystrophin
hormone
- “to excite”
- chemical messengers released into blood, to send signals throughout the body
- long distance chemical signals traveling thru blood or lymph
- endocrine system
Endocrinology
study of hormones and endocrine system
target cells
tissue cells that are given hormone influences
cyclic AMP
Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3’-5’-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is derived from adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway.
steps of Cyclic AMP
- a hormone(1st messenger) binds to its receptor on the plasma membrane
- This binding causes the receptor to change its shape and activates G-protein by causing GTP to attach to it
- When GTP attaches to G Protein and activates it, active G protein attaches to the enzyme Adenylate Cyclase
- It catalyzes the formation of the second messenger cyclic AMP from ATP
- Cyclic AMP activates protein kinase A. A kinase is an enzyme that catalyzes phosphorylation of proteins. The phosphorylation activates some proteins, & inhibits others.
6) The action of cAMP is short-lived becuase it is rapidly degraded by the intracellular enzyme phosphodiesterase.
upregulation
target cells form more receptors in response to rising blood levels of cells
ex. high estrogen levels cause cells to produce more progesterone receptors
downregulation
target cells become disensetised in high blood levels of hormones; they lose their receptors
ex. progesterone induces loss of estrogen receptors
permissiveness
one hormone can’t work completely without the other being present
ex. thyroid is necessary for reproductive development
synergism
each hormone will have the same effect alone but when together there is much larger effect
ex. glucagon and epinephrine together cause the release of glucose from the liver into the blood to by 150% of that of releases when each is working alone
antagonism
one hormone opposes the action of the other
ex. insulin which lowers blood glucose levels is antagonized by glucagon which raises glucose levels
tropic hormone
-4 of the 6 ant. pituitary hormones- TSH, ACTH, FSH and LH- are TROPINS or tropic hormones.
These hormones regulate the secretory action of other endocrine glands. All ant, pituitary hormones except GH affect their target cells via a cyclic AMP second-messenger system.
tropic vs. nontropic
Non-tropic hormones are hormones that directly stimulate target cells to induce effects. This differs from the tropic hormones, which act on another endocrine gland.
-ex. glucocorticoids, vasopressin, estrogen, testosterone, estrogen, oxytocin, epinephrine & norepinephrine
nervous vs. endocrine action
The nervous system controls rapid, precise
responses (ex. reflex)
• The endocrine system controls activities that
require long duration (ex. body growth)
– energetically more efficient
• These two systems interact and regulate each other
Endocrine glands
- produce hormones
- ductless glands
- include: pineal gland, pituatary, thyroid, parathyroid, adrenal
Organs that perform both endocrine and other functions:
- hypothalamus
- thymus
- pancreas
- ovary(female)
- testis(male)
- placenta
2 major categories of hormones
- amino acid based
2. steroid based
Amino acid-based hormones
(made up of proteins, chains of amino acids)
1) water-soluble
2) attaches to EXTRAcellular receptors
3) can’t cross cell membrane
ex. antidiuretic hormone
steroid-based hormones
(made of lipids, with a cholesterol base):
1) lipid soluble
2) crosses cell membrane
3) attaches to INTRAcellular receptors
ex. estrogen and testosterone
5 ways hormones alter target cells:
1) induce secretion
2) stimulates protein synthesis within the cell( aldosterone in kidneys, more Na+K+ pumps)
3) induce mitosis ex. growth hormone
4) change membrane permeability/potential)
5) activate or inactivate enzymes ex. insulin
lipid soluble hormones(steroids & TH) work by
-direct gene activation since they can cross the cell membrane
Direct gene activation
-hormones move into the target cells by DIFFUSION and attach to an intracellular receptor.
The hormone/receptor complex moves into the nuclear chromatin and attaches to a specific region of the cell’s DNA, causing a gene to be turned “on”.
This means that the gene is being transcribed (mRNA being made), then translated on a RIBOSOME in cytoplasm.
