11.2 and 11.3 Flashcards
Endoskeletons vs. Exoskeletons
The internal bones comprise what is called an endoskeleton. Many animals, like insects, have another kind of skeleton called an exoskeleton (made of chitin rather than bone).An endoskeleton is formed on the inside of an animal’s body, while an exoskeleton is formed on the outside of an animal’s body.
Like an endoskeleton, an exoskeleton also provides support and attachment points for muscles. The attachment points for muscles are found on the outside of the bones of an endoskeleton, and on the inside of an exoskeleton.
Many individual bones and segments of exoskeletons also act as levers, to maximize efficiency for a variety of movements.
Origin (immovable) vs. insertion (movable) attachment points
When a muscle contracts, one end of the muscle is connected to a bone (or exoskeleton) that does not move. The other end of that muscle is connected to a bone that does move. The immovable attachment point of the muscle is called the origin and the movable attachment point is the insertion.
Discuss antagonistic pairs and movement
The immovable bone is an anchor for the desired movement. Because each muscle can only shorten in order to cause a single movement, muscles must work in pairs so that the opposite movement of the bone can also occur. The pairs of muscles that accomplish the opposite movement are called antagonistic pairs.
▪ Sliding Filament Theory Overview
A motor neuron carries an action potential until it reaches the final synapse, called a neuromuscular junction
A neurotransmitter called acetylcholine is released into the synaptic gap between the neuron end and the sarcolemma of the muscle fiber
The acetylcholine binds to receptors on the sarcolemma
Sarcolemma ion channels open and sodium ions (Na+) move through the membrane
The resulting action potential moves though the T tubules, causing the release of calcium ions (Ca2+) from the sarcoplasmic reticulum
The released calcium ions flood into the sarcoplasm
The myosin heads then attach to binding sites on the actin
The myosin heads all flex towards the center of the sarcomere
The entire sarcomere shortens as the Z lines move towards each other
ATP binds to the myosin head, resulting in the detachment of myosin from the actin, and awaits another action potential from a motor neuron.
Importance of ATP and calcium in muscle contractions.
ATP keeps each myosin head ready for action, waiting for an action potential from a motor neuron. Each use of a muscle requires a new ATP to prepare the myosin heads for a new cycle of activity to begin.
Calcium is important to the transmission of nerve impulses to the muscle fiber via its neurotransmitter triggering release at the junction between the nerves. Inside the muscle, calcium facilitates the interaction between actin and myosin during contractions.
Differentiate between the regulatory proteins (troponin & tropomyosin) involved in a muscle contraction.
Troponin: Binds to tropomyosin at regular intervals along the length of tropomyosin. This has binding sites for calcium. The released calcium ions flood into the sarcoplasm.
Tropomyosin: When a muscle is not contracting, the binding sites on actin are covered with tropomyosin.
The calcium ions bind to troponin, which stimulates the tropomyosin filament to slide, uncovering the actin binding sites.
Thus the release of calcium ions and the interaction with troponin and tropomyosin represent the link between the nervous system and the muscular system, as well as the skeletal system that is being moved.
Outline the anatomy of the urinary system & the kidney (nephrons)
The function of the kidney is to filter waste products from the blood. There is a major blood vessel called the renal artery that takes blood into each of the kidneys.
The filtered blood drains away from the kidney by a blood vessel known as the renal vein.
Urine is the fluid produced by the kidneys; it consists of water and dissolved waste products that have been removed from the bloodstream.Urine collects within each kidney in an area called the renal pelvis. The renal pelvis drains this urine into a tube called the ureter, which then takes the urine to the urinary bladder. The layer of tissue surrounding the renal pelvis is called the renal medulla; the layer to the outside of that is the renal cortex.
Each kidney is made up of about 1.25 million filtering units known as nephrons. Each of these are composed of a glomerulus, bowman’s capsule, and a tubule, as well as a peritubular capillary bed. The tubule that extends from the bowman’s capsule consists of the proximal convoluted tubule, loop of henle and distal convoluted tubule.
Each nephron contains a very small branch of the renal artery known as an afferent arteriole. This brings unfiltered blood to the nephron.
Ultrafiltration
Ultrafiltration is used to describe the process by which various substances are filtered through the glomerulus under the high blood pressure in the capillary bed. The fluid from the glomerulus passes through the basement membrane which helps prevent large molecules like proteins from becoming part of the filtrate.
Types of transport for the following: salt ions, water, glucose
Salt Ions: the majority of the salt ions (Na+, Cl-, K+) must leave the filtrate and be returned to the bloodstream by reabsorption. The salt ions are first actively transported into the tubule cells and then into the intercellular fluid outside the tubule. Finally, salt ions are taken into the peritubular capillary bed.
Water: the movement of salt ions out of the filtrate and into the tubule cells, intercellular fluid, and peritubular capillary bed, induces water to follow the same route by osmosis. Water moves from a hypotonic region to a hypertonic region following the pathway of the solutes. Under normal circumstances much of the water remains in the filtrate awaiting a control mechanism that will determine how much water the body can afford to eliminate in the urine.
Glucose: in a nephron, all the glucose that is in the glomerular filtrate is reabsorbed into the bloodstream. This occurs through active transport. If glucose was being moved by facilitated diffusion, the highest percentage that could be reabsorbed would be 50% because the concentration gradient disappears once that percentage is reached
Much of the water in the original filtrate remains after the filtrate has left the proximal convoluted tubule. This water and the remaining dissolved solutes, enters the descending portion of the loop of Henle.
This segment of the loop of Henle is permeable to water but relatively impermeable to salt ions. The filtrate then enters the ascending portion of the loop of Henle, where the tubule is relatively impermeable to water but permeable to salt ions.
Osmoregulators vs. Osmoconformers!
Osmoregulators: Animals whose internal tissues have a different solute concentration compared with their environment. These animals need a way to regulate water balance and expend a lot of energy in order to achieve this.
Osmoconformers: Animals that have internal tissues that have the same solute concentration as their environment. Marine worms and mollusks are osmoconformers. The solute concentration is almost identical to sea water. An equal amount of water moves into and out of their cell. They do not need a mechanism to take in or eliminate water as water moves freely due to the osmotic balance.
Comparison of renal artery vs. renal vein components- glucose, blood cells, proteins, urea, ions, water.
Comparisons can be made between the composition of the blood entering a kidney in the renal artery with the blood leaving a kidney in the renal vein.
In a healthy animal the blood leaving in the renal vein, compared with the renal artery, would have:
A lowered amount of urea
A lowered amount of salt ions (Na+, K+, Cl-, etc.)
A lowered amount of water
A nearly identical amount of glucose
A nearly identical amount of protein
Absolutely no change in blood cells
Describe the path of blood & filtrate as they flow through the nephron
Blood flows into your kidney through the renal artery. This large blood vessel branches into smaller and smaller blood vessels until the blood reaches the nephrons. In the nephron, your blood is filtered by the tiny blood vessels of the glomeruli and then flows out of your kidney through the renal vein.
