AP Biology: 42 Circulatory Flashcards
Transport systems
Functionally connect the organs of exchange with the body cells
Most complex animals =internal transport systems
Exchange fluids between organs and outside environment
More complex animals
Have one of two types of circulatory systems: open or closed
Both of these types of systems have three basic components
A circulatory fluid (blood)
A set of tubes (blood vessels)
A muscular pump (the heart)
In insects, other arthropods, and most molluscs
Blood bathes the organs directly in an open circulatory system
CLOSED CIRCULATORY SYSTEMS
Blood is confined to vessels and is distinct from the interstitial fluid
More efficient at delivering oxygen to cells
Humans and other vertebrates have
a closed circulatory system
Often called the cardiovascular system
Blood flows in a closed cardiovascular system
Consisting of blood vessels and a two- to four-chambered heart
Arteries
carry blood away from heart
Thicker walls due to increased pressure of pumping from heart
Veins
Return blood to the heart
Capillaries
Thin tubules that reach all tissues. Exhange materials with the tissues
Thin walls facilitates diffusion easier
A fish heart has
has two main chambers
One ventricle and one atrium
Blood pumped from the ventricle
Travels to the gills, where it picks up O2 and disposes of CO2
Frogs and other amphibians
Have a three-chambered heart, with two atria and one ventricle
The ventricle pumps blood into a forked artery
That splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit
Reptiles have
double circulation
With a pulmonary circuit (lungs) and a systemic circuit
Turtles, snakes, and lizards
Have a three-chambered heart
In all mammals and birds
The ventricle is completely divided into separate right and left chambers
The left side of the heart pumps and receives only oxygen-rich blood
While the right side receives and pumps only oxygen-poor blood
A powerful four-chambered heart
Was an essential adaptation of the endothermic way of life characteristic of mammals and birds
The structure and function of the human circulatory system
Can serve as a model for exploring mammalian circulation in general
A closer look at the mammalian heart
Provides a better understanding of how double circulation works
A region of the heart called the
the sinoatrial (SA) node, or pacemaker Sets the rate and timing at which all cardiac muscle cells contract
Impulses from the SA node
Travel to the atrioventricular (AV) node
At the AV node, the impulses are delayed
And then travel to the Purkinje fibers that make the ventricles contract
The pacemaker is influenced by
Nerves, hormones, body temperature, and exercise
Cardiovascular diseases
Are disorders of the heart and the blood vessels
Account for more than half the deaths in the United States
One type of cardiovascular disease
atherosclerosis
Is caused by the buildup of cholesterol within arteries
Hypertension
high blood pressure
Promotes atherosclerosis and increases the risk of heart attack and stroke
A heart attack
Is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries
A stroke
Is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head
GAS EXCHANGE SURFACES
Supplies oxygen for cellular respiration and disposes of carbon dioxide
Animals require
large, moist respiratory surfaces for the adequate diffusion of respiratory gases
Between their cells and the respiratory medium, either air or water
Gills are
outfoldings of the body surface
Specialized for gas exchange
In some invertebrates
The gills have a simple shape and are distributed over much of the body
Many segmented worms have
flaplike gills
That extend from each segment of their body
The gills of clams, crayfish, and many other animals
Are restricted to a local body region
The effectiveness of gas exchange in some gills, including those of fishes
Is increased by ventilation and countercurrent flow of blood and water
The tracheal system of insects
Consists of tiny branching tubes that penetrate the body
The tracheal tubes
Supply O2 directly to body cells
Spiders, land snails, and most terrestrial vertebrates
Have internal lungs
A system of branching ducts
Conveys air to the lungs
In mammals, air
air inhaled through the nostrils
Passes through the pharynx into the trachea, bronchi, bronchioles, and dead-end alveoli, where gas exchange occurs
The process that ventilates the lungs is breathing
The alternate inhalation and exhalation of air
An amphibian such as a frog
Ventilates its lungs by positive pressure breathing, which forces air down the trachea
Mammals ventilate their lungs
By negative pressure breathing, which pulls air into the lungs
Lung volume increases
As the rib muscles and diaphragm contract
Besides lungs, bird have
eight or nine air sacs That function as bellows that keep air flowing through the lungs Air passes through the lungs In one direction only Every exhalation Completely renews the air in the lungs
The metabolic demands of many organisms
Require that the blood transport large quantities of O2 and CO2
Gases diffuse down
pressure gradients
In the lungs and other organs
Diffusion of a gas
Depends on differences in a quantity called partial pressure
A gas always diffuses
from a region of higher partial pressure
To a region of lower partial pressure
In the lungs and in the tissues
O2 and CO2 diffuse from where their partial pressures are higher to where they are lower
Respiratory pigments
Are proteins that transport oxygen
Greatly increase the amount of oxygen that blood can carry
The respiratory pigment of almost all vertebrates
Is the protein hemoglobin, contained in the erythrocytes
Like all respiratory pigments
Hemoglobin must reversibly bind O2, loading O2 in the lungs and unloading it in other parts of the body
Loading and unloading of O2
Depend on cooperation between the subunits of the hemoglobin molecule
The binding of O2 to one subunit induces the other subunits to bind O2 with more affinity
Cooperative O2 binding and release
Is evident in the dissociation curve for hemoglobin
A drop in pH
Lowers the affinity of hemoglobin for O2
Cells require a balance
Between osmotic gain and loss of water
Osmoconformers, (marine animals)
Are isoosmotic with their surroundings and do NOT regulate their osmolarity
Osmoregulators expend
energy to control water uptake and loss
In a hyperosmotic or hypoosmotic environment
Most invertebrates are
osmoconformers
Most marine vertebrates and some invertebrates are
osmoregulators
Bony fish
hypoosmotic to sea water
Loss of water by osmosis, gain salt via diffusion and food
Balance water loss by drinking sea water
FRESHWATER ANIMALS
Constantly take in water from their hypoosmotic environment
Lose salts by diffusion
Balance water
excrete large amounts of dilute urine
Replace salt with food and diffusion across gills
Land Animals Water Management
By drinking and eating moist foods and by using metabolic water
Desert animals
Get major water savings from simple anatomical features
NITROGEN WASTES COMPARISON
Are the nitrogenous breakdown products of proteins and nucleic acids
Ammonia
Animals that excrete nitrogenous wastes as ammonia
Need access to lots of water
Release it across the whole body surface or through the gills
The liver of mammals and most adult amphibians
Converts ammonia to less toxic urea
Urea is carried to the
the kidneys, concentrated
And excreted with a minimal loss of water
Insects, land snails, and many reptiles, including birds
Excrete uric acid as their major nitrogenous waste
Uric acid is largely insoluble
water
And can be secreted as a paste with little water loss
Type of waste is dependent on
an animal’s evolutionary history and habitat
The amount of nitrogenous waste produced
Is coupled to the animal’s energy budget
EXCRETORY SYSTEM BASICS
Structurally: Tubular component
Function: Regulate solute movement between internal fluids and the external environment
Produce urine by refining a filtrate derived from body fluids
Key functions of most excretory systems are
A protonephridium
Filtration, pressure-filtering of body fluids producing a filtrate
Reabsorption, reclaiming valuable solutes from the filtrate
Secretion, addition of toxins and other solutes from the body fluids to the filtrate
Excretion, the filtrate leaves the system
A protonephridium
Is a network of dead-end tubules lacking internal openings
The tubules branch throughout the body
And the smallest branches are capped by a cellular unit called a flame bulb
These tubules excrete a dilute fluid
And function in osmoregulation
Each segment of an earthworm
Has a pair of open-ended metanephridia; release dilute urine
In insects and other terrestrial arthropod
Remove nitrogenous wastes from hemolymph and function in osmoregulation
Allow water conservation; dry product
KIDNEYS= VETERBRATE MECHANISM OF REGULAITON
Functional Unit: Nephrons and associated blood vessels
Principal site of water balance and salt regulation
Each kidney
Is supplied with blood by a renal artery and drained by a renal vein
The mammalian kidney has two distinct regions
An outer renal cortex and an inner renal medulla
The nephron, the functional unit of the vertebrate kidney
Consists of a single long tubule and a ball of capillaries called the glomerulus
Filtration occurs as blood pressure
Blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman’s capsule
Nonselective filtration- has contents of blood that are not cellular
From Bowman’s capsule
the filtrate passes through three regions of the nephron
The proximal tubule, the loop of Henle, and the distal tubule
Fluid from several nephrons
Flows into a collecting duct
Nephron lined with transport epithelium
Reabsorbs solutes and water
Filtrate becomes urine
As it flows through the mammalian nephron and collecting duct
Secretion and reabsorption in the proximal tubule
Substantially alter the volume and composition of filtrate
Reabsorption of water continues
As the filtrate moves into the descending limb of the loop of Henle
The mammalian kidney
Can produce urine much more concentrated than body fluids, thus conserving water
Two solutes, NaCl and urea, contribute to the osmolarity of the interstitial fluid
Which causes the reabsorption of water in the kidney and concentrates the urine
Urea diffuses out of the collecting duct
As it traverses the inner medulla
Urea and NaCl
Form the osmotic gradient that enables the kidney to produce urine that is hyperosmotic to the blood
Antidiuretic hormone (ADH)
Increases water reabsorption in the distal tubules and collecting ducts of the kidney
The renin-angiotensin-aldosterone system (RAAS)
Is part of a complex feedback circuit that functions in homeostasis
Another hormone, atrial natriuretic factor (ANF)
Opposes the RAAS
