LEC 4 circulatory system

what does circulatory system do

LINKS exchange surfaces with cells throughout body

what is a gastrovascular cavity and which animals have this

-central cavity that serves as TWO-WAY DIGESTIVE TRACT with SINGLE OPENING for food intake/waste reoval, while also facilitating circulation of nutrients/fluid in body

-this incomplete digestive system lacks mouth/anus. relies on single opening and diffusion of nutrients (body wall enclosing cavity is only 2 cells thick)

-small/thin animals like cnidarians (jellyfish, hydra) and flatworms

-in these animals, cells can exchange materials directly with surrounding medium

list the 5 primary functions of circulatory system

1. TRANSPORT oxygen/nutrients

2. TRANSPORT signaling molecules (like hormones) n immune cells

3. REMOVE CO2/waste

4. PROTECTION

5. REGULATE BODY TEMP (by control blood flow to skin by vasodilation (widen blood vessels) and vasoconstriction (narrow blood vessels)

what 3 basic components does any circulatory system have

-a circulatory fluid

-blood vessels (a set of tubes)

-a muscular pump (heart)

4 examples of circulatory fluid

-Interstitual fluid (extracellular fluid that bathes cells/tissues, delivering nutrient/collecting waste)

-Blood (circulates in closed circulatory system)

-Lymph (circulates in secondary system of vertebrates called lymphatic system)
-Hemolymph (MIX OF BLOOD AND INTERSTITUAL FLUID that circulates in open circulatory system)

what animals have open circulatory system? what is the blood like? what is a hemocoel?

arthropods, insects, spiders, scorpions, bivalves, snails

-blood flow FREELY in cavities and directly bathe organs (not in vessels)

-blood pumped into cavity called Hemocoel where blood mixes with interstitual fluid (=hemolymph)

what does hemolymph do as animal moves and heart beats?

hemolymph circulates to BATHE ORGANS (supply O2/nutrients and remove cellular waste) within hemocoel and re-enter heart

open circulatory system is more ideal for animals with _____. why?

lower metabolic rates (less active in processes like locomotion/digestion/respiration) b/c LESS NEED FOR O2

-blood pressue remains low (absence of smooth muscles needed to contract vessels) = means oxygen take longer to reach body cells in extremities (not problem for small animals b/c shorter distance to reach cells)

compare the heart in closed vs open circ system

open: sac-like or tubular heart (has OSTIA(lateral openings) which close when heart contracts and open when heart relax)

-called “suction pumps”

-beating rhythm predonimantly set thru nerve impulses (neurogenic hearts - nerve starts the beat)

closed: chambered hearts have muscular VENTRICLES that pump blood in body with pressure

-called “pressure pumps”

-rhythm predominantly set in specialized neuromyocardial cells WITHIN heart (myogenic hearts - muscle starts the beat - because contracts produced spontaneously without stimulation from nerve cells)

animals with closed ccirculatory system? what does blood not come in contact with in closed syst. how does blood flow? ideal for animals with? why?

-ALL VERTEBRATES (mammal, fish, bird/reptile, amphibian) and some invertebrates like earthworms, octopus/squid

-blood flow one direction in vessels and seperate from interstitual fluid (dont touch tissue directly)

-ideal for animals with HIGHER metabolic rates b/c LARGER NEED FOR OXYGEN (blood pressure remains high, means oxygen takes shorter time to reach body cells)

advantages and disadvantages of open and closed circulatory systems

OPEN:

ADVTG:

1. require less energy (to distribute fluid)

2. animals less vulnerable to pressure

3. less O2 needed (b/c org sustain themself w/ low metabolic rate

DISADVTG:

1. less efficient to move O2/nutrients (not ideal for large org)

2. LOW BP (blood pressure) = harder to reach extremities in large org

3. limited capability to increase/decrease distribution/velocity of blood flow (if changes needed)

4. slower movement/weak adaptability to new enviro (b/c low metabolic rate)

CLOSED:

ADVTG:

1. more efficient to move O2/nutrients to tissues/cells

2. provide more POWER in form of pressure so blood reach all extremities of body

3. efficient distribution of antibody, stronger immune responses

4. MORE CAPABILITY to inc/dec distro/velocity of blood flow

5. FASTER movement/better adaptability due to higher metabolic rates

DISADVTG:

1. REQUIRE MORE ENERGY (heart must work harder to pump blood faster to reach destination quickly)

2. severe injury to large vessel can cause rapid blood loss

3. high-pressure system can get physical strain and blockages/blood clots in vessels = health complications

compare single vs double circulation, and examples of animals

SINGLE CIRCULATION

-blood pass thru heart ONCE on each loop around body

-bony fish, rays, sharks

DOUBLE CIRCULATION

-blood pass thru heart TWICE on each loop around body

-maintains HIGH blood pressure in organs

-deoxygenated and oxygenated blood pumped seperatley from right/left sides of heart

-mammals, amphibians, reptiles

describe heart and blood path of bony fish, rays, sharks

-single circulation with 2 chambered heart (1 atrium, 1 ventricle)

-blood enter heart via thin walled chamber: sinus venosus

-in bony fish: blood leave heart via bulbus arteriosus

-in sharks/rays: blood leaves heart via conus arteriosus

which animals with double circulatory system use pulmocutaneous vs pulmonary circuit and describe each. and whats the circuit where oxygenated blood flow.

