Transcript BIOLOGY 12 - Circulation Heart and Vessels

BIOLOGY
12
The Circulatory
System:
Heart and
Vessels
Introduction
The circulatory system is
considered a closed
system because blood
remains in blood vessels
heart -- arteries – capillaries
veins – and back to heart
and only nutrients, gases,
and wastes are exchanged
at the capillaries.
Introduction
Functions:
1. Transport O2 from lungs to tissues
2. Transport CO2 from tissues to lungs
3. Transport nutrients from small
intestine to tissues.
4. Transport water from digestive
tract to tissues and from tissues to
lungs, skin, and kidneys
Introduction
5. Transport wastes from tissues to
kidneys.
6. Transport hormones from glands
to target tissues.
7. Transport body heat from interior
of body to periphery (skin) for
disposal.
8. Maintain a constant pH in the
tissues - blood is a buffer.
Introduction
9. Regulate fluid levels in the
tissues (along with lymphatic
system).
10. Seal punctures to body by
forming clots and sealing
wounds.
11. Fight infection; destruction of
foreign protein and dead cells.
Comparison of Blood Vessels
Blood Vessels
A. ARTERIES and arterioles
Three layers:
1) endothelial lining: squamous epithelium
2) muscularis: thick layer of smooth muscle
and elastic connective tissue.
3) serosa: outer layer of elastic connective
tissue.
• Arteries are thick walled to withstand the
pressure created by heart contraction and
to assist the pumping of the blood.
• Transport blood away from heart.
Blood Vessels
B. Veins and venules
• Same three layers but much thinner
muscularis.
• Contain one-way valves to prevent
backflow.
• Blood moves by contraction of
surrounding skeletal muscle.
• Little internal blood pressure.
• Carry blood from body to heart
Blood Vessels
C. Capillaries
• Connect arterioles to venules
• Very thin, one cell layer thick
squamous epithelium.
• Very narrow - one rbc or less
diameter.
• Blood flow regulated by sphincters
• Are the site of all metabolic
exchange.
BLOOD is regulated by sphincters at the base of the
arterioles. These sphincters are controlled by the medulla
and regulate the direction of blood flow into capillary beds.
IMPORTANT for sending blood to the digestive system after
eating. Temperature regulation: sending blood to the surface
to get rid of heat when the body is overheated. When the
body is cold blood is diverted to internal organs to maintain
core body temperature.
HEART EXTERNAL ANATOMY
The heart can be described as a double pump made up
of 4 chambers, approximately the size of two fists. It is
located directly behind the sternum (breast bone)
HEART INTERNAL ANATOMY
HEART LAYERS
HEART LAYER
MYOCARDIUM
ENDOCARDIUM
PERICARDIUM
DESCRIPTION AND FUNCTION
• thick muscular layer of the heart
• responsible for contracting and pushing blood
out of the chambers
• thin layer of squamous epithelium
• responsible for protecting inner layers of chambers
• outer layer (sac) containing pericardial fluid
• responsible for lubricating the heart
Right side
the right side receives CO2
or deoxygenated blood
from the BODY and
pumps it to the LUNGS to
exchange the CO2 for O2
Left side
the left side receives O2
or oxygenated blood from
the LUNGS and pumps it
to the BODY
The Heart
Note the valves:
A. Atrioventricular valves - prevent
backflow between ventricle and
atrium
B. Semilunar valves: between
ventricles and leaving arteries prevent backflow when ventricles refill.
Chordae tendenae prevent valve
inversion.
The Heart
• Heart contracts in two phases:
1. Systole: ventricles contract, atria
relax
2. Diastole: atria contract,
ventricles relax
• Lub-dub sound due to opening and
closing of valves.
The Heart
Control of Heartbeat
• The heart will continue to beat even
if all nerve connections to it are
severed, but at an unchangable rate.
• Nerves and hormones adjust the
intrinsic heart beat.
• The heart contains its own nervous
tissue that initiates the heartbeat.
The Heartbeat
• Between the vena cava and the
right atrium is a patch on nerves (a
ganglion) called the SA node
Sino-Atrial Node
• This is the hearts natural
pacemaker and receives a signal
from the MEDULLA initiating a wave
of stimulation that goes over both
atria causing them to contract.
EKG
• A branch from the S-A node goes to a second
ganglion located in the wall between the right
atrium and ventricle called the Atrio-ventricular
node.
