Unit 3 Flashcards
1
Q
Cardiac Cycle
A
all cardiac events that occur during one heartbeat
2
Q
Contraction of atria or ventricles
A
Systole
3
Q
Relaxation of atria or ventricles
A
Diastole
4
Q
Why can cardiac muscle initiate its own rhythmic contractions without nervous stimulation?
A
“Leaky” cell membranes allow influx of Na+ and Ca2+ ions which slowly depolarize the cells to threshold, firing an action potential.
“Pacemaker” cells in the sinoatrial node depolarize fastest and control the rate of contraction of all other cardiac cells
The action potential moves relatively slowly through the atrioventricular node to ensure that atria contract first, and ventricles fill with blood before they contract
5
Q
factors that affect cardiac contraction strength
A
inotropes
6
Q
factors that affect heart rate
A
chronotropes
7
Q
epinephrine (effect on heart)
A
increases heart rate
8
Q
acetylcholine (effect on heart)
A
decreases heartrate (muscarinic receptors)
9
Q
Atropine (effect on heart)
A
increases heartrate by cholinergic antagonistic action
10
Q
calcium (effect on heart)
A
increases force of contractions
11
Q
Potassium (effect on heart)
A
regulates heart rhythm
12
Q
digitalis (effect on heart)
A
positive inotrope (increases contraction strength)
13
Q
blood flow in the center of a vessel, not in contact with the endothelium
A
laminar flow
14
Q
What components in blood affect viscosity?
A
15
Q
How does blood vessel length affect blood flow?
A
longer vessels = slower flow rate because of drag on greater surface area of endothelium
16
Q
What is wave summation?
A
when muscle is stimulated frequently enough that twitches overlap
17
Q
What is the absolute refractory period?
A
the period during which APs can’t be generated no matter how strong the stimulus
18
Q
How long is the total refractory period of cardiac muscle?
A
200-250 ms
19
Q
What is an extrasystole?
A
an extra contraction
20
Q
When is it possible to stimulate an extrasystole?
A
21
Q
What is vagal escape?
A
sympathetic stimulation of the heart to increase rate and blood pressure in response to a muscarinic stimulation causing reduction of blood pressure
22
Q
What causes vagal escape?
A
sympathetic reflexes
23
Q
how many APs does the SA node generate per minute without external stimulation?
A
100
24
Q
Which organelle in a cardiac muscle cell stores calcium?
A
sarcoplasmic reticulum
25
What are the different layers of "bundling" within a skeletal muscle?
A **muscle** is covered by **epimysium** and is a bundle of...
**Fascicles** which are covered by **perimysium** and are bundles of...
**Muscle fibers (muscle cells) **which covered by **endomysium** and are bundles of...
**Myofibrils** which are bundles of...
**Actin** and **myosin** proteins
26
What is the cell membrane of a muscle cell?
sarcolemma
27
What are the 3 types of muscle and their general functions and structure?
**Skeletal** - position and move skeleton, large, multinucleate, striated cells
**Cardiac** - pump blood (heart), short, branched, striated uninucleate cells connected by intercalated disks
**Smooth** - movement of material into, out of and within body, small, uninucleate, unstriated cells
28
What is the cytoplasm of a muscle cell?
29
What is the name and function of the structure that wraps around each myofibril like a piece of lace?
And its parts?
Sarcoplasmic Reticulum
30
Describe the T-tubules. What are they, what do they do and what is the structure they make up with the terminal cisternae?
31
What neurotransmitter is used at neuromuscular junctions?
Acetylcholine
32
What are 4 characteristics/abilities of muscle tissue?
1. Can shorten (contraction)
2. Can stretch/lengthen (relaxation)
3. Elasticity (returns to normal)
4. Excitability (can create APs or be stimulated by nerve)
33
What is a **motor unit**?
A unit in the somatic NS and musculoskeletal system consisting of **a motor nerve and all the muscle cells it innervates**
34
How many motor units per muscle?
How does this ratio affect control?
- Varies greatly, but **most muscles have \> 1 motor unit**
- nerve to muscle cell ratios can be anything... 1:13, 1:137, 1:529, etc.
