Final (after midterm) Flashcards
1
Q
How are the majority of oxygen molecules transported in the body?
A
by hemoglobin of the erythrocytes
2
Q
How is the rest of oxygen transported
A
Dissolved in blood and transported directly in bloodstream
3
Q
Describe the structure of hemoglobin
A
- 4 subunits
- Forms quaternary protein structure
- Each subunit is arranged in a ring like shape with iron atoms bound to the heme in the centre of the subunit
4
Q
what is oxyhemoglobin
A
When oxygen binds to hemoglobin
5
Q
Why can oxygen be more quickly picked up and dropped off once O2 molecules bind to the hemoglobin
A
conformational change
6
Q
What is conformational change
A
Change in shape of macromolecule often induced by environmental factors
7
Q
what is Heme
A
Portion of hemoglobin that contains iron and binds O2
8
Q
What happens after the first O2 molecule is dropped off
A
the next O2 molecule dissociates more readily helping facilitate internal respiration
9
Q
What happens when all 4 heme sites are occupied
A
hemoglobin is saturated 100%
10
Q
What happens when 1-3 heme sites are occupied
A
the hemoglobin is partially saturated
11
Q
Hemoglobin saturation level
A
refers to the percent of the available heme units bound to O2 at any given time
12
Q
Oxygen hemoglobin dissociation curve
A
graph describing the relationship of partial pressure to the binding of O2 to heme and its subsequent dissociation from heme
13
Q
Key points of O2-Hb Dissociation Curve
A
- gases diffuse from higher to lower partial pressures
- affinity of an O2 molecule for heme increases as more O2 molecules are bound
14
Q
What happens as the O2 increases in O2-Hb Dissociation curve
A
there is a greater number of O2 bound to heme
15
Q
Partial pressure of O2 inside arteries vs inside veins
A
Arteries: 100 mmHg
Veins: 40 mmHg
16
Q
Highly active tissues vs Less active tissues
A
High: lower partial pressure
Less: higher partial pressure
17
Q
what causes hemoglobin and O2 to dissociate faster?
A
Higher temperature
18
Q
Low temperature inhibits
A
Dissociation
19
Q
Highly active tissues release..
A
A large amount of heat
20
Q
Highly active tissues increase
A
the ability for O2 to dissociates from hemoglobin which helps provide active tissues with more O2
21
Q
What hormones affect the O2-Hb curve
A
Androgens
Epinephrine
Thyroid
Growth hormone
22
Q
How do hormones affect the O2-Hb curve
A
stimulates the production of 2,3- diphosphoglycerate (DPG) by erythrocytes
23
Q
What is a byproduct of glycolysis
A
Diphosphoglycerate (DPG)
24
Q
Elevated DPG promotes
A
dissociation of O2 from hemoglobin
25
What factors influence the O2-Hb curve
Partial pressure
Temperature
Hormones
Blood pH
26
what is the Bohr effect?
phenomenon that arises from the relationship between pH and O2's affinity from hemoglobin
27
How does acidic blood affect the O2-Hb curve
promotes O2 dissociation from hemoglobin
28
How does high pH affect the O2-Hb curve
inhibits O2 dissociation from hemoglobin
29
Left shift of O2-Hb curve
increased affinity for O2
| decrease everything else
30
Right shift for O2-Hb curve
Decreased affinity for O2
| increase everything else except pH decreases
31
3 ways Co2 is transported
1. in form of bicarbonate
2. blood plasma as some Co2 molecules dissolved in the blood
3. bound to hemoglobin on erythrocytes
32
Majority of the CO2 molecules are transported in the form of
Bicarbonate
33
Where is bicarbonate produced
Erythrocytes after CO2 diffuses into the capillaries
34
Carbonic anhydrase causes
CO2 and H2O to form carbonic acid
35
Carbonic acid dissociates into what?
Bicarbonate and Hydrogen
36
H3O builds up in
the erythrocytes
37
Chloride shift phenomenon
HCO3 leaves erythrocytes and moves down its concentration gradient into the plasma to exchange for Cl ions
38
How does chloride shift occur
Exchanging one negative ion for another negative ion
39
What occurs at the pulmonary capillaries?
the chemical reaction that produced HCO3 is reversed and CO2 and H2O are products
40
What forms Carbonic acid
H and HCO3
41
Dissolved CO2 route
travels from the tissues to the bloodstream to the pulmonary capillaries and is diffused across the respiratory membrane into the alveoli and is exhaled through pulmonary ventilation
42
Urinary systems vital roles in maintaining homeostasis
- cleansing the blood
- regulation of pH
- regulation of bp
- regulating the concentration of solutes in the blood
- determined the concentration of RBC
- Concerts calcidiol to calcitriol (last step in vitamin D activation
43
Final synthesis step in vitamin D activation
Concert calcidiol to calcitriol
44
What symptoms might someone experience if the kidneys fail?
```
weakness
lethargy
shortness of breath
anemia
widespread edema
Metabolic acidosis
rising potassium levels
heart arrhythmias
```
45
Incontinence
failure of nervous control or the anatomical structures leading to a loss of control of urination
46
4 types of Incontinence
1. Stress
2. Urge
3. Overflow
4. Neurogenic
47
Kidney is a regulator of
Plasma
48
Kidneys receive how much of resting cardiac output?
20-25%
49
Adrenal gland is located where
superior aspect of kidney
50
What is the responsibility of the adrenal cortex
influence renal function through the production of the hormone aldosterone
51
What is the role of Aldosterone?
stimulate sodium reabsorption
52
what does the adrenal medulla release?
catecholamines (epinephrine and norepinephrine)
53
Renal colums are
Connective tissue extensions that radiate downward from the cortex through the medulla to separate the renal pyramids
54
Renal pyramids are
bundles of collecting ducts that transport urine from the nephrons to the calyces of the kidney for excretion
55
What structure divides the kidney into 6-8 lobes?