• When the impulse reaches the AV node from the
SA node, it is transmitted along nerves called
Purkinji fibers to the base of both ventricles.
P wave
stimulatation of the atria (depolarization)
contraction of the R and L atria
QRS wave stimulation of the ventricles through the
septum (depolarization) contraction of the R and L
ventricles
T wave recovery (repolarization) Na+ K+ pump
active transport and redistribution of ions across the
membranes of nerve cells in heart muscle cells
The Heart
• The impulse then moves up more
fibers to tiny nerve branches called
the Purkinje fibers that go into the
ventricular muscle and cause it to
contract from the bottom up.
• This neural-electrical activity of the
heart beat can be seen in an ECG
(electrocardiogram)
The Heart
• The rate can be adjusted by
effects of both nerves from the
autonomic nervous system and
hormones.
• These effects are both
stimulatory and inhibitory
depending upon the needs of the
body.
Pattern of Blood Flow
• We have a four chambered heart
which is actually a double pump.
• we have two circulatory systems:
1. Pulmonary: right side pumps blood
to lungs.
2. Systemic: left side pumps blood to
rest of the body.
This means that blood goes through
the heart twice for every round
through the body.
Vascular
Pathways
Arteries carry blood
away from heart and
veins carry blood back
to heart.
All arteries carry
oxygen except
and all
veins carry CO2
except
Systemic
Blood
Vessels
• Exchange
occurs mostly
by diffusion slow!
• Three aspects of
capillary
structure
facilitate this
passage:
1. Pressure
2. Velocity
3. Surfacearea
Fetal Circulation
• The fetus is, biologically, an
endoparasite.
• To survive, it needs numerous
adaptations, most of which
involve the circulatory system.
• Further, these modifications can’t
be too elaborate as they must be
shut off at the baby’s first breath
upon being born.
Fetal Circulation
• We will look at five circulatory
adaptations
1. Foramen Ovale: a hole in the
septum between the right and left
atrium.
• Used to bypass the lungs
2. Ductus Arteriosis: a shunt that
connects the pulmonary trunk to the
dorsal aorta, another lung bypass
Fetal Circulation
3. Ductus Venosus: connects
umbilical vein to posterior vena cava.
• Allows blood to bypass fetal liver.
4. Umbilical blood vessels
• A. umbilical arteries (2): carry blood
from fetal iliac arteries to placenta.
• B. Umbilical vein (1): placenta to
vena cava
Fetal Circulation
5. Fetal Hemoglobin
• Produced by expression of
different gene than normal
hemoglobin.
• Has greater affinity for oxygen
than adult hemoglobin - necessary
for fetus to pull oxygen from
maternal circulation.
The Blood
• An adult has between 4 and 6 l. of
blood.
• Blood is divided into two
components:
1. The plasma - a straw colored
liquid that makes up 60% of the
blood volume.
2. The Cellular Component - made
of red blood corpuscles, white
blood cells, and the platelets.
Plasma
• Plasma is 90% water: the
other 10% contains:
Blood Proteins (7% - 10%)
Albumin: helps maintain the correct
osmotic balance in the tissues by
controlling the thickness of the
blood.
Fibrinogen: together with platelets,
form blood clots to seal wounds.
Immunoglobins: form antibodies to
attack foreign protein
Plasma
.
Water soluble elements (other 3%)
• Together, these elements help
control blood pH (about 7.4) and
adjust osmotic balance in the
tissues (with albumin).
Plasma
• These elements include:
Oxygen: necessary for cellular
respiration oxidation of glucose
Carbon dioxide: transported in
plasma as dissolved CO2 (small
amount) or reacted with water as
bicarbonate ion, HCO3-.
Plasma
Nutrients glucose, amino acids, fatty acids, and
nucleotides (absorbed from digestive system).
Hormones from glands to target organs ADH for
water balance in kidneys and Insulin for
maintaining proper blood sugar levels
Vitamins niacin (vitamin B) is necessary for
cellular respiration, A, K, D, C are necessary for
many chemical reactions (cellular health
Salts (blood electrolytes) there are a host of
inorganic ions such as sodium, potassium,
calcium, etc.
Wastes from cell metabolism (breakdown of
proteins and nucleic acids) - mostly urea, some
creatinine and ammonium salts
Cellular Component
Red Blood Corpuscles
(erythrocytes).
• In mammals, rbc’s lack a nucleus
and most other cell components.