- the fewer muscle cells per nerve, the greater the degree of fine control over that muscle
35
Describe the transfer of a signal between motor neuron and muscle cell at the motor end plate.
1. AP travels to axon terminal of motor nerve
2. **Voltage-gated Ca channels open** at synaptic knob, **Ca diffuses in**, **attaches to synaptic vesicles**
3. Synaptic vesicles full of **acetylcholine** exocytosize to synaptic cleft and **attach to chemically-gated** Na channels
4. **Na diffuses in** to create AP on muscle cell which travels deep into cell
36
What are the bundles of proteins within a single muscle cell called?
What 2 major proteins make them up?
And what is a single functional unit within this bundle called?
**- Myofibrils**
**- Actin and Myosin**
**- Sarcomere**
37
How are myofilaments laid out within a relaxed myofibril?
Describe it and draw it.
- Alternating bands of thicker myosin and thinner actin myofilaments line the cell (w/ Z-discs intersecting actin and M lines intersecting myosin)
38
How is acetylcholine removed from the chemically-gated Na channels?
1) enzymatic breakdown via **acetylcholinesterase **into acetyl and choline
2) re-uptake into the pre-synaptic axon terminal
39
How does innervation of skeletal and cardiac muscle differ?
- Each skeletal muscle cell is innervated by communication with a synapse
- Many cardiac muscle cells are innervated by one synapse and communication via intercalated disks (gap junctions) between cells
40
How does an AP affect myofibrils of a muscle cell nearly simultaneously?
T-tubules extending deep into cell allow fast (extracellular, non-cytosolic) travel of ions to the deeper myofibrils
41
Describe the transmission of action potentials deep into muscle cells via T-tubules and the release of calcium from terminal cisternae of the sarcoplasmic reticulum.
Draw it.
1) APs begun by ACh at motor end plate travel along sarcolemma into T-tubules
2) APs cause voltage change at triad, opening Ca channels on terminal cisternae for diffusion of Ca into sarcoplasm
42
What are some functions of muscle?
1) produce movement
2) open and close passageways
3) maintain posture and stabilize joints
4) generate heat
43
What is the theory behind muscle contraction called?
Describe it.
**Sliding Filament Theory**
or **Contraction Coupling Process**
**- **Myosin pulls actin (z-lines) closer together
44
What is the functional unit of a muscle?
What is it made up of?
**Sarcomere**
- **Actin** and **myosin** filaments
- **Z-lines** bisect actin filaments
- **M-lines** bisect myosin filaments
- **A-bands** are areas where myosin is
- **I-bands** are where it is not
- **H-zone** is portion of A-band w/out actin
45
Describe the structure of actin and its accessory proteins.
Draw it.
**2 strands** of **globular actin**
**2 strands** of **tropomyosin**
**Troponin complexes**
46
How does myosin bind to actin? Describe the process.
Draw it.
1) **Ca ions** bind to **troponin complexes**
2) **Tropomyosin** then moves away from **myosin binding sites** on **actin**
3) **Myosin** heads w/ **actin binding sites** move in and bind
47
How is a myosin filament structured?
Describe and draw it.
Myosin filaments are made of many myosin molecules.
There is a "**tail**" of two strands twisted together and "**head**s" like two golf club heads at the end of the tail (AKA **cross-bridge heads**).
48
Describe the contraction cycle.
Draw it.
1) Myosin heads bent w/ ATP attached, unbound to actin
2) Myosin hydrolyzes ATP, energy "cocks" head, myosin binds weakly to actin
3) **"Power Stroke"** - Ca signal moves tropo/tropo complex, P leaves myosin, heads re-bend pulling actin toward M-line, ADP leaves myosin
4) Myosin is bound to actin, ATP re-binds myosin, cycle repeats.
49
What are some sources of ATP within the muscle?
1) **stored ATP** (lasts 6 seconds)
2) **creatine phosphate** (donates phosphate to ADP to make ATP, lasts 10 seconds)
3) **cellular respiration** ( 2 ATP glyc, 2 ATP krebs, 26 ATP ETC)
****
50
What is the force of contracting muscle and its opposing force called?
Contraction - **muscle tension**
Opposing force - **load**
51
What is a single contraction-relaxation cycle in skeletal muscle called?