AMPHIBIANS - deoxygenated blood flow thru Pulmocutaneous circuit (pick up O2 thru LUNGS and SKIN)

REPTILE/MAMMALS - deoxygenated blood flow thru Pulmonary circuit (pick up O2 thru LUNGS)

-oxygenated blood deliver O2 thru Systemic circuit

whats atria and ventricle

atria - upper chamber (recieve blood returning to heart)

ventricle - lower chamber (pump blood out heart into arteries)

how many atria, ventricles, and full/partial/no septum and is there mixing of oxygenated/deoxygenated blood? for amphibians, reptiles (turtle/lizard)(and what 3 sections their septum divide into), crocodilian reptiles (croc/alligator) (and what special feature), mammals/birds, fish

-AMPHIBIANS: 2 atria, 1 ventricle (no septum), Yes some mixing

-REPTILES (turt/liz): 2 atria, 1 ventricle (divided by partial septa into 3 sub-chambers: cavum pulmonale, cavum arteriosum, cavum venosum), even less mixing than amphibians

-CROC REPTILES: 2 atria, 2 ventricles (complete septum seperates them, but still some mixing between left/right aortas but no mixing in heart) (faramen of Panizza- small opening (valve-like) at base of right and left aortas)

-MAMMALS/BIRDS: 2 atria, 2 ventricles (complete septum, NO MIXING)

whats an advantage of amphibians circulation type? what does sinus venosus and pulmonary vein do? what 2 special features they have?

-recall amphibian: closed double circulatory syst, 2 atria recieve blood from 2 diff circuits: pulmocutanous and systemic, then some blood mixing in their ONE ventricle

-advantage: their one ventricle pump blood into a forked artery that splits output into both circuits, good because redirect blood to skin instead of lungs when underwater

-sinus venosus BRING DEOXYGENATED BLOOD from body into RIGHT atrium

-pulmonary vein BRING OXYGENATED BLOOD from lung/skin into LEFT atrium

-conus arteriosus: ventricle pumps blood via this into both circuits

-SPIRAL FOLD: flap-like structure in conus arteriosus: 1. minimize mixing of oxy and deoxy blood 2. helps direct oxygenated blood to systemic circuit and deoxygenated blood to pulmocutaneous circuit

in mammals/birds, which side of heart recieves/pumps oxygenated vs deoxygenated blood

left side: oxygenated blood

right side: deoxygenated blood

3 main types of blood vessels? for arteries and vein, whats the exception that carries deoxy blood

1. arteries (blood flow away from heart)(mostly oxygenated blood, exception is pulmonary artery)

2. veins (blood flow TO heart (mostly deoxygenated blood, exception is pulmonary vein)

3. capillaries (exchange O2, CO2, nutrients, waste between blood and tissues)

what do arteries branch into? where do these carry blood to? what are capillary beds

arteries branch into arterioles and carry blood to capillaries

-capillary beds: networks of capillaries, sites of exhance of gases/nutrients

____ converge into veins and return blood from ____ to heart

Venules converge into veins and return blood from capillaries to heart

describe 3 layers of blood vessel wall structure

1. inner layer: Tunica intima (vascular endothelium is inner lining (provide frictionless path for blood), and is supported by an internal elastic membrane) -however, NO internal elastic memb in veins!!! b/c veins are low-pressure capacitance so no need to stretch/recoil like arteries, instead, veins designed for higher compliance (stretch to hold blood without recoil)

2. middle layer: Tunica media (made of smooth muscle + elastin) and controls vasoconstriction/vasodilation (NO external elastic memb in veins)

3. outer layer: Tunica externa (or adventitia) (made of collagen fibers to support/shape vessel)

-also contains vasa vasorum (tiny blood vessels) and nervi vasorum (small nerves)

list differences between artery and vein

artery:

-under HIGH bp

-THICK wall

-blood flow AWAY from heart

-most arteries contain OXYGENATED blood

-blood move 1 direction due to HIGH BP and smooth muscle contraction

-DEEPER IN BODY

-SMALLER LUMEN (help maintain high bp)

vein:

-under LOW bp

-THIN wall (contribute to high compliance (can stretch to hold high pressure of blood)

-blood flow TO heart

-most veins contain DEOXYGENATED blood

-blood move 1 direction due to ONE-WAY VALVES, smooth/skeletal muscle contraction

-NEAR SURFACE OF SKIN (superficial)

-LARGER LUMEN

in inner layer of blood vessel (tunica intima), describe endothelium appearance in veins vs arteries

aarteries: WAVY/pleated endothelium (due to more contraction of smooth muscles)

veins: SMOOTH endothelium

in veins vs arteries, which layer thickest? and why? what is each layer called again

ARTERIES: tunica MEDIA thickest (to withstand high bp and maintain vessel shape) (recall media layer for vasoconstrict/dilate)

VEINS: tunica externa thicker than media (media thin) b/c less smooth muscle reduce rigity of vein wall = contribute to higher compliance of veins) cause recall media made of smooth muscle

-also externa thickes because: 1. prevent wall from collapse under low bp 2. protect from damage since veins are superfically located in body (near surface)

whats the smallest blood vessel? whats their epithelium layer and shape and why is this good?

CAPILLARY

-simple squamous endothelium (easy for exchange between blood and interstitual fluid)

where in capillaries does exchange of substances take place? what drives fluids in/out capillaries and at which ends

-take place across THIN EDOTHELIAL WALLS of capillaries

-difference between blood pressure and osmotic pressure drives fluids out capillaries at arterial end and drives fluids into capillaries at venous end

-bp associated with pressure pushing on walls of capillaries (not constant throughout capillary)

-osmotic pressure assiciated with water movement (constant) from hypotonic enviro (interstitual fluid) to hypertonic enviro (blood)

what is bulk flow and whats the formula

Bulk flow of fluid occurs when EXTERNAL FORCE applied to FLUID, setting it in motion

law of bulk flow: Q = delta P/R

where Q=flow rate (L/min) and P=pressure gradient (perfusion pressure, NOT transmural pressure) and R=resistance

what 3 factors affect resistance in circulatory system