• They do anaerobic respiration to
generate the small amount of ATP
they need to function.
• Basically, an rbc is a bag of
hemoglobin.
Cellular Component
• Rbc’s live about 120 days before
wearing out.
• You have about 75 trillion rbc’s
and each one contains about 300
million molecules of hemoglobin!
• Rbc’s can also transport some
CO2 (small amount) as
carbaminohemoglobin.
Cellular Component
• Hemoglobin is made from an iron
based pigment called Heme
together with 4 globular proteins.
• Hemoglobin binds to O2 in the lungs
(cool temperature, low pressure)
and release it in the tissue
capillaries (warm, high pressure).
• Hemoglobin + O2 ---> oxyhemoglobin
Hb + O2 ----> HbO2
Cellular Component
White Blood Cells (leukocytes):
• Overall function is body defense.
• There is about one wbc for every 1000
rbc’s
• Are true cells with all the cell organelles
and can live a long time - some a life
time.
• Wbc’s can and do leave the blood
stream where they patrol the tissues
searching for foreign protein.
Cellular Component
Thrombocytes Platelets: cell
fragments from formation of other
blood cells.
• Function in helping seal wounds
and form clots.
• All of the blood cells originate in
bone marrow from stem cells
(except lymphocytes)
Blood Cells
• In summary the 3 main functions of blood are:
A. TRANSPORT ; nutrients, gases,
vitamins, minerals, hormones and
wastes
B. FIGHT INFECTION; our blood stream
is patrolled by an army of white
blood cells which provide us with
our immunity
C. CLOTTING; if not for the chemicals
involved in closing and repairing
cuts we would bleed to death
60% of blood is PLASMA
40% of blood consists of
FORMED ELEMENTS
• Erythrocytes
• Leukocytes
• Thrombocytes
How does your body replace blood cells?
1. LOW OXYGEN TENSION
STIMULATES THE LIVER
2. Liver releases the protein
GLOBULIN
3. Kidney releases REF
renal erythropoietin
factor which combines
with the globulins
5. INCREASE IN
RBC which
increases
bodies ability to
carry more OXYGEN
4. Erythropoietic stem cells in long and flat
bones are stimulated to produce more RBC’S
What causes a decrease in carrying
capacity of oxygen in our blood?
Loss of blood due to trauma
Lack of hemoglobin due to anemia
- pernicious lack of vitamin B12
- iron deficiency due to poor diet
High altitude due to less oxygen in the air
Erythrocytes
Leukocytes
Thrombocytes
origin /life span
approximately 120
days then broken
down in spleen
1 day to lifetime if
they are memory
cells
vary
number / kinds
only 1 type
Approximately 600
to 800 rbc to every
1 wbc
5 main w.b.c.
lymphocytes are
the most common
fragments of
megakaryocytes
produced in bone
marrow
shape, size,
nucleus
present
disc shaped much
smaller than w.b.c.
and have no
nucleus
Vary in shapes can
move using
pseudopods and
have a large
nucleus
no nucleus small
and contain a
protein to aid in
blood clotting
function
carry O2
fight infection
blood clotting
diagram
Cellular Component
AGRANULOCYTES
Mononucleocytes: single lobed nucleus
• Do not contain visible granules (lysosomes)
GRANULOCYTES
Polymorphonucleocytes: nucleus takes on many
different shapes.
Cellular Components
Contain visible granules: called
Neutrophils (55% - 65%): major
phagocytic cell - attacks pathogens
Eosinophils (2% - 3%): attack larger
cells and parasites
Basophils: help in body repair by
releasing histimine.
• Neurtophils 60-70% of all wbc’s
• Engulf and destroy microbes
• Last only a few days because they self destruct
• Stimulated by chemicals, this attraction is
called chemotaxis
• Monocytes 5% of all wbc’s
• Develop into large “marcrophages” and can
extend pseudopods and attach to the
carbohydrate chains of microbes engulfing
foreign invaders
• Lymphocytes 20-30% of all wbc’s
• These are the blood cells responsible for
producing ANTIBODIES
Blood Clotting
damaged cells release
THROMBOPLASTIN
(enzyme)
PROTHROMBIN activator
Released from platelets into
blood
Calcium
PROTHROMBIN already
present in plasma
THROMBIN also in
plasma
Calcium
FIBRINOGEN a blood
protein in plasma
FIBRIN threads trap
red blood cells and
they dry up (CLOT)
Capillary Exchange
Blood Pressure
• Blood pressure is the pressure force
exerted by blood against the walls of
the arteries.