What are its parts?
**Twitch**
**Latent Period** - between muscle AP production and tension development
**Contraction Phase**
**Relaxation Phase**
52
How can nervous signals cause contraction force increase?
- by increasing frequency of APs stimulating muscle fiber to cause **summation**
- increased AP frequency does not allow full relaxation between stimuli
53
What is the state of continuous maximal contraction called?
And its two kinds?
**Tetanus**
**incomplete** or **unfused tetanus** - slight relaxation between stimuli
**complete** or **fused tetanus** - no relaxation
54
How are **graded muscle contractions** of different strengths and durations created?
Recruitment of **different types and numbers of motor units**.
Low threshold neurons control fatigue-resistant slow-twitch minimal force fibers.
Medium threshold neurons stimulate fatigue-resistant fast-twitch oxidative-glycolytic fibers
High threshold neurons stimulate glycolytic fast-twitch fibers
55
What kind of contraction creates force and moves a load?
**Isotonic Contraction**
56
What kind of contraction creates force but does not move a load?
**isometric contractions**
57
Describe the flow of blood from its entrance into the heart to its exit from the heart.
1. Superior and Inferior Vena Cava
2. Right Atrium
3. Tricuspid Valve
4. Right Ventricle
5. Pulmonary Semilunar Valve
6. Pulmonary Trunk & Arteries
7. Lungs (pulmonary capillaries)
8. Pulmonary Veins
9. Left Atrium
10. Biscuspid (Mitral) Valve
11. Left Ventricle
12. Aortic Semilunar Valve
13. Aorta
58
What is the primary function of the cardiovascular system?
Transporting materials to and from all parts of the body.
1) Nutrients, water, gases from outside
2) materials between cells
3) wastes from cells
59
What are the 3 components of the cardiovascular system?
Heart
Blood Vessels
Blood
60
What are the two circuites of the cardiovascular system?
Systemic
Pulmonary
61
What are the serous membranes around the heart?
Visceral pericardium - directly on heart
Parietal pericardium - lines pericardial cavity
62
What does an electrocardiogram look like?
Draw it.
63
What does each part of the PQRST of an EKG represent?
**P Wave** - atrial depolarization (from SA node)
**QRS Wave** - ventricle depolarization (and atrial repolarization)
**T Wave** - ventricle repolarization
64
What are the structures of the conduction system of the heart?
Draw them.
**Sinoatrial (SA) Node** - pacemaker (right atrium)
**Atrioventricular (AV) Node** - delays signal to ventricles by 2 ms so they contract after atria
**Bundle of His** - send signals from AV node to bundle branches
**Left/Right Bundle Branches** - run down IV septum to Purkinje fibers
**Purkinje Fibers -** conduct signals along walls of ventricles
65
What is a miscommunication in the heart's electrical system known as?
Where does it usually occur and why?
**Fibrillation**
Usually in left atrium because of distance from SA node
66
How do the atrial and ventricular contractions move?
Atrial start superiorly and move inferiorly to move blood down into ventricles
Ventricular are opposite to move blood up and out semilunar valves
67
Describe an action potential in electrical conduction cells of the heart.
Draw its graph.
1. **Increased Na permeability** causes a constant drift from **-60 mv resting state** to threshold
2. **-40 mv threshold** is reached, **voltage-gated Ca channels open**
3. **+20-30 mv max voltage** is reached **via Ca influx**
4. **K efflux repolarizes** to resting, no hyperpolarization
68
Describe an action potential being created in a myocardial contractile cell.
Draw its graph.
1. **-90 mv resting state** rises to **-60 mv threshold** due to **Na influx**
2. voltage-gated **fast Na** **and slow Ca channels** open to **depolarize cell to +30 mv**
3. **fast Na channels close, slow Ca channels stay open, causing Ca plateau**, lengthens abs. refractory period and allows for simultaneous contraction of multiple cells
4. **K+ efflux repolarizes**
69
What part of the cardiovascular system's pressure is being measured when blood pressure is measured?
During what activity?
**arterial pressure during ventricular activity**
**systole** - contraction
**diastole** - relaxation
70
What is pulse pressure?
Its ideal value?
