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Circulation and Gas Exchange/ Osmoregulation and Excretion (The Heart…
Circulation and Gas Exchange/
Osmoregulation and Excretion
Vocab
Arteries
Blood vessels that deliver oxyen-rich blood from the heart to the tissues of the body
Arterioles
Transports blood from arteries to capillaries
Venules
Allow blood to return to the veins
Veins
Carry oxygen-depleted blood toward the heart
Capillaries
Smallest of blood vessels
Transfer oxygen and nutrients from the bloodstream to other tissues in the body
Single Vs Double Circulation
Single Circulation
Blood passes through the heart once in each complete circuit through the body
Blood entering the heart collects in the atrium before transfer to the ventricle
Blood that leaves the heart passes through two capillary beds before returning to the heart - when blood flows through the capillary beds, blood pressure drops
Double Circulation
Pumps for the two circuits are combined into the heart and simplifies coordination of the pumping cycles
The right side of the heart delivers oxygen-poor blood to the capillary beds of the gas exchange tissues where oxygen moves IN and carbon dioxide moves OUT
called pulmonary circuit if capillary beds are in the lungs
called pulmocutaneous circuit if it includes capillaries in both the lungs and the skin (amphibians)
After the oxygen-rich blood leaves the gas exchange tissues, it enters the other pump, the left side of the heart
After exchanging the carbon dioxide and the oxygen, the blood returns to the heart and completes the systemic circuit
The Heart
Systole
The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries
Diastole
Phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood
Cardiac Cycle
Refers to the mechanical and electrical events that repeats with every heartbeat
Cardiac Output
The product of two variables: stroke volume and heartbeat
Heartbeat is the number of times a heart beats per minute while stroke volume is the amount of blood circulated by the heart with each beat
CO = SV X HR
ECG/EKG
Electrocardiograms that measure electrical activity and collect data on the health of your heart. Measures heart rate, stress, fatigue, heart age, breathing index, and mood
Bundle Branches - part of the electrical system of the heart. It directs the impulse to the left and right ventricles
Purkinje fibers are a unique cardiac end-organ. It receives conductive signals originating at the atrioventricular node and simultaneously activates the left and right ventriclces by directly stimulating the ventriclar myocardium
Sinoatrial node is a small boy of muscle tissues in the wall of the right atrium that acts as a pacemaker by producing a contractile signal at regular intervals
Atrioventricular node takes the signal from the SA node and then sends the electrical impulses from the atria to the ventricles
Artery Vs Vein
Arteries have thick, elastic, muscular walls
the thicker and more muscular walls of arteries help them to withstand and absorb the pressure waves which begin in the heart and are transmitted to the blood
Veins have thin walls with few elastic fibers and one-way valves whereas arteries do not have any
Veins convey blood back to the heart at a lower pressure so that they don't require thick walls. Vein uses its valves to redirect flow of blood to the heart
Blood Pressure
Measured by beats/min
Normal is 120/80 mm Hg
Usually lowest at nighttime when you're sleeping then it rises for a few hours before you wake up and continues to rise throughout the day. Reaches its peak in the middle of the afternoon then begins dropping again
Hypertension is 140/90!!!
Capillaries
Transfer oxygen and other nutrients from the bloodstream to other tissues and the body
Only one cell thick
Because it lacks smooth muscle - blood flow is altered by constriction or dilation of the arterioles that supply capillary beds or opening and closing precapillary sphincters
Blood Composition
Plasma
Liquid matrix
Blood electrolytes
The proteins called albumins act as a buffer against pH changes and help maintain the osmotic balance between blood and interstitial fluid
Fibrinogens which are clotting factors that help plug leaks when blood vessels are injured
Erthyrocytes
Red blood cells - most numerous
Main function is to transport oxygen
Round discs to increase surface area
Hemoglobin are iron-containing protein that transports oxygen
Leukocytes
White blood cells that fight infection
Phagocytes, B cells, and T cells
Platelets
Specialized bone marrow cells
Atherosclerosis
Hardening of the arteries by accumulation of fatty deposits
Results of high ratios of LDL and HDL
Causes damage to the arterial lining and results in inflammation. Plaque begins to grow and the walls of the arteries become thick and stiff. A thrombus can form in the artery if the plaque ruptures
Can lead to a heart attack or stroke
Gas Exchange
When food is swallowed, the larynx moves upward and tips the epiglottis over the glottis which opens the trachea/windpipe
Air then passes through
Branches into two bronchi
Bronchioles
Mucus escalator
Alveoli (air sacs)
oxygen enters the alveoli and diffuses across the capillaries
Osmoregulation
General term for the processes by which animals control solute concentrations and balance water loss and gain.
Osmolarity
The number of moles of solute per liter of solution
Osmosis
How water enters and leaves cells
Occurs when two solutions separated by a membrane differ in total solute concentration
Osmoregulator
Control internal osmolarity independent of that of the external environment
Allows them to live in environments that are uninhabitable
Osmoconformer
Being isoosmotic with its surroundings
Marine animals
Execretion
Process that rids the body of nitrogenous metabolites and other metabolic waste products
Excretory Processes
Filtration
Water and small solutes corss the membrane forming a solution called filtrate
converted into a waste fluid --- called reabsorption which recovers useful molecules and water from the filtrate and returns them to the body fluid
nonessential solutes and wastes are left in the filtrate and are added to secretion which occurs through active transport
Nephron
Proximal tubule: reabsorption
Descending limb of the loop of Henle
Reabsorption of water continues as the fltrate moves into the descending limb of the loop of Henle
Ascending limb of the loop of Henle
Filtrate reaches the tip of the loop and then returns to the cortext in the ascending limb
Distal tubule
Collecting Duct
Homeostatic Regulation of the Kidney
ADH (antidiuretic hormone)
Vasopressin
When osmolarity rises, ADH release into the bloodstream also increases
In the kidney, ADH makes the epithelium more permeable to water
Thus, it increases water reabsorption in water, reduces urine volume, and lowers blood osmolarity back toward the set point
Mutations
ADH receptor gene inactivated
Causes severe dehydration and solute imbalance
The RAAS
JGA, a specialized tissue consisting of cells of and around the afferent arteriole which supplies blood to the glomerulus
whenever blood pressure or volume drops in the afferent arteriole then the JGA releases the enzyme renin
This initates angiotensinogen
Raises blood pressure by constricting arterioles