Homeostasis Flashcards
Environmental change is a fact of ?
Conditions around organisms? And therefore?
Some animals are able to keep their internal conditions unchanged despite the changing environment around them. ? are excellent examples of animals that keep their internal conditions stable.
A mammal’s internal environment is essentially the?
Some factors which must be regulated in the blood and tissue fluid are the concentration of?
Homeostasis is the?
Life
change quickly all the time, living things need to respond.
Mammals
blood circulating in the body and the tissue fluid formed from it ,which surrounds the cells, delivering nutrients and removing waste products.
ions, water potential, temperature, PH and O2 levels.
Maintenance of constant (steady state) conditions in the body.
Most homeostatic responses have three features:?
controlled system, corrective mechanism, (-) feedback system
A controlled system: usually located in the? and is capable of ? A control system has?
These sensors can be found in the? (e.g?) or throughout the? (e.g?)
A corrective mechanism- when a? the effector(?) is ? (By?) and this causes? To bring about? Resulting in? i.e For example?
A negative feedback system? The corrective mechanisms involve a? Once the factor?, a feedback loop?, causing ?This prevents? E.g?
brain, detecting any deviation from the norm, sensors (receptors) which monitor the factor being controlled.
Brain (osmo receptors are present in the hypothalamus to monitor the water potential of the blood),
body (thermoreceptors are present in the skin to monitor body temp)
Sensor (receptor) detects a deviation from the normal conditions (the set point), the effector (organ, muscle or gland) is stimulated (by hormones or via the nervous system) and this causes a corrective mechanism to bring about the changes resulting in regulation of this factor i.e it is restored towards its normal level. For example, sweating is a corrective mechanism when a mammal overheats.
The corrective mechanisms involve a negative feedback system. Once the factor returns to its normal level (the set point) a feedback loop sends info to the effectors, causing the corrective mechanism to be turned off. This prevents over- correction. E.g. when a mammal’s body temperature drops and returns toward the set point, the stimulation of the sweat glands is reduced.
The concept of negative feedback is central to any ?
This is best explained through the example of a?
A fall in temperature is detected by a? which then sends an? As a result the temperature of the water? Once the temperature has increased to the set temperature the thermostat (sensor) then? causing it to be ?
homeostatic mechanism
simple water bath
A fall in temperature is detected by a thermostat (sensor) which then sends an electrical signal to a water heater (effector). As a result the temperature of the water rises. Once the temperature has increased to the set temperature the thermostat (sensor) then sends another electrical signal to the water heater effector causing it to be switched off to stop the corrective mechanism (negative feedback).
The two mammalian kidneys are what shaped? organs. Situated at?
They? by? indicated by the fact that?(via?).
The 2 major functions of the mammalian kidney are?
Bean, waist level on either side of the backbone.
They regulate the internal environment by constantly adjusting blood composition, indicated by the fact that they receive approximately 25% of the cardiac output (via the aorta and renal arteries).
Excretion- the removal of toxic waste products from metabolic processes and osmoregulation-the control of the water potential of body fluid
Excretion- the removal of toxic waste products from metabolic processes:
I.e? 2 toxic substances are?
The removal of substances produced by chemical reactions, which are useless to the body/ poisonous if built up.
Urea and creatinine
Urea-?
Creatinine-?
These waste products are transported from?
Osmo regulation? (?) and? The correct water potential is necessary for? The kidney regulates the water potential of the blood through?
Urea-this is a N2-containing compound which is produced during the breakdown of excess amino acids (and nucleic acids) in the liver.
Creatinine- this is a waste product produced from the breakdown of creatine phosphate (a molecule involved in ATP generation ) in muscles.
These waste products are transported from cells to the kidneys via the blood.
Osmo regulation? The control of the water potential of body fluids i.e. the balance of dissolved substances (inorganic ions , sugars, amino acids etc) and water. The correct water potential is necessary for cells to function efficiently. The kidney regulates the water potential of the blood through controlling the volume and concentration of urine produced.
Structure of the mammalian urinary (Excretory) system- blood travels initially through? And reaches the?
The kidneys?
Useful products are? Whereas excretory products and excess water are?
Filtered blood leaves the kidney via the ?
The excretory products and excess water pass into the? This is stored in the? and is released through the? under the control of the?
The aorta and reaches the renal artery under high pressure,
Filter the blood.
Kept in the blood, eliminated.
renal vein
The excretory products and excess water pass into the ureter as urine. This is stored in the bladder and is released through the urethra under the control of the sphincter muscles.
Structure of the mammalian kidney-
Inside a kidney there are?-an? These layers surround a? which is continuous with that of the? The medulla is? whose apices protrude into the pelvis. Each kidney contains?, each of which has a? Part of each ? lies in the?
Inside a kidney there are? 2 layers- an outer cortex (dark region) and inner medulla (lighter region). These layers surround a central cavity known as the pelvis, which continues to the ureter. The medulla is sub-divided into a number of zones known as pyramids whose apex extends into the pelvis. Each kidney contains many microscopic tubules called nephrons, each of which has a rich blood supply. Part of each nephron lies in the cortex and part in the medulla.
