APK 3110C Unit 3

what type of chambers are the atria?

receiving

what type of chambers are the ventricles?

pumping

which chamber has the thickest walls?

left ventricle because it has to pump blood to the entire body

what are cardiac muscle fibers like?

Highly oxidative, high capillary density, high # of mitochondria

______ hold cells together

desmosomes

_______ rapidly conduct cell action potentials

gap junctions

Cardiac excitation-contraction coupling includes __________________________________

calcium-induced calcium release

cardiac myocyte action potential

Phase 0: Na influx via fast Na channels

causes depolarization to about +52 mV

Phase 1: K & Cl leave while Na channels

close, causing partial repolarization

Phase 2: Ca enters & K leaves, causing a

plateau.

Phase 3: K leaves, Na & Ca channels close,

causing repolarization

Phase 4: -90 mV resting membrane

potential maintained via Na/K ATPase pump

Atherosclerosis

Plaque buildup, limiting blood flow

In the heart? "Coronary Artery Disease"

maximum possible heart rate is

250 BPM

intrinsic control of the heart

HR is 100BPM

Electrical signal spreads via gap junctions.

Observed in heart transplant patients (no neural innervation).

10 electrodes

12 leads

wiggers diagram

one cardiac cycle

P Wave

QRS complex

ST segment

T wave

PR interval

QT interval

systole

contraction

diastole

relaxation

70% passive,

30% atrial contraction

tachycardia

above 100BPM

bradycardia

below 60 BPM

Atrial fibrillaiton

irregular and chaotic

atrial flutter

sawtooth rhythm

____ and ____ increase the risk of blood clots, with common symptoms

including palpitations, dizziness, and shortness of breath

Afib and atrial flutter

Atrial flutter/fibrillation are closely related, often co-occurring, characterized by rapid, inefficient, or chaotic atrial contraction

The most frequent cause of sudden cardiac death

ventricular fibrillation

not enough time for the heart to fill with blood.

not enough blood is pumped out of the body.

ventricular tachycardia

elite endurance athlete has a BPM of

35 BPM

vagus nerve ______ heart rate

vagal tone

(parasympathetic NS)

decreases

sympathetic NS _____ heart rate

(ex: catecholamines) norepinephrine and epinephrine

increases

Isovolumetric Contraction (after S1):

All valves are closed; pressure _______

sharply without a change in volume.

rises

Isovolumetric Relaxation (after S2):

All valves are closed; pressure ______

rapidly without a change in volume

drops

arteries....

carry blood away from heart

arterioles...

control blood flow, feed

capillaries.

capillaries...

provide a site for nutrient

and waste exchange.

venules

collect blood from capillaries

veins...

carry blood from venules to heart

Mean blood pressure=

1/3 SBP + 2/3 DBP

average cardiac output (rest) is ____ L/min

4-5L

functional syncytium

pumping of the heart as one unit

torsional contraction

increased contractility during intense

exercise to enhance left ventricular filling

systole contraction

Heart twists gradually, storing energy like a spring.

diastole contraction

Abrupt untwisting allows atrial filling (dynamic relaxation)

muscle blood flow at rest is _____ L/min

0.75L

cardiac output during heavy exercise is ____ L/min

25L

muscle blood flow during heavy exercise is about ___ L/min

20L

blood volume distribution

at rest, veins contain ____ of blood volume

2/3

-elastic balloon-like vessel walls

-blood reservoir

blood volume distribution

venous reservoir can be sent back to heart and into arteries

-sympathetic stimulation

-venoconstriction

venous blood return

what kind of posture makes venous return to the heart more difficult?

upright

venous blood return

assisted by 3 mechanisms:

-one way venous vales

-muscle pump

-respiratory pump

vascular resistance

force that opposes flow

nL/r^4

*radius is the most important

_____ control 70-80% of the pressure fall from left ventricle to right atrium

arterioles

metabolic vasoldialtion

-build up of local metabolic by-products

-decrease O2

-increase CO2, K+, H+, lactic acid

intrinsic blood flow regulation is...

1. metabolic vasodilation

2. endothelial cells (mostly vasodilation)

3. Myogenic Vasodilation/Vasoconstriction

Nitric oxide (NO), prostaglandins, Endothelium-derived hyperpolarizing

factor (EDHF) are secreted by what?

vascular endothelial cells

myogenic vasodilation/vasoconstriction

pressure goes up with constriction

pressure goes down with dilation

more sympathetic activity causes __more or less____ vasoconstriction?

more

functional sympatholysis

-offsets sympathetic vasoconstriction to increase blood flow

-lowers alpha-adrenergic receptor activation

local metabolic signaling helps tissue meet ___ demand (_______)

O2, vasodilate

Integrative control of blood pressure

Autonomic

Baroreceptors sense pressure, send afferent signals

to brain, brain sends efferent signals to heart/blood vessels

Integrative control of blood pressure

Mechanoreceptors and metaboreceptors

Mechanoreceptors

and metaboreceptors

in muscle send afferent

signals to the brain

Extrinsic Neural Control of Blood Flow

-Redistributes blood at the organ/system level

-Innervates artery/arteriole smooth muscle

Main functions of blood

- Transportation (O2, waste)

- Temperature regulation

- Acid-base balance

average total blood volume

5-6L in males

4-5L in females

55% plasma

45% formed elements

blood

plasma contains....

