New chapter 45 Heart

diffusion

high concentration to low concentration

no energy required

why do simple animals not need a circulatory system?

the gastrovascular cavity is in very close proximity to the cells, so diffusion can be used to transport nutrients

what is the circulatory system

fluid circulating, set of interconnected vessels, a muscular pump (heart)

3 main types of blood vessels

veins, arteries, capillary

open vs. closed circulatory system

open: hemolymph, blood and interstitial fluid is combined. lower pressure, so lower energy demand and the fluid can be used for other purposes like extending legs

ex. insects, arthropods

closed: blood is distinct from interstitial fluid. more efficient transport of oxygen and nutrients, more benificial to complex nutrients.

ex. annelids, cephalopods, vertebrates

order of blood vessels

1. arteries (thick, elastic walls to hold the high pressure of blood being pumped)

2. arterioles (carry blood away from heart)

3. capillary (forms networks called capillary beds, site of actual exchange between blood and interstitial fluid)

4. venules

5. veins (return blood from capillary bed to heart, thinner walls)

what does failure of veins lead to

varicose veins (pooling of blood)

single circulation circuit

blood leaves heart, passes through 2 capillary beds, returns to heart

1. blood leaving heart is oxygen poor

2. capillary bed in gills are picking up oxygen

3. distributed through body capillaries

4. oxygen poor again before returning to heart

double circulation circuit

heart pumped from right side of the heart in one circuit, goes to respiratory surface, oxygen rich blood returns to heart and is pumped out in a separate circuit to the body

higher blood pressure than single circuit

intermittent breathers

vertebrates with double circulation

passes a lot of time without passing gas exchange

pulmocutaneous circuit

in amphibians, uses the gills and skin for gas exchange.

temporary bypass of lungs

keeps circulating the blood, alters the blood flow to the lungs with a ridge in the ventricle that diverts the oxygen rich blood into system circuit and poor into pulmonary circuit

systemic circulation

moves blood between heart to the rest of the body

what is the order of the heart pumping

right side-

inferior vena cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lung

left side-

lung, pulmonary ventricle, left atrium, mitral valve, left ventricle, aortic valve, aorta

coronary arteries

first to branch of aorta, provides blood for the heart itself

where do further branches of aorta lead to

capillary beds in abdominal organs and hind limbs

this is where Oxygen diffuses from blood to tissues and CO2 diffuses from tissue to blood

what is formed when capillaries rejion

venules that convey blood to the veins and oxygen poor blood is directed to the heart

human heart (left vs. right, atria vs. ventricle)

mostly consists of cardiac muscle

right side: pumps deoxygenated blood to lungs to get oxygen

left side: pumps oxygenated blood to the rest of body

atria: top of heart, collection chambers for blood returning to heart

ventricle: bottom of heart, thicker walls

systole

contraction/pumping phase

pressure in artiereis during ventricular systole, highest pressure in arteries

diastole

relaxing/filling phase

not actively pumping blood through

cardiac output

colume of blood pumped into systemic circulation per minute

stroke volume

amount of blood pumped in single contraction

valves and types

prevent backflow of the heart

AV: separate atrium and ventricle from each other

semilunar valve: controls blood flow to aorta and pulmonary artery

what is lub dub sound produced by

recoil of blood against AV and semilunar valves

blood bouncing back into valves as they slam shut

why is a heart murmur caused

back flow of blood caused by defective valve

heart cardiac cycle

1. atrial and ventricular diastole (all of heart is relaxed)

2. atrial systole and ventricular diastole (atria squeeze blood into ventricles)

   1. atrial diastole and ventricular systole (ventricle squeezes blood out of heart and atria ready for blood filling again)

Sinoatrial node

pacemaker of the heart, sets the rate/time of cardiac muscles contracting, makes sure that the heart properly contracts

what is the pacemaker regulated by

2 portions of the nervous system

sympathetic: speeds up pacemaker

parasympathetic: slows it down

central lumen

all blood vessels have this, lined with epithelial later

why is it good that capillaries have very thin walls

allows exchange of materials to be very easy because anything that squeezes out between the endothelial cells is in the interstitial fluid and can be exchanged with the body

pulse

rhythmic bulging of artery walls with each heart beat

arteries distend with every pulse of blood the heart pumps out

vasoconstriction

increases bp, makes the blood vessels smaller so less room for blood to push through

vasodilation

drops bp, induced by nitric oxide

makes the blood vessels larger so more room for blood to push through

how is fainting caused

inadequate blood flow to the head

what do animals with big necks have

high systolic pressure bc they need to pump blood a greater distance against gravity

