Mcat Biology Lecture 7

Front 1

cardiovascular system

Back 1

1. heart
2. blood
3. blood vessels

Front 2

Blood Path

1st half: Systemic circulation (must be able to trace blood path)

Back 2

1. left ventricle
2. aorta
3. arteries then to arterioles
4. capillaries
5. venules
6. veins
7. superior & inferior vena cava
8. right atrium

Front 3

2nd half: Pulmonary circulation

Back 3

1. right ventricle
2. pulmonary arteries
3. pulmonary veins
4. left atrium

Front 4

closed circulatory system

Back 4

since there are no openings for blood to leave vessels

Front 5

left ventricle

Back 5

contacts with most force to propel blood through systemic circulation

Front 6

heart

Back 6

large muscle

unlike skeletal muscle it is not connected to bone

fibers form a net which contracts upon itself, squeezing blood into arteries

systole: ventricles contract
diastole: relaxation of entire heart and contraction of atria

contraction of heart propels blood via hydrostatic pressure

Front 7

Sinoatrial node (SA node)

Back 7

group of specialized cardiac muscle cells that automatically contracts heart

rate of contractions is controlled by autonomic nervous system, however the ANS does not initiate the contracts

located in right atrium, contracts by itself in regular intervals

pace of SA node is faster than normal heartbeats

Front 8

electrical synapses

Back 8

made from gap junctions

spread contractions to surrounding cardiac muscles

Front 9

vagus nerve

Back 9

parasympathetic nervous system

innervates SA node to slow contractions

Front 10

Atrioventricular node (AV node)

Back 10

located in wall of cardiac muscle between atria

action potential of SA node spreads to AV node

slower to contract, which creates a delay and allows atria to finish contracting before ventricles begin contraction

Front 11

bundle of His

Back 11

action potential travels from AV node to bundle of His

conductive fibers

located in wall separating ventricles

Front 12

purkinje fibers

Back 12

action potential travels from bundle of his and branches out through ventricular (location) fibers via purkinje fibers

conductive fibers

allow for more unified, stronger contraction

Front 13

arteries

Back 13

elastic and stretchable

wrapped in smooth muscles, innervated by SNS

epinephrine is vasoconstrictor causing arteries to narrow

larger arteries have less smooth muscle per volume than medium sized arteries and are less affected by SNS innervation

medium sized arteries constrict enough to SNS stimulation to reroute blood

Front 14

arterioles

Back 14

very small

wrapped by smooth muscle

constriction of arterioles can be used to regulate blood pressure and rerouting blood

Front 15

capillaries

Back 15

microscopic blood vessels

walls are only 1 cell thick and diameter is equal to single red blood cell

nutrient and gas exchange with any tissue other than vascular tissue takes place only across capillary walls (not across arterioles or venules)

Front 16

4 methods of material to cross capillary walls

Back 16

1. pinocytosis
2. diffusion or transport through capillary cell membranes
3. movement through pores in cells called fenestrations
4. movement through space between cells

Front 17

Capillary net fluid flow

Back 17

found close to all cells of body

as blood flows into capillary, hydrostatic pressure is greater than osmotic pressure, thus net fluid flow is out of capillary into interstitium

osmotic pressure remains constant throughout capillary

hydrostatic pressure drops from arteriole end to venule end

osmotic pressure overcomes hydrostatic pressure at venule end of capillary and net fluid flow is into capillary and out of interstitium

net result of fluid exchange by capillaries is 10% loss of fluid to interstitium

Front 18

venules and veins

Back 18

similar in structure to arterioles and arteries

lumen is larger than comparable arteries

contain greater volume of blood than arteries and arterioles

veins/venules/venus sinuses hold about 64% blood of body at rest, act as reservoir for flood, compared to arteries/arterioles/capillaries which hold 20% of blood