Renal columns
56
Renal pyramids and columns together constitute...
Kidney lobes
57
Renal hilum
entry site for structures servicing the kidneys
58
what emerges from the hilum?
renal pelvis
59
What 2 structures form the renal pyramid
Major and minor calyxes
60
renal arteries vs renal veins
arteries: from descending aorta
Veins: return cleansed blood to the inferior vena cava
61
Nephrons
Functional units of the kidney responsible for cleansing the blood and balancing the contents of the circulatory system
62
Afferent arterioles supply blood through
high pressure glomerulus capsule
63
Bowman's capsule
continuous sophisticated tubule whose proximal end surrounds the glomerulus and receives the filtrate
64
What two structures form the renal corpuscle?
Glomerulus and Bowman's capsule
65
Blood flow through kidneys
```
Renal artery
segmental arteries
interlobular arteries
Arcuate arteries
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
Peritubular capillaries
Interlobular veins
Arcuate veins
interlobar vein
```
66
What is found in the renal corpuscles
proximal convoluted tubules and distal convoluted tubules
67
Cortical nephrons
short loop of Henle that barely dips beyond the cortex
68
Juxtamedullary nephrons
long loops of henle extending deep into the medulla
69
Principal task of the nephron
balance the plasma to hemostatic set points and excrete potential toxins in the urine
70
3 principle functions of nephron
1. Filtration
2. Reabsorption
3. Secretion
71
Tubules
Get rid of toxins
72
Control of nephron in 3 areas
1. maintain bp
2. aid in RBC production
3. Assist in calcium absorption
73
What is the projection in Bowman's capsule
Filtration slits
74
Filtration slits
small gaps between the digits basically forming a strainer for the blood
75
fenestrations permit and prevent
Permit very rapid movement of filtrate from the capillary to the Bowman's capsule
Prevent filtration of blood cells or large proteins
76
Substances pass freely at what size
4-8nm
77
Factors that affect the ability of substance to cross the barrier
1. Size
| 2. Electric charge
78
Filtrate does not contain ____ or ________ and has a slight predominance of ____ charged substances
RBC's or large proteins
| Positively
79
Proximal convoluted tubule is formed by
simple cuboidal cells with prominent microvilli on luminal surface
80
What is the most essentially function of the proximal convoluted tubule?
microvilli create a large surface area to maximize the reabsorption and secretion of solutes
81
Descending vs ascending loop of henle
Descending: initial short thick portion and long thin portion
Ascending: initial short thin portion and long thick portion
82
Thick portion of loop consist of
simple cubiodal epithelium
83
Thin portion of loop consist of
simple squamous eppithelium
84
Distal convoluted tubule is formed by
simple cuboidal epithelium
85
differences in distal and proximal convoluted tubule
distal is shorter and less active in absorption/secretion fewer microvilli and no brush border
86
Juxtaglomerular apparatus
juncture just outside Bowman's capsule
87
What happens at the Juxtaglomerular apparatus
afferent and efferent arterioles enter and leave Bowman's capsule
88
Macula densa and juxtaglomerular cells together
monitor the composition and rate of fluid flowing through the distal convoluted tubule
89
Mascula densa releases
Paracrine signlas
90
Juxtaglomerular cell
a modified smooth muscle cell lining the afferent arteriole that can contract or relax in response to ATP or adenosine
91
Paracrine signals consist of
ATP and adenosine
92
What happens if the osmolarity of the filtrate is too high
filtration and urine formation decrease and water is retained
93
What happens if the osmolarity of filtrate is too low
filtration and urine formation increase and water is lost by way of the urine
94
Active renin
Protein which cleaves several amino acids from angiotensinogen to produce angiotensin I
95
Angiotensin II
Systemic vasoconstrictor in turn increases blood pressure and stimulates the release of aldosterone from adrenal cortex
96
What does aldosterone stimulate?
Na reabsorption by the kidney which also results in water retention and increased blood pressure
97
Natriuretic hormones
Peptides that stimulate kidney to excrete Na
98
What do Natriuretic hormones inhibit
aldosterone release
Na recovery
ADH release
99
Collecting ducts are lined with
simple squamous epithelium with receptors for ADH
100
Aquaporin channel proteins
allow water to readily pass from the duct lumen through the cells and into the interstitial spaces to be recovered by the vasa recta
101
Absence of ADH
water is excreted in the form of dilute urine
102
Glomerular filtration rate
Volume of filtrate formed by both kidneys per minute
103
At rest the heart pumps
~5 litres of blood/minute
104
How much blood enters the kidneys to be filtered
1 litre (20%)
105
Filtrate volume in men and women
Men: ~180 litres/day
Women: ~150litres/day
106
What percent of filtrate is returned to circulation by reabsorption. How much urine will be produced/day
95% of filtrate
| ~1-2 Litres of urine
107
Glomerular filtration rate is influenced by the
Hydrostatic pressure and colloid osmotic pressure
108
Particle movement in filtration is constrained by
Particle size
109
Hydrostatic pressure
pressure produced by fluid against a surface
110
What occurs if you have fluid on both sides of a barrier
both fluids exert a pressure in opposing directions
111
Net fluid movement is in what direction
Direction of the lower pressure
112
Osmosis
movement of solvent across a membrane that is impermeable to solute
113
Osmotic pressure exists until
the solute concentration s the same on both sides of a semipermeable membrane
114
water will be pulled
to the higher solute concentration
115
Glomerular filtration occurs when
glomerular hydrostatic pressure exceeds the pressure of Bowman's capsule
116
Blood colloid osmotic pressure is higher
in the glomerular capillary
117
osmotic pressure is higher
in the glomerular capillary (30 mmHg) rather than the bowman's capsule
118
Absence of proteins in the lumen result in
osmotic pressure in the capsule to be near zero
119
what is the only pressure moving fluid across the capillary wall into the lumen of Bowman's space
