Untitled Deck Flashcards
1
Q
What are the components of blood?
A
Plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets
2
Q
What is the most numerous cell type in blood?
A
Erythrocytes (red blood cells)
3
Q
What is the function of hemoglobin?
A
Hemoglobin binds to and transports oxygen. Each hemoglobin molecule has 4 globin molecules, each with a heme group. Oxygen forms weak bonds with the heme
4
Q
What is anemia?
A
A condition characterized by low hematocrit and/or low hemoglobin levels
5
Q
What is the role of leukocytes?
A
Leukocytes are white blood cells involved in host defense. They defend against pathogens, remove toxins and waste, and remove or degrade damaged cells
6
Q
What is plasma composed of?
A
Plasma is primarily composed of water (93%), dissolved solutes (that maintain pH and osmolality), albumins, fibrinogen, and clotting factors including platelets
7
Q
What is serum?
A
Serum is plasma without fibrinogen and clotting factors
8
Q
What is hematocrit?
A
Hematocrit is the percentage of total blood volume occupied by cells
9
Q
What are the five functions of blood?
A
Transportation of dissolved gases, nutrients, hormones, and metabolic waste; Regulation of pH and ion composition of interstitial fluids; Restriction of fluid loss via clotting; Defense against toxins; Stabilization of body temperature
10
Q
What is the average lifespan of a red blood cell?
A
120 days
11
Q
What happens to old or damaged red blood cells?
A
They are engulfed by macrophages in the liver, spleen, and bone marrow before they rupture (hemolyze), or macrophages remove hemoglobin molecules, iron, and cell fragments from RBCs that hemolyze in the bloodstream
12
Q
Describe the breakdown of hemoglobin in macrophages.
A
Hemoglobin is broken down into heme and globin. Globin is broken down into amino acids, which are reused. Heme has iron removed and is converted to biliverdin, then bilirubin, which is transported to the liver for excretion
13
Q
What happens to bilirubin in the liver?
A
Bilirubin is excreted in bile and transported to the large intestine
14
Q
What happens to bilirubin in the large intestine?
A
Bacteria convert bilirubin to urobilins and stercobilins. Some are absorbed into the circulation and excreted in urine by the kidneys, while the rest are eliminated in feces
15
Q
What causes jaundice?
A
Jaundice is caused by the inability to excrete bilirubin, resulting in a buildup of bilirubin in the body
16
Q
What is erythropoiesis?
A
Production of red blood cells
17
Q
Where does erythropoiesis occur?
A
Red bone marrow (vertebrae, sternum, ribs, skull, scapulae, pelvis, and proximal limb bones)
18
Q
What is the role of erythropoietin (EPO)?
A
Stimulates and increases cell division in erythroblasts and speeds up the maturation of red blood cells. It is upregulated in response to hypoxia (low oxygen levels)
19
Q
What conditions can lead to increased erythropoietin production?
A
Anemia, decreased blood flow to the kidneys, decreased oxygen content in the lungs, and damage to the respiratory surface of the lungs
20
Q
What is iron deficiency anemia?
A
A type of anemia caused by insufficient iron levels, leading to the production of smaller than usual red blood cells with reduced hemoglobin and hematocrit levels. Women are at higher risk due to smaller iron reserves and menstrual blood loss
21
Q
What is pernicious anemia?
A
A type of anemia caused by vitamin B12 or intrinsic factor deficiency, leading to the production of large cells (megaloblastic anemia) and often neurological symptoms
22
Q
What is blood doping?
A
The practice of re-infusing packed red blood cells prior to competition to enhance athletic performance. This artificially raises the hematocrit level
23
Q
How does training at high altitude affect hematocrit?
A
Training at high altitude can increase hematocrit levels, although to a lesser degree than blood doping, and is a legal method
24
Q
What happens to red blood cells in narrow capillaries?
A
Red blood cells can stack like dinner plates, forming a rouleau
25
What is sickle cell anemia?
