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Chapter 42 & 44 (Chapter 42: Circulation and Gas Exchange (42.1:…
Chapter 42 & 44
Chapter 42: Circulation and Gas Exchange
Descriptions of types of hearts
Double circulation: Amphibian
some mixing of the blood in the heart’s ventricle, which reduces the efficiency of oxygenation
two atria receive blood from the two different circuit (lungs and the systems)
two atria and one ventricle
The mixing is mitigated by a ridge within the ventricle that diverts oxygen-rich blood through the systemic circulatory system and deoxygenated blood to the pulmocutaneous circuit
Single circulation: Fish
The heart pumps deoxygenated blood to the gills where it gets oxygenated
Oxygenated blood is then supplied to the entire fish body, with deoxygenated blood returned to the heart
Double circulation: Mammals
6.) Aorta, which conveys blood to arteries leading throughout the body to
1.) The right ventriclepumps blood to the lungs via
2.) the pulmonary arteries. As the blood flows through
3.) capillary beds in the left and right lungs, it loads O2 and unloads CO2 to pulmonary veins
4.) To the left Atrium of the heart to the
5.) Heart's left ventricle, which pumps the oxygen-rich blood outs to the body tissues through the systemic circuit to the
7.) Capillary beds in the head and arms (forelimbs) to
8.) Capillary beds in the abdominal organs and legs (hind limbs)
9.) Oxygen-poor blood from the head, neck, and forelimbs is channeled into a large vein the superior vena cava.
10.) Another Inferior vena cava from from lower parts of the body
11.) The two vena cava empty their blood into the right atrium
42.1: Circulatory systems link exchange surfaces with cells throughout the body
Open and Closed Circularity Systems
Heart
powers circulation by using metabolic energy to elevate the circulatory fluid's hydrostatic
Closed Circulatory system
have the blood closed at all times within vessels of different size and wall thickness
Blood
the red liquid that circulates in the arteries and veins and carrying oxygen to and carbon dioxide from the tissues of the body
Open Circulatory system
pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells
Hemolumph
a fluid equivalent to blood in most invertebrates, occupying the hemocoel.
Single Circulation
Ex.) Sharks, rays, and bony fishes
Have a heart that consist of an atrium and a ventricle
Blood that leaves the heart passes through two capillary beds throughout the body.
Double Circulation
Ex.) Amphibians, reptiles, and mammals
the pumps of for the two circuits are combined into a single organ, the heart
Provides a flow of blood to the brain, muscles, and other organs. The heart repressures the blood after it passes through the capillary beds of the lungs or skin
Veins
the vessels that carry blood back to the heart
Arteries
Carry blood from the heart to organs throughout the entire body
Veins
Capillaries
any of the fine branching blood vessels that form a network between the arterioles and venules
42.3: Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels
Blood Vessel Structure and Function
Endothelium
defined as a central lumen (cavity) for blood vessels
Blood flow velocity
Blood travels 500 times more slowly in the capillaries than in the aorta
Blood slows as it moves from arteries to arterioles to the much narrower capillaries
After passing through the capillaries, the blood seeds up as it enters the venules and veins
Capillary Function
are the smallest blood vessels in the body, connecting the smallest arteries to the smallest veins
play the central role in the circulation
delivering oxygen in the blood to the tissues
picking up carbon dioxide to be eliminated
Blood Pressure
Regulation of Blood Pressure
Vasoconstriction
it increases blood pressure upstream in the arteries
Vasodilation
an increase in diameter that causes blood pressure in the arteries to fall
Blood Pressure and Gravity
Blood pressure is generally measured for an artery in the arm at the same height as the heart
Gravity is also a consideration for blood flow in veins, especially those in the legs
Changes in Blood Pressure during the cardiac cycle
Pulse
the rhythmic bulging of the artery walls with each heartbeat
Systemic pressure
Arterial blood pressure is highest when the heart contracts during ventricular systole
Fluid Return by the Lymphatic System
Lymphatic system
a network of tissues and organs that help rid the body of toxins, waste and other unwanted materials
Lymph nodes
are small glands that filter lymph, the clear fluid that circulates through the lymphatic system
Lymnph
a system composed of lymph vessels and intervening lymph nodes
42.4: Blood Composition and Function
Blood Composition and Function
Plasma
the colorless fluid part of blood, lymph, or milk, in which corpuscles or fat globules are suspended
Cellular Elements
Erythrocytes
a red blood cell that (in humans) is typically a biconcave disc without a nucleus
Hemoglobin
imparts the red color to blood, and transport oxygen and carbon dioxide to and from the tissues
Sickle-cell disease
an abnormal form of hemoglobin polymerizes into aggregates
Leukocytes
a white blood cell and functions to fight infections
Platelets
a small colorless disk-shaped cell fragment without a nucleus
Blood Clothing
Thrombus
a blood clot formed in situ within the vascular system of the body and impeding blood flow
42.2: Coordinated cycles of heart contraction drive double circulation in mammals
Maintaining the Hearts Rhythmic Beat
Sinoatrial node
a small body of specialized muscle tissue in the wall of the right atrium of the heart that acts as a pacemaker by producing a contractile signal at regular intervals
Atrioventricular node
It electrically connects the atria and ventricles
Electrocardiogram
a record or display of a person's heartbeat produced by electrocardiography
The Mammalian Heart: A Closer Look
Cardiac cycle
defined as the complete sequence of pumping and filling blood
Systole
defined as the contraction phase of rhythmic cycle
2 Factors determine cardiac output
Heart rate
defined as the rate of contraction
Stroke volume
defined as the amount of blood pumped by a ventricle in a single contraction
Cardiac output
defined as the volume of blood each ventricle pumps per minute
Diastole
defined as the relaxation phase of rhythmic cycle
Atrioventricular valve
lies between each atrium and ventricle
Semilunar valves
are pushed open by the pressure generated during contraction of the ventricles
Heart murmur
a sound of blood flowing through the heart, due to anything from healthy heart exertion during exercise to a diseased heart valve or other abnormality.