hydrostatic pressure
120
What works agaisnt the hydrostatic pressure
capsular pressure and osmotic
121
Net filtration pressure
~10 mmHg
122
To cope with narrow range of filtration pressures the kidney employs
auto-regulatory processes
123
A blood pressure goes up smooth muscle afferent arterioles ____ while efferent arterioles slightly ____
contracts, dilate
124
net result of the autoregulatory system
relatively steady flow of blood into the glomerulus and a relatively steady filtration rate over a wide range of alterations to systemic blood pressure
125
When blood pressure falls below 60 mmHg
renal function is impaired and can cause systemic disorders that are severe enough to threaten survival
126
Reduction of stimulation results in
vasodilation and increased blood flow through the kidneys during resting conditions
127
Sympathetic stimulation increases
vasoconstriction resulting in diminished glomerular flow which produces less filtrate
128
Renin is released when
blood pressure falls too much
129
Angiotensin II stimulates
aldosterone production to augment blood volume through retention of more Na and water
130
4 main structures responsible for recovery
1. Proximal convoluted tubule
2. Loop of Henle
3. Distal convoluted tubule
4. Collecting ducts
131
Reabsorption/ Secretion steps
1. Plasma volume entering afferent arteriole = 100%
2. 20% of volume filters
3. >19% of fluid is reabsorbed
4. >99% of plasma entering the kidney returns to systemic circulation
5. <1% of volume is excreted to external environment
132
Glomerular corpuscle main function
filters blood to create a filtrate mainly void of cells and large proteins
133
When the filtrate enters the PCT
it undergoes modification through secretion and reabsorption before true urine is produced
134
Where is majority of the water in filtrate recovered
PCT
Loop of Henle
DCT
135
How much of filtrate reaches the collecting ducts
~10%
136
Proximal convoluted tubule recovers
majority of Na, K, glucose, amino acids and other organic substances
137
The amount of water absorbed or lost is directly regulated by _______ _______ and indirectly by ______
Directly: anti-diuretic hormone (water) and aldosterone (sodium)
Indirectly: renin
138
Collecting ducts are heavily influenced by
ADH and regulate column of water reabsorbed
139
If plasma osmolarity rises
more water is recovered and urine volume decreases (dehydrated)
140
If plasma osmolarity decreases
Less water is recovered and ruin volume increases (well-hydrated)
141
Aldosterone is secreted by ____ in response to
adrenal cortex
| angiotensin II stimualtion
142
Aldosterone stimulates
principal cells to manufacture luminal Na and K channels
| ATPase pumps on the basal membrane of the cells
143
Antagonist for Aldosterone
Atrionatriuretic peptide (ANP)
144
ANP promotes
excretion of salt and water from the body
145
ANP is released
if atrial pressures are high
146
Obligatory water reabsorption
Water flows passively to maintain an isotonic fluid environment inside the capillary
147
Facultative wate reabsorption occurs in
the collecting ducts through the activation (and inactivation) of aquaporins
148
Apical surface
one facing the lumen or open space of a cavity or tube
149
Basal surface
faces the connective tissue base to which the cell attaches if the cell membrane closer to the basement membrane if there is a stratified layer of cells
150
Symport vs Antiport mechanism
Symport: two ions are transported in the same direction across the membrane
Antiport: two ions are transported in opposite directions across the membrane
151
Recovery of bicarbonate
In the lumen of the PCT combines with H+ to form carbonic acid
Enzymatically catalyzed into Co2 and water which then diffuses across the apical membrane into the cell
152
2 sections of the Loop of Henle
Thick and thin descending section
| Thin and thick ascending section
153
Cortical vs Juxtamedullary nephrons
Cortical: do not extend far into the medulla
Juxta: loops that extend variable distances some very deep into the medulla
154
As the filtrate moves through the loop the osmolarity changes from ___ in the cortical to ______ at the bottom of the loop
isosmotic with blood
| Very hypertonic solution
155
Ascending loop made of
cuboidal epithelium and is impermeable to water
156
Hypotonic filtrate
removing Na from the filtrate and retaining water
157
additional Na in the interstitial space contributes to
Hyperosmotic medulla
158
Counter current
Descending and ascending loops are next to each other and fluid flows in opposite direction
159
Blood flows slowly in the vasa recta particularly for 3 reasons
1. Maintenance of the countercurrent multiplier system
2. Allows blood cells to lose and regain water without crenating or bursting
3. A rapid flow would remove too much Na and urea in turn destroying osmolar gradient
160
How does urine pass through the ureter?
propelled by waves of peristalsis to drain into the bladder
161
Physiological sphincter
One way valve that allows urine to enter the bladder and prevent reflux of the urine from the bladder back into the ureter
162
Urinary bladder
collects urine from both ureters
| made up of detrusor muscle
163
Detrusor muscle
irregular cross crossing bands of smooth muscle
164
Interior surface of Urinairy bladder is made of
Transitional epithelium structurally suited for the large volume fluctuations of the bladder
165
Micturation
voluntary control of urination that relies on consciously preventing relaxation of the external urethral sphincter to maintain urinary continence
166
Normal micturition
result of stretch receptors in the bladder wall that transmit nerve impulses to the sacral region of the spinal cord to generate spinal reflex
167
Parasympathetic neural outflow
causes contraction of the detrusors muscle and relaxation of the involuntary internal urethral sphincter
168
Voiding
regulated voluntary skeletal muscle of the external urinary sphincter
169
Why do women have a higher instances of UTIs?
They have much shorter urethra which is less of a barrier to fecal bacteria than males who possess a much longer urethra
170
What is the minimum amount of urine that they kidneys must produce per day to rid the bod of wastes?