Specific proteins are then synthesized from this info to promote metabolic activities, or synthesis of other proteins
All the amino acid based hormones except thyroxin use
Second messenger systems
- the hormone is the 1st messenger in these systems and when is attaches to the receptors on the membrane of the target cell , it causes the formation of an intracellular second messenger
Best studied 2nd messenger system
1) cyclic AMP system
2) PIP-Calcium
3 types of stimuli can trigger release of hormones
- humoral stimuli
- neural stimuli
- hormonal stimuli
humoral stimuli
changes of blood level & certain levels ions or nutrients will trigger hormone release
ex. parathyroid hormone is secreted in response to low Ca2+ levels, others are insulin & aldosterone
neural stimuli
nerve fibers stimulate hormone release
ex. Sympathetic nervous system stimulates the adrenal medulla to release norepinephrine and epinephrine during stress
hormonal stimuli
- same hormones will cause the release of other hormones
ex. release of most pituitary hormones is regulated by releasing and inhibiting hormones produced by the hypothalamus. The anterior pituitary hormones can control release of other hormones. Once the hormones of the target gland are high, they then inhibit production of anterior pituitary hormones.
Anterior pituitary hormones
- growth hormone GH
- thyroid-stimulating hormone TSH
- Adrenocorticotropic hormone ACTH
- Follicle-stimulating hormone FSH
- Luteinizing hormone-LH
- Prolactin PRL
Growth hormone GH
- nontropic
- anabolic hormone because it is a tissue building hormone
- GH stimulates most body cells to increase in size & divide
- Hypersecretion:children(gigantism), adults (acromegaly)
- Hyposecretion: children(pituitary dwarfism), adults -no prob
Thyroid Stimulating hormone TSH
- tropic
- release caused by TRH from anterior pituitary but there is no TIH
- rising blood levels of TH will inhibit TSH secretion
Adrenocorticotropic
- tropic
- AKA corticotropin
- stimulates the ADRENAL CORTEX to release corticosteroid hormones(glucosteroid) to help resist stressors.
- CRH from the hypothalamus triggers release and rising levels of gluco-corticoids inhibits release.
- ACTH has a daily rhythm with levels peaking in the morning.
- things like fever, low blood sugar and other stressors can change the normal ACTH rhythm by triggering CRH release
Gonadotropins- Follicle-stimulating hormone FSH, Luteinizing hormone LH
- tropic & nontropic
- act on gonads (testes & ovaries)
- role for FSH is to trigger gamete formation(sperm or egg)
- LH triggers secretion of reproductive hormones
- these are absent until puberty , when GnRH from the anterior pituatary begins to stimulate their release
Prolactin PRL
-nontropic
- stimulates milk production
-both PRH and PIH regulate its secretion
-PIH is also neurotransmitter dopamine(inhibits prolactin).
-levels rise briefly before the menstrual period; this causes breast tenderness & swelling
Hyposecretion- not a prob except for nursing women
Hypersecretion- -abnormality of adenohypophyseal tumors, in women causes inappropriate lactation, lack of menstrual cycle and in men, impotence.
Posterior pituitary hormones
- oxytocin
2. Antidiuretic hormones ADH or vassopressin
Oxytocin
- non-tropic
- peptide mostly from neurons in paraventricular nucleus of hypothalamus
- target organs: uterus, stimulates uterine contractions; initiates labor; breast; initiates milk ejection
- in nonpregnant, nonlactating females and males oxytocin is involved in sexual arousal and orgasms, also promotes nurturing & affectionate behavior
Antidiuretic hormone ADH or vasopressin
- non-tropic
- peptide, mostly from neurons in supraoptic nucleus of hypothalamus
- works against diuresis (urine production)
- ADH targets the kidney tubules via cAMP, and causes them to reabsorb more water, leading to lower urine production
- alcohol inhibits ADH secretion and leads to copious urination and next day hangover effects of dehydration
- AKA vasopressin because it can cause vaso constriction when blood pressure is too low
Hyposecretion of ADH
- Diabetes Insipidus(tasteless)- marked by large amounts of urine and intense thirst
- this can be caused by a blow to the head that damages the hypothalamus or posterior pituitary
hypersecretion of ADH
- syndrome of inappropriate ADH secretion (SIADH)
- can be caused by meningitis, injury or surgery to the brain or cancer cells that are secreting ADH
- symptoms include fluid retardation, headache, disorientation due to brain edema(brain swelling), weight gain, decrease solute concentration in the blood
thyroid gland hormones
- Thyroid hormone (TH) made up of : thyroxine (T4) and triiodothyroxine (T3) AND 2. CALCITONIN
-T4 is the main hormone, and T3 is actually a conversion from T4
-T4 has four bound iodine atoms and T3 has 3
IPFL2R52
Thyroid Hormone TH
- TROPIC
- TH is the body’s major metabolic hormone that affects virtually every cell in the body
- falling TH blood levels trigger release of TSH, and rising TH levels inhibit release of TSH
- also, GHIH, dopamine, rising levels of glucocorticoids, and high blood concentration of iodine inhibit TSH release
Hyposecretion of TH
- MYXEDEMA- hypothyroid syndrome; symptoms include: chills, constipation, thick dry skin, adema, you become lethargic and mentally slow
- MYXEDEMA resulting from the LACK of IODINE- Goiter (enlarged thyroid)
- in infants- CRETINISM- severe hypothyroidism, this leads to mental retardation, get sgort bodies with thick tongue and neck
- if diagnosed early enough, it is preventable by hormone relacement therapy.