2 mechanisms to regulate distribution of blood in capillary beds

-constriction or dilatation of arterioles that supply capillary beds with blood

-pre capillary sphincters to control the flow of blood between arterioles and venules (can shut off the entire bed)

how is blood flow regulated

nerve impulses, hormones

where does exchange of substances between blood and interstitial fluid

the epithelial walls of capillaries

edema

swelling caused by disruption in the flow of lymph (fluid lost by capillaries)

common to see after removing lymph nodes bc the lymphatic system pathway has been altered

what does blood consist of

cell/cell fragments: 45%

erythrocytes, leukocytes, platelets

plasma: 55%

substances in transit

plasma

proteins influence blood pH and keep the osmotic balance between blood and interstitial fluid.

lipid transport, immunity, and blood clotting

examples of substances in transit

nutrients, metabolic waste, respiratoy gas, hormones

erythrocytes

rbc, transports oxygen through the body

very abundant

contains hemoglobin: iron protein that transports oxygen

leukocytes

wbc, body’s defense

uses phagocytosis on bacteria/debris or immune responses by foreign substances

platelets

fragments of cells involved in blood clotting

what is stimulated by hormone erythropoietin (EPO)?

causes erythrocyte production, body releases more of this when oxygen delivery is low.

athletes abuse this bc more rbc=more oxygen, so they can do more exercise

coagulation

formation of solid clot from the liquid blood

fibrinogen to fibrin to thrombus

atherosclerosis

caused by buildup of plaque within the arteries, cholesterol (important to maintain normal membrane fluidity, but excessive leads to plaque buildup)

arteries lose elasticity

low density lipoprotien

“better”

goes to make cell membrane

high density lipoprotein

takes extra to liver to make bile

heart attack

damage/death of cardiac muscle tissue because of blockage of coronary arteries

stroke

death of nervous tissue in brain resulting from the rupture or blockage of arteries in the head

angina pectoris

chest pain because of partial blockage of coronary arteries, warning sign of heart attack

treatment of plaque buildup

insert stent to widen obstructive artery, use balloon and stent (balloon through opening in major blood vessel), inflate balloon to expand stent

increases blood low

what is gas exchange

taking oxygen and discharging co2 to the environment

how does gas exchange occur

occurs by diffusion

ex. skin, lungs, trachea, gills

countercurrent exchange system

blood flows in opposite direction to water passing over gills so blood is always less saturated with oxygen than the water its meeting

tracheal system

network of branching tubes running throughout the body, openings through the body

oxygen supplied directly to cells

insects yse this

pharynx

directs air down into lungs and food into stomach

swallowing

move larynx upward and tip the epiglottis over the glottis in the pharynx, preventing food from entering the trachea

where should air be when not swallowing

should pass through glottis through larynx, trachea, bronchi, bronchioles, alveoli (air sacs where gas exchange takes place)

what happens if alveoli is contaminated

not stretchy, not moist, impede diffusion of o2 and co2

positive pressure breathing

forcing air down trachea

ex. amphibians

what do birds use to breathe

negative pressure breathing, no diaphragm, additional air sacs through the body (good for flight bc more space for gas exchange, lighter)

avain respiration

unidrectional aur flow, air is always fresh, keeps air sacs in body always full

tidal volume

volume of air inhaled with each breath

how is breathing regulated in humans

involuntary mechanisms, control centers found in medulla (if medulla detects something, breathing patterns change)

respiratory pigments

makes sure gas exchange is efficient, increases oxygen in what blood can carry

proteins to transport oxygen and increase oxygen that blood can carry

bore shift

more co2, less oxygen, helps make hemoglobin more efficient. co2 concentration affects how attracted oxygen is to hemoglobin

hemoglobin

plays small role in co2 transportation and assists in buffering blood

adaptations for animals that live underwater

a lot of blood

stockpile oxygen and use it slowly, can store oxygen in muscles in myoglobin proteins

change buoyancy to glide

route blood to vital tissues

derive ATP in muscles from fermentation once oxygen is depleted