500mL/day
171
Virtual absence of urine production
Anuria
172
Excessive urine production
Polyuria
173
Oligouria
Output below minimum urine production caused by severe dehydration or renal disease
174
Ph of urine is often between values of
low of 4.5 to a high 8
175
Specific gravity
measure of urine weight vs pure water weight
| used as an indication of osmolarity
176
UTI
presence of leukocytes in the urine
177
Protein found in the urine indicates
damage to the glomerulus allowing protein to "leak" into filtrate
178
what are Ketones and if in the urine what does this indicate
Byproduct of fat metabolism
Indicate that the body is using fat as an energy source as compared to glucose
Deficiency of carbs or proteins or Diabetes
179
Where in the body does ammonia come from and how is it excreted
When proteins are broken down their nitrogen groups are removed
Rapidly converted to urea in the liver and transported to kidneys for excretion
180
How are calcium and vitamin D related in the body?
When vitamin D is absorbed it must be activated, causing OH group to be added to calcidiol to form calitrol which increases absorption of Ca2+ in the digestive tract
181
Not enough Ca2+ leads to
```
Osteoporosis
Rickets
Problems with cell proliferation
Neuromuscular function
Blood clotting
Inflammatory respinse
```
182
What organs produce EPO
Kidney - 85%
| Liver
183
Consequence of kidney failure related to RBC could be
Anemia due to loss of EPO production
184
Consequences of kidney failure related to vascular volume
High or low blood pressure
Stroke
Heart attack
Aneurysm
185
Loss of glucose control could cause ___ in the kidneys
Osmotic dieresis
186
Water makes up how much of the body mass
infants: 75%
Adult women: 55%
Adult men: 60%
Older adults: 45-50%
187
What is intracellular fluid composed of?
all fluids enclosed in cells by their plasma membranes
188
Extracellular fluid is composed of
Fluid that surrounds all cells in the body and consists of interstitial fluid and blood plasma
189
Majority of extracellular fluid is
Interstitial fluid
190
Blood plasma and extracellular fluid contains high concentrations of
Na and Cl
191
Intracellular fluid contains high concentrations of
K+ and HPO4(2-)
192
How much water is generated metabolically?
300mL
193
How much water do we typically ingest and lose in a day?
2.5L
194
What organ provides the greatest regulation to homeostatic fluid levels
Kidneys
195
Plasma osmolarity
Sensory receptors in the thirst centre of the hypothalamus that monitor concentration of solutes of the blood
196
Kidneys ____ water but cannot ___
Conserve
| Replace
197
What happens when there is a decreased blood pressure due to lowered blood volume?
Baroreceptors in aorta and carotid arteries detect decreases in BP that results from lowered BV
Heart is signals to increase rate and strength of contractions to compensate
Blood vessels constrict
198
Second step when there is decreased blood pressure due to lowered blood volume
Kidneys activate renin-angiotensin hormonal system
Angiotensin II stimulates thirst and the release of aldosterone from adrenal glands
Aldosterone increase Na+ absorption in distal tubules
199
Role of ADH in fluid balance
increases aquaporin numbers in collecting ducts to allow more water to be absorbed
200
7 most important electrolytes in terms of body functioning
1. Sodium
2. Potassium
3. Chloride
4. Calcium
5. Phosphate
6. Magnesium
7. Bicarbonate
201
Highest levels of sodium are found where
in the extracellular fluid
202
what happens if there is an increase in salt intake but not fluid
Thirst response stimulated by the body to increase water
| Vasopressin is secreted to increase renal absorption
203
Highest levels of potassium are found in
Intracellular fluid
204
Highest levels of potassium are found in
Intracellular fluid
205
Major extracellular anion
Chloride
206
Role of chloride in electrolyte balance
Major contributor to osmotic pressure gradient between ICF and ECF
Maintain electrical neutrality of ECF
207
_____ & ______ are reabsorbed from the renal filtrate.
| ______ is excreted into the renal filtrate
Sodium and chloride
| Potassium
208
Signal transmission at a chemical synapse
1. Action potential travels to synaptic end of presynaptic neuron
2. Triggers calcium channels to open
3. Calcium influx causes synaptic vesicles to release their neurotransmitter into synaptic cleft through exocytosis
4. Neurotransmitters travel across cleft abd bind to receptors on postsynaptic neuron
5. Ligand gated channels open, causing either inhibition or excitation
209
Calcium role in intracellular fluids
Weak base to buffer
210
Where is magnesium found?
Bone matrix
211
Role of Magnesium in the body
activates several enzyme systems needed for metabolism of carbs and proteins
212
Buffer
substance that minimizes changes in pH by dampening hydrogen ion concentrations
213
3 buffer systems
1. Phosphate
2. Proteins
3. Bicarbonate-carbonic acid buffers
214
Phosphate buffer system is used in.
intracellular fluid and urine from kidneys
215
What occurs in the phosphate buffer system
Monohydrogen phosphate ions act as a weak base and dihydrogen phosphate ions act as a weak acid
216
Protein buffer system
Protein molecules act as both a weak acid and base
| Working across the whole body
217
What is the most important protein buffer?
Hemoglobin
218
How does hemoglobin works to regulate pH
Co2 diffuses into RBC and combines with water to form carbonic acid which dissociates into bicarbonate and hydrogen ions
Bicarbonate diffuses into the blood and is replaced with Cl ions in RBC
Hydrogen ions are buffered by Hb molecules
219
More bicarbonate or carbonic acid in the blood? Why?
Bicarbonate because many of our metabolic wastes are acids so we need the weak base to offset this
220
How does breathing regulate pH
When holding our breath our Co2 levels rise
Co2 combined with water to form carbonic acid lowers pH
When we hyperventilate or normally breath excess Co2 becomes expired increasing pH
221
Increased breathing at rest leads to
decrease in Co2, and increase in blood pH
222
Decreased breathing at rest leads to an
increase in CO2 and decrease in blood pH
223
Major side effect of acidosis
Depression of the central nervous system
224
Major effect of alkalosis
Over-excitability of the central and peripheral nervous system
225
Respiratory acidosis, respiratory alkalosis, metabolic acidosis and metabolic alkalosis
Resp. aci: increased PaCO2
Resp. alka: decreased PaCO2
Met. acido: decrease HCO3
Met. alka: increased HCO3
226
ROME
Respiratory
Opposite
Metabolic Equal
227
Functions of muscular tissue?