Hypersecretion of TH
- autoimmune disorder-GRAVES DISEASE- abnormal antibodies produced against thyroid follicle cells, mimick TSH and that cuases release of TH
- symptoms include: EXOPTHALMOS (symptoms of hyperthyroidism)-protrusion of eyeballs
Calcitonin
- NON-TROPIC
- produced by parafollicular cells of the thyroid, lowers blood CA2+ levels, antagonizing effects of parathyroid hormone
- it acts on the skeleton, causing release of calcium from bone and inhibits bone resorption, and stimulates calcium uptake
parathyroid hormones
- these 4 glands are located posterior of the thyroid
- the hormone secreted by the parathyroids is the PARATHYROID HORMONE PTH
parathyroid hormone PTH
- NON-TROPIC
- elevates blood calcium levels in 3 ways:
1. increase CA2+ released by bone
2. enhance resorption CA2+ by kidney
3. Promote activation of Vitamin D by kidney -increase CA2+ absorption from food in intestine - vitamin D is ingested pr produced in its inactive form and must be transformed by the kidneys to vitamin D form.
hyperparathyroidism
- caused by a parathyroid gland tumor
- symptoms include: brittle bones (calcium is leeched out), depression of the CNS and formation of kidney stones due to excess calcium
hypoparathyroidism
- caused by parathyroid gland trauma or removal
- symptoms include TETANY-loss of sensation, muscle twitches and convulsions
hormones secreted by adrenal glands
Steroid hormones-3 classes for each layer of adrenal gland- CORTICOSTEROIDS
- outer-zona glomerulosa- MINERALCORTICOIDS
- middle-zona fasciculata- GLUCOCORTICOIDS
- inner- zona reticularis- GONADOCOTICOIDS
mineralcorticoids
- NON-TROPIC
- help water and mineral balance
- main is ALDOSTERONE- this hormone targets the distal parts of the kidney tubules, where it causes more K+ to be excreted in the urine, and more NA+ to be reabsorbed in the blood
- the result is that blood levels of NA + increase and blood levels of K+ decrease
- release is caused by low Na+ in the blood, low blood volume, low blood pressure, high blood K+
- effects ~20 min
- RENIN-enzyme that increases blood pressure
hypersecretion of aldosterone-mineralcorticoid
-ALDOSTERONISM, caused by adrenal tumors
glucocorticoids- CORTISOL
- NON-TROPIC
- cortisol is secreted in sig. amounts
- ACTH( adrenocorticotropic hormone0 promotes cortisol release
- secretion follows diurnal pattern, levels highest in the early morning
- stress causes an increase in cortisol production, because cortisol promotes GLUCONEOGENESIS( formation of new glucose using fats & proteins)
hypersecretion of cortisol
- CUSHING’S SYNDROME
- cause is high doses of glucocorticoid drugs
- other causes: an ACTH-releasing pituitary tumor or tumor of the lungs, kidneys , pancreas or adrenal glands
- symptoms of Cushings syndrome: moonface, a buffalo hump, bruise easily, poor wound healing
hyposecretion of cortisol
-ADDISON’S DISEASE- discoloration, weight loss, low blood glucose & sodium, rise in K+
gonadocorticoids
- NON-TROPIC
- these are androgens, male sex hormones
- their role contributes to the onset of puberty, sex drive in women
hypersecretion of androgens
-in females, production of a beard, male pattern body hair and enlarged clitoris
hormones secreted by adrenal medulla are..
