ch. 42 Flashcards
how do small molecules move between cells and their surroundings
diffusion
why is diffusion only efficient over small distances
because the time it takes to diffuse is proportional to the square of the distance
how do most animals exchange materials with the environment?
via a fluid-filled circulatory system
cnidarians and circulatory system
- gastrovascular cavities function in both digestion and distribution of substances throughout body
- body wall enclosing gastrovascular cavity is 2 cells thick
flatworms and circulatory
gastrovascular cavity and flat body that minimizes diffusion distances
what does a circulatory system have
- circulatory fluid
- set of interconnecting vessels
- muscular pump (heart)
ex. of phylums/organisms with open circulatory system
- insects
- arthropods
- some molluscs
open circulatory system
hemolymph bathes organs directly
closed circulatory system
blood is confined to vessels and is distinct from interstitial fluid
ex. of phylum/organisms with closed circulatory
- annelids
- cephalopods
- vertebrates
what does hemolymph lack
special cells to help transport oxygen
what is the closed circulatory system called in humans/other vertebrates
cardiovascular system
3 main types of blood vessels
- arteries
- capillaries
- veins
blood flow progression away from heart and back
- arteries
- arterioles
- capillaries
- venules
veins
capillary beds
networks of capillaries that are sites of the chemical exchange between blood and interstitial fluid
how are arteries and veins distinguished?
by direction of blood flow, not O2 content
how many chambers are in vertebrate hearts
2+
single circulation
blood leaving heart passes through 2 capillary beds before returning
ex. of organisms with single circulation
bony fish, rays, sharks
- 2 chambered heart
double circulation
oxygen-poor and oxygen-rich blood are mostly pumped separately from right ad left sides of heart
ex. of organisms with double circulation
amphibians, reptiles, mammals
in reptiles/mammals, where does oxygen-poor blood flow through to pick up oxygen through the lungs?
pulmonary circuit
in amphibians, where does oxygen-poor blood flow through to pick up oxygen through the lungs?
pulmocutaneous circuit
where does oxygen-rich blood deliver oxygen
through the systemic circuit
does double or single circulation maintain a higher blood pressure
double
how many chambers are in the hearts of frogs and amphibians
3
- 2 atria and 1 ventricle
amphibian heart process
ridge in ventricle diverts most of oxygen-rich blood into systemic circuit and most oxygen-poor blood into pulmocutaneous circuit
what happens to blood flow when a frog is underwater
the blood flow to the lungs is nearly shut off
how many chambers in heart of turtles, snakes, and lizards
3
- 2 atria, 1 ventricle
- partially divided by incomplete septum
septum in hearts of alligators, caimans, and other crocodilians
divides ventricles
- pulmonary/systemic circuits connect where arteries exit heart
how many chambers in heart of mammals and birds
4
- 2 atria, 2 ventricles
- left side pumps/receives oxygen-rich, right side pumps/receives oxygen-poor
endotherms (mammals/birds) require more _____ than ectotherms
O2
flow of blood to lungs (mammal)
- contraction of right ventricle pumps blood to lungs via pulmonary arteries
- blood flows through capillary beds in left/right lungs - loads O2, unloads CO2
- oxygen-rich blood returns to left atrium of heart via pulmonary veins
flow of blood to body (mammal)
- oxygen-rich blood flows into left ventricle and is pumped out to body tissues via systemic circuit
- blood leaves left ventricle via aorta to arteries
- first branches are the coronary arteries, supplying heart muscle
- further branches lead to capillary beds in abdominal organs/hind limbs
- O2 diffuses from blood to tissues, CO2 diffuses from tissues to blood
- capillaries rejoin, forming venules, conveying blood to veins then back to heart
where does oxygen-poor blood from the head, neck, and forelimbs enter the heart
superior vena cava
where is blood drained from the trunk and hind limbs
inferior vena cava
where do the vena cava empty their blood
right atrium of heart
how big is the human heart
size of clenched fist
walls of atrium and ventricles
- atria - thin walls
- ventricles - thicker walls - contract more forcefully
cardiac cycle
rhythmic cycle in which heart contracts and relaxes
systole
contration or pumping phase
diastole
relaxation or filling phase
cardiac output
volume of blood pumped into the systemic circulation per minute
what does cardiac output depend on
heart rate and stroke volume
heart rate
number of beats per minute
stroke volume
amount of blood pumped in a single contraction
what prevent back flow of blood in the heart?
4 valves:
- atrioventricular valves
- semilunar valves
atrioventricular valves
separate each atrium and ventricle
- tricuspid and bicuspid
semilunar valves
control blood flow to aorta and pulmonary artery
- aortic semilunar, pulmonary semilunar
Lub-dup sound of heart
caused by recoil of blood against AV valves (lub) then against semilunar (dup) valves
heart murmur
back flow of blood through a defective valve
autorhythmic
contract without any signal from the nervous system
- some cardiac cells
sinoatrial (SA) node
pacemaker
- sets rate/timing at which cardiac muscle cells contract
electrocardiogram (ECG or EKG)
recorded impulses that travel during the cardiac cycle
what portions of the nervous system regulate the pacemaker?