```
producing body movements
stabilizing body positions
Storing and mobilizing substances within the body
Generating heat
Supporting soft tissue
Guarding entrances and exits
```
228
Properties of muscular tissue
electrical excitability
Contractility
Extensibility
Elasticity
229
Contractility of the muscle
stimulated muscles cells shorten or contract through sliding filament theory
230
Extensibility of muscle
Capacity to stretch to the normal resting length after contracting
231
Spasticity
Lack of extensibility
232
elasticity of the muscle
ability to recoil or bounce back to the muscles original length after being stretched
233
3 types of muscular tissues
1. cardiac
2. smooth
3. skeletal
234
Characteristics of cardiac muscle
short branching cells with single nucleus and light striations
Joined via intercalated discs
have gap junctions to allow communication
involuntary control
235
Characteristics of smooth muscle
```
Long cells containing a single nucleus
Cylindrical shape with tapered end
No striations
Involuntary control
takes the longest to contract
```
236
Characteristics of skeletal muscle
Long and multi nucleated
Cylindrical shape and heavily striated
Voluntary control
Arranged in bundle of contractile filaments
237
Characteristics of oxidative muscle fibres
appear dark red
generate ATP through aerobic respiration
High concentrations of mitochondria and capillaries
Slow velocity of twitch contractions
very fatigue resistant
238
Characteristics of glycolytic muscle fibres
Appear lighter
mainly generate ATP through glycolysis
Low concentrations of mitochondria and capillaries
faster twitch contraction velocities
Fatigue rapidly but are good for short duration explosive movements
239
Characteristics of Oxidative-glycolytic fibres
appear red-pink in colour
Generate ATP through both aerobic and anaerobic glycolysis
High concentrations of mitochondria and capillaries
Moderate velocity and power twitch contractions
fairly fatigue resistant and are good for sustained speed events
240
The force developed by the whole muscle is dependent on
the recruitment pattern and proportion of fibre types present in the muscle
241
Sarcolemma
The cell membrane of the muscle fibres which is covered with transverse tubules
242
Transverse Tubules
Contain interstitial fluid and facilities rapid conduction of action potentials
243
Sarcoplasm
Cytoplasm within the muscle cells which contains large quantities of glycogen and myoglobin
244
Mitochondria
The powerhouse of the cell where ATP is created
245
Sarcoplasmic Reticulum
Contains the calcium required for trigger a muscular contraction
246
Myofibril
The contractile organelles of the muscle cell
247
Thin vs Thick filaments
Thin: 8nm diameter and 1-2 um in length
Thick: 16nm diameter and 1-2um in length
248
Anatomy of a sarcomere
Z disc: separates one sarcomere from another
A band: dark middle part of the sarcomere where the actin and myosin overlap
I band: Lighter band which only consists of the thin Actin filaments
H zone:Narrow region in the centre of each A band which only consists of the thick Myosin filaments
M line: Region in the centre of the H zone containing proteins to hold the myosin filaments together at the centre f the sarcomere
249
Myofibrils built from three main types of proteins
1. Contractile proteins: generate force during contraction
2. Regulatory Proteins: switch contractions on/off
3. Structural proteins: maintain alignment of thick and thin filaments, give myofibrils their elasticity and link myofibrils to sarcolemma and extra cellular matrix
250
What are the two contractile proteins in skeletal myofibrils
Actina and myosin
251
Actin vs Myosin
Actin: main protein for thin filament
Myosin: main protein for thick filament
252
Myosin heads are responsible for
grabbing and pulling the actin filament past itself during cross bridging
253
What are the two binding sites of myosin heads
ATP and Actin
254
What proteins control access to myosin binding sites
Tropomyosin and troponin
255
Tropomyosin
When muscles are relaxed the myosin binding sites on actin are covered by the tropomyosin filament
256
Troponin
Is the gatekeeper that controls when tropomyosin will open the myosin binding sites
257
Tintin
Forms elastic filaments around myosin linking them to the M line and Z discs
Elasticity and extensibility
258
Nebulin
Wraps around the actin filament and helps anchor them to the Z discs
Regulates length of actin filaments during development
259
Alpha Actinin
Structure component of Z discs and enables actin and titin to bind
260
Myomesin
Structural component which forms the M line of the sarcomere
Binds to titin and enables adjacent myosin filaments to bind
261
Dystrophin
Binds the thin filaments to the integral membrane proteins in the sarcolemma
Reinforces the sarcolemma and aids in force transmission to the tendons
262
Somatic motor neuron
Neuron transmitting the efferent signal from the brain to the muscle fibre
263
Synapse between the motor neuron and sarcolemma occurs at ________ and inititates ______
motor end plate
| Propagation of a muscle action potential
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Muscle action potential at the NMJ steps
1. voltage gated calcium channels open causing an influx of calcium
2. Acetylcholine binds to ligand-gated Na channels on the motor endplate causing an influx of Na into the muscle
3. Depolarizes the muscle and results in Ca release from the sarcoplasmic reticulum
4. Acetylcholine is rapidly broken down by acetylcholinesterase of Ca from the sarcoplasmic reticulum
265
Sliding filament theory
1. Myosin cross bridges pull on actin filaments
2. Actin filaments slide inwards toward the H zone
3. X discs come toward each other and the sarcomere shortens
4. Causes the shortening of the whole muscle fibre and ultimately the entire muscle
266
Contraction cycle
1. Myosin head hydrolyzes previously bound ATP and is orientated to the Actin filament
2. Myosin head binds to actin to form cross bridge
3. Myosin head pivots pulling the actin filament towards the centre of the sarcomere (power stroke)
4. ATP binds to the myosin head detaching from the actin cross bridge
267
What happens with calcium ions when action potential isn't present
Calcium ions concentrations are maintained in the sarcoplasmic reticulum
268
What happens to tropinin and tropomyosin without calcium ions
tropinin stays inactive and tropomyosin doesn't move to open the myosin binding sites on the actin filament
269
What happens with calcium when action potential is present
calcium ions are rapidly released from the sarcoplasmic reticulum
270
Isotonic vs Isometric
Isotonic: tension is constant while muscle length changes
Isometric: muscle contracts but does not change length
271
Concentric vs Eccentric
Concentric: angle of the joint decreases
Eccentric: angle of the joint increases
272
Schematic of the series elastic elements
1. Muscle at rest
2. Isometric contraction
3. Isotonic contraction
273
Isotonic shortening phase
Cross bridges are visible in skeletal muscle length
| Tension is constant
274
Tone
established by the alternating involuntary activation of small groups of motor units in a muscle
Keeps the muscle firm even when relaxed
Only maintain form and do not produce movement
275
The strength of the muscle contraction depends on
How many motor units are activated
276
Motor unit recruitment
increasing the number of active motor units
| Weakest first
277
Fewer muscle fibres per motor unit prodcues what kind of movements
Precise and delicate
278
Larger number of muscle fibers per motor unit produce what kind of movements?