A genetic disorder where red blood cells become sickle-shaped when oxygen is released. These sickle-shaped cells cannot easily pass through capillaries and small vessels, leading to blood clots and potentially stroke
26
What is direct communication between cells?
Direct communication happens between cells connected by gap junctions that allow for the exchange of ions and small molecules. An example is cardiac muscle cells
27
What is paracrine communication?
Paracrine communication involves the release of chemicals that act on neighboring cells in relatively low concentrations. An example is testosterone secretion from the testes to stimulate spermatogenesis
28
What is endocrine communication?
Endocrine communication uses chemical messengers called hormones that are transported in the bloodstream to affect distant tissues
29
How do hormones work?
Hormones can only be interpreted by cells with specific receptors
30
How are hormones transported?
Hormones are transported through the bloodstream using blood vessels as conduits
31
What increases the half-life of hormones?
Binding to transport proteins increases the half-life of hormones
32
What is an example of endocrine communication?
Leptin is secreted by adipose tissue to decrease food intake
33
What is synaptic communication?
Synaptic communication is a quick form of communication over long distances. It generally results in a short-lived response
34
What is an exception to the short-lived nature of synaptic communication?
An exception is the release of epinephrine and norepinephrine from the adrenal medulla into the bloodstream, which combines neural and endocrine responses
35
Provide an example of synaptic communication.
The vagus nerve decreases heart rate
36
What is essential for a cell to respond to a hormone?
A cell must have a receptor for a specific hormone to respond to it
37
What is the role of first and second messengers in hormone action?
The hormone acts as the first messenger, which activates a cascade of multiple second messengers. This results in the amplification of the original signal
38
Where are G-proteins located?
Bound to receptors in the cell membrane
39
What is downregulation of hormone receptors?
Downregulation occurs when high levels of circulating hormone lead to a decrease in the number of receptors on the cell membrane
40
What is upregulation of hormone receptors?
Upregulation occurs when low levels of circulating hormone result in an increase in the number of receptors on the cell membrane
41
What types of hormones use intracellular messengers?
Only lipid-soluble hormones, which can pass through cell membranes, use intracellular messengers
42
How do intracellular messengers work?
They bind to cytoplasmic or nuclear receptors and can then enter the nucleus to act as a transcription factor or inhibit transcription
43
What are the three types of endocrine reflex control?
Humoral stimuli: Changes in the extracellular fluid; Hormonal stimuli: Presence or absence of a hormone; Neural stimuli: Arrival of neurotransmitters at neuroglandular junctions
44
What is the function of the hypophyseal portal system?
The hypophyseal (pituitary) portal system allows the hypothalamus to secrete hormones, and the anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis) to receive hormones
45
Describe the process of hormone delivery in the adenohypophysis.
The hypothalamus releases regulatory factors/hormones at the median eminence, which enter the bloodstream through fenestrated (permeable) capillaries. Portal vessels link two capillary beds, delivering the factors to the adenohypophysis
46
Describe the process of hormone delivery in the neurohypophysis.
Axons from the hypothalamus run to the posterior lobe and release hormones directly into the bloodstream through capillaries
47
What are the two types of hypothalamic regulatory hormones in the adenohypophysis?
Releasing hormones: Stimulate the synthesis and secretion of a hormone at the adenohypophysis; Inhibiting hormones: Prevent hormone synthesis
48
How are hypothalamic regulatory hormones controlled?
They are controlled by negative feedback mechanisms
49
What is the function of anterior pituitary hormones?
Anterior pituitary hormones are released into the bloodstream to target organs. Examples include TSH, FSH, LH, prolactin, growth hormone, and ACTH
50
What is the function of target organ hormones?
Hormones are released from the target organ into the bloodstream. Examples include thyroid hormone, glucocorticoids (adrenal cortex), and IGF-1 (liver)
51
What is the significance of hormone receptors on tissues other than the target organ?
