Exam 3 Flashcards
a single action potential will produce a _____, multiple successive action potentials will produce a _______, too many action potentials will produce ________
twitch
twitch summation
tetanus
Do twitches normally voluntarily take place in the body?
no
2 primary factors which can be adjusted to accomplish gradation of whole-muscle tension-
- Number of muscle fibers contracting within a muscle
* Tension developed by each contracting fiber
Motor Unit-
One motor neuron and the muscle fibers it innervates
Number of ________ per motor unit and number of motor units per ______ vary widely
- muscle fibers
- muscle
______ results from sustained elevation of cytosolic calcium
o Twitch summation
In tetanus, contraction is usually ____ times stronger than a single twitch
3 to 4
Muscle contraction is faster/slower than an action potential?
slower
First energy storehouse tapped at onset of contractile activity is ______
creatine phosphate
how does creatine phosphate provide quick energy?
it transfers its phosphate to ADP
3 energy sources for contraction are:
- creatine phosphate
- oxidative phosphorylation
- fermentation
Where does oxidative phosphorylation take place to make muscle energy?
Takes place within muscle mitochondria if sufficient O2 is present
Fermentation provides muscles energy under what conditions?
anaerobic and high intensity exercise
muscle fatigue is a defense mechanism to protect muscle from what?
from reaching point at which it can no longer produce ATP
muscle fatigue occurs when:
exercising muscle can no longer respond to stimulation with same degree of contractile activity
smooth muscle is not striated, implying that its filaments _______
do not form myofibrils
smooth muscle is not arranged in ______ pattern like skeletal muscle
sarcomere
smooth muscle cells are ______ shaped
spindle
smooth muscle cells are usually arranged in _______ within muscle
sheets
smooth muscle cells have dense bodies containing same protein found in _____
Z lines
Smooth muscle cell has 3 types of filaments:
thick myosin filaments, thin actin filaments, intermediate filaments
Smooth muscle
- Thick myosin filaments are longer than _____
- Thin actin filaments lack _____
- intermediate filaments do not ______. They actually _________
- those in skeletal muscle
- troponin
- directly participate in contraction; form part of cytoskeletal framework that supports cell shape
Right AV valve is aka:
tricuspid valve
Left AV valve also called:
bicuspid or mitral valve
Fibrous cords which prevent valves from being everted
Chordae tendinae
Chordae tendinae are controlled by ______
Papillary muscles
Heart wall consists of what 3 distinct layers?
Endothelium, Myocardium, and Epicardium
Epithelial tissue which lines entire circulatory system
endothelium
Constitutes bulk of heart wall
Myocardium
heart layer composed of cardiac muscle
myocardium
Thin external layer which covers the heart
epicardium
cardiac muscle fibers are interconnected by ________ and form _______
- intercalated discs
- functional syncytia
Within intercalated discs- two kinds of membrane junctions:
- Desmosomes
* Gap junctions
Heart is enclosed by ________, which has two layers:
- pericardial sac
- Tough, fibrous covering and Secretory lining
pericardial sac secretes:
pericardial fluid
pericardial fluid does what?
Provides lubrication to prevent friction between pericardial layers
autorhythmicity
Heart beats rhythmically as result of action potentials it generates by itself
cells specialized for initiating and conducting action potentials responsible for contraction of working cells
Autorhythmic cells
Do autorhythmic cells contract?