Powerful and coarsely controlled
279
Latent period
delay between the arrival of AP and the initiation of contraction
280
Contraction period
Ca2+ binds to troponin and the actin-myosin cross bridges are formed
281
Relaxation period
Ca2+ is actively pumped back into the SR and myosin heads detach from actin and muscle tension decreases
282
Refractory period
Muscle tissue is unable to response to a subsequent AP
283
Wave summation
occurs when a second action potential triggers muscle contraction before the first contraction has finished resulting in a stronger contraction because the muscle hasn't reset
284
Unfused (incomplete) vs Fused (complete) tetanus
Unfused: produced partial summation of individual twitches
Fused: produces full summation of individual twitches
285
Passive length tension relationship
as the muscle is stretched beyond resting length it produces a force (non-contracting) due to the elastic components of the muscle and fascia
286
Active length tension relationship
Force produced by contractile mechanism
287
Optimum length; Length-tension relationship
maximum active force
288
Active force of a muscle contraction depends on
the length of the sarcomeres in the muscle before contraction
289
When is the number of active cross bridges the greatest in a muscle? If it was stretched beyond this what happens?
When it is at the optimum length
| Number of active cross bridges decrease because the overlap between actin and myosin decrease
290
What happens when the velocity of a concentric muscle action is increased?
less force is capable of being generated during that concentration
291
What happens when the velocity of an eccentric muscle action is increased?
more force is capable of being generated during that contraction
292
Force-velocity relationship and equation
Force production decreases as the velocity of the contraction increases
Power = Force x velocity
293
How are improvements of maximal power output of a muscle achieved?
by increasing the maximal force we can move and/or increasing movement velocity
294
The lighter the load the _____ we can move
faster
295
Which muscle fibers are most likely going to be used for high force-velocity activities?
Tye 2a and 2b
296
Pennation angle and force production relationship
As pennation angle increases, the max force generation increases at cost of velocity.
As pennation angle approaches 0, muscle fibers can produce less force but can do it more quickly
297
Heavy strength training _______ pennation angle. Sprint training __________pennation angle
Increases
| Decreases
298
The electrical potential difference within muscles measured by EMG amplitude is a function of both:
muscle fiber recruitment and motor unit firing rates
299
An increase in EMG activity during a prolonged contraction could be a result of additional recruitment. However, it could also be a result of:
Changes in peripheral factors, including an increase in intracellular action potentials as a result of altered calcium ion availability
300
Two kinds of muscle fatigue
Peripheral and central
301
What are some mechanisms of central fatigue?
- psychological factors
| - protective reflexes
302
What are three areas in which peripheral fatigue might occur?
- neuromuscular junction
- excitation contraction coupling
- Ca2+ signal
303
What are some mechanisms for peripheral fatigue at the neuromuscular junction?
- decreased neurotransmitter release
| - lowered receptor activation
304
What are some mechanisms for peripheral fatigue during excitation contraction coupling?
change in muscle membrane potential meaning that action potential can't propagate as easily
305
What are some mechanisms for peripheral fatigue during Ca2+ signalling?
- sarcoplasmic reticulum has a calcium leak
- lowered calcium release
- lower calcium troponin interaction
306
How do muscles produce ATP to power their contraction cycle?
- creatine phosphate
- fermentation
- cellular respiration
307
How does creatine phosphate work?
Catalyzes transfer of a phosphate group from creatine phosphate to ADP and rapidly yield ATP
308
What are the characteristics of PCr?
- does not require oxygen to be present
| - provides peak power output for 10-15 seconds
309
What is anaerobic glycolysis?
Reaction that converts blood glucose into pyruvic acid to generate ATP
310
What are the characteristics of anaerobic glycolysis?
- does not require oxygen to be present
| - provides peak power output for 30-40 seconds and can be sustained at high levels for up to 2 minutes
311
What is cellular respiration?
Pyruvic acid can enter mitochondria and undergo a series of oxygen requiring reactions to generate large amounts of ATP
312
What are the characteristics of cellular respiration?
- requires oxygen
- requires more processing time
- can be used for long haul activities
313
Lactate
metabolic fuel source within the brain
314
is a metabolic fuel source within the
- elevated body temp
- heart and lungs working harder
- muscles used undergo tissue repair process
315
What is the effect of endurance based activities on muscle fibers?