Any tissue with the receptor for a circulating hormone can be activated by that hormone
52
From where is antidiuretic hormone (ADH), also called arginine vasopressin, released?
It is released from supraoptic neurons in the hypothalamus
53
What stimulates the release of ADH?
Osmoreceptors sensing a rise in solute concentrations and a drop in mean arterial pressure (MAP) stimulate ADH release
54
What is the function of ADH?
ADH reduces water loss at the kidneys
55
From where is oxytocin released?
Paraventricular nucleus of the hypothalamus
56
What are the functions of oxytocin?
Oxytocin stimulates smooth muscle contraction in the uterus and the ejection of milk from mammary glands
57
Where is the pancreas located?
Between the inferior border of the stomach and the proximal small intestine
58
What are the islets of Langerhans?
Clusters of endocrine cells in the pancreas
59
What are the functions of alpha and beta cells in the pancreas?
Alpha cells produce glucagon, released when blood glucose falls. Beta cells produce insulin, released when blood glucose rises
60
What is the normal blood glucose range?
70-110 mg/dL
61
Which pancreatic cells release insulin?
Beta cells
62
What are insulin-dependent cells?
Most cells in the body have insulin receptors and are considered insulin-dependent
63
What are insulin-independent cells?
Cells without insulin receptors, such as those in the brain, kidneys, lining of the digestive tract, and red blood cells, are insulin-independent
64
What are the effects of insulin on target cells?
Increased glucose uptake via an increased number of glucose transporters; Increased glucose utilization and ATP production; Stimulates glycogen formation; Increased amino acid absorption and protein synthesis; Triglyceride formation in adipose tissue
65
Which pancreatic cells release glucagon?
Alpha cells
66
What are the functions of glucagon?
Glucagon mobilizes energy reserves by: Stimulating the breakdown of glycogen in the liver and skeletal muscle; Stimulating the breakdown of triglycerides in adipose tissue; Stimulating glucose production in the liver (gluconeogenesis)
67
What are the functions of the hypothalamus?
The hypothalamus is responsible for the production of ADH, oxytocin, and regulatory hormones
68
What are the functions of the anterior lobe of the pituitary gland?
The anterior lobe of the pituitary gland produces ACTH, TSH, GH, PRL, FSH, LH, and MSH
69
What are the functions of the posterior lobe of the pituitary gland?
The posterior lobe of the pituitary gland releases oxytocin and ADH
70
What are the functions of the thyroid gland?
The thyroid gland produces thyroxine (T4), triiodothyronine (T3), and calcitonin (CT)
71
What are the functions of the adrenal medulla?
The adrenal medulla produces epinephrine (E) and norepinephrine (NE)
72
What are the functions of the adrenal cortex?
The adrenal cortex produces cortisol, corticosterone, aldosterone, and androgens
73
What is an estrogen response element?
Estrogen has nuclear receptors that bind to specific DNA sequences called estrogen response elements, which can increase or decrease transcription
74
What is the effect of tomoxifen on estrogen?
Tomoxifen blocks the effects of estrogen at breast tissue by binding to estrogen receptors
75
Besides nuclear receptors, what other type of receptor does estrogen have?
Estrogen also has membrane-bound receptors in addition to nuclear receptors
76
Where is the thyroid gland located?
It curves around the anterior trachea and has two lobes connected by the isthmus
77
What is the function of C cells in the thyroid gland?
C cells produce calcitonin, which decreases blood calcium concentration
78
What are the triggers for calcitonin release?
Increased circulating calcium levels
79
How does calcitonin decrease blood calcium levels?
By inhibiting osteoclasts and stimulating calcium excretion at the kidneys
80
When is calcitonin most important?
During childhood, starvation, and late pregnancy
81
What do follicle cells in the thyroid gland produce?
Thyroglobulin
82
How is iodide incorporated into thyroglobulin?
Iodide is absorbed from the digestive tract, transported through the bloodstream, taken up by follicle cells, and incorporated into thyroglobulin at the follicle cavity
83
What are the two thyroid hormones produced from thyroglobulin?
