BIO-202 Exam 2

SA Node

Initiates and sets HR

Generates action potential

AV Node

Conducts action potential to ventricles

Creates brief delay in action potential

AV Bundle

Delivers impulse to ventricles and bottom of the heart

Purkinje Fibers

Stimulate contractile cells of ventricles

Ventricles contract

Name 4 phases of the cardiac cycle

Atrial systole

Isovolumetric contraction

Ventricular ejection

Isovolumetric relaxation

Atrial Systole

Blood is in atria

SA node fires

Atria depolarize (contract)

Blood ends up in ventricles

P wave !!

Isovolumetric Contraction

Atria repolarize (relax)

Blood is in ventricles

Ventricles contract (depolarize)

Heart sound (S1) occurs (“lub”)

Volume of blood does not change (no blood leaves)

QRS complex !!

Ventricular Ejection

Pressure builds and blows open the semilunar valves

Rapid ejection of blood

Some blood is left in the ventricles (end systolic volume)

Isovolumetric Relaxation

Ventricles repolarize (relax)

Semilunar valves close (S2)

Heart sound (S2)

Ventricles expand but do not fill yet

T wave !!

Differences between Cardiac and Skeletal muscle

1. Some cardiac muscles depolarize spontaneously
2. Cardiac have long refractory periods, for a long and sustained contraction, to prevent fatigue
3. Gap junctions in cardiac muscle allow for synchronized contractions

P wave

SA node depolarizes and spreads AP

Atria contract (depolarize)

PR Interval

AP travels down interventricular septum

QRS complex

Action potential travels down interventricular septum

Atria repolarize (relax)

Ventricles depolarize (contract)

ST Interval

From ventricular depolarization to repolarization

T wave

Ventricules repolarize (relax)

Arrythmia

Irregular heartbeat

Ectopic Foci

Something other than SA node stimulates heart beat

Systole

Contraction

Diastole

Relaxation

Auscultation

Listening to heart (in any way)

Murmur

Extra heart sound out of the normal

Type of murmur depends on the valve involved

Stenosis

Heart valve is narrow

Regurgitating

Valve is loose when closes, blood leaks through

Cardiac Output (CO)

Amount of blood ejected by ventricles in 1 minute

Usually your entire blood volume

How do you figure out cardiac output(CO)?

Equation:

CO = BPM \* SV

*remember to move decimal 3 places to the left to convert it to liters!*

What levels do you want for HR and SV?

Want high SV and low HR

Pulse

Surge of pressure in artery

Measure of HR

Ventricle contract, blood bulges

Chronotropy

Increase or decrease in HR

Positive chronotropic agent

Increases HR

Negative chronotropic agent

Decreases HR

What is the regulator of HR

Medulla

Cardioaccelatory Center

Increases HR

Sympathetic

Nerves = Cardiac nerves

Neurotransmitter = Norepinephrine

Receptor = Beta 1 receptors

How does the cardioaccelatory center increase HR?

Norepinephrine closes Ca channels early

Beta receptors close K channels early

-Takes RMP to -50 instead of -60

-Less time to get to threshold (-40)

Cardioinhibitory Center

Decreases HR

Parasympathetic

Nerves = Vagus nerve

Neurotransmitter = Acetylcholine

Receptor = muscarinic receptors

How does the cardioinhibitory center decrease HR?

\-ACh and muscarinic receptors keep K open longer

\-(-80 RMP instead of -60)

\-More time to get to threshold

Chronotropic Chemicals

Neurotransmitters (Epinephrine and Norepinephrine):

\-Increase HR

Drugs:

\-Caffeine

\-Increases HR

\-Inhibits enzymes from breaking down cyclic-AMP

\-Keeps sympathetic stimulation longer

\-(If not in sympathetic it does nothing)

\-Nicotine

\-Increases HR

\-Stimulates epinephrine and norepinephrine release

Hormones:

\-Increases HR

\-Thyroid hormone has receptors and targets on heart

Electrolytes

\-Potassium (K)

\-Too much K decreases HR

\-Too little K increases HR

\-Calcium (Ca)

\-Too much Ca decreases HR

\-Too little Ca increases HR

Stroke Volume (SV)

How much blood is pushed out in 1 heartbeat

3 factors that affect SV

Preload

Contractility

Afterload

What factors increase and decrease SV?

Increase preload = increase SV

Increase contractility = increase SV

Increase afterload = decrease SV

Preload

Blood entering atria of heart

Increase preload = increase SV and force of contraction

Frank-Starling Law of Heart

\-The more you stretch ventricles, triggers the heart to contract harder

\-Ventricles eject as much blood as they receive

-more they are stretched (higher preload), contract harder

Contractility

\-Contraction force for a given period

\-Contraction phase

\-Increase contractility = increase SV

\-Factors that increase contractility

-hypercalcemia, NE and epi, glucagon, digitalis

\-Factors that decrease contractility

-hyperkalemia, hypocalcemia

Afterload

\-Pressure that opposes the opening of semilunar valves

\-High afterload = decrease SV

\-Continuous high afterload = heart failure

What happens if HR and SV increase?

Increase in CO

Where is blood at rest

\-Veins, digestive organs, kidneys

\-During exercise it goes to muscles

Artery

\-Carry blood away from heart

\-Get o2 to tissues

\-Elastic

\-High pressure and speed

\-Increase blood flow by vasodilation

\-Has tunica layers

\-Thicker tunica media

Vein

\-Carries blood to heart

\-Has valves

\-Low speed and pressure

\-Not elastic

\-Has tunica layers

Capillaries

\-Exchange of o2, co2, nutrients, and hormones

\-Where things exit bloodstream

-Have holes in them

\-Single layer of simple squamous epithelium

\-Inside tissues

\-No tunica layers

3 tunica layers

Tunica Externa

Tunica Media

Tunica Interna

3 types of capillaries

1. Continuous
2. Fenestrated
3. Sinusoid

Continuous Capillaries

\-No holes (virus and bacteria cannot get out)

\-Only diffusion and osmosis (lipid-soluble)

\-Ex. Brain

Fenestrated Capillaries

\-Most common

\-Tiny holes to allow substances to leave bloodstream

\-How hormones exit bloodstream

\-Platelets, RBCs, and WBCs cannot exit

\-Ex. Muscle and skin

Sinusoid Capillaries

\-Large holes

\-Allow large cells and proteins to enter and exit bloodstream

\-Store and remove platelets, RBCs, and WBCs

\-Ex. liver and spleen

3 types of resistance

1. Vascular resistance
2. Blood viscosity
3. Turbulance

Vascular Resistance

\-Blood banging into artery wall

\-lower resistance by vasodilation

\-Increase in vessel length = increase in resistance

Blood Viscosity

\-Thickness of blood

\-Increase pressure to push it around

\-Viscosity increases with dehydration and type 2 diabetes

Turbulance

\-Plaque obstructs blood

-slows it down

-need to push harder to get it through

Order vessels from highest to lowest pressure

Arteries

Capillaries

Veins

Order vessels from highest to lowest speed

Arteries

Veins

Capillaries

Systolic Pressure

Pressure on artery walls when ventricle contracts

Diastolic pressure

Pressure on artery wall when ventricle relaxes

Hypertension

High blood pressure, above 140/90

Hypotension

Low blood pressure

Local control of blood pressure

\-Autoregulation

\-Tissues secrete chemicals to dilate vessels (histamine, bradykinin, nitric oxide)

When local control of BP is not enough

\-Medulla oblongata

\-has autonomic reflexes (baroreflexes, chemoreflexes)

Baroreflex

\-In carotid and aortic bodies

\-Measure pressure

\-Tell medulla to constrict/dilate

\-High pressure = dilate

Chemoreflex

\-In carotid and aortic bodies

\-Measure blood chemistry (o2, co2, pH)

Functions of lymphatic system

1. Filters blood (Exits capillary then goes to lymphatic vessel)
2. Lipid absorption (Fats go to lymphathic vessel to go to bloodstream)
3. Immunity (Pathogens are killed in lymph node)