- sympathetic (speed up)
- parasympathetic (slow down)
what is the pacemaker regulated by?
- nervous system
- hormones
- temperature
basic anatomy of blood vessels
central lumen lined with epithelial layer (endothelium)
endothelium
smooth epithelial layer of blood vessels that minimizes resistance
how wide are capillaries?
slightly wider than a red blood cell
walls of capillaries
- thin
- endothelium + basal lamina
- facilitate exchange of materials
composition of arteries and veins
endothelium, smooth muscle, connective tissue
artery walls
thick, elastic walls to accommodate high pressure of blood pumped from the heart
vein walls
thinner-walled, blood flows back to heart as result of muscle action
what maintains unidirectional flow in veins?
valves
what do physical laws governing movement of fluids through pipes affect
- blood flow
- blood pressure
where is the velocity of blood flow the slowest
capillary beds
- result of high resistance and large total cross-sectional area
- allows for exchange of materials
where does blood flow from
areas of higher pressure to areas of lower pressure
where is blood pressure force exerted
in all directions - including walls of blood vessels
what plays a role in maintaining blood pressure
recoil of elastic arterial walls
what dissipates much of blood pressure
resistance to blood flow in narrow diameters of tiny capillaries/arterioles
systolic pressure
pressure in arteries during ventricular systole
- highest pressure in arteries
diastolic pressure
pressure in arteries during diastole
- lower than systolic
pulse
rhythmic bulging of artery walls with each heartbeat
how do homeostatic mechanisms regulated arterial blood pressure
by altering diameter of arterioles
vasoconstriction
contraction of smooth muscle in arteriole walls
- increases blood pressure
vasodilation
relaxation of smooth muscles in arterioles
- causes blood pressure to fall
major inducer of vasodilation
nitric oxide
potent inducer of vasoconstrction
peptide endothelin
where is blood pressure generally measured
artery in the arm at the same height at the heart
normal blood pressure for healthy 20-year-old
- 120 mm Hg systole
- 70 mm Hg diastole
what has a significant effect on blood pressure
gravity
fainting
inadequate blood flow to heat
why do animals with long necks require very highs systolic pressure
to pump blood great distance against gravity
why are there one-way valves in veins
blood pressure is low - prevents back flow of blood
what is the return of blood enhanced by
- contraction of smooth muscle in venule walls
- skeletal muscle contraction
how many of the capillaries does blood flow through
5-10% at any given time
true or false: capillaries in major organs are not usually filled to capacity.
false
2 mechanisms that regulate distribution of blood in capillary beds
- constriction/dilation of arterioles that supply capillary beds
- precapillary sphincters that control flow of blood between arterioles/venules
what is blood flow regulated by
nerve impulses, hormones, other chemicals
capillary function
exchange of substances between blood and interstitial fluid
what drives fluid out of capillaries
blood pressure
what pulls fluid back into capillaries
blood proteins
what is responsible for much of the blood’s osmotic pressure
blood proteins
is there a net loss of net gain of fluid from capillaries
net loss
lymphatic system
returns excess fluid that leaks out from capillary beds back to circulatory sysem
lymph
fluid los by capillaries
where does the lymphatic system
drains into veins in the neck
edema
swelling caused by disruptions in flow of lymph
lymph nodes
organs that filter lymph and play an important role in body’s defense
what happens to lymph nodes when the body is fighting an infection
they become swollen
blood composition
connective tissue consisting of several kinds of cells suspended in liquid matrix called plasma
plasma
inorganic salts as dissolved ions, sometimes called electrolytes
plasma protein function
- influence blood pH
- helps maintain osmotic balance between blood/interstitial fluid
- lipid transport
- immunity
- blood clotting
what is plasma similar in composition to
interstitial fluid
- plasma has higher protein concentration
2 types of blood cells
- red blood cells (erythrocytes) - transport O2
- white blood cells (leukocytes) - defense
platelets
fragments of cells involved in clotting
eryth
red
leuk
white
erythrocytes
- most numerous
- hemoglobin
- lack nuclei/mitochondria
hemoglobin
iron-containing protein that transports O2
- each molecule of hemoglobin binds up to 4 molecules of O2
sickle-cell disease
caused by abnormal hemoglobin proteins that form aggregates
- erythrocyte - sickle shape
- sickled cells can rupture/block blood vessels
how many types of white blood cells
5
leukocytes
- defense by phagocytizing bacteria/debris
- mounting immune responses against foreign substances
- in/out of circulatory system
where do erythrocytes, leukocytes, and platelets develop from
common source of stem cells in red bone marrow
- ribs, vertebrae, sternum, pelvis
erythropoietin
stimulates erythrocyte production when O2 delivery is low
2 types of stem cells in bone marrow
- lymphoid progenitor cells
- myeloid progenitor cells
coagulation
formation of a solid clot from liquid blood
how is a clot formed
a cascade of complex reactions that converts inactive fibrinogen to fibrin
thrombus
a blood clot formed within a blood vessel, can block blood flow
cardiovascular diseases
disorders of the heat and blood vessels
- minor disturbances of vein/heart function to life-threatening disruptions of blood flow to heart/brain
atherosclerosis
buildup of fatty deposits (plaque) within arteries
- cholesterol key player
low-density lipoprotein
delivers cholesterol to cells for membrane production
- bad
high-density lipoprotein
scavenge excess cholesterol for return to liver
- good
how does risk for heart disease increase
- with high LDL to HDL ratio - lot of cholesterol around that isn’t getting delivered to cells
- inflammation
myocardial infarction (heart attack)
damage/death of cardiac muscle tissue resulting from blockage of one or more coronary arteries
stroke
death of nervous tissue in the brain, usually resulting from rupture/blockages of arteries in the head
angina pectoris
chest pain caused by partial blockage of the coronary arteries
stent purpose
widens artery and pushes plaque to side
gas exchange
uptake of O2 from environment and discharge of CO2 to the environment
what drives gas exchange?