Structure of a nephron- the functional unit of the kidney that allows excretion and osmoregulation to take place is the? The nephron is responsible for the production of the? It’s estimated that each kidney contains?, each of which is around?. Each nephron is composed of ?
the functional unit of the kidney that allows excretion and osmoregulation to take place is the? nephron. The nephron is responsible for the production of the urine. It’s estimated that each kidney contains one million nephrons, each of which is around 3 cm long. Each nephron is composed of several regions, each having different features and functions.
The nephron originates as the? Which is a?
Between the Inner and outer walls of the Bowman’s capsule there’s a? The outer wall of the capsule consists of?The inner wall of the capsule consists of cells called?, which have?
Blood enters the Bowman’s capsule via a? and leaves via a ? Within the ‘cup’ of the Bowman’s capsule , the afferent arteriole? called the?
Bowman’s capsule (renal capsule), cup-shaped capsule.
Between the? Inner and outer walls of the Bowman’s capsule there’s a capsular space. The outer wall of the capsule consists of unspecialised squamous epithelial cells. The inner wall of the capsule consists of cells called? Podocytes, which have spaces between them leading to the capsular space.
Blood enters the Bowman’s capsule via a wide afferent arteriole (a branch of the renal artery) and leaves via a narrow efferent arteriole. Within the ‘cup’ of the Bowman’s capsule , the afferent arteriole branches to form a tightly coiled dense network of capillaries called the glomerulus.
After leaving the Bowman’s capsule, the efferent arteriole? to ? around the? Blood is ?into the ?
The Bowman’s capsule extends into a coiled tube called the? (?).
The proximal convoluted tubule extends into the? which dips down into the?. The descending part of the limb is called the?
Then there’s a? and the ascending limb? to reach the ?
The loop of Henle extends into the?
The distal convoluted tubules of many? join a?
Many collecting ducts? and empty their contents (urine) into the?
After leaving the Bowman’s capsule, the efferent arteriole branches to form a further capillary network (the vasa recta system) around the rest of the nephron. Blood is drained from these capillaries into the renal vein.
The Bowman’s capsule extends into a coiled tube called the? Proximal convoluted tubule (proximal= first ; convoluted= coiled).
The proximal convoluted tubule extends into the? loop of henle which dips down into the medulla of the kidney. The descending part of the limb is called the? Descending limb
Then there’s a? Sharp Bend and the ascending limb? Returns back up through the medulla to reach the ? Cortex again.
The loop of Henle extends into the? Distal convoluted tubule (distal = second; convoluted= coiled).
The distal convoluted tubules of many? nephrons join a? Collecting duct
Many collecting ducts? Join at the base of the pelvis and empty their contents (urine) into the? Ureter which takes it to the bladder.
Excretion in the kidney involves 2 main processes?
Ultrafiltration and selective reabsorption.
Ultrafiltration Is a process that occurs at the? In the glomerulus, water and small molecules (with a?) within the blood plasma (?) are? The fluid in the capsular space is referred to as the? Larger components of the blood (?) are?
Note: some small plasma proteins?
Bowman’s capsule, smaller relative molecular mass(RMM) of 68000) within the blood plasma (glucose , amino acids, salts, water and urea) are forced out (filtered) of the blood capillaries and into the capsular space of the Bowman’s capsule. The fluid in the capsular space is referred to as the glomerular filtrate. Larger components of the blood (plasma proteins and blood cells) are too big to pass through into the Bowman’s capsule.
Note: some small plasma proteins may pass through the basement membrane into the filtrate
The process of ultrafiltration relies on? through the? i.e ? This high hydrostatic pressure occurs because:?
The process of ultrafiltration relies on the high hydrostatic pressure of the blood entering the glomerular capillary network through the afferent arteriole i.e this is the driving force for filtration. This high hydrostatic pressure occurs because:? The renal arteries are short and relatively close to the the heart.
The efferent arteriole, which carries blood away from the glomerulus is smaller/ narrower in diameter than the afferent arteriole; which creates a bottleneck.
The coiling of capillaries in the glomerulus restricts blood flow= increased pressure.
The glomerular filtrate has a solute composition similar to? All components of the blood plasma (with a RMM of less than 68000) are able? to form the? (?). However, plasma proteins and blood cells are? The major difference between glomerular filtrate and blood plasma is that the filtrate?
The glomerular filtrate has a solute composition similar to that of blood. All components of the blood plasma (with a RMM of less than 68000) are able to pass through into the capsular space to form the filtrate (glucose, hormones, water, ions, amino acids, vitamins,urea, Uric acid and creatinine). However, plasma proteins and blood cells are too large to pass through the basement membrane. The major difference between glomerular filtrate and blood plasma is that the filtrate doesn’t contain plasma proteins, blood cells or platelets.