Systolic minus diastolic
30-40 mm Hg
71
What is cardiac output?
the amount of blood pumped out of the heart each minute
72
How is cardiac output calculated?
What is the usual cardiac out put in an adult?
Heart Rate x Stroke Volume
(75 bpm x 70 mL = 5,250 mL)
about 5.2 L/min
73
What happens to cardiac output if heart rate changes?
Cardiac output stays the same.
An increased HR means a decreased stroke volume, so CO stays same.
Decreased HR = increase SV.
74
What is the amount of blood pumped out of each ventricle each beat?
**Stroke Volume**
about 70 mL
75
What 3 factors affect stroke volume?
1. **Contractility** -
2. **Preload** - degree of stretch (Frank-Starling Law)
3. **Afterload** - diastolic value
76
What 3 factors affect **peripheral resistance**?
1. **diameter** - smaller diameter = less laminar flow
2. **length** - greater length = more drag against sides
3. **viscosity** - more viscous = slower flow
77
What are the 3 layers of a blood vessel?
1. **Tunica Interna** - endothelium
2. **Tunica Media** - smooth muscle
3. **Tunica Externa** - CT
78
What are the differences between arteries and veins?
**Arteries**
* away from heart
* small lumen
* higher pressure
* thicker tunica media
* maintain shape
**Veins**
* towards heart
* large lumen (contain 60% of blood)
* low pressure
* thin tunica media
* shaped by surrounding tissues
* have valves
79
What are the different types of arteries?
**Elastic** - aorta, pulmonary, their branches
**Muscular - **AKA medium or distributing, renal, brachial, femoral, etc.
**Arterioles - **just before capillary beds, control BP and capillary flow via vasoconstriction/dilation
80
What are the different types of veins?
**Large Veins** - sup. & inf. vena cava (0-5 mm Hg)
**Medium Veins** - brachial, femoral, renal, etc. (10 mm Hg)
**Venules** - drain capillary beds (20 mm Hg)
81
What are the three types of capillaries and where are they found?
1. **continuous - **solid endothelium (common)
2. **fenestrated** - holes in endothelium (kidneys)
3. **sinusoidal** - very porous endothelium (spleen, liver, red bone marrow)
82
What are the two forces that influence movement of substances between capillaries and tissues?
Which forces fluid out of capillaries and which draws fluids back in?
What is each based on and can each change?
**Blood Hydrostatic Pressure** - normal blood pressure based on pumping of heart, descreases as distance from heart increases, pushes fluids out of capillaries
**Blood Osmotic Pressure - **keeps fluids in, based on non-diffusable solutes, doesn't change
83
Draw the capillary with its differing pressures on each end, showing how they influence movement of substances into and out of tissues.
84
What is the composition of blood?
Components and percentages.
**Plasma (55%) **- water, ions, hormones, gases, wastes
**Formed Elements (45%)** - RBCs (**44%**), WBCs and platelets (**1%**)
85
What are the 5 functions of blood?
1. **Transport**
2. **Temperature Control**
3. **Immunity**
4. **pH Control**
5. **Blood Clotting**
86
Describe erythrocytes, their functions and characteristics.
- released mature from bone marrow **without nucleus or organelles**
**- binconcave **for flexibility and surface area
- **live 100-120 days** b/c of lack of organelles
- **contain hemoglobin** to **carry oxygen and carbon dioxide**
87
Describe hemoglobin, its structure and function.
- a **quaternary protein structure**
- consists of four **4 Heme groups** and **4 Globin proteins**
**- carries O2 and CO2 separately**
**- 200-250 million** per RBC, so on RBC can carry both gases
88
Which gas loads more easily onto hemoglobin?
Describe loading of gases.
CO2 loads more easily
first O2 loads easily, second requires pressure, 3rd/4th are easy
89
Describe RBC movement through capillaries and how it is advantageous to function.
Draw it.
Biconcave RBCs bend into kidney bean-like shape and move slowly through capillaries to allow for gas exchange.
90
How does the body compensate for elevational changes in oxygen pressure?
It increases erythropoiesis at higher elevations to increase its ability to transport oxygen.
91
How are erythrocytes broken down and removed from the body?