partial pressure of gases
partial pressure
pressure exerted by a particular gas in a mixture of gases
- also apply to gases dissolved in liquids (water)
why is breathing air not very efficient
it is relatively easy
why can we not breathe in water
- less O2 available
- requires greater efficiency
how does gas exchange occur across respiratory surfaces
diffusion
respiratory surfaces in animals
skin, gills tracheae, and lungs
gills
outfoldings of the body that create a large surface area for gas exchagne
ventilation
moves respiratory medium over the respiratory surface
how do aquatic animals ventilate
move through water to move water over gills
countercurrent exchange system
where blood flows in opposite direction to water passing over the gills
- blood is always less saturated with O2 than the water it meets
- in fish gills, more than 80% of O2 dissolved in water is removed as water passes over the respiratory surface
tracheal system of insects
consists of network of branching tubes throughout body
- tracheal tubes supply O2 directly to body cells
- respiratory/circulatory systems separated
what must larger insects do to meet O2 demands
ventilate tracheal system
lungs
infolding of the body surface
what do the size and complexity of lungs correlate with
animal’s metabolic rate
where is air inhaled
nostrils
- filtered, warmed, humidified, and sampled for odors
pharynx
directs air to lungs and food to stomach
where does air pass through
pharynx, larynx, trachea, bronchi, bronchioles, alveoli
where does gas exchange occur in lungs
alveoli
how are sounds created
exhaled air passes of the vocal cords in the larynx
what moves particles up to the pharynx?
cilia and mucus that line the epithelium of the air ducts
mucus escalator
cleans respiratory system and allows particles to be swallowed into esophagus
characteristics of alveoli
- lack cilia
- susceptible to contamination
surfactants
secretions that coat the surface of the alveoli
- reduce adhesive properies
why are preterm babies vulnerable to respiratory distress syndrome
- lack surfactant
- treatment provided by artificial surfactants
how does an amphibian breathe
- ventilates its lungs by positive pressure
- forces are down trachea
- reduce breathing
- CPAP (continuous positive airway pressure)
how a bird breathes
- air sacs that function as bellows to keep air flowing through lungs
- air passes through lungs in one direction only
- 2 cycles of inhalation and exhalation
- ventilation highly efficient
how to mammals ventilate their lungs
negative pressure breathing
- lung volume increases as the rib muscles and diaphragm contract
tidal volume
volume of air inhaled with each breath
vital capacity
maximum tidal volume
residual volume
air that remains in lungs after exhalation
what is breathing controlled by
involuntary mechanisms in medulla oblongata
what does the medulla regulate
rate and depth of breathing in response to pH changes in cerebrospinal fluid
what monitors O2 and CO2 concentrations in the blood
sensors in the aorta and carotid arteries
- these signal breathing control centers
where does additional modulation of breathing take place
pons
what happens in the alveoli
O2 diffuses into blood, CO2 diffuses into air
respiratory pigments
proteins that transport oxygen
- increase amount of oxygen that blood can carry
hemocyanin
- copper as oxygen-binding component
- arthropods and mollusks
what animals is hemoglobin found in
most vertebrates and invertebrates
- vertebrates - in erythrocytes
how much O2 can a single hemoglobin molecule carry
4 molecules of O2
- 1 for each iron-containing heme group
what does the hemoglobin dissociation curve show
a small change in the partial pressure of oxygen can result in a large change in delivery of O2
Bohr shift
CO2 produced during cellular respiration: 1. lowers blood pH
2. decreases affinity of hemoglobin for O2
true or false: hemoglobin plays a minor role in transport of CO2 and assists in buffering the blood
true
how much CO2 from respiring cells diffuses into the blood and is transported in blood plasma bound to hemoglobin?
7%
- remainder diffuses into erythrocytes and reacts with water to form H2CO3 (dissociates into H+ and bicarbonate ions)
what do deep-diving air breathers do
stockpile O2 and use it slowly
where can diving mammals store oxygen
in muscles in myoglobin proteins
how do diving mammals conserve oxygen
- changing buoyancy to glide passively
- routing blood to vital tissues
- deriving ATP in muscles from fermentation once oxygen in depleted
