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Physiology > Exam 3 > Flashcards

Exam 3 Flashcards

include 2nd half chapter 17

1
Q

cardiac conduction steps

A
  1. SA node fires
  2. excitation spreads through atrial myocardium
  3. AV node fires
  4. excitation spreads down AV bundle
  5. subendocardial conducting network distributes excitation through ventricular myocardium
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2
Q

what is contraction of the heart called?

A

systole

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3
Q

what is relaxation of the heart called?

A

diastole

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4
Q

how do the cells of the SA node act rhythmically?

A

they are autorhythmic

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5
Q

what is the normal heartbeat triggered by the SA node called?

A

sinus rhythm

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6
Q

steps of action potentials in cardiomyocytes

A
  1. voltage-gated Na+ channels open
  2. Na+ inflow depolarizes the membrane and triggers the opening of still more Na+ channels, creating a positive feedback cycle and rapidly rising membrane voltage
  3. Na+ channels close when the cell depolarizes, and the voltage peaks at nearly +30 mV
  4. Ca2+ channels entering through slow Ca2+ channels prolongs depolarization of membrane, creating a plateau. Plateau falls slightly because of some K+ leakage, but most K+ channels remain closed until end of plateau
  5. Ca2+ channels close and Ca2+ is transported out of cell. K+ channels open, and rapid K+ outflow returns membrane to its resting potential
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7
Q

what is the significance of the Ca+ plateau?

A

causes a loner, more sustained contraction as opposed to quick twitch

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8
Q

how long is the refractory period in cardiac muscle? and why is it important?

A

-250 ms (as opposed to 2 ms in skeletal muscle)
-this prevents summation and tetanus of any kind

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9
Q

p-wave

A

atria contracts

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10
Q

QRS interval + T-wave

A

ventricles contract

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11
Q

arrythmia

A

any deviation from the regular rhythm of the heartbeat driven by the SA node
-include ventricular fibrillations

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12
Q

what is cardiac output?

A

the amount of blood ejected by each ventricle in one minute is called the cardiac output (CO)

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13
Q

ventricular fibrillations

A

uncontrolled, uncoordinated contractions of the ventricles
-if not brought under control, death may occur quickly

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14
Q

cardiac output equation

A

CO= heart rate (HR) x stroke volume (SR)

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15
Q

tachycardia

A

a persistent resting adult heart rate above 100 beats/min. may occur due to stress, stimulants, heart disease, etc.

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16
Q

bradycardia

A

a persistent resting adult heart rate lower than 60 beats/min. common during sleep and in endurance-trained athletes

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17
Q

what can affect heart rate?

A

-autonomic nervous system (often in response to information received from baroreceptors
and/or chemoreceptors (which measure
oxygen levels, carbon dioxide levels, and
pH).

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18
Q

factors that affect stroke volume

A

-calcium increases strength of each contraction
-epinephrine and norepinephrine both increase heart rate, but they also increase the strength of each contraction

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19
Q

what is the frank-starling law

A

stroke volume is proportional to end-diastolic volume. (the ventricles eject as much blood as they receive)

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20
Q

3 main categories of blood vessel?

A
  1. arteries
  2. veins
  3. capillaries
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21
Q

what do arteries do?

A

carry blood away from the heart

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22
Q

what do veins do?

A

carry blood toward the heart

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23
Q

what are capillaries?

A

-microscopic, thin-walled vessels that connect the smallest arteries to the smallest veins
-the site of the transfer of material into and out of tissues

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24
Q

what are capillaries responsible for?

A

-exchange of materials (gases, nutrients, wastes, hormones)
-no cell in the body is more than about five cell widths away from a capillary (except in ligaments, tendons, cartilage, cornea, and the lens)

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25
Q

3 routes for exchange of materials across capillary walls

A
  1. thru endothelial cells
  2. thru spaces between the endothelial cells
  3. thru the filtration pores of fenestrated capillaries
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26
Q

capillary bed

A

web-like networks in which capillaries are arranged

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27
Q

how is blood flow to particular capillaries regulated?

A

by constriction or dilation of upstream arterioles or by precapillary sphincters

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28
Q

what is blood flow?