42.5: Gas Exchange occurs across specialized respiratory surfaces
Tracheal Systems in Insects
defined as a network of air tubes that branch throughout the body
Gills in Aquatic Animals
Ventilation
maintains the partial pressure gradients of 02 and CO2 across the gill that are necessary for gas exchange
Countercurrent exchange
the exchange of a substance or heat between two fluids flowing in opposite directions
Mammalian Respiratory Systems: A Closer look
Larynx
an air passage to the lungs and holding the vocal cords in humans and other mammals
Trachea
extending from the larynx to the bronchial tubes and conveying air to and from the lungs
Bronchi
extensions of the windpipe that shuttle air to and from the lungs
Bronchioles
any of the minute branches into which a bronchus divides
Alveoli
any of the many tiny air sacs of the lungs which allow for rapid gaseous exchange
Surfactant
it coats the aveoli and reduces surface tension
42.6: Breathing Ventilates
Positive pressure breathing
Lets birds force air down the trachea
Diaphragm
a sheet of skeletal muscle that forms the bottom wall of the cavity
Negative pressure breathing
In mammals, pulls air into the lungs when the rib muscles and diaphragm contract
Ch. 44: Osmoregulation and Excretion
44.1: Osmoregulation balances the uptake and loss of water and solutes
Osmoregulatory Challeges and Mechanisms
Osmoconformer
defined as to be osoosmotic with its surroundings
Osmoregulator
to control internal osmolarity independent of that of the external environment
Osmosis and Osmolarity
Osmolarity
the concentration of a solution expressed as the total number of solute particles per liter.
Freshwater vs. Marine animals
Marine Animals
2 Osmoregulatory strategies
Bony fish constantly loses water by
osmosis
.
Trimethylamine oxide (TMAO):
TMAO protects proteins from the denaturing effect of urea
function as osmoregulation for sharks
they actively transport specific solutes that establish levels in hemolymph different from those in the ocean
most marines are osmoconformers
Freshwater Animals
they face the problem of gaining water by osmosis
the body fluids of freshwater animals must be hyperosmotic
water balance relies on excreting large amounts of very dilute urine and drinking almost no water
44.2: An animal's nitrogenous wastes reflect its phylogeny and habitat
Uric Acid
is relatively nontoxic and does not readily dissolve in water
Ex.) Birds, and many other reptiles, insects, land snails
It can be excreted as a semisolid paste with very little water loss
Ammonia
ammonia excretion is most common in aquatic species
Ex.) Most aquatic animals, including most body fish
in many invertebrates, ammonia release occurs across the whole body surface
Urea
in vertebrates, urea is the product of an energy-consuming metabolic cycle that combines ammonia with carbon dioxide in the liver
advantage for urea in nitrogenous waste excretion is very low toxicity
Ex.) Mammals, most amphibians, sharks, some bony fish
*
44.3: Diverse excretory systems are variations on a tubular theme
**
Protinephridia
consists of a network of dead-end tubules that branch throughout the body
they are found in rotifers, some annelids, mollusc larvae, and lancelets
Ex.) Flatworms
Malpighian tubules
Water follows the solutes into the tubule by osmosis.
Ex.) Insects and other Terrestrial arthropods
remove nitrogenous wastes and that also function in osmoregulation
Metanephridia
defined as excretory organs that collect fluid directly from the coelom
Ex.) most annelids, such as earthworms
they are immersed in coelomic fluid and enveloped by a capillary network
Kidneys
functions in both osmoregulation and excretion
vertebrate excretory system includes ducts and the other structures that carry urine from the tubules out of the kidney and, eventually, the body
Vertebrate kidneys are typically nonsegmented
Parts of a Nephron
Glomerulus
Small blood vessels, in particular a cluster of capillaries around the end of a kidney tubule, where waste products are filtered from the blood.
Bowman's Capsule
a cup-like sack at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine.
Peritubular Capillaries
tiny blood vessels that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron.
Collecting Duct
a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.
Proximal Tubule
the segment of the nephron in kidneys which begins from the renal pole of the Bowman's capsule to the beginning of loop of Henle
Loop of Henle
a part of a kidney tubule which forms a long loop in the medulla of the kidney, from which water and salts are resorbed into the blood.
Distal Tubule
is a portion of kidney nephron between the loop of Henle and the collecting tubule.
Vasa Recta
the capillary networks that supply blood to the medulla, are highly permeable to solute and water.
44.5: Hormonal circuits link kidney function, water balance, and blood pressure
Aquaporin
are integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane
Juxtaglomerular apparatus
its main function is to regulate blood pressure and the filtration rate of the glomerulus
Aldosterone system
a hormone system that regulates blood pressure and fluid and electrolyte balance, as well as systemic vascular resistance
Atrial Natriuretic peptide
causing a reduction in expanded extracellular fluid (ECF) volume by increasing renal sodium excretion
Renin-angiotensin
a hormone system that regulates blood pressure and fluid and electrolyte balance, as well as systemic vascular resistance
The nephron is organized for stepwise processing of blood filtration
Loop of Henle
the part of a kidney tubule which forms a long loop in the medulla of the kidney, from which water and salts are resorbed into the blood
Proximal tubule
selective secretion and reabsorption alter filtrate volume and composition
Renal Medulla
the filtering of waste materials and elimination of fluid from the body
Countercurrent multiplier system
the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.