1- epinephrine
2- norepinephrine
-these centers of the adrenal glands are part of the sympathetic nervous system
epinephrine
NON-TROPIC
- released in larger amounts and is a better stimulator of metabolic activities, bronchiole dilation-and increased blood flow to the skeletal muscles
- also used ad HEART STIMULANT and to dilate bronchioles during acute asthma attacks or anaphalaxys
norepinephrine
- NON-TROPIC
- peripheral vaso-constriction and influences blood pressure
hyposecretion of both hormones of adrenal medulla
-no real effect, these hormones just intensify the activities of neurons
hypersecretion of adrenal medulla hormones
-caused by a tumor, causes uncontrolled sympathetic nervous system activity, hyperglycemia, increased metabolic rate, rapid heartbeat and palpitations, hypertension, intense nervousness and sweating-kicks body into overdrive
pineal gland hormone
- pineal gland secretes melatonin
melatonin
- TROPIC
- peaks during night
- powerful antioxidant and amine hormone derived from serotonin, causes drowsiness
pancreas hormone-producing cells
- 1)Alpha cells- produce GLUCAGON
- 2)beta cells-produces INSULINGLUCAGON
glucagon-alpha cells
-NON-TROPIC
-hyperglycemic hormone (raises blood sugar) that targets the liver
Promotes following actions in liver:
1. breakdown of glycogen to glucose (glycogenolysis)
2. synthesis of glucose from lactic acid and noncarbohydrate molecules (gluconeogenesis)
3. release of glucose to the blood by liver cells, causing glucose levels to rise
Insulin- beta cells
- NON-TROPIC
- hypoglycemic hormone (lowers blood suger)
- Does this in 3 main ways:
1. by enhancing membrane transfer of glucose into body cells especially fat and muscle cells( but not the liver, kidney and brain
2. by inhibiting the breakdown of glycogen to glucose
3. by inhibiting the conversion of amino acids or fats to glucose - elevated blood glucose levels or rising plasma levels of amino acids & fatty acids stimulate insulin release
hypersecretion of insulin
-hyperinsulinism; hypoglycemia, tremors, disorientation, convulsions
hyposecretion or hypoactivity of insulin
- Diabetes mellitus
- become nauseated -hyperglycemia
- this triggers “fight or flight” response that casues glycogenolysis( sugar breakdown), lipolysis(breakdown of fat) and gluconeogenesis making glucose levels even higher
signs of diabetes mellitus
1-polyurea-high urine leads to dehydration
2- polydipsia- excessive thirst
3- polyphagia- excessive hunger and food consumption ( because although glucose is produced it cannot be used)
Hemoglobin
-protein makes RBC’s red, this binds easily & reversibly with oxygen
erythropoietin EPO
- direct hormonal stimulus for creating RBC production
- EPO is produced by the kidneys & liver; so when kidney cells become low on O2 (hypoxic), the signaling molecule HYPOXIA-INDUCIBLE FACTOR. HIF is no longer broken down.
- accumulation of HIF speeds up the production/release of erythropoietin
anemia
-RBC disorders where blood has abnormal low capacity to carry O2 , you can get pale, short of breath (lungs try to compensate for lack of O2)
Antigens
- (agglutinigins)
- blood type differentiation -ABO blood types based off this
- Glycoproteins on cell surface ; cell-cell recognition, cause destruction of cells that don’t have appropriate antigen present
antibodies
- agglutinins
- exist in the plasma
- attack antigens not present in persons own blood cells
- ex. blood type A will produce Antigens, Anti-B antibodies
Functions of blood
- Distribution
- Regulation
- Protection
Distribution of blood
- Deliver oxygen & nutrients to all body cells
2 . Takes waste (CO2 & metabolic wastes) from cells to areas if elimination (eg. Lungs, kidneys) - Transports hormones from endocrine organs to target areas.