A

-the amount of blood flowing through an organ, tissue, or blood vessel in a given amount of time
-flow= difference in pressure/ resistance

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29
Q

what is blood pressure?

A

the force that blood exerts against the wall of a vessel

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30
Q

how can blood pressure be measured directly?

A

by inserting a catheter or needle connected to an external manometer

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31
Q

systolic pressure

A

peak pressure recorded during ventricular systole

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32
Q

diastolic pressure

A

the minimum arterial pressure, measured during ventricular diastole,

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33
Q

what is pulse pressure?

A

the difference between the systolic and diastolic pressure

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34
Q

what is the mean arterial pressure (MAP) equation?

A

diastolic pressure + 1/3 pulse pressure
-gravity effects MAP (MAP will be higher in ankles v. head)

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35
Q

health consequences of high blood pressure

A

-heart attack
-stroke
-heart failure
-aneurysm
-metabolic syndrome

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36
Q

arteriosclerosis

A

when blood pressure increases with age as the arteries become less distensible

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37
Q

atherosclerosis

A

-growth of lipid deposits in the walls of the arteries
-the deposits can become calcified, thus making the arteries more rigid. associated with high blood pressure

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38
Q

hypertension

A

chronic resting blood pressure higher than 140/90

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39
Q

hypotension

A

chronic low blood pressure

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40
Q

3 main variables that determine blood pressure:

A
  1. cardiac output
  2. blood volume
  3. resistance to flow
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41
Q

peripheral resistance depends on what 3 factors?

A
  1. blood viscosity
  2. vessel length
  3. vessel radius (can be altered via vasoconstriction and vasodilation)
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42
Q

3 examples of local control (for regulation of blood pressure and flow)

A
  1. autoregulation- if a tissue isn’t receiving enough blood, it’ll become hypoxic and waste products accumulate. stimulates vasodilation.
  2. over a period of time, hypoxic conditions will cause growth of additional blood vessels (angiogenesis)
  3. during trauma, inflammation, exercise, etc., platelets, endothelial cells and other cells secrete a variety of chemicals that will cause vasodilation
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43
Q

baroreflexes

A

-neural control
-baroreceptors can be found in the aortic arch and in the carotid sinuses
-if BP increases, this causes decrease in heart rate/cardiac output and vasodilation in general. this is regulated through the ANS

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44
Q

chemoreflexes

A

-neural control
-chemoreceptors for oxygen, carbon dioxide, and pH are found in the aortic arch and in carotid bodies
-low levels of oxygen, high levels of carbon dioxide, and acidosis all cause vasoconstriction. this increases BP and respiration rate.

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45
Q

what hormones cause increases in blood pressure?

A
  1. aldosterone
  2. angiotensin II
  3. antidiuretic hormone
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46
Q

how does aldosterone increase blood pressure?

A

promotes sodium and water retention in the kidneys

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47
Q

how does angiotensin II increase blood pressure?

A

-causes vasoconstriction

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48
Q

how does antidiuretic hormone increase blood pressure?

A

promotes water retention and vasoconstriction

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49
Q

5 mechanisms that help venous return:

A
  1. pressure gradient (promotes flow to heart)
  2. gravity (from head to neck)
  3. skeletal muscle pump (contractions of muscles and presence of valves pushes blood in one direction)
  4. thoracic pump (when you inhale, thoracic cavity expands and thoracic pressure drops, then diaphragm increase abdominal pressure. this moves blood towards heart)
    5.cardiac suction (suction from the empty atria draws blood in)
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50
Q

venous return

A

the flow of blood back to the heart

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51
Q

what is the respiratory system responsible for?

A

ventilation of the lungs and gas exchange within the lungs

52
Q

principal organs of respiratory system?

A

-nose
-pharynx
-larynx
-trachea
-bronchi
-lungs

53
Q

what are alveoli?

A

the site of gas exchange between the air and the blood

54
Q

pulmonary ventilation

A

repetitive cycle of inspiration and expiration

55
Q

respiratory cycle

A

one complete breath

56
Q

why does air flow in and out?