Front 19

Cross-sectional area

Back 19

veins is 4X that of arteries

capillaries >>> arteries or veins

since blood volume flow rate is constant, blood velocity is inversely proportional to cross-sectional area

blood moves slowest through capillaries

Front 20

blood pressure

Back 20

increases near the heart

decreases to its lowest in capillaries

Front 21

blood velocities

Back 21

blood flow:
Q = Av

velocity is greatest in arteries where cross-sectional area is smallest

velocity is lowest in capillaries where cross-sectional area is largest

Front 22

blood flow

Back 22

arteries carry blood away from heart

veins carry blood toward heart

Front 23

Respiratory system / tract

Back 23

provides path for gas exchange between external environment and blood

1. nose
2. pharynx
3. larynx
4. trachea
5. bronchi
6. bronchioles
7. alveoli
8. blood

Delivers O2 to blood and expels CO2

Prepares are by warming, moistening and cleaning.

Front 24

diaphragm

Back 24

contraction signaled by medulla oblongata of midbrain

skeletal muscle, innervated by phrenic nerve

relaxed: dome-shaped, chest cavity shrinks, elasticity of lungs and increased pressure in chest cavity forces air out

contracted: flattened, expanding chest cavity, creating negative gauge pressure pushing air into lungs (gauge pressure is measured relative to local atmospheric conditions.

Patm forces air into lungs

Front 25

nasal cavity

Back 25

space inside nose

air:
1. filters
2. moistens
3. warms

Front 26

coarse hair

Back 26

from of nasal cavity

traps large dust particles

Front 27

mucus

Back 27

secreted by goblet cells

traps smaller dust particles

moistens air

Front 28

capillaries

Back 28

within nasal cavity

warm air

Front 29

cilia

Back 29

moves mucus and dust back toward pharynx

removed by spitting or swallowing

Made of microtubles: so any problem in the production of microtubles would result in a problem with breathing.

Front 30

pharynx

Back 30

throat

functions as passageway for food and air

Front 31

larynx

Back 31

voice box

sits behind epiglottis

if nongaseous food enters larynx, coughing reflex is triggered forcing material back out

contains vocal cords

Front 32

epiglottis

Back 32

near larynx

cartilaginous member that prevents food from entering trachea during swallowing

Front 33

trachea

Back 33

windpipe

lies in front of esophagus

composed of ringed cartilage covered by ciliated mucous cells, which collect dust and usher it toward pharynx

splits into 2, left and right bronchi, before entering lungs

Front 34

bronchi

Back 34

2, left and right bronchi

each branches many times to become bronchioles

Front 35

bronchioles

Back 35

terminate in grape-like clusters called alveolar sacs composed of tiny alveoli

Front 36

alveoli

Back 36

oxygen diffuses into capillary where it's picked up by red blood cells

RBC release CO2, which diffuses into alveolus and is expelled upon exhalation

Front 37

cilia location

Back 37

1. respiratory tract
2. fallopian tubes
3. ependymal cells of spinal cord

made up of microtubules

problem with microtubule production might result in problems:
1. breathing
2. fertility
3. circulation of cerebrospinal fluid

Front 38

Air: Gas Exchange

Back 38

inhaled air: 79% N and 21% O
exhaled air: 79% N, 16% O and 5% CO2

partial pressure O inside lungs: 110 mm Hg
partial pressure CO2 inside lungs: 40 mm Hg

thus, O diffuses into capillaries and CO2 diffuses into alveoli

Front 39

hemoglobin

Back 39

protein that rapidly and reversibly binds 98% O in blood inside erythrocytes forming oxyhemoglobin

composed of 4 polypeptide subunits, each with 1 heme cofactor (organic molecule with 1 atom of Fe at its center)

each Fe atom can bind 1 O2 molecule
cooperativity:
as 1 O2 binds 1 Fe, it accelerates O2 binding of other Fe
as 1 O2 release 1 Fe, it accelerates O2 release of other Fe

Front 40

oxyhemoglobin

Back 40

O bound hemoglobin

Front 41

oxygen dissociation curve

Back 41

in arteries, room air, O saturation is 97%

as O2 pressure increases, O2 saturation of hemoglobin increases sigmoidally

small fluctuations in O pressure have little effect on O saturation of hemoglobin

O saturation of Hb depends:
1. CO2 pressure
2. pH
3. temperature of blood

shifted to right (lowering Hb affinity for O): increase in CO2 pressure, H+ concentration or temperature

CO has greater affinity for Hb than O, however shifts curve to left

Front 42

CO2 carried by blood in 3 forms

Back 42

1. physical solution
2. bicarbonate ion (10X more CO2)
3. carbamino compounds (combined with Hb and other proteins)

O pressure in tissues is 40 mm Hg

As blood moves through systemic capillaries, O diffuses to tissues and CO2 diffuses to blood

Front 43

carbonic anhydrase

Back 43

enzyme that governs bicarbonate ion formation (reversible reaction)

CO2 + H2O --> HCO3- + H+

inside RBC (not in plasma)

Front 44

Chloride Shift

Back 44

carbonic anhydrase is inside RBC (not plasma)

when CO2 absorbed in lung, bicarbonate ion diffuses into cell

to balance electrostatic forces, chlorine moves out of cell

Front 45

CO2 & breathing rate

Back 45

acidosis (too much acid in blood): body compensates increasing breathing rate, expelling CO2, raising pH of blood

exercise, leads to increase CO2 and decrease pH

Haldane Effect: as hemo becomes saturated with O2 its capacity to hold carbon dioxide is reduced.

Front 46

Note

Back 46

Nitrogen is stabke b/c of 3-bonds and doesn't react with chemicals in the blood. However, scuba divers need to be careful of the bends b/c as they dive pressure increases and N enters the blood they need to allow time for N to diffuse back out of blood and lungs, or it will form bubbles and block vessels.

Front 47

lymphatic system

Back 47

collects excess interstitial fluid and returns it to blood

removed proteins and large particles that cannot be taken up by capillaries

recycles interstitial fluid and monitors blood for infection

tissues are drained by lymphatic vessels, except CNS

Front 48

open system

Back 48

lymph system

fluid enters at one end and leaves at another

once inside, particles cannot push their way out

Front 49

interstitial fluid pressure

Back 49

slightly negative gauge pressure

as it rises towards zero, lymph flow increases

factors:
1. blood pressure
2. plasma osmotic pressure
3. interstitial osmotic pressure
4. capillary permeability

Front 50

lymph fluid flow

Back 50

intermittent valves allow for fluid flow in only 1 direction

propelled through valves:
1. smooth muscles contraction when stretched
2. squeezed by adjacent skeletal muscles, body movements, arterial pulsations and compression from object outside body

greater in active individual than individual at rest

Front 51

thoracic duct & right lymphatic duct

Back 51

large veins in which lymph system empties

Front 52

lymph nodes

Back 52

secondary lymph tissue

contain large quantities of lymphocytes

throughout lymphatic system

Front 53

Blood

Back 53

connective tissue, contains cells and matrix

regulates extracellular environment of body by transporting nutrients, waster products, hormones and heat

protects body from injury and foreign invaders

separates into 3 parts:
1. plasma
2. buffy coat (WBC)
3. RBC

Front 54

hematocrit

Back 54

% by volume of RBC

normally 30-50%

greater in men than women

Front 55

plasma

Back 55

contains matrix of blood

includes: water, ions, urea, ammonia, proteins and organic/inorganic compounds

proteins: albumin, immunoglobulins and clotting factors

Front 56

albumins

Back 56

transport fatty acids and steroids

regulate osmotic pressure of blood

Front 57

immunoglobulins

Back 57

antibodies

Front 58

serum

Back 58

plasma in which clotting protein fibrinogen is removed

Front 59

erythrocytes

Back 59

RBC

like bags of Hg

no organelles, no nucleus, do not reproduce, do not undergo mitosis

disk-shaped vesicles

main function is transport O and CO2

squeezing through capillaries wears out plasma membranes every 120 days, causing them to burst in liver or spleen

Front 60

leukocytes

Back 60

WBC

contain organelles, but do not contain Hg

function to protect body from foreign invaders

Front 61

Stem cell

Back 61

blood cell precursor residing in bone marrow

blood cells differentiate from this precursor

Front 62

platelets

Back 62

small portions of membrane-bound cytoplasm torn from megakaryocytes

tiny cells without nucleus, contain actin and myosin

membrane is designed to adhere to injured endothelium and to each other, forming loose platelet plug

half-life of 8-12 days in blood

Front 63

coagulation

Back 63

involves many factors starting with platelets and including plasma proteins prothrombin and fibrin

1. dozen or so coagulation factors form complex called protrombin activator
2. protrombin activator catalyzes converstion of prothrombin (plasma protein) into thrombin
3. thrombin is enzyme that governs polymerization of plasma protein fibrinogen to fibrin threats that attach to platelets and form tight plug

appears in seconds after small injuries and 1-2 minutes after large injuries

Front 64

immune system

Back 64

protects from infectious microbes and toxins in 2 ways:
1. innate immune system
2. acquired immunity

Front 65

innate immune system

Back 65

1. skin act as barrier to organisms and toxins
2. stomach acid and digestive enzymes destroy ingested organisms and toxins
3. phagocytotic cells
4. chemicals in blood

Front 66

inflammation

Back 66

results with injury to tissue

includes:
1. dilation of blood vessels
2. increased premeability of capillaries
3. swelling of tissue cells
4. migration of granulocytes and macrophages to inflamed area

causative agents:
1. injury
2. histamine
3. prostaglandins
4. lymphokines

wall-off effected tissue and local lymph vessels from rest of body, impeding spread of infection

Front 67

acquired immunity

Back 67

1. humoral (B-cell) immunity
2. cell-mediated (T-cell) immunity

Front 68

humoral immunity

Back 68

promoted by B lymphocytes, which differentiate and mature in bone marrow and liver

B cell capable of making single type of antibody (immunoglobulin) which displays on membrane

Front 69

antibody

Back 69

immunoglobulin

made by B cell

1. recognized foreign particles
2. cause B cell differentiation to plasma cells and memory cells
3. cause mast cells to release histamine
4. activate complement
5. mark for phagocytosis
6. optimize
7. cause agglutination (accumulate, precipitate)
9. neutralization of toxins

Front 70

antigens

Back 70

foreign particles recognized by antibodies of B cells

Front 71

helper T cell

Back 71

CD4+ T cell


assist B cell to differentiate into plasma cells and memory cells

Front 72

plasma cells

Back 72

synthesize free antibodies

release free antibodies into blood

Front 73

primary response

Back 73

1st time immune system is exposed to antigen

requires 20 days to reach full potential

Front 74

secondary immune response

Back 74

faster more potent response because of memory B cells during reinfection

requires 5 days to reach full potential

Front 75

Cell-mediate immunity

Back 75

involves T lymphocytes which mature in thymus

T cells have T cell receptor, similar to antibody on B cells

Front 76

helper T cells

Back 76

assist in activating B cells as well as killer and suppressor T cells

cells attacked by HIV

Front 77

memory T cells

Back 77

similar function to memory B cells

prime immune system for secondary immune response

Front 78

suppressor T cells

Back 78

play negative feedback role in immune system

keep immune system from over reacting

Front 79

killer T cells (cytotoxic t-cells)

Back 79

bind to Ag-carrying cell and kill them

do not phagocytize cells

responsible for fighting cancers and attacking transplanted tissue

Front 80

NOTE

Back 80

Single antibody is specfic for a single antigen and that a single B lymphocyte produces only ONE antibody type.

Front 81

blood types

Back 81

identified by A and B surface antigens

if RBC has A antigen, body does not make A antibodies

type O: neither A nor B surface antigens, makes both A and B antibodies (universal donor)

type AB: both A and B surface antigens, makes neither A nor B antibodies (universal recipient)

genes that produce A and B antigen are co-dominant, therefore individual may be heterozygous or homozygous

type O blood: 2 recessive alleles

Front 82

Rh factors

Back 82

surface proteins on RBC first identified in Rhesus monkeys

Rh-negative: nonfunctional Rh products
Rh-positive: functional Rh products

problems for mother and fetus, mother after previous pregnancy might reject fetus because of antibodies again Rh factors (requires blood replacement of fetus)