Thyroxine (T4) contains four iodide ions, and triiodothyronine (T3) contains three iodide ions
84
How are T3 and T4 released into the bloodstream?
Thyroglobulin is endocytosed into the follicle cell, T3 and T4 separate, and diffuse across the membrane into the bloodstream
85
What percentage of thyroid hormone released is T4?
90%
86
Which thyroid hormone is primarily responsible for cellular effects?
T3
87
How does the concentration of iodide in follicle cells compare to that in the blood?
Follicle cells contain approximately 30 times more iodide than blood
88
How is iodide transported into follicle cells?
Via a TSH-sensitive carrier
89
What is goiter, and what causes it?
Goiter is the enlargement of the thyroid gland. It results from constant TSH stimulation, which increases thyroglobulin production, increasing the size of the follicles
90
Where are the parathyroid glands located?
Embedded in the posterior thyroid
91
What is the function of chief cells in the parathyroid gland?
Produce parathyroid hormone (PTH) and monitor circulating calcium levels
92
What happens when blood calcium levels fall?
PTH is released, stimulating osteoclasts and the release of calcium from bone
93
How does PTH affect osteoblasts?
PTH inhibits osteoblasts
94
How does PTH affect calcium reabsorption?
PTH increases calcium reabsorption at the kidneys
95
What is the role of calcitriol in calcium regulation?
PTH stimulates calcitriol production, which increases the absorption of calcium and phosphate at the digestive tract
96
Where are the adrenal glands located?
Above the kidneys
97
What are the two main layers of the adrenal gland?
The adrenal cortex (outer layer) and the adrenal medulla (inner layer)
98
What are the three zones of the adrenal cortex, and what hormones do they produce?
Zona glomerulosa (outermost): Produces mineralocorticoids (aldosterone); Zona fasciculata (middle): Produces glucocorticoids (cortisol); Zona reticularis (innermost): Produces androgens
99
What is the function of aldosterone?
Aldosterone retains sodium ions at the kidneys, sweat glands, salivary glands, and pancreas, preventing sodium loss in urine, sweat, saliva, and digestive secretions
100
What stimulates aldosterone secretion?
A drop in blood sodium, blood volume, mean arterial pressure (MAP), or hyperkalemia
101
How does aldosterone affect potassium levels?
Retention of sodium results in increased loss of potassium
102
What are the symptoms of hyperaldosteronism?
Increased MAP, hypokalemia
103
What is the function of the reticularis?
Produces androgens.
104
What is the function of aldosterone?
Aldosterone retains sodium ions at the kidneys, sweat glands, salivary glands, and pancreas, preventing sodium loss in urine, sweat, saliva, and digestive secretions.
105
What stimulates aldosterone secretion?
A drop in blood sodium, blood volume, mean arterial pressure (MAP), or hyperkalemia.
106
How does aldosterone affect potassium levels?
Retention of sodium results in increased loss of potassium.
107
What are the symptoms of hyperaldosteronism?
Increased MAP, hypokalemia, flaccid paralysis, hyporeflexia, and constipation.
108
What are the symptoms of hypoaldosteronism?
Decreased blood volume, decreased MAP, hyperkalemia, cardiac arrhythmias, and muscle weakness.
109
What are the functions of cortisol?
Increases glucose synthesis, glycogen formation, and fat degradation.
110
How is cortisol secretion regulated?
By negative feedback involving corticotropin-releasing hormone (CRH) from the hypothalamus and adrenocorticotropic hormone (ACTH) from the anterior pituitary.
111
What are the anti-inflammatory effects of cortisol?
Cortisol inhibits the activities of white blood cells and other components of the immune system.
112
What are the symptoms of Addison's disease?
Insufficient ACTH or glucocorticoids, leading to decreased blood glucose, decreased MAP with stress, and changes in pigmentation.