A

due to variations in pressure in the thoracic cavity caused by changes in the volume of the thoracic cavity
-contraction enlarges the thoracic cavity and decreases the pressure inside that cavity

57
Q

what muscles drive respiration?

A

diaphragm and intercostal muscles

58
Q

what 2 factors regulate resistance to airflow?

A

-diameter of the bronchioles
-pulmonary compliance

59
Q

what stimulates bronchodilation to increase airflow?

A

-epinephrine and sympathetic nerves (norepinephrine)

60
Q

what stimulates bronchoconstriction?

A

parasympathetic nerves, cold air, and chemical irritants

61
Q

pulmonary compliance

A

the ease with which the lungs expand

62
Q

how can you reduce compliance?

A

lung diseases such as tuberculosis

63
Q

what does pulmonary surfactant do?

A

disrupts the hydrogen bonds and reduces surface tension to increase compliance!

64
Q

infant respiratory distress syndrome

A

the lack of pulmonary surfactant in premature infants. it causes a difficulty breathing.

65
Q

what drives the movements of oxygen and carbon dioxide in and out of the blood?

A

differences in partial pressures of those individual gases

66
Q
A
67
Q
A
68
Q

2 ways that oxygen is carried in transport?

A
  1. 98.5% is bound to hemoglobin
  2. the rest is dissolved in the blood plasma
69
Q

oxyhemoglobin

A

hemoglobin that is carrying oxygen

70
Q

deoxyhemoglobin

A

hemoglobin that is NOT carrying oxygen

71
Q

what is the utilization coefficient?

A

the percentage of oxygen that is released from hemoglobin at the systemic capillaries

72
Q

3 ways that carbon dioxide is carried in transport?

A
  1. about 90% of carbon dioxide reacts with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions
  2. about 5% is bound to hemoglobin
  3. about 5% is dissolved in the blood
73
Q

carbon dioxide loading steps:

A
  1. The conversion of carbon dioxide to
    bicarbonate and hydrogen ions occurs
    much more quickly inside RBC’s due to
    the presence of carbonic anhydrase.
    2.The bicarbonate gets pumped out of the
    RBC in exchange for a chloride ion. This is
    called the chloride shift.
    3.The hydrogen ion binds to hemoglobin and
    promotes the release of oxygen.
74
Q

acidosis

A

a blood pH lower than 7.35
-can correct acidosis by hyperventilating- thus driving off carbon dioxide. shifts the carbonic acid rxn to the left

75
Q

alkalosis

A

-blood pH greater than 7.45
-can correct by hypoventilating-allows for accumulation of carbon dioxide. drives the same reaction to the right

76
Q

parts of the urinary system

A

-kidneys
-ureters
-urinary bladder
-urethra

77
Q

functions of the kidneys

A
  1. filter the blood and excrete metabolic wastes, toxins, drugs, hormones, salts, and hydrogen ions
  2. regulate blood pressure, blood volume, and blood osmolarity by regulating water output
  3. regulate the electrolyte and acid-base balance of body fluids
78
Q

main nitrogenous wastes

A
  1. 50% is urea (from proteins)
  2. uric acid (from nucleic acids)
  3. creatinine (from creatine phosphate)
79
Q

why do you want to get rid of nitrogenous waste from the body?

A

they are toxic! :D

80
Q

parts of the renal tubule

A

in order:
1. proximal convoluted tubule
2. the loop of henle- with descending and ascending limbs
3. distal convoluted tubule

-distal convoluted tubule drains into collecting duct, then drains into a space that leads to the ureter

81
Q

4 steps of urine formation:

A
  1. glomerular filtration
  2. tubular reabsorption
  3. tubular secretion
  4. water conservation
82
Q

how does fluid name change as it moves through the nephron?

A

-fluid in capsular space is called glomerular filtrate
-fluid in the tubule is called tubular fluid
-fluid from the collecting duct and onward is called urine

83
Q

glomerular filtration

A

-when water and some other materials (electrolytes, glucose, amino acids, etc.) pass from capillaries of the glomerulus into the capsular space of the nephron
-driven by the high pressures in the glomerular capillaries (afferent arteriole is larger than efferent arteriole)

84
Q

what is glomerular filtration rate (GFR)?