- **primarily in spleen**, also in **liver if necessary**
- **reticular fibers** of these organs create network **for flexible RBCs**
**- old, inflexible RBCs phagocytized by WBCs**
**- Hemoglobin is recycled**
92
Describe hemoglobin recycling.
- Broken into Heme and Globin
- **Heme is reused** or **turned into bilirubin** by spleen, **sent to liver** and **made into bile salts** (either stored in GB or straight to SI)
- **Globin** is **re-used or broken down into amino acids**
93
Name the two subcategories and 5 types of leukocytes.
What are the characteristics of the 2 subcategories?
**Granulocytes (granules, lobed nuclei)- **basophils, neutrophils, eosinophils
**Agranulocytes (no granules, large, unlobed nuclei) - **lymphocytes, monocytes
94
What is most common leukocyte?
Describe it.
**Neutrophil**
- lobed nuclei
- phagocytic
- pink granules
95
What is the 2nd most common granulocyte?
Describe it
**Eosinophil**
- phagocytic
- involved in parasitic infection and allergy
- red/orange granules
96
What is the least common leukocyte?
Describe it.
**Basophil**
**- **involved in allergy
- releases **histamine** in inflammation and **heparin** for anti-coagulation
- blue-purple granules
97
What is the 2nd most common WBC?
Describe it.
**Lymphocytes**
**-** large central nuclei almost to plasma membrane
- two kinds, B and T
- specific to certain pathogens, have 'memory' for antigens
**T Cells** (thymus)
**-** attacks and kills cells
- **helper T cells** help lymphocyte production
**B Cells** (bone)
- produce antibodies
- mark pathogens for removal
98
What is the largest WBC?
Describe it.
**Monocyte**
**-** phagocytic
- large, kidney-shaped nucleus
- migrates to tissues to become macrophage
99
What is hematocrit?
the volume percentage of RBCs in blood
about 45% for men
about 40% for women
100
How does blood typing work?
Draw out the chart.
A has A-antigen and B-antibody
B has B-antigen and A-antibody
AB has both antigens and neither antibody
O has neither antigen and both antibodies
101
Describe how Rh factor works.
Rh factor is a surface antigen on RBCs.
Rh+ people have it, Rh- people don't
Rh+ people can receive either blood type because they do not create antibodies to Rh factor.
Rh- people can only receive Rh- blood because they DO produce antibodies. (They can receive + blood once, but then are sensitized).
102
What are the names for the surface antigens and their antibodies in ABO typing?
**Agglutinogens** (antigens)
**Agglutinins **(antibodies)
103
What are platelets called and where do they come from?
**Thrombocytes**
**- **from megakaryocytes
104
What is blood clot formation called? Describe its 3 steps.
**Hemostasis**
**1. Vascular Spasm **- damaged endothelium releases vasoconstrictors
**2. Platelet Plug - **releases platelet-activating factor (PAF) which attracts platelets
**3. Coagulation** - **fibrin** net forms around platelet plug
105
What is a floating blood clot called?
**Thrombus**
106
What is the process of fibrin net breakdown and release of platelets?
**Fibrinolysis**
107
What are the two types of coagulation and their characteristics?
**Intrinsic**
- natural
- internal
- slow
**Extrinsic**
**- **fast
- usually due to trauma
108
What is the important protein in coagulation called?
Describe its creation.
**Thrombin**
1. **Ca++ **acts on **Factor X**
2. Factor X **becomes active**
3. **Ca++** acts on **Active Factor X**
4. Active factor X acts on **Prothrombin**
5. **Prothrombin** converts into **thrombin**
109
What molecules does thrombin act on to aid in clotting and clot breakdown?
_Clot Formation_
1. thrombin acts on **fibrinogen** to form **fibrin **and **Factor XIII** to form **Active Factor XIII**
2. Fibrin plus **Ca++** and active factor XIII forms **cross-linked fibrin net** around the platelet plug
_Clot Breakdown_
1. thrombin acts on **plasminogen** to form **plasmin**
2. plasmin performs fibrinolysis on cross-linked fibrin net, breaking it down to release platelets
110
what are the stem cells that blood cells come from?
**hemocytoblasts**
hematopoietic stem cells
111
what is the pH range of blood?
7.35-7.45
112