- can induce changes in type 2x to become more like 2a
- promotes increase capillary and mitochondrial density
- improves neuromuscular connections, metabolism, and efficiency of respiratory muscles
316
What is the effect of strength based activities on the muscle fibers?
- induce changes in type 2x fibers and transition them more towards 2b
- promotes increased capillary and mitochondrial density
- improves bone density, metabolism, helps offset age related declines across the body
317
Muscle spasm
sudden involuntary contraction of single muscle within a large group of muscles
318
Muscle cramp
Involuntary and often painful muscle contractions. Caused by inadequate blood flow to muscles, overuse and injury, and abnormal blood electrolyte levels
319
What type of muscle fibers cannot undergo mitosis
Mature skeletal
320
How does muscle tissue grow?
Through hypertrophy or enlargement of already existing muscle cells
321
Hyperplasia
increase number of muscle fibers
322
What happens to our muscle tissue as we age?
It declines. Muscle strength and flexibility decreases, reflexes slow, and slow oxidative fiber numbers increase
323
What are the main three forms of stretching?
- static stretching
- dynamic stretching
- proprioceptive neuromuscular facilitation
324
Static stretching _____ athletic performance?
decreases
325
Dynamic stretching ______ performance
increases and decreases
326
Proprioceptive neuromuscular facilitation _____ performance
decreases
327
What happens to ROM when stretching is performed?
It improves across all styles of stretching
328
Reductions in performance following stretching are though to be due to:
- changes in tendon stiffness and the force-length relationship
- contractile 'fatigue' or damage
- diminished electromechanical coupling
- reduced central drive
329
The shape of cardiac cells enables:
greater sarcomere lengthening and shortening across cardiac cycle
330
What is the role of intercalated discs in cardiac muscle?
Enable cardiac cells to have a strong attachment to one another and prevent separation during heart beats with desmosomes
331
What is the role of gap junctions in cardiac muscle?
Allow muscle action potentials to spread from one muscle fiber to another
332
What is different about cardiac muscle action potentials? Why?
Action potentials are slower. Helps to:
- prevent tetanus
- reduce fatigue
- enable adequate filling time for the heart chambers
333
______________ muscle cells have more mitochondria than skeletal muscle
cardiac muscle cells
334
What law dictates that as you dive deeper and hydrostatic pressure increases, the volume of your lungs shrink?
Boyle's law
335
What are the three possible outcomes of excessive pressure on the lung and chest during apnea?
1. Alveolar collapse
2. Infiltration of liquid
3. Disruption of the alveolar-capillary
336
What is Henry's Law?
At constant temperature, the amount of gas absorbed is proportional to the solubility coefficient of the particular gas and their partial pressure
337
What might expanding air in the lung cause?
- expanding air may cause pneumothorax
- arterial gas embolisms occur when nitrogen bubbles are forced into bloodstream through alveoli, resulting in blockages of smaller vessels
- cerebral arterial gas embolisms can also result
338
What is decompression sickness?
Caused by nitrogen dissolved in tissues due to rapid decrease in pressure
339
How can we decrease risk of arterial gas embolism?
- avoidance of breath holding
- avoidance of rapid ascent
- not diving with pulmonary infections or disease
340
Adding a snorkel increases what space in the lungs?
Dead space
341
Instead of increasing snorkel length or volume, it would be more beneficial to increase:
tidal volume
342
The deeper we go with a snorkel, the more challenging it is to breathe in. Why?
Because the pressure on the chest wall is increased, so it pushes against the lungs trying to expand.
343
The mammalian diving response consists of what four behaviours?
- apnea
- bradycardia
- peripheral vasoconstriction
- splenic contraction
* can also have blood pressure fluxes
344
Mammalian diving response is triggered by what nerve?
trigeminal
345
Apnea time during diving depends on:
1. physiological response to hypercapnia and hypoxia
2. intensity of metabolism
3. capacities for O2 and CO2
4. psychological tolerability to hypercapnia and hypoxia
346
Describe the changes in cardiac rhythm during the mammalian diving response
- There is an initial anticipatory tachycardia
- When face is submerged, trigeminal nerve is triggered and there is increased parasympathetic input to SA node
- arrhythmias can arise
347
Describe the changes in artery constriction during the mammalian diving response
- increase in sympathetic outflow to periphery, reducing blood flow to peripheral tissues and skin
- anaerobic metabolism on periphery (lactate increases)
- blood is centralized to brain and heart
- 100% increase of cerebral flow through middle cerebral artery
348
Describe the changes that take place in arterial pressure during the mammalian diving response
- peripheral vasoconstriction increases total peripheral resistance and increases BP
- involuntary breathing can also cause swings in BP
349
Describe changes in cardiac output during mammalian diving response
- haemodynamics at the onset of maximal breath hold after full inspiration can be compared to second phase of Valsalva
- high lung volumes reduce ventricular filling and therefore cardiac output
350
Describe the contraction of the spleen during mammalian diving response
- spleen is significant reservoir of blood
- contraction occurs during diving and exercise
- increased adrenergic activity
351
What is considered high altitude?
high altitude: 1500-3000m
- very high altitude 3000-5000m
- extreme altitude: above 5000m
- 'death zone': above 8000m
352
People exposed to high altitudes who are not adapted to them are at increased risk for:
- acute mountain sickness
- HAPE
- HACE
- chronic mountain sickness
353
Normobaric hypoxia occurs when:
- atmospheric pressure remains the same
| - the fraction of inspired oxygen content has been reduced to levels below 17%
354
Hypobaric hypoxia occurs when:
- the fraction of inspired oxygen content has been unaltered (stays at 21%)
- atmospheric pressure has been reduced
355
What is barometric pressure?
measure of the pressure exerted by the weight of air above us
356
As we ascent, barometric pressure
falls
357
What is our first cardiovascular response to being at high altitude
Resting cardiac output increases via a rapid increase in heart rate
358
When gaining altitude, the increase in cardiac output matches the decrease in ______________________
arterial oxygen content
359
After a few days, how do cardiovascular responses change when we are at high altitude?
cardiac output returns to normal or slightly below. HR remains elevated by SV is decreased to compensate
360
What mechanisms have been proposed for the drop is stroke volume and cardiac output at high altitude?