not
specialized region in right atrial wall near opening of superior vena cava
Sinoatrial node SA
Pacemaker of the heart
sinoatrial node
• Small bundle of specialized cardiac cells located at base of right atrium near septum
AV node (atrioventricular)
Cells originate at AV node and enters interventricular septum
Bundle of His (atrioventricular bundle)
Bundle of His divides to form _________ which travel __________
- right and left bundle branches
- down septum, curve around tip of ventricular chambers, travel back toward atria along outer walls
• Small, terminal fibers that extend from bundle of His and spread throughout ventricular myocardium
Purkinje fibers
only point of electrical contact between atrium and ventricle
AV node
Action potential briefly delayed at _______ to ensure _____________
- AV node
- atrial contraction precedes ventricular contraction to allow complete ventricular filling)
From the AV node, impulse travels rapidly down __________ by means of ___________
- interventricular septum
- bundle of His
following the bundle of his, impulse rapidly disperses throughout myocardium by means of __________
-Purkinje fibers
rest of ventricular cells not activated directly by autorhythmic cells activated by _____________
-cell-to-cell spread of impulse through gap junctions
Action potentials of cardiac contractile cells exhibit prolonged________ accompanied by prolonged ___________. This ensures adequate ___________
- positive phase (plateau)
- period of contraction
- ejection time
The prolonged plateau of cardiac action potentials is primarily due to ____________
activation of slow L-type Ca2+ channels
Ca2+ entry through L-type channels in T tubules triggers:
larger release of Ca2+ from sarcoplasmic reticulum
Ca2+ induced Ca2+ release leads to :
cross-bridge cycling and contraction
Because long refractory period occurs in conjunction with prolonged plateau phase, _____________ of cardiac muscle is impossible
summation and tetanus
Long refractory period occurs in conjunction with prolonged plateau phase, which ensures ______________ which are essential for pumping blood
alternate periods of contraction and relaxation
ECG is not a direct recording of _____________, it is a recording of ________________
- actual electrical activity of heart
- part of electrical activity induced in body fluids by cardiac impulse that reaches body surface
ECG is not a recording of a single action potential in a single cell, it is a recording of ________________
overall spread of activity throughout heart during depolarization and repolarization
ECG does not record the actual potential in heart, it records the comparison of:
voltage detected by electrodes at two different points on body surface
ECG does not record potential at all when ventricular muscle is:
either completely depolarized or completely repolarized
• Inadequate delivery of oxygenated blood to heart tissue
Myocardial ischemia
Occurs when blood vessel supplying area of heart becomes blocked or ruptured
Acute myocardial infarction (heart attack)
Volume of blood ejected by each ventricle each minute
cardiac output
cardiac output is determined by:
heart rate times stroke volume
Heart rate is varied by altering:
balance of parasympathetic and sympathetic influence on SA node
• Determined by extent of venous return and by sympathetic activity
stroke volume
o States that heart normally pumps out during systole the volume of blood returned to it during diastole
• Frank-Starling Law of the Heart
Frank-Starling Law of the Heart describes the relationship between:
the EDV (end diastolic volume) and stroke volume
heart muscle is nourished and oxygenated by blood from the:
coronary circulation, not the chambers of the heart
during systole, _________ are compressed by contracting heart muscle, so the heart receives most of its own blood supply during:
- coronary vessels
- diastole
Coronary artery disease (CAD) can cause __________ and possibly lead to:
- myocardial ischemia
- acute myocardial infarction
The reason permeability to potassium drops when funny channels open is because:
the voltage gated potassium channels are also closing and there are more voltage gated channels than funny channels
_____ can least tolerate disrupted supply.
Brain
Flow rate through a vessel=
volume of blood passing through per unit of time
flow rate is directly proportional to:
and inversely proportional to:
pressure gradient
vascular resistance
F=
delta P / R
pressure difference between beginning and end of a vessel
pressure gradient
resistance is proportional to:
1/radius^4
Arteries act as__________ to provide driving force for blood when heart is relaxing
pressure reservoir
what provides tensile strength to arteries?
what provides elasticity to arteries?
collagen fibers
elastin fibers
blood pressure can be measured indirectly using a
sphygmomanometer
Sounds heard when determining blood pressure
Korotkoff sounds
o Pressure difference between systolic and diastolic pressure
pulse pressure
Average pressure driving blood forward into tissues throughout cardiac cycle.