90% H2O

7% plasma proteins

3% other

blood

formed elements contain....

99% red blood cells

1% white blood cells and platelets

hematocrit=

-total % volume composed of formed elements

45% formed elements (rbc)/100% total blood volume =45%

plasma increase/decrease

Increase by 10% with training or heat acclimation

- Decrease by 10% with dehydration in the heat

as red blood cell count (hematocrit) increases...

viscosity increases

Blood~2x viscous as water

Red Blood Cells

- No nucleus, unable to reproduce

- Replaced regularly via hematopoiesis

- New replace old every ~4 months

hemoglobin

-Heme (pigment, iron, O2) + globin (protein)

- O2-carrying protein in RBCs

- 20 mL O2 per 100 mL blood

250 million Hemoglobin per RBC x 4 O2 per hemoglobin = 1 billion O2 per RBC

Plasma volume must ______ as RBCs _______

increase, increase

Occurs in athletes after training/acclimation

- Hematocrit and viscosity remain stable

- Otherwise, blood flow or O2 transport may

suffer (recall: Resistance = nL/r4)

In the Wiggers diagram, _______________________ occurs when all heart valves are ______, causing ventricular pressure to rise sharply without changes in blood volume.

isovolumetric contraction, closed

Known as the primary resistance vessels, the _______ are the vessels responsible for approximately 70-80% of the total __________ across the systemic circulation.

arterioles, pressure drop

Because the venous system is a low-pressure environment, returning blood to the heart (especially from the lower body) requires _____ valves, the ________________________, and the respiratory pump

one-way, skeletal muscle pump

Hematocrit refers to the total percentage of blood volume composed of formed elements; if this value increases without a corresponding increase in plasma volume, ______ will rise, potentially hindering _______.

blood viscosity, blood flow

During exercise, the body uses _______________ to locally offset _____________________, ensuring that blood flow is redistributed to active skeletal muscles

functional sympatholysis, sympathetic vasoconstriction

Tidal Volume (L/breath) x Breathing Rate (breaths/min) =?

minute ventilation (L/min)

FEV1/FVC ratio is used for what?

Forced expired volume in 1 second/

Forced vital capacity

used to asses and diagnose airway disorders

tidal volume

normal breath

500mL

inspiratory reserve volume

extra amount of air you can breath in after a normal breath

usually about 3000mL

expiratory reserve volume

extra amount of air you can forcefully exhale after a normal exhale

approx 1000mL-1200mL

residual volume

air left in your lungs after you exhale as hard as you possibly can

approx 1200mL

respiratory gases at sea level

class 12 slide 10

O2 line

whats the role of the respiratory system?

O2 in air -> blood & CO2 in blood -> air

- Pulmonary ventilation (external respiration)

- Pulmonary diffusion (external respiration)

- Transport of gases via blood

- Capillary diffusion (internal respiration)

oxygen cascade

159 mmHg in air

Dilutes as it mixes in lungs

Leaves heart ~100 mmHg

Falls to 40 mmHg post-muscle

Returns to heart at 40 mmHg

Alveoli and pulmonary capillaries inside each alveolus

exchange zone

(everything else is a transport zone)

respiratory membrane (ie alveolar-capillary membrane)

pleura

lung lining

transport of oxygen in the blood

>98% bound to hemoglobin (Hb) in red blood cells

- O2 + Hb: oxyhemoglobin

- Hb alone: deoxyhemoglobin

<2% dissolved in plasma

max amount of oxygen blood can carry

- Based on Hb content (12-18 g Hb/100 mL blood)

- Anemia -> decrease Hb content -> decrease O2 capacity

Typical arterial oxygen saturation

- Hb 98% to 99% saturated at rest (0.75 s transit time)

- Lower saturation (usually still >95%) with exercise (shorter

transit time)

there's about ___ L oxygen in 5L of blood

1

artery has ____ ml of O2 per 100 ml of blood

vein has ____ ml of O2 per 100 ml of blood

20, 15-16

O2 is transported in muscle by _______

myoglobin

__________ has a higher affinity for O2

myoglobin

partial pressure of oxygen in our arterial blood is _____

100 mmHg

total pressure of our blood at sea level is _____

760mmHg

During the ______ process of inspiration, the ____________________ move the rib cage up and out while the diaphragm flattens, causing lung volume to ____________ and intrapulmonary pressure to decrease

active, external intercostals, increase

In the oxygen cascade, the partial pressure of oxygen (PO2) starts at ____ mmHg in the air, but it drops to approximately ____ mmHg as it leaves the heart and further decreases to ___ mmHg upon its return to the heart from the muscles

159, 100, 40

Most oxygen in the blood is transported by ________; oxygen within the muscle cells is transported by __________, which maintains a much higher affinity for O2.

hemoglobin, myoglobin

CO2

mostly central chemoreceptors

O2

mostly peripheral chemoreceptors

Neuromuscular communication

brain to respiratory muscles