A

the amount of filtrate formed per minutes by the two kidneys. it is not always constant. Regulation of GFR comes through regulation of glomerular blood pressure

85
Q

tubular reabsorption

A

-process of reclaiming water and other filtrates from the tubular fluid and returning them to the blood. about 99% are reabsorbed

86
Q

tubular secretion

A

-This is the process by which the renal
tubule extracts materials from the
peritubular capillaries and secretes them
into the tubular fluid.
* This includes movement of nitrogenous
wastes, drugs, and other contaminants.

87
Q

where does water conservation mainly occur?

A

the collecting duct

88
Q

why does water move out as urine moves through the collecting duct?

A
  1. the medullary portion of the CD is more permeable to water than salts
  2. the osmolarity of the extracellular fluid is four times higher in the lower medulla than it is in the cortex
89
Q

the ureters

A

-tubes that carry urine from the kidneys to the urinary bladder
-peristaltic waves are used to push the urine toward the bladder

90
Q

urinary bladder

A

stores urine until it is released periodically in larger volumes

91
Q

urethra

A

-carries urine from the bladder out of the body
-everyone has an external urethral sphincter; consists of skeletal muscle and is under voluntary control

92
Q

urination process

A
  1. stretch receptors in bladder send signals to spinal cord
  2. spinal cord sends signals to cause contraction of the smooth muscle in the bladder
    (if it isn’t a good time for urination, the external urethral sphincter will remain contracted, and urine will be retained until the sphincter relaxes)
93
Q

how many layers does the adrenal cortex have?

A

-3
-each produces different types of steroid hormones

94
Q

thyroid gland

A

-largest gland to have a fully endocrine function
-located adjacent to the trachea below the larynx, has a bi-lobed shape
-composed mostly of follicles surrounding thyroglobulin
-thyroglobulin is a protein that is the structural precursor to thyroid hormone

95
Q

thyroid function

A

Thyroid hormone consists of two tyrosine residues that are
combined together (see below). Either three or four iodines
are attached to form triiodothyronine (T3) or tetraiodothyronine
(T4, Thyroxine). Together, T3 and T4 are called thyroid
hormone.
* When stimulated to do so by thyroid-stimulating hormone,
thyroglobulin is converted into either T4 (90%) or T3 (10%) and
released into the bloodstream.
* T4 gets converted to T3 at the target tissues, and it is T3 that
binds to receptors in the target tissues.

96
Q

physiological roles of thyroid hormone

A

1.growth and development
2. thermogenesis and metabolic rate- increase metabolic rate by increasing production of ATP and heat

97
Q

2 examples of glucocorticoids

A
  1. cortisol
  2. corticosterone
98
Q

stress response steps

A

1.first stages of stress involve release of epinephrine and norepinephrine from sympathetic division (breakdown and use of glucose)
2.aldosterone released to promote sodium and water retention
3.in later stages, cortisol is released from adrenal cortex (cortisol breaks down lipids and proteins to promote gluconeogenesis)

99
Q

glucocorticoid effects on immune system

A

-stimulate fat and protein catabolism
-stimulate gluconeogenesis
-anti-inflammatory effects
-OVERSECRETION can suppress the immune system

100
Q

what does long-term stress lead to?

A

-inhibition of reproductive function
-suppression of the immune system
-formation of peptic ulcers

101
Q

aldosterone

A

-hormone called a mineralocorticoid because it helps to regulate the levels of electrolytes
-stimulates kidneys to retain sodium and water
-helps to maintain blood volume and blood pressure
-the release is under the control of the renin/angiotensin system (know in depth)

102
Q

main androgen released by adrenal cortex

A

DHEA (dehydroepiandrosterone)
-can be converted to testosterone and dihydrotestosterone
-very important in the development of male reproductive tract
-in men, androgens released testes outweighs amount secreted by adrenal cortex

103
Q

amount of estrogens secreted in women?

A

-in adult women, amount of estrogen released from adrenal cortex is less than from the ovaries
-in post-menopausal women, adrenals become the primary source of estrogens

104
Q

what are the islets of langerhans?