mean arterial pressure
Mean arterial pressure =
diastolic pressure + 1/3 pulse pressure
major resistance vessels
arterioles
Arteriole radii can be adjusted independently to:
• Distribute cardiac output among systemic organs, depending on body’s momentary needs
arterioles help regulate:
arterial blood pressure
vasodilation results from:
relaxation of smooth muscle layer
Specific local chemical factors that produce relaxation of arteriolar smooth muscle:
- Decreased O2
- Increased CO2
- Increased acid
- Increased K+
- Increased osmolarity
- Adenosine release
- Prostaglandin release
________ lie at junctions between capillary cells
pores (narrow water filled gaps)
capillaries permit passage of:
water soluble substances
Lipid soluble substances readily pass from blood to tissues through:
endothelial cells by dissolving in lipid bilayer barrier
size of capillary pores vary from:
organ to organ
Factors which enhance venous return: (3)
- Driving pressure from cardiac contraction
- Skeletal muscle activity
- Respiratory activity
hypertension is blood pressure above:
140/90
hypotension is blood pressure below:
100/60
• Blood pressure elevated by variety of unknown causes rather than by a single disease entity
primary hypertension
Potential causes of hypertension being investigated:
- Defects in salt management by the kidneys
- Excessive salt intake
- Diets low in K+ and Ca2+
- Plasma membrane abnormalities such as defective Na+-K+ pumps
- Excess vasopressin
secondary hypertension occurs secondary to:
another known primary problem
secondary hypertension accounts for about ___% of hypertension cases
10%
Examples of secondary hypertension:
- Renal hypertension
- Endocrine hypertension
- Neurogenic hypertension
Hypotension occurs when: (2)
- There is too little blood to fill the vessels
* Heart is too weak to drive the blood
Orthostatic (postural) hypotension
Transient hypotensive condition resulting from insufficient compensatory responses to gravitational shifts in blood when person moves from horizontal to vertical position.
average blood volume in men/women?
5 liters in women
5.5 liters in men
Plasma proteins compose ___% of plasma’s total weight
6-8%
what are the 3 groups of plasma proteins?
albumins, globulins, fibrinogen
most abundant plasma protein
albumins
key factor in blood clotting
fibrinogen
RBC’s do not rupture when migrating narrow capillaries because:
they have a flexible membrane
each subunit of hemoglobin contains a:
heme group
a non protein, iron containing compound
heme group
what two enzymes do erythrocytes posses?
glycolytic enzymes and carbonic anhydrase
generates ATP needed to fuel active transport mechanisms involved in maintaining proper ionic concentrations within cell
glycolytic enzymes
Critical in CO2 transport
o Carbonic anhydrase
• Catalyzes reaction that leads to conversion of metabolically produced CO2 into bicarbonate ion (HCO3-)
o Carbonic anhydrase
what is primary form in which CO2 is transported in blood?
bicarbonate ion
o Erythrocytes must be replaced at rate of:
2 million to 3 million cells/ second
a condition of too many RBCs.
Polycythemia
immune system is made up of:
Made up of leukocytes, their derivatives, and variety of plasma proteins
immune system does 3 things:
- Defends against invading pathogens
- Identifies and destroys cancer cells that arise in body
- Functions as a “cleanup crew” that removes worn-out cells and tissue debris
o 5 different types of circulating leukocytes
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Lymphocytes
neutrophils are very important in:
inflammatory responses
what is the most abundant leukocyte?
neutrophil
eosinophils make up about ____% of leukocytes
1-4%
basophils make up about ____% of leukocytes
.25-.5%
basophils
Quite similar structurally and functionally to:
synthesize and store:
- mast cells
- histamine and heparin
Can prevent clotting of blood samples drawn for chemical analysis and is Used extensively as anticoagulant drug
heparin
o Emerge from bone marrow while still immature and circulate for day or two before settling down in various tissues in body
monocytes
monocyte life span can range from:
several months to years
lymphocytes live about _______ days
100 to 300
T lymphocytes directly destroy specific target cells by:
releasing chemicals that punch holes in the victim cell (cell-mediated immunity)
platelets lack _____, but have _______
nuclei; organelles and cytosolic enzymes for generating energy and synthesizing secretory products
platelets have high concentrations of:
actin and myosin
platelets remain functional for an average of ___ days
10
Hormone produced by liver increases number of platelets
Thrombopoietin
Prevents blood loss from a broken blood vessel
hemostasis
hemostasis involves what 3 major steps?
vascular spasm, formation of a platelet plug, blood coagulation
Reduces blood flow through a damaged vessel
vascular spasm
Platelets aggregate on contact with _________ in damaged wall of the vessel
exposed collagen
Transformation of blood from liquid into a solid gel
Blood coagulation (clotting)
