Please enable JavaScript.
Coggle requires JavaScript to display documents.
Regulation in the Body (Circulation and Gas Exchange (Linking Exchange…
Regulation in the Body
Circulation and Gas Exchange
Blood Components
Plasma
Cells suspended in a liquid matrix
45% of blood is made up of cellular elements and the remainder is plasma
Ions and proteins dissolved in plasma aid in osmotic regulation, transport, and defense
Salts and proteins help as buffers against pH changes and maintains osmotic balance
Can also contain nutrients, metabolic waste, respiratory gases, and hormones
Cellular Elements
Leukocytes
5 types of White Blood Cells (WBCs)
Function: fight infection
Some are phagocytic
Lymphocytes - mount immune responses against foreign substances
Found outside of circulatory system, in interstitial fluid and lymphatic system
Platelets
Structural and molecular functions of blood clotting
Erythrocytes
Red Blood Cells (RBCs)
The highest amount of blood cells
Mature mammalian RBCs lack nuclei, leaving room for hemoglobin
Lack mitochondria and get ATP through anaerobic metabolism
1 RBC = 250mil hemoglobin = 1bil O2 molecules
Gas Exchange
Respiratory Surfaces
Tracheal Systems - Insects
Network of air tubes that branch throughout the body
Tracheae, kept open by rings of chitin, connect to external openings along insect's body surface
Moist epithelial lining allows for gas exchange at tips of the finest branches
Respiratory systems of insects consists of branched internal tubes
Air sacs are formed from enlarged portions of tracheae near organs that require large supplies of O2
Lungs - Vertebrates that Lack Gills
Localized respiratory organs subdivided into many pockets
Bridged by circulatory system, transports gases b/w lungs and rest of the body
Evolved both in organisms with an open circulatory system and vertebrates
Ex: spiders, land snails, frogs, humans
Amphibians rely heavily on gas exchange across skin, lungs only help a small amount
Most reptiles (except turtles) and all mammals depend entirely on lungs for diffusion of gases
Gills - Aquatic Animals
Outfoldings suspended in the water
Greater surface area than that of the entire body
Ventilation - mvmt of respiratory medium over respiratory surface
Ventilation occurs by moving gills thru water or water over gills
Ex: crayfish, lobsters, octopus, squids
Countercurrent exchange - exchange of substance or heat b/w two fluids flowing in opposite directions
Oxygen transfer occurs in gill capillaries, when water has higher P(O2) than blood
Blood Pressure and Flow Reflects Structure and Arrangement of Blood Vessels
Blood Vessel Structure and Function
Endothelium - single layer of epithelial cells lining central lumen
Capillaries, smallest blood vessels, allow for exchange of substances b/w blood and interstitial fluid
Arteries and veins have two walls made up of two tissue layers around endothelium, outer layer made of connective elastic fibers and collagen and inner contains smooth muscle and elastic fibers
Arterial walls are thick, strong, and elastic, accommodating for blood pumped at high pressure by heart
Smooth muscles direct path of bloodflow, signaled by nervous system or circulating hormones
Blood Pressure
Generated by contraction of a ventricle
Site of highest pressure = arteries
Changes in Blood Pressure
systolic pressure - highest arterial BP when heart contracts during ventricular systole
pulse - spike in BP that stretches walls of arteries
diastolic pressure - Lower BP when ventricles are relaxed
Regulation of BP
vasoconstriction - increases BP upstream in arteries: smooth muscles in arterial walls contract and arterioles narrow
vasodilation - BP in arteries fall due to relaxation of smooth muscles and increase in diameter of arterioles
Nitric oxide (NO) induces vasodilation and endothelin (peptide) induces vasoconstriction
Signals from nervous and endocrine system regulate prod. of NO and endothelin
Gravity and its Effects on BP
For normal, healthy 20 yr old: 120/70
Diastolic BP can
NEVER
be higher than systolic
Head is above chest when standing (duh), thus arterial BP in brain is less than BP in heart
When fainting, nervous system detects BP in brain is below necessary levels, causing body to collapse and the brain to be at same level as heart
Lymphatic System
lymph - recovered fluid
Lymph circulates in lymphatic system before draining into large pair of veins of CV system at base of neck
Lost fluid and proteins from capillaries to tissues are recovered and returned to blood
Linking of CV and lymphatic system completes recovery of lost fluid
Disruptions in mvmt of lymph results in fluid accumulation = edema
lymph nodes - filters lymph, important in body defense system
WBCs within lymph nodes multiply rapidly when body is fighting infection
Breathing
In Humans
Regulated by medulla oblongata
Bicarbonate buffer system regulates pH of blood due to CO2 levels
Inhalation and exhalation of air
In Birds
Passes air over gas exchange surface in one direction
Positive Pressure Breathing
Parabronchi - sites of gas exchange
Passing of air thru entire system takes two cycles in inhaling and exhaling
Highly efficient, incoming fresh air doesn't mix w/ air that already went thru gas exchange
In Mammals
Negative pressure breathing - pulling air into lungs
Muscle contractions expand thoracic cavity, lowering pressure in lungs and pulling in air
Diaphragm - skeletal muscle that forms bottom wall of chest cavity
Passive exhalation
Tidal Volume - volume of air inhaled and exhaled with each breath
Vital Capacity - tidal volume during maximal inhalation and exhalation
Residual Volume - remaining air after forced exhalation
Later in life, lungs lose resilience and residual volume increases and vital capacity decreases
Contracting rib muscles pulls ribs upward and sternum outward
In Amphibians
Positive Pressure Breathing - ventilation due to forced air flow
Muscles lower floor of oral cavity, nostrils and mouth close, oral cavity floor rises and forces air down trachea
Exhalation occurs by recoil of lungs and compression of muscular body wall
Heart Contraction = Double Circulation
Mammalian Heart and Circulation
Most blood that enters atria flows in the ventricles while chambers are relaxed
Rest of blood transferred by contraction of the atria before ventricles contract
Atria have thinner walls than ventricles, ventricles contract more forcefully
Cardiac cycle - one complete sequence of pumping and filling (contraction and relaxation)
systole - contraction phase
diastole - relaxation phase
cardiac output - volume of blood each ventricle pumps per min
stroke volume- amount of blood pumped by ventricle per contraction
heart rate - # beats per min
Avg. stroke volume in humans = 70mL
AV valve lies b/w each atrium and ventricle, anchored by strong fibers
Semilunar valves are located at two exits of heart: pulmonary artery and where aorta leaves the left ventricle
Maintaining Heart Beat
Autorhythmic cells - can contract and relax w/o signals from nervous system
Sinoatrial (SA) node - group of AR cells in wall of R. atrium, near where superior vena cava enters the heart, also called pacemaker; sets rate and timing of all cardiac muscle contractions
ECG - measures electrical impulses produced by SA node
Impulses from SA node spread thru walls of atria, relayed at AV node, delayed then passes to heart apex and spread throughout ventricles
Atrioventricular (AV) node - AR cells located in wall b/w L and R atria, relay point for impulses sent from SA node
Linking Exchange Surfaces
Gastrovascular Cavities
functs in distribution of substances and digestion
Fluid bathes inner and outer layer tissues - for exchange and cellular waste
Cells lining cavity have direct access to nutrients
Circulatory Systems
Three main parts: fluid, interconnecting vessels, and muscular pump (heart)
Open Circulatory System
Hemolymph,
interstitial fluid
bathes body cells
Ex: anthropods and some mollusks
Heart pumps hemolymph through vessels into spaces
surrounding
organs
Relaxation of heart sucks hemolymph back
Exchange of gas and chemicals occurs in sinuses
Body mvmt helps circulate hemolymph
Lower hydrostatic pressures in open circ. sys. requires less energy
Spiders use hydrostatic pressure to extend legs
Closed Circulatory System
Chemical exchange occurs between blood and interstitial fluid (also interst. fl. and body cells)
Ex: annelids, cephalopods, and all vertabrates
Blood in vessels, pumped to large vessels that branch into smaller ones to access organs and tissues
Benefits: higher BP = efficient O2 and nutrient transfer
diffusion - mvmt of molecules
Organization of Vertebrate Circulatory Systems
Capillaries - microscopic vessels w/ very thin & porous cell walls
Arterioles - branched arteries within organs
Arteries - blood from heart to organs
Capillary beds - network of capillaries within tissues, passing w/in a few cell diameters of every cell in body
Venules - "downstream end" of capillaries
Veins - blood back to heart
Portal veins carry blood b/w pairs of capillary beds
Atria - receives blood entering heart
Ventricles - pumps blood out of heart
Single Circulation
Blood travels in a single circuit (returns to starting point)
Two chambered heart, atrium and ventricle
Blood collects in atrium before transferring to ventricle
Ventricle contracts blood to capillary beds in gills, net diffusion of O2 in blood and CO2 out
When blood flows thru capillary bed, drop in BP limits blood flow but mvmt of muscles help keep BP up
Double Circulation
Two circuits of blood flow, pulmonary (or pulmocutaneous) and systemic circuit
Pulmonary (or pulmocutaneous) circuit - right side pumps O2 poor blood to cap. beds of gas exchange tissues
Systemic circuit - left side pumps O2-enriched blood from GE tissues to cap beds in organs and tissues throughout body
Heart repressurizes blood after passing through cap beds of lungs or skin
Amphibian hearts have 2 atria and 1 ventricle, ridge in ventricle helps it breath underwater
Mammalian hearts have two atria and two divided ventricles, left receives and pumps oxygenated blood while right does with oxygen-poor blood
Osmoregulation and Excretion
Diverse Excretory Systems
Filtrate - Water and small solutes that form a solution
Reabsorption - recovers useful molecules and water from filtrate and returns it to body fluid
Filtration - driven by hydrostatic pressure, body fluid comes in contact with a semipermeable membrane
Secretion - occurs by active transport, pumping determines whether water moves by osmosis in or out of solute
Protonephridia
Network of dead-end tubules branched throughout body
Flame bulbs cap branches, consists of tubule cell and cap cell (has tuft of cilia projecting into tubule)
Beating of cilia draws water and solutes from interstitial fluid through flame bulb, releasing filtrate into tubule network
Filtrate moves thru tubules and empties as urine via external openings
Ex: rotifers, some annelids, mullosc larvae, and lancelets
In freshwater flatworms, production helps balance osmotic uptake of water
Metanephridia
Excretory organs that collect fluid directly from coelom
Immersed in coelomic fluid and covered by capillary network
Ciliated funnel surrounds internal opening of each metanepridium, cilia beats and fluid drawn into collecting tubule
Storage bladder opens to outer surface
Earthworms living in damp soil produce hypoosmotic filtrate (dilute urine), and excretes N. wastes to environment
Ex: most annelids
Malpigian Tubules
Removes N. wastes and function in osmoregulation
Extend from dead-end tips floating in hemolymph to openings to digestive tract
Transport epithelium secretes solutes from hemolymph to lumen of tubule
N. wastes eleminated as nearly dry matter with feces
Conserves water effectively
Ex: insects and terrestrial anthropods
Kidneys
Functions in both osmoregulation and excretion
Consists of tubules, highly organized and work like network of capillaries
Nonsegmented
Ex: vertebrates and some chordates
Include ureter, urinary bladder, and urethra
Outer renal cortex and inner renal medulla; tubules packed inside carry and process filtrate
Remaining fluid leaves as uring in inner renal pelvis, exiting kidney via ureter
Nephrons and its Function
Two types: cortical and juxtamedullary nephrons
Cortical nephrons - reach only short distance into medulla; 85% of all nephrons
Juxtamedullary nephrons - production of hyperosmotic urine, helps conserve water
glomerulus - ball of capillaries off of long tubule
Bowman's capsule - cup-shaped swelling that covers glomerulus
distal tubule - helps refine filtrate and empties it into collecting duct
Proximal tubule - portion of nephron downstream from Bowman's capsule, helps refine filtrate
peritubular capillaries - tiny blood vessels forming a network around proximal and distal tubules
loop of Henle - hairpin turn, with descending and ascending limb, aids in water and salt reabsorption
vasa recta - hairpin-shaped capillaries that serve renal medulla, serves loop of Henle
Nitrogenous Waste
Urea
Product of energy-consuming metabolic cycle: combines NH3 and CO2 in liver
CH4N2O
Low toxicity but uses lots of energy to produce
Animals that go from living in water to land go from excreting ammonia to excreting urea
Ex: frogs and many amphibians
Uric Acid
C5H4N4O3
Relatively nontoxic and doesn't really dissolve in water
Excreted as semisolid paste with little water loss
More expensive energetically than urea, uses considerable amounts of ATP for synthesis
Ex: insects, land snails, and many reptiles
Gout in humans is caused by deposits of uric acid crystals
Gout also evident in T. rex
Ammonia
NH3
Animals that excrete NH3 need lots of water
Common in aquatic species
In invertebrates, ammonia release occurs across entire body surface
Nitrogenous Wastes and Evolution
Type and amount of nitrogenous waste depends on environment
Terrestrial turtles excrete mainly uric acid and aquatic turtles excrete urea and ammonia
Amount of nitrogenous waste also depends on energy budget and diet
Endotherms eat more food and produce more N. waste than ectotherms
Predators get energy from protein and excrete more N. waste than an animal that rely on lipids or carbs for energy
Osmosis
Mvmt of water across a semipermeable membrane
Osmoregulation - processes an organism goes through to control solute concentration and balancing water losses and gains
Osmolarity - moles of solute per liter of solution
Marine Animals
Most marine invertebrates are osmoconformers, same osmolarity as seawater
Actively transport
specific
solutes that est. lvls in hemolymph different than those in ocean
Osmoregulatory marine vertebrates have two strategies: balancing water loss by drinking lots of seawater and trimethylamine oxide
Drinking seawater, salts are eliminated thru gills and kidneys
High concentration of urea can denature proteins, but sharks produce TMAO protecting proteins from denaturing
Combination of TMAO, salts, urea, and compounds results in higher solute concentration: water slowly
enters
shark body thru osmosis and food
Ex: cod and other "bony fishes"
Ex: marine sharks and other chondrichthyans (cartilaginous fish)
Freshwater Animals
Body fluids of freshwater animals are hyperosmotic (higher salt concentration
Issue is
gaining
water through osmosis
Water balance relies on excreting large amounts of diluted urine and drinking almost no water
Salt lost by diffusion is gained again by eating and salt uptake in gills
Ex: perch and bony fish
Salmon migrate between freshwater and sea water
In freshwater: osmoregulate and in ocean: produce more cortisol, increasing number and size of salt-secreting cells and osmoconforms
Osmoconformer - to be isoosmotic with surroundings
Osmoregulator - control internal osmolarity independent of external conditions