Blood Pressure

Pressure in arteries

Hydrostatic pressure

\-Pressure of blood on walls of capillary

\-Wanting to push blood out

Osmotic pressure

\-Fluid wants to come into blood

\-Water outside bloodstream wants to enter blood stream because it is attracted to albumin (albumin cannot exit bloodstream)

High hydrostatic pressure

Stuff leaves bloodstream (filtration)

High osmotic pressure

Stuff enters bloodstream (reabsorption)

Arteriole end

\-High hydrostatic pressure

\-Low osmotic pressure

\-Filtration

\-Goes from 40 to 10

Venule end

\-Low hydrostatic pressure

\-High osmotic pressure

\-Reabsorption

\-Osmotic is always at 25

\-Hydrostatic is at 10

Water portion

1. Plasma (in bloodstream)
2. Interstitial fluid (came out of capillaries, in between cells)
3. Lymph Fluid (in lymphatic vessel)

Which direction does lymph flow?

Toward the heart

Where are there not lymphatic vessels?

Bones, bone marrow, teeth, CNS

What keeps lymph from exiting the lymphatic vessels or going backwards?

Mini valves

What causes mini valves to open?

When fluid pressure in interstitial space (between cells) is greater than pressure in lymphatic capillary, mini valves open.

\-Lymph cant leak out because increased pressure in lymphatic capillaries keep gates closed

Lymph nodes and cancer

Lymph nodes can be route for cancer to spread

What speed and pressure does lymph flow at?

Low speed and pressure

What does lymph fluid need to move?

Needs muscle contraction to move it around

Where does lymph re enter the bloodstream?

At junction of jugular and subclavian veins

What can increase lymphatic return?

Exercise

Lacteal

\-Special lymphatic capillaries in the small intestine

\-Transport lipids from digestive tract to bloodstream

Primary lymphatic organs

\-Where cells actually mature

\-T cells and B cells become immunocompetent (become mature, learn to fight)

\-Red bone marrow and Thymus

Secondary Lymphatic Organs

\-Where mature lymphocytes live

\-Lymph nodes, spleen, tonsils

3 Types of Lymphocytes

1. T lymphocytes (Matured in thymus) (Out of bone marrow to thymus)
2. B lymphocytes (Mature in bone marrow) (Ready to go as they leave bone marrow)
3. Natural killer lymphocytes

Lymph nodes

\-Cluster near groin, armpit, and neck regions

\-Functions


1. Filters lymph with macrophages that eat viruses and bacteria
2. Activates immune system (B cells make antibodies when stimulated in lymph node)

\-Lymph enters lymph node through 4+ afferent vessels

\-Lymph exits lymph node through 2 vessels (slows the lymph down even more, allows for lymphocytes to clean fluid)

Lymphadenopathy

All lymph node diseases

Lymphadenitis

\-Swollen, painful, moveable lymph node

\-Responding to foreign antigen

What are the 4 types of tonsils?

1. Palatine (back of mouth)
2. Lingual (tongue)
3. Pharyngeal (nose)
4. Tubal (ear)

Tonsils

\-Gather and remove pathogens entering in air or food

\-Have dead end passageways where pathogens get stuck and attack

\-Gather, stuff gets stuck

Spleen

\-Extracts aged and defective blood cells and platelets

\-Macrophages remove debris and foreign matter from blood

\-Storage and removal organ

\-Has sinusoid capillaries

Red pulp

\-In spleen

\-Clusters of macrophages and RBCs

White Pulp

\-In spleen

\-Where T cells, B cells, and macrophages are in spleen (suspended on reticular fibers)

Thymus

\-Secretes hormone thymosin and thymopoietin (causes T cells to mature)

\-Stops growing in adolescence (starts to atrophy slowly) (dont need to make T lymphocytes after adolescence, they self-replicate)

\-No pathogen fighting in this organ

Innate Immunity

\-Born with it

\-Rapid Response (activate as soon as pathogen enters)

\-Not specific (fight all bacteria)

\-First exposure = just innate response

Adaptive Immunity

\-Acquired

\-Slow response (10-14 days to make antibodies after exposure)

\-Specific for pathogen, cells can last for 10 years

\-Once youve been exposed (2nd exposure) your response will be faster (hours)

\-Vaccine = first exposure