113
What are the symptoms of Cushing's syndrome?
Overproduction of glucocorticoids, leading to suppressed glucose metabolism, mobilized lipid reserves, protein breakdown, and adipose distribution changes (around the face and base of the neck).
114
What hormones are produced by the adrenal medulla?
Epinephrine and norepinephrine.
115
What percentage of medullary secretions is epinephrine?
75% to 80%.
116
What percentage of medullary secretions is norepinephrine?
20% to 25%.
117
What is the effect of T3 on cellular metabolism?
Increases cellular metabolism.
118
How are T3 and T4 transported in the bloodstream?
They are bound to transport proteins like thyroid-binding globulin and transthyretin, with only 0.3% unbound and active. Carrier proteins release free T3 and T4 as free reserves are used by tissues.
119
Why is the general US population not at risk for iodine deficiency?
US salt is iodized, and fish and dairy products are good sources of iodine.
120
What are the overall functions of the urinary system?
Excretion (removal of waste from body fluids), elimination (discharge of waste into the environment), and regulation of blood volume and solute concentration.
121
How does the urinary system regulate blood pressure?
It regulates mean arterial pressure (MAP) by controlling blood volume.
122
Which plasma concentrations does the urinary system regulate?
Sodium (Na+), potassium (K+), and chloride (Cl-).
123
How does the urinary system regulate pH?
By controlling the loss of hydrogen ions (H+) and bicarbonate.
124
What nutrients does the urinary system conserve?
Glucose and water.
125
What endocrine functions does the kidney have?
The kidneys act as endocrine glands, secreting renin and erythropoietin (EPO).
126
What are the two main regions of the kidney?
The renal cortex (outer portion) and the renal medulla (inner portion).
127
Where are most nephrons located?
Approximately 85% of nephrons are located in the renal cortex.
128
What is the primary function of the renal medulla?
It contains clusters of pyramids and is the primary region where collecting ducts are found.
129
What is the pathway of urine flow from the collecting duct to the urethra?
Collecting duct → renal papilla → minor calyx → major calyx → renal pelvis → ureter → bladder → urethra.
130
What is the function of the renal plexus?
Primarily composed of sympathetic fibers, the renal plexus controls blood flow to the kidney, regulating filtration and reabsorption.
131
What percentage of cardiac output is pumped to the kidneys each minute?
25%.
132
What is the pathway of blood flow through the kidney?
Renal artery → segmental artery → interlobar artery → arcuate artery → interlobular artery → afferent arterioles → glomerulus → efferent arterioles.
133
What is the pathway of blood flow from the peritubular capillaries back to the renal vein?
Peritubular capillaries → venules → interlobular vein → arcuate vein → interlobar vein → renal vein.
134
What are the two main components of a nephron?
The renal corpuscle and the tubules.
135
What are juxtamedullary nephrons?
Nephrons with glomeruli located deep in the cortex, near the medulla, with a loop of Henle extending completely into the medulla. They play a key role in urine concentration.
136
What are the components of the renal corpuscle?
Bowman's capsule and the glomerulus.
137
What is the function of Bowman's capsule?
It collects filtrate from the glomerulus and sends it to the proximal convoluted tubule. It also encases the glomerulus.
138
What is the function of the glomerulus?
A cluster of fenestrated capillaries that filters blood, forming filtrate.
139
What is filtration?
The process where blood pressure forces water and solutes (excluding RBCs) across the glomerular wall into the capsular space.
140
What substances make up the filtrate?
Metabolic wastes, excess ions, glucose, free fatty acids, amino acids, and vitamins.
141
What are the characteristics of the proximal convoluted tubule (PCT)?
Lined with cuboidal epithelium with microvilli for increased surface area. Responsible for reabsorption of water, solutes (PO4, Na+, K+, Ca++), and secretion of hydrogen ions, acids, and toxins.
142
What is reabsorption?
The movement of substances from the tubular fluid back into the peritubular fluid and eventually into the peritubular capillary (venous system).
143
What is secretion?
The movement of substances from the peritubular fluid into the tubular fluid for eventual excretion in the urine.
144
Describe the structure and function of the loop of Henle.
A U-shaped structure with a thin descending limb (permeable to water, impermeable to solutes) for water reabsorption and a thick ascending limb (impermeable to water, actively pumps solutes out) for solute reabsorption.
145
What are the characteristics and functions of the distal convoluted tubule (DCT)?
Lined with cuboidal epithelium (no microvilli), involved in secretion of H+ ions, acids, and toxins, reabsorption of water, and houses the juxtaglomerular apparatus.
146
What is the juxtaglomerular apparatus?
A specialized region in the DCT near the renal corpuscle, containing JG cells and macula densa cells, involved in sensing NaCl concentration in tubular fluid and regulating renin and EPO secretion.
147
What are the three pressures involved in glomerular filtration?
Glomerular hydrostatic pressure (GHP), capsular hydrostatic pressure (CsHP), and blood colloid osmotic pressure (BCOP).
148
What is glomerular hydrostatic pressure (GHP)?
Blood pressure within the glomerulus, pushing fluid into Bowman's capsule (50 mmHg).
149
What is capsular hydrostatic pressure (CsHP)?
Pressure opposing filtration, pushing fluid from the capsule back into the glomerulus (15 mmHg).
150
What is blood colloid osmotic pressure (BCOP)?
Osmotic pressure due to plasma proteins, pulling fluid from the capsule back into the glomerulus (25 mmHg).
151
How is filtration pressure (FP) calculated?
FP = (GHP - CsHP) - BCOP. Normally, FP is around 10 mmHg.
152
What is glomerular filtration rate (GFR)?
The amount of filtrate the kidneys produce each minute.
153
What is autoregulation of GFR?
An intrinsic mechanism for local regulation of blood flow and GFR, independent of hormones or the nervous system.
154
How does the renin-angiotensin-aldosterone system (RAAS) regulate GFR?
Renin, released in response to decreased GFR, triggers the conversion of angiotensinogen to angiotensin II, which increases GFR through various mechanisms.
155
What are the effects of angiotensin II on GFR?
Constricts efferent arterioles, increases Na+ and water reabsorption in the PCT, stimulates thirst, increases sympathetic nervous system activity, and promotes aldosterone release.
156
How does aldosterone regulate GFR?
Increases sodium reabsorption and potassium secretion in the DCT and collecting duct, contributing to increased blood volume and GFR.
157
What is the neural control of GFR?
Primarily mediated by sympathetic nervous system fibers. Increased sympathetic tone leads to vasoconstriction of afferent arterioles, decreasing GFR.
158
What are the primary reabsorption and secretion processes in the PCT?
Reabsorption of water, sodium, glucose, amino acids, and ions. Secretion of potassium, hydrogen ions, calcium, and phosphate.
159
What is the medullary concentration gradient, and how is it established?
A gradient of increasing solute concentration from the cortex to the medulla, established by the countercurrent multiplier system in the loop of Henle, facilitating water reabsorption and urine concentration.
160
What are the key reabsorption and secretion processes in the DCT?
Reabsorption of sodium, chloride, and calcium (regulated by PTH), secretion of potassium, hydrogen ions, and phosphate.
161
How does aldosterone affect sodium and potassium levels?
Increases sodium reabsorption and potassium secretion in the DCT and collecting duct.
162
What are the key reabsorption and secretion processes in the collecting system?
Reabsorption of water (regulated by ADH), sodium (in exchange for potassium, regulated by aldosterone), bicarbonate, and urea. Secretion of hydrogen ions (pH regulation).
163
What is the role of ADH in the collecting system?
Regulates water reabsorption by increasing the permeability of the DCT and collecting duct to water.
164
How does the collecting system regulate pH?
By secreting hydrogen ions in exchange for bicarbonate when the peritubular fluid pH decreases.