- response to correct for respiratory alkalosis that arises from hypoxic ventilatory response
- related to an activation of the sympathetic nervous system (increases in plasma catecholamines and muscle sympathetic nerve activity)
- could improve coupling of the right ventricle to pulmonary circulation
- an adaptive decrease in the oscillatory component of pulmonary arterial load
361
Describe the changes in blood viscosity at altitude
- increased blood viscosity
- initially from dehydration due to water loss from increased ventilation and urine output
- with a few weeks partial acclimatization, RBC production is increased via erythropoiesis
362
What are some mechanisms to reduce plasma volume when we ascent to high altitude?
- increased respiration rates
- increased perspiration rates
- increased urine output
- decreased water intake
363
Why would there be increases to pulmonary vascular resistance at high altititudes?
- hypoxemia induces pulmonary vasoconstriction
| - results in mild pulmonary hypertension
364
Pulmonary vascular resistance increases the risk of what happening?
mild interstitial edema and incidence of HAPE
365
What is the first respiratory response to occur when we are at high altitude?
- hypoxemia induces increased ventilation (hyperventilation)
366
Why do we see reduced A-a gradients at high altitude?
- diffusion limitations
- ventilation/perfusion mismatching
- opening of shunts
367
What are the diffusion limitations at high altitude?
- there is lower driving pressure for oxygen to move from air to blood (steeper on the curve)
- reduced oxygen saturation levels move arterial blood on steeper part of O2-Hb curve
- this means it is harder to pick up oxygen, and harder to drop it off at the tissues as well
368
What are the ventilation/perfusion mismatching issues at high altitude?
- increased pulmonary artery vasoconstriction causes there to be increase in interstitial edema to develop
- this decreases ability for oxygen to diffuse into pulmonary capillaries (has to diffuse across fluid)
369
How does the opening of shunts contribute to the decrease in A-a gradients?
- causes blood to bypass gas exchange locations
- can occur as a result of intrapulmonary shunts
- often a result of the opening up of small ducts present between the right and left atria (patent foramen ovale PFO)
370
How does the opening of shunts contribute to the decrease in A-a gradients?
- causes blood to bypass gas exchange locations
- can occur as a result of intrapulmonary shunts
- often a result of the opening up of small ducts present between the right and left atria (patent foramen ovale PFO)
371
As cardiac output doesn't change, the main driver for a-v gradient changes at high altitude is
increasing the oxygen carrying capacity in the blood
372
Does hypoxia influence the creatinine phosphate ATP system? Why?
Research has shown no. Likely because oxygen respiration and fermentation do not contribute significantly to the energy necessary during such explosive short efforts
373
A reduction in power output during explosive exercises at high output could be caused by:
- motor command efficiency is decreased
| - muscle wasting
374
As we acclimatize to high altitude, glucose uptake by muscles ______________
increases
375
What is produced in higher than normal amounts at high altitude during exercise? Is this always the case?
lactate. once acclimatized, the level of lactate produced for a given workload will be greatly reduced
376
Lower production of lactate after acclimatization at altitude can be attributed to what?
- alteration to epinephrine levels (decrease)
- increased uptake of lactate by brain
- loss of muscle mass
377
What happens to VO2max as we gain altitude?
VO2max decreases about 1% per 100m elevation gain above 1500m.
378
What are proposed methods for the reduction in VO2max at altitude?
- alterations to lung function
- decreased peak heart rate
- alterations to central nervous system
379
What role does the central nervous system play at high altitude during exercise?
When the somatosensory and motor cortex perceive a sense of effort and exercise is volitionally terminated when the sense of effort and other sensations like muscle pain become more intense than is tolerable
380
What are some strategies for avoiding AMS?
- ascend no more than 400m per day and after every 1000m gained, take an extra rest day
381
AMS develops above heights of
2400m
382
Objects in low Earth orbit are subjected to about ___________% of the Earth's ground-level gravity
90
383
What should be considered regarding radiation exposure in space?
- on Earth, the atmosphere acts as a natural shield to a lot of the radiation that bombards the earth on a daily basis
- astronauts are exposed to heavy ions and proton fluxes far more than those on earth
384
What are some of the immediate cardiovascular changes we see in astronauts?
- reduction in intrathoracic pressure through blood shifting towards head
- head swells and legs get thinner
- causes space motion sickness
- imbalance in expected and actual sensory vestibular inputs which causes motion sickness
- heart does not require as much contractility to pump blood to head, hence heart becomes atrophied
385
Higher blood pressure in space is compensated for by what:
increased level of urine production and reduced thirst
386
What happens to hematocrit levels of astronauts?
It increases
387
What musculoskeletal changes do we see in space?
- bone mineral loss
| - muscle wasting
388
Why would astronauts experience bone mineral loss?
due to microgravity environment, weight bearing bones like spine, neck, legs lose their density because they are no longer weight bearing
389
Why would astronauts experience muscle wasting?
- Antigravity muscles (supporting muscles) are not used to counter gravity and therefore begin to atrophy
- skeletal muscle protein degradation
390
what are the causes of concussions
direct blow to the head face neck or elsewhere on the body with an impulsive force transmitted to the head
391
early management & treatment of concussion
- remove from play
- not left alone
medically evaluated following the injury
- Return to play should be medically advised
- players should not return to play while symptomatic
392
Children vs Adult concussions
- adults recover faster than kids
- children often present with different symptoms; more emotional and more cognitive based symptoms
- adults have more physical symptoms
393
What is a concussion
traumatic brain injury induced by biomedical forces