• It goes up and down rhythmically with
the contraction and relaxation of the
ventricles.
• It is measure in mm Hg with normal
being around 120/80 (systole/diastole).
Blood Pressure
- Hypertension is abnormally high bp
and can be caused by many factors:
occlusion of the arteries
- loss of elasticity in arteries
(hardening of the arteries).
- smoking (contracts smooth muscle)
- Stress increases resistance by
contracting surrounding muscles.
- Fat - increases km of blood vessels
Blood Pressure
Hypotension is lower than normal
blood pressure and is often related
to low heart volume outputs. Low
blood pressure can also lead to
kidney failure.
The Lymphatic System
Immune System consists of
SPLEEN which is the largest gland in the immune
system and acts as a filter for dead white blood
cells and pathogens
LYMPH NODES are located in the in the neck,
under arms, and groin area and also filter out
pathogens and toxins
LYMPH VESSELS
run parallel to veins and
pick up any excess fluids and wbc’s
LYMPH FLUID
is made up of excess water and
white blood cells that leave the circulatory system
The Lymphatic System
The lymph vessels are similar to
veins because they are made up of
muscles and have valves. However
they do not carry any blood only
lymph fluid.
Recall in Biology 11 that blocked
lymphatic vessels by the filarial
worm leads to elephantiasis!
Inflammatory Reaction
IMMUNE SYSTEM
• Skin is our first barrier against
foreign invaders (pathogens)
Pathogens can only penetrate our
circulatory system when this barrier is
broken. We have several orifices where
pathogens can enter our circulatory system
»Oral cavity
»Nasal cavity
»Anal opening
»Vaginal orifice
»Urethras
• Some ways we are protected besides
our skin acting as a barrier are;
• Mucous membranes
• Sebaceous glands
• Sweat glands
• Anti-microbial proteins like lysozyme
• Phagocytic cells
Antigen Antibody Reaction
• Antigens will stimulate
lymphocytes to produce
chemical proteins called
antibodies which are
specific to each antigen
and help the immune
system by eliminating
the foreign antigens.
Antigen is short for “antibody generator.”
Autoimmune Diseases
• Sometimes the immune system loses
tolerance for self and turns against certain
molecules of the body, causing one of the
many autoimmune diseases.
• Lupus
• Rheumatoid arthritis
• Diabetes mellitus
• Multiple sclerosis
Blood Types
• There are actually about 25 or so
blood typing differences in human
blood.
• Two are most critical: ABO and Rh
1. ABO system.
• This is an example of a multiple
allele gene system where there
are three possible alleles in the
human gene pool: IA, IB, and I.
Blood Types
• If you receive blood containing an
antigen foreign to you, your
antibodies will attach to the
antigen and cause all the rbc’s to
clump together (termed
agglutination) and you quickly die.
• Therefore, it is critically important
that blood transfusions be done
correctly.
Antibodies
present
Blood
types
Antigens
present
Receive
blood
from
A
all cells
have the
A antigen
on outside
B
antibodies
are present
in plasma
A
B
all cells
have the
B antigen
on outside
A
antibodies
are present
in plasma
B
AB
50% have
A and 50%
have B
antigens
Plasma has
NO
antibodies
present
A
AB
O
All RBC’s
lack any
antigens
on outside
of RBC’s
Both A and
B
Antibodies
are present
in plasma
O
O
B
Blood typing test
A antigen
serum
B antigen
serum
Blood
type
Rh antigen
factor
A
B
AB
O
only O
O
Blood Types
2. The Rh System:
• This has two possible alleles:
positive means you produce the
Rh antigen on your rbc’s or
negative - no antigen.
• Negatives produce anti Rh
antibodies and the same clumping
problem exists.
Stimulus low blood pressure 90/65
Normalcy 120/80
Response is;
1. Less urine more water
reabsorbed back into blood
2. Heart beats faster to keep
blood pressure up
3. Arteries constrict to narrow
the opening in blood vessels
Effectors are;
1. KIDNEY (nephron tubules)
2. HEART
3. ARTERIES and ARTERIOLES
Receptors are
osmoreceptors that detect
water levels in blood
Autonomic nervous system
which includes MEDULLA and
HYPOTHALMUS and
PITUITARY GLAND