Human Physiology
Unit Seven
Functions of the Circulatory System
Transportation
Gases
Nutrients
Wastes (metbolic, ions & excess water
Regulation
Body temperature
Hormone transport
Protection
Immunity
Pulmonary and Systemic Circuits
Coronary Circuit
Aorta
Coronary
arteries
Right
atrium
Cardiac
veins
Coronary
sinus
Right
atrium
Hepatic Circuit
Hepatic
vv.
Superior
mesenteric a.
Right
Hepatic renal a.
portal v.
Descending
aorta
Inferior
vena
cava
Superior
mesenteric v.
Right
common
iliac a.
Left
renal a.
Inferior
mesenteric a.
Left
common
iliac a.
Renal Circuit
Inferior
vena cava
Renal
veins
Descending
aorta
Renal
arteries
Blood Vessel Anatomy
The Venous Pump
Heart Circulation
Heart Circulation
Heart Conduction
The ECG (Electrocardiogram)
The ECG and Cardiac Cycle
The ECG and the
Heart
Abnormal Heart Functions
Bradycardia - a resting cardiac rate of
less than 60bpm
Tachycardia - a resting cardiac rate of
more than 100bpm
Fibrillation - the uncoordinated
contraction of several groups of
myocardial fibers
Abnormal Heart Functions
Circus rhythms - a continuous
recycling of electrical waves due to
malfunctioning non-refractory tissues
Flutter - rapid contraction rates caused
by extremely rapid rates of electrical
excitation
Abnormal Heart Functions
Heart block - the event in which
electrical impulses are partially or fully
blocked from passing into the ventricles
Atherosclerosis – the blockage of vessels
by plaques leading to inadequate blood
supply
Atherosclerosis
Abnormal Heart Functions
Heart murmurs - abnormal heart
sounds produced by the irregular
movement of blood through the heart
Valve stenosis and septal defect are two
of the most common causes of murmurs
Ischemia
Ischemic tissue - tissue that does not
receive adequate amounts of oxygen due
to inadequate blood flow
Angina pectoris - chest pain caused by
high levels of lactic acid due to
myocardial ischemia
Ischemia
Myocardial infarction - “heart attack”
caused by prolonged ischemia
Signs of myocardial infarction
* Creatine phosphokinase
* Lactate dehydrogenase
* S-T segment depression
Cardiac Output
Cardiac output - the volume of blood
pumped per minute by each ventricle
Stroke volume - the volume of blood
pumped per beat by each ventricle
Cardiac rate - the number of beats
produced by the heart per minute
Therefore - CO = SV X CR
Control of Cardiac Rate
Cardiac rate is controlled by two
extrinsic factors:
* autonomic nervous control
* hormonal control
The average cardiac resting rate is
70bpm
Control of Stroke Volume
Stroke volume is controlled by three
variables, two intrinsic and one
extrinsic:
* end diastolic volume (EDV) (intrinsic)
* contractility (intrinsic)
* total periperal resistance (TPR)
(extrinsic)
The average stroke volume is 70-80mls
per beat
Control of Stroke Volume
The Frank-Starling Law states that the
relationship between stroke volume,
EDV and contractility is an intrinsic
property of the heart
If TPR increases, stroke volume
decreases, resulting in an increased
EDV for the next cycle
If EDV increases, contractility increases,
and therefore stroke volume increases
Blood Volume and Its Control
Blood volume is the amount of extracellular water
found in the blood
Increasing blood volume would increase EDV and
therefore stroke volume
Decreasing blood volume would decrease EDV and
therefore stroke volume
Blood Volume and Its Control
Blood volume can be regulated by ADH and
aldosterone
ADH (antidiuretic
hormone) promotes
thirst and the retention
of water
Blood Volume and Its Control
Aldosterone promotes
salt retention, which
will lead to water
retention
Adrenal cortex

Aldosterone

salt retention
(water retention)

Increased blood
volume
Blood Pressure
Blood pressure - the pressure exerted
on the vessels of the circulatory system
Systolic pressure - pressure exerted
on the arteries during systole
Diastolic pressure - pressure exerted
on the arteries during diastole
Pulse pressure - systolic pressure
minus the diastolic pressure
Blood Pressure
Mean arterial pressure - the diastolic
pressure plus one third the pulse
pressure
Blood pressure decreases as blood moves
farther away from the heart. Therefore
arteries are under the highest pressures,
while capillaries and veins are under little or
no pressure
Blood Pressure
Poiseuille’s Law
Blood flow =
Pr4()
L(8)
Vessel length and blood viscosity do not change
significantly, therefore the most important variable in
changing blood flow is vessel radius
Fluid Exchange Between Capillaries and Tissues
Edema
The excessive accumulation of
fluid in the interstitial spaces of the
tissues
This condition can be temporary or
chronic, depending upon its cause
Edema
Five causes of edema:
> Hypertension
> Plasma colloid leakage
> Myxedema
> Decrease in plasma proteins
> Obstruction of lymphatic vessels
Blood Pressure Regulation Through
Resistance Changes
Angiotensin II compound produced
in the blood during
times of low blood
volume or pressure
This is an example of
extrinsic control
Blood Pressure Regulation Through
Resistance Changes
Sympathetic enervation - causes
vasoconstriction and increases cardiac
output
Parasympathetic enervation - causes
limited vasodilation and decreases
cardiac output
These are examples of extrinsic control
Blood Pressure Regulation Through
Resistance Changes
Myogenic action - direct responses of
vascular smooth muscle in response to
changes in pressure
Metabolic changes - decreases in
oxygen or pH, and increases in carbon
dioxide lead to localized vasodilation
These are examples of intrinsic control
The Baroreceptor Reflex
Integrating
Center
Sensor
Stimulus
Effectors
Response
The Baroreceptor Reflex
Adaptation to Exercise
Arterial Pathology
Shock - rapid drop in blood pressure
due to a variety of causes
There are four types of shock:
~ hypovolemic
~ anaphylactic
~ neurogenic
~ cardiogenic
Arterial Pathology
Hypertension - high arterial blood
pressure (systolic above 140mmHg)
Hypertension types:
~ primary (essential)
~ secondary
Arterial Pathology
Hypotension - low arterial blood
pressure (systolic below 100mmHg)
Aneurysm - a blood filled sac found
on arteries where the arterial wall is
weakened
Arterial Pathology
Atherosclerosis – the blockage of
vessels by plaques leading to
inadequate blood supply
Hemostasis