Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > B15 - Homeostasis > Flashcards

B15 - Homeostasis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is homeostasis?

A

When the body maintains a dynamic equilibrium, small fluctuations over a narrow range of conditions
- it is essential to monitor changes in the internal environment like pH of blood, core body temperature, conc. of urea and Na+ ions in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are receptors and effectors?

A
  • help maintain a dynamic equilibrium by detecting change in the internal and external environment of an organism
  • info from sensory receptors transmitted to the brain
    -impulses sent along motor neurones to trigger change and restore equilibrium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are feedback systems?

A
  • when sensory receptors (detect change) and effectors (trigger a response to restore equilibrium) work together to maintain a constant and steady environment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are negative feedback systems?

A

effectors work to restore conditions to original state and reverse the initial change
- e.g. blood sugar levels of insulin and glucagon
1. ideal conditions
2. increase/ decrease detected by sensory receptors
3. responses by effectors lower/ raise levels
4. return to ideal conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a positive feedback system?

A
  • change in the internal environment detected by sensory receptors and effectors work to reinforce the change and increase the response
  1. change detected
  2. responses reinforce change
  3. conditions change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are examples of positive feedback?

A
  • blood clotting cascade: where a blood vessel damaged, platelets stick to damaged region and release factors that initiate clotting and attract more platelets
  • childbirth: where the baby presses against the cervix, stimulating the production of oxytocin which stimulates the uterus to contract pushing the head of the baby against the cervix and releasing more oxytocin until the baby is born
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is thermoregulation?

A

the maintenance of the core body temperature to maintain optimum enzyme activity
(at high temps, enzymes denature)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What physical processes lead to heat loss?

A
  • latent heat of evaporation - objects cool down as water evaporates from surface e.g. sweating
  • radiation - transmission of electromagnetic waves to and from air, water and ground
  • convection - heating and cooling of organism (hot air rises and cool sink causing convection current around organism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What physical process lead to heat gain?

A
  • exothermic chemical reactions
  • conduction - heating as a result of frequent collisions of molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are ectotherms (outside heat)?

A
  • organisms that use surroundings to warm their bodies
  • e.g. invertebrate animals, fish, amphibians, reptiles
  • ectotherms in water don’t need to thermoregulate due to high heat capacity of water
  • on land, the temp varies per season so organisms have found multiple ways to adapt and cool down/ warm up
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are endotherms (inside heat)?

A
  • rely on metabolic processes to warm up and maintain a very stable core body temp
  • survive in a range of environments due to multiple adaptations e.g. metabolic rate of endotherms is x5 than ectotherms (warming and cooling are metabolic processes)
  • e.g. mammals and birds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do ectotherms warm up using behavioural response?

A
  • need to be warm enough for metabolic reactions to be fast enough so might bask in the sun with maximum surface area exposed e.g. locusts and butterflies orientate themselves for maximum sun exposure and spread wings to increase s. area so warm enough to fly
  • can increase temp through conduction via pressing themselves on warm ground
  • exothermic metabolic reactions e.g. iguanas contract muscles and vibrate to increase metabolism to raise their body temp
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do ectotherms cool down via behavioural responses?

A
  • minimise s. area exposed to sun, hide on burrows, caves
  • press bodies against cool ground/ rocks
  • minimise movement to reduce metabolic heat generated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do ectotherms regulate temp using physiological responses?

A
  • lizards in colder climates are usually darker to absorb more radiation than light colours
  • some alter heart rate to increase/ decrease metabolic rate and regulate temp
  • need less food than endotherms since use less energy to regulate temp so can life in very difficult environments where food is in short supply
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an endocrine gland?

A
  • group of cells specialised to secrete hormones directly into the bloodstream
  • e.g. adrenal gland and pancreas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Endocrine Glands

A
  • pituitary gland - produces growth hormone, which controls growth of bones and muscles, release ADH (increases reabsorption of water in kidneys), releases gronadotrophin (controls development of ovaries and testes)
  • Thyroid gland - produces thryoxine; controlling rate of metabolism and rate of glucose is used in respiration
17
Q

Ultrastructure of the kidney and their functions

A
  • Renal artery: supplies oxygenated blood from the aorta to the kidneys
  • Renal vein: takes deoxygenated blood from the kidneys to the heart via the inferior vena cava
  • Medulla: A darker region made up of Loop of Henle, collecting ducts and blood vessels
  • Ureter: tube carrying urine to the bladder
  • Cortex: a lighter outer region made of the Bowmans capsule, convoluted tubules and blood vessels
  • Renal Pelvis: A funnel shaped cavity that collects urine into the ureter
  • Renal fascia and cortex: outer membrane protecting the kidneys
18
Q

What are the different blood vessels in the kidneys and their functions?

A
  • Afferent arteriole: a tiny vessel from the renal artery, bringing in oxygenated blood, it enters and is wide
  • Efferent arteriole: a vessel leaving the renal capsule, thinner than afferent causing increase in pressure in the glomerulus, carries blood away from glomerulus and forms the blood capilleries
  • glomerulus: branched knot of capilleries which fluid is forced out of blood to form the efferent arteriole
  • Blood capilleries: concentrated network surrounding the convoluted tubules and loop of Henle, reabsorb water, mineral salts and glucose, merge to form the renal vein
19
Q

What is the 2 stage process in producing urine?

A
  1. ultrafiltration - small molecules and ions are filtered out of the blood into the renal capsule, occurs due to the pressure maintained by the afferent and efferent arterioles - occurs in the barrier between glomerulus and filtrate in renal capsule
  2. reabsorption - molecules and ions which are required by the body are taken back from the nephron - occurs in proximal convoluted tubule
20
Q

What makes up the three part fiter system?

A
  • Endothelium of blood capillery
  • Basement membrane
  • Epithelium of renal capsule
21
Q

describe the three part filter system

A
  • endothelium of blood capillery: very thin, perforated with thousands of pores of 10nm diameter, provides barrier to cells not plasma proteins
  • basement membrane: meshwork of collagen fibres and glycoprotein fibres, water and small molecules can pass through, proteins are too large and are repelled by negative charges on fibres
  • epithelium of renal capsule: made of cells which are modified for filtration (podocytes)
22
Q

Describe the structure of a podocyte

A
  • each cell has many foot like extensions projecting from its surface
  • extensions wrap around the capillaries of the glomerulus and interlink with extensions of neighbouring cells
  • extensions fit, leaving small filtration slits which the filtered fluid passes through
23
Q

Examples of ions and small molecules that can pass through the three part filter into the glomerular filtrate in the renal capsule

A
  • RMW less than 69000 e.g:
  • water, glucose, amino acids, vitamins and drugs (penicillin and ethanol)
24
Q

what is left behind in the glomerular capillary?

A

cells, platelets and plasma proteins

25
Q

What occurs in the proximal convoluted tubule?

A
  • indirect active transport is used to reabsