EXAM 2 Flashcards
1
Q
What is the average heart rate
A
75 beats/minute
2
Q
Without the nervous system control the heart would beat about…
A
100 beats/minute (intrinsic SA node depolarization rate due to leak channels)
3
Q
Why would there be a difference in heart rate without the nervous system control?
A
The autonomic nervous system modulates SA node activity
4
Q
Visceral motor responses are initiated from…
A
Internurons in “brain centers”
5
Q
A center is a collection of interneurons that _____ _____ input about a specific function and create ______ ______ to alter that function
A
Receive sensory
Motor output
6
Q
Cardiovascular control centers include…
A
Cardiac control (heart)
- cardioacceleratory center
- cardioinibitory center
Vasomotor center
7
Q
Together the cardiac control and vasomotor center regulate ..
A
Blood pressure and heart function
8
Q
Interneurons of the cardiioacceleratory center will lead to an
A
Increase in heart rate
9
Q
Postganglionic neuron of the cardioacceletory system secretes
A
Norepinephrine (NE)
10
Q
Adrenergic receptors (in the cardioacceletory system) on cells of the SA node bind to…
A
Norepinephrine, causing an increased rate of action potentials of SA node
11
Q
Interneurons of the cardioinhibitory center will lead to..
A
A decrease in heart rate
12
Q
Visceral motor neurons are a part of what system
A
The parasympathetic system
13
Q
Postganglionic neurons of the cardioinhibitory systems secrete..
A
Acetylcholine (ACh)
14
Q
Cholinergic receptors on cells (in the cardioinhibitory center) of the SA node bind to
A
ACh
- this allows potassium to leave the cell - hyperpolarizing reaction
- rate of action potentials decrease
15
Q
Sensory input is integrated to create..
A
Motor output to SA node
16
Q
What are proprioceptors
A
Sensory input from muscles and tendons
- informs brain on changes in physical activity
17
Q
What are baroreceptors
A
Sensory input from blood vessels
- informs brain on changes to pressure in vessels
18
Q
What are chemoreceptors
A
Sensory input from blood vessel
- informs brain on changes carbon dioxide or oxygen levels in the blood
- important in respiratory system, but has some affect on heart rate
19
Q
_____ _____ paths are associated with heart rate
A
Visceral motor
20
Q
Blood vessels are dynamic structures that control…
A
The delivery of blood to/from body tissues
21
Q
What is the function of arteries and what are examples of arteries
A
Carry blood away from heart
- elastic arteries
- muscular arteries
- arterioles
22
Q
What are capillaries
A
Thinnest type of blood vessel involved in gas exchange
23
Q
What is the function of veins and examples of veins
A
Returns blood to the heart
- venules
- small veins
- large veins
24
Q
The largest volume of blood is located in the…
A
Veins and venules
25
What are the three layers of tissue that make up most blood vessels
Tunica intima, tunica media, and tunica externa
26
What is the tunica intima
Similar structure to anatomical membranes
Consists of one layer of epithelial cells (endothelium) and thin layer of connective tissue (subendothelial layer)
Arteries only: internal elastic membrane
Inner layer
27
The endothelium is a _______ _______ ________
Selectively permeable barrier
- cells regulate what enters/exits bloodstream
- smooth surface normally repels blood cells and platelets
28
What is the tunica media
Middle layer
Smooth muscle layer
Elastic fibers (in arteries only!)
29
What is vasomotion and what controls it
Contraction or relaxation of smooth muscle
- smooth muscle controls vasomotion, especially in arteries
30
What is vasoconstriction
Contraction of tunica media
31
What is vasodilation
Relaxation of tunica media
32
Smooth muscle cells have an internal network of _____ and ______ connected to ______ _______
Actin
Myosin
Dense bodies
33
What is seen at an internal view of smooth muscle
Network of myosin and actin connected at dense bodies (collection of proteins, like z-disks)
34
What is seen at the surface view of smooth muscle (relaxed)
Dense bodies also connect to network of intermediate filaments (provide “skeleton” for cells) AND to neighboring cells
35
What is seen on smooth muscle during contraction
Myosin and actin interact when calcium levels increase, resulting in contraction
36
How is smooth muscle excited
It is excited by neurotransmitters released from autonomic efferent neurons into diffuse junctions
37
Action potentials from ANS result in…
Excitation of many smooth muscle cells… this is different from skeletal muscle
38
What is the tunica externa
The outermost layer
Connective tissue with mostly COLLAGEN
Anchor vessel to surrounding tissues
Vasa vasorum - vessels of the vessels
39
What are the three types of arteries
Elastic, muscular and arterioles
40
What do elastic arteries act as
Pressure reservoirs
(Expand and recoil as heart ejects blood)
41
What are muscular arteries
Deliver blood to specific body organs
More muscle in tunica media - responsible for vasoconstriction
42
What are arterioles
Smallest artery = many only have two layers
Feed into capillary beds
Vasoconstriction/dialation control blood flow into capillary beds
Blood within arterioles has lots of resistance - also called resistance vessels
43
What are aneurysms
A balloon like bulge in the wall of a blood vessel due to weakened arterial walls
- may be heredity or acquired
44
What is scurvy
A nutritional deficiency
Lack of vitamin C in diet disrupts proper production of collagen
- results in weakened blood vessels - spontaneous bruising
- also swollen gums (same reason as above) and loss of teeth (collagen is important in bone/teeth health)
45
What do capillaries connect
Arterioles and venules
46
Capillaries are the major site of exchange between…
Blood and tissues
47
Only _____ _______ is present to promote rapid diffusion of material from blood into tissue or vice versa
Tunica intima
48
Flow of blood through capillary beds is controlled by…
Sphincter muscle cells
49
Only about _____ of body’s capillary beds are “open” at any given time
1/4
This is because capillary beds are “open” (perfused) or “closed” based on contraction of sphincters
50
What does perfused mean
When the capillary beds are open
51
_______ ________ funnels blood through a “closed” capillary bed
Thoroughfare channel
52
Relaxed _______ ______ allow perfusion of “true capillaries”
Precapillary sphincters
53
What are the two major types of capillaries in our bodies
Continuous and fenestrated
54
What are the most common type of capillary
Continuous capillaries
55
What are some characteristics of continuous capillaries
Least permeable
Wall of vessel is a single endothelial cell thick
Cells overlap to make intercellular clefts where some molecules can travel through via diffusion
56
______ _________ have pores between endothelial cells
Fenestrated capillaries
57
What are some characteristics of fenestrated capillaries
Pores between endothelial cells
More permeable
Found in locations where rapid transport is important
58
Where are fenestrated capillaries found
Locations where rapid transport is important like kidneys and small intenstines
59
What are some characteristics of sinusoidal capillaries
Most permeable
Large fenestrations and incomplete basement membrane
Only found in limited locations like the liver and spleen
60
Where are sinusodial capillaries found
Limited locations like the liver and spleen
61
Gases and nutrients pass between the blood and interstitial fluid via _________ at capillaries
Diffusion
62
What are the two major routes for diffusion through capillaries
- through a cell
- through spaces between cells
63
Does water move across the capillary walls
Yes
64
What is filtration
Net movement of water out of capillaries
65
What is reabsorption
Net movement of H2O into capillaries
66
Direction of water movement depends on
Osmosis and hydrostatic (blood) pressure
67
______ are blood reservoirs (pool blood due to low pressure) that return blood to the heart
Veins
68
Capillaries beds drain into…
Venules, medium-sized veins, large veins, heart
69
What structure ensures one way flow of blood
Backflow valves (folds of tunica intima)
70
Blood pressure in venules and medium veins is ______ of that in ascending aorta (largest artery)
<10%
71
What is a muscular pump
Veins rely on compression from nearby skeletal muscle and valves to push blood against gravity
How it works:
Valves above the contracting muscle open allowing blood to move toward
Valves below the contracting muscle are forced closed, preventing back flow of blood to the capillaries
72
What is a respiratory pump
Moves blood toward the heart with pressure changes during inhalation
73
What happens to abdominal pressure during inhalation
It increases
Squeezing local veins and forcing blood toward the heart
74
What happens to thoracic pressure during inhalation
It decreases
Local veins expand and speed blood entry into right atrium
75
What happens in the respiratory pump during inhalation
Increases blood flow into thoracic veins
Decreased intrathoracic pressure
Diaphragm contracts
Blood in the abdominal cavity moves superiorly (compression in veins)
Increased intra-abdominal pressure
76
What happens to the respiratory pump during exhalation
Increases blood flow into heart and abdominal veins
Increased intrathoracic pressure
Diaphragm relaxes
Decreased intra-abdominal pressure
Release of compression in abdominal region
77
Malfunctioning valves can lead to
Varicose veins
78
What are varicose veins
Occurs when blood pools in veins of lower limbs
Causes veins to stretch
Valves cannot completely close causing more pooling of blood
Risk - standing for long periods
Hemorrhoids are varicose veins of the anal canal
79
What is the track of “normal” blood flow
Heart -> artery -> capillary (gas & nutrient exchange) -> vein -> heart
80
What are two exceptions to the normal blood flow pattern
Portal system
- blood travels to two capillary beds before returning to heart
Anastomosis
- alternative blood routes to bypass a capillary OR several vessels that lead to the same location
81
What is blood pressure
The force blood exerts against an arterial wall
82
What is systolic pressure
Pressure during ventricular contraction
83
What is diastolic pressure
Pressure during ventricular relaxation
84
What is mean arterial pressure (MAP)
Average pressure in vessels, important when considering blood flow to present organ failure
85
What is the MAP required for organ function
60mmHg
86
What are the three main variables that affect blood pressure
Cardiac output, resistance of vessels, and blood volume
87
What is cardiac output
Amount of blood the heart (ventricles) pump(s) per minute INTO ARTERIES
CO = HR x SV
- change in heart rate (SA node - sympathetic AND parasympathetic)
- change in stroke volume (change in ventricular myocyte contractility - sympathetic only)
88
What is resistance of blood flow in vessels
Combined effect of blood composition, vessel diameter and vessel length
Vessel diameter can change (vasomotion)
89
What is vasomotion
Vessel diameter can change
90
What is vasoconstriction
Smaller lumen, higher blood pressure
SYMPATHETIC ACTION
91
What is vasodilation
Larger vessels, lower blood pressure
PARASYMPATHETIC ACTION
92
What is blood volume
Total volume of blood in the vessels
Includes blood cells, proteins, plasma, etc.
Mainly regulated by the lymphatic system, kidneys, and hormones
93
How does the body maintain blood pressure at rest?
Goal at rest is to maintain pressure using a visceral neural circuit
- things like postural changes, hydration state, stress, or disease can alter blood pressure at rest
Sensory input must be gathered
- input from baroreceptors about current pressure in major arteries
- proprioceptors can also provide input, but not important during rest, the situation changes if we consider exercise or times of fight/flight
CNS must integrate sensory input
- occurs at the cardiovascular control center in medulla (CVCC)
Motor output negates any changes away from homeostasis
- example of negative feedback loops
94
The blood pressure neuronal circuit starts with…
Sensory input to integrating center (Cardiovascular control center - CVCC)
95
What neurons provide afferent input to cardiovascular centers in the hindbrain
Baroreceptors and chemoreceptors
96
What are baroreceptors (in relation to CVCC)
Neurons with mechanically-gated sodium channels in membrane of dendrites
When artery stretches because of an increase in pressure, channels open and neurons depolarize
Rate of action potentials = amount of stretch (more stretch, more action potentials)
97
What is the function of chemoreceptors in relation to the CVCC
Important for monitoring pH to control respiration AND cardiac output
98
Visceral motor responses are either sympathetic or parasympathetic depending on..
The sensory input
99
When do sympathetic visceral motor responses occur
When blood pressure is too low
Visceral motor neurons cause
- increased heart rate
- activation of cardioacceleratory center
- inhibition of cardioinhibitory center
Vasoconstriction
- constriction of blood vessels regulated by sympathetic release of norepinephrine/epinephrine
100
When do parasympathetic visceral motor responses occur
Occurs when blood pressure is too high
Visceral motor neurons cause:
- decreased heart rate
- activation of cardioinhibitory center
- inhibition of cardioacceleratory center
Vasodilation
- dilation of blood vessels due to decrease in norepinephrine (lack of secretion)
101
Blood pressure homeostasis summary
Motor neurons of the cardiac and vasomotor centers work together to maintain blood pressure homeostasis
Balance between sympathetic action (increased heart rate and vasoconstriction) and parasympathetic action (decreased heart rate and vasodilation)
Blood volume also plays a role, controlled by lymphatic system and kidneys
102
What are the two major fluid compartments that water is distributed between
Intracellular (water in cells) and extracellular fluid
103
What are the types of extracellular fluid
Interstitial fluid: water between cells of tissue
Plasma: water in blood vessels
Other: water in lymphatic vessels, etc.
104
How does water move through fluid locations?
Water transport relies on pressure gradients: hydrostatic gradient and/or osmotic gradient
105
What is hydrostatic pressure
Physical force resulting in net movement of fluid (including water) in one direction ->> pushes
106
What is osmotic pressure
Chemical force resulting in net movement of water in one direction ->> pulls
107
What is osmosis
The diffusion of water across a membrane
- dependent on the amount of dissolved “stuff” in water
108
Water diffuses from where its concentration is _____ to where its concentration is ________
High (dilute solute), low (concentrated solute)
109
Is there a way to “pump” a molecule of water by active transport
No, the body relies on osmotic gradients to “suck” water
110
How does hydrostatic pressure and osmotic pressure drive the movement of water at capillary beds
Hydrostatic pressure “pushes” water
Osmosis “pulls” water to location of higher solute concentration
- driven by proteins in our plasma or interstitial fluid
111
Where do hydrostatic and osmotic forces work
In capillary and interstitial fluid
- NOTE: interstitial forces are typically low… often ignored
112
What is bulk flow
Describes the movement of water at a capillary bed
113
What is bulk flow determined by
Balance of forces
- net pressure out of bed = filtration
- net pressure into bed = reabsorption
114
NFP equation
NFP = (HPc + OPi) - (HPi + OPc)
115
NET filtration is caused by
High HPc
- results in the daily loss of ~24L of fluid to our tissues from our blood
- this fluid is called interstitial fluid
116
_____ and ______ occur at capillary beds
Osmosis and filtration
117
What system is critical for maintaining blood volume and immunity
The lymphatic system
118
What are the two parts of the lymphatic system
Network of vessels that extends to all tissues of the body
Organs and tissues that produce and maintain immune cells
- organs include lymph nodes
- immune cells include white blood cells
119
What are two major functions of the lymphatic system
Fluid recovery (maintain blood volume)
Site of immune cells (disease fighting cells)
- these roles overlap!
120
_______ ________ help recover the remaining fluid (~4 L) lost to tissue at the capillary beds
Lymphatic vessels
121
What is a lymph
When an interstitial fluid moves into the lymphatic system
122
What is the function of the lymphatic vessels
Help recover the remaining fluid lost to tissue at the capillary beds
Transport lymph through nodes and back to blood vessels
This helps retain fluid AND filter lymph for pathogens
123
Lymph nodes house _____ ______ _____ that help with immunity
White blood cells
124
How do lymph nodes help with immunity
They house the white blood cells
Lymph enters the node and travels through spaces called sinuses
- locations of the white blood cells
Capillaries provide oxygen and nutrients for the cells
125
Lymph flow overview
Interstitial fluid at the capillaries enters lymphatic capillaries, is filtered by white blood cells in lymph nodes and transported back into the bloodstream and the left and right subclavian veins
126
What are the different types of fluid deficiencies
Volume Depletion (Hypovolemia)
- blood loss, normal osmolarity
Dehydration (negative water balance)
- water loss, hypertonic osmolarity
*all result in drop in blood pressure
127
What are different types of fluid excess
Volume excess (hypervolemia)
- blood gain, normal osmolarity
Hypotonic hydration (positive water balance)
- water gain, hypotonic osmolarity
* increased blood pressure
128
What is the major goal in fetal circulation
To get oxygen/nutrients to the brain and rest of the body
129
Where does the fetus receive oxygen/nutrients from
The mothers placenta via diffusion
130
What parts of the body are not fully developed/functional in fetuses
Pulmonary and digestive systems are not yet functional - lungs are still collapsed and fluid-filled
131
What are fetal structures that make circulation possible
Ductus venosus
Portal sinus
Foramen Ovale
Ductus arteriosus
132
Fetal circulation: starting point
Placenta: diffusion of wastes, oxygen and nutrients
Oxygenated blood blood returns to fetus via the umbilical vein
Deoxygenated blood leaves fetus via the umbilical arteries
133
Fetal circulation: getting to the heart (2 pathways)
Path 1 (most blood): umbilical vein to ductus venosus and then directly to IVC to heart (skips liver)
OR
Path 2: umbilical vein to portal sinus to liver then to portal vein to heart (provides O2 to liver)
134
Fetal circulation: through the heart
After entering the right atrium:
30% is shunted to left atrium via the foramen ovale
Other 70% blood is pumped into right ventricle, then to pulmonary artery
- at pulmonary artery 90% of the blood enters the ductus arteriosus and is shunted to the aorta
135
What happens after birth
With first breath the lungs EXPAND
Resistance to blood flow to lung decreases
Blood now flows to lungs via pulmonary arteries
136
What is the ductus venosus
A shunt that allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation
137
What is the foramen ovale
An aperture in the muscular tissue between the left and right atrium that allows blood to cross the atria and bypass pulmonary circulation
138
Blood essentials
About 5 liters in the body
- 5-6 L for males, 4-5 L in females
Temp is roughly 38 degrees Celsius (100.4 Fahrenheit)
5x viscosity of water (due to solid components and plasma proteins)
Slightly alkaline (average pH of 7.4)
139
Blood consists of formed elements that are suspended in a liquid matrix called
Plasma
140
What is blood made up of
Plasma
- 55%
-least dense component
Buffy coat
-leukocytes and platelets
-<1%
Erythrocytes
-45%
-most dense component
141
What are formed elements
Also known as erythrocytes
45% of whole blood
RBCs, WBCs, and platelets
142
What is plasma made up of
Water, proteins, nutrients, electrolytes (sodium) and wastes
143
What are the primary similarities between plasma and interstitial fluid
Composition: H2O (92%), nutrients, electrolytes and proteins
144
What are the primary differences between plasma and interstitial fluid
Levels of respiratory gases
- oxygen concentration higher in plasma than interstitial fluid
- carbon dioxide concentration higher in interstitial fluid than plasma
Protein concentrations
- each 100 mL of plasma has ~7.6 g of protein = ~5x that of interstitial fluid
- large size and globular shapes prevent proteins from leaving bloodstream
145
What are two important proteins in plasma
Albumin - 60% of proteins; water balance (helps maintain blood osmotic pressure
Fibrinogen - clotting
146
What are the three types of cells that formed elements consist of
Red blood cells, white blood cells and platelets
147
What are red blood cells
Also known as erythrocytes
Essential for oxygen transport in blood
148
What are white blood cells
Also known as leukocytes
Participate in body’s defense mechanisms
Five classes, each with different functions
149
What are platelets
Small membrane-bound cell fragments involved in blood clotting
150
What is hematopoiesis
The production of formed elements in red bone marrow
- red bone marrow is primarily found in the spongy bone
151
Where does hematopoiesis start from
It starts from pluripotent stem cells
152
What is hemostasis
It prevents blood loss by setting a cascade of events into motion that involve clotting
153
What are the steps of hemostasis
A cut through the wall of a vessel damages endothelial cells, which release inflammatory chemicals
1st step: smooth muscle responds by vasoconstricting
Vasoconstriction reduces blood loss and aids in repair
Platelets bind to the exposed collagen from the damaged vessel wall = platelet plug
Binding to collagen also causes platelets to secrete chemicals that attract more platelets
Chemicals from platelets also result in coagulation = formation of a clot
Secretions from platelets convert fibrinogen in plasma to fibrin. Requires many proteins called clotting factors.
Fibrin forms long insoluble strands, creating a network of proteins that traps more platelets and red blood cells = clot.
The clot is eventually dissolved as endothelial cells regrow.
154
What is the general anatomy of the urinary system
Kidneys connected to ureters (muscular tubes)
Ureters connect to bladder (muscular sac that holds urine)
Bladder connects to urethra (tube to external environment)
Notice renal artery carrying blood to kidney
155
What are the three layers of connective tissue that hold kidneys in place
Fibrous capsule, perinephric fat capsule, renal fascia
156
What is the fibrous capsule
The innermost layer of the kidney tissue
Dense irregular tissue
157
What is perinephric fat capsule
The middle layer of the kidney tissue
Loose connective (adipose) tissue
158
What is the renal fascia
The outer layer of the kidney tissue
Dense irregular connective tissue anchors kidney to surrounding structures
159
What is the function of the renal artery
Delivers blood to the kidney
- to segmental arteries to smaller branches
- to afferent arterioles (deliver blood to capillaries where filtration will occur)
(This is oxygenated blood)
160
What is the function of the renal vein
Collects blood from the kidneys
(This is deoxygenated blood)
161
What is the nephron
The functional unit of the kidney
A tube like structure made of ephithelial cells
Intimately associated with capillary beds
162
What is the renal cortex
Superficial kidney tissue
Contains nephrons, blood vessels, nervous and connective tissue
Start of urine production
163
What is the renal medulla
Deep kidney tissue
Contains nephron loops, blood vessels, nervous and connective tissue
164
What is the renal pelvis
The funnel that urine production leaves through
165
All structures associated with the urinary system are…
Continuous with the outside world and have a lumen (inside opening)
166
What is the major function of the kidneys
Regulate the total amount of water in the body and the concentration of solutes in that water (osmolarity)
- Alter blood volume by absorbing or secreting water this plays a role in regulation of blood pressure
Alter blood pH by absorbing or secreting protons
•Coordinated with respiratory system
167
What do kidneys remove?
•Metabolic waste
–By-products from normal metabolism
•Some of the most toxic are nitrogenous wastes
–Urea protein metabolism, produced in liver
–Uric acid DNA metabolism, produced in liver
–Creatinine protein metabolism, produced in muscles
•All are removed by filtration and secretion and found in urine
168
What are the two types of nephrons
•Based on location in kidney
–Cortical (mainly in cortex) –
•85% of nephrons
–Juxtamedullary
•Nephron loops extend deep into medulla
•Modified capillaries = vasa recta
•Produce more concentrated urine
169
Structure of the nephron
•Five regions:
Renal Corpuscle:
1. Glomerulus in glomerular (Bowman’s) capsule
•Filtration
Renal Tubule:
2. Proximal convoluted tubule (PCT)
•Reabsorption and Secretion
3. Nephron Loop (Loop of Henle)
•Reabsorption and Secretion
4. Distal convoluted tubule (DCT)
•Reabsorption and Secretion
5. Collecting duct
•Final urine concentration
170
What are the steps of urine formation
•Filtration INITIAL movement of molecules from capillary into nephron
•Reabsorption Movement of molecules in nephron back into the capillary
•Secretion Movement of a molecule from the capillary into the nephron AFTER filtration