A

-clusters of cells that secrete several hormones, including glucagon and insulin

105
Q

when is glucagon released

A

between meals after the carbohydrates, fats and proteins from our previous meal have been moved into our tissues (it makes sure glucose levels in the blood dont get too low)

106
Q

what does glucagon do?

A

-causes glycogenolysis (breakdown of glycogen into glucose)
-gluconeogenesis (formation of glucose from fats and proteins)
*both provide glucose to maintain glucose levels in the blood

107
Q

when is insulin released?

A

-during and immediately following a meal
(targets are the liver, skeletal muscle, and adipose tissue)

108
Q

insulin function

A

-stimulates cells to absorb glucose, fatty acids, and amino acids either to store them or to metabolize them for energy.
-it therefore promotes the synthesis of glycogen, fat, and proteins and enhances cellular growth and differentiation

109
Q

how does leptin affect appetite-regulating centers?

A

-low levels indicate a deficiency in body fat, so it increases appetite and food intake
-high levels of leptin tend to suppress appetite
-also serves as a signal for onset of puberty, which is delayed in individuals with abnormally low body fat

110
Q

receptors found on the surface of target cells

A

peptide hormones and catecholamines

111
Q

receptors found in the cell

A

steroid hormones and thyroid hormone

112
Q

effect timeline or protein hormones vs. steroids or thyroid hormones

A

-protein hormones have very rapid effects
-steroids and thyroid hormones take hours or days

113
Q

know up-regulation v. down-regulation of receptors

A

-upregulation creates a stronger response
-downregulation creates a diminished response

114
Q

2 ways that endocrine disorders can occur

A

-alterations in hormone release
-or due to changes in responsiveness of target tissues

115
Q

hyposecretion

A

inadequate hormone release

116
Q

hypersecretion

A

excessive hormone release

117
Q

growth hormone disorders

A

-gigantism- hypersecretion of growth hormone early in life
-acromegaly- thickening of bones and soft tissues- hypersecretion later in life
-pituitary dwarfism- hyposecretion early in life

118
Q

what is a goiter

A

-overgrowth of the thyroid gland due to excessive release of TSH
-may develop due to dietary deficiency of iodine

119
Q

congenital hypothyroidism

A

-hyposecretion of thyroid secretion from birth
-symptoms- stunted physical development, irreversible brain damage, low body temperature, and lethargy
-childhood hypothyroidism also called cretinism

120
Q

myxedema

A

-adult hypothyroidism
-low metabolic rate, sluggishness and sleepiness, weight gain, thickened/course skin, thickening of the nose, swelling of subcutaneous tissue, mental dullness, and thinning hair

121
Q

Hashimoto’s disease

A

-autoimmune
disorder in which antibodies attack the
thyroid gland and decrease the ability to
produce thyroid hormone. It is the most
common cause of hypothyroidism in North
America.
* A goiter develops.

122
Q

graves disease

A

-most common type of hyperthyroidism
-Due to antibodies that bind to the TSH
receptor on the thyroid gland and cause
overstimulation of the thyroid gland.
* Symptoms include a goiter, elevated
metabolic rate, nervousness, weight loss,
abnormal sweating, and bulging of the
eyes.

123
Q

diabetes mellitus

A

-due to a hyposecretion or lack of effectiveness of insulin
-symptoms: excessive urine output, intense thirst, hunger, hyperglycemia, glucose in urine, and ketones in urine
-long term effects: muscle atrophy and emaciation, osmotic diuresis and electrolyte
deficiencies due to ketonuria, ketoacidosis (which can depress the nervous system and cause diabetic coma), atherosclerosis, blindness, renal failure, and diabetic neuropathy.

124
Q

type 1 diabetes

A

-lack of production of insulin (genetic or caused by disease)
-5-10% of cases in the US
-insulin doses are effective

125
Q

type 2 diabetes

A

-due to insulin resistance
-may be due to genetic mutations
-may be due to obesity

126
Q

main androgen released by adrenal cortex

A

DHEA (dehydroepiandrosterone)
-can be converted to testosterone and dihydrotestosterone
-very important in the development of male reproductive tract
-in men, androgens released testes outweighs amount secreted by adrenal cortex

Physiology (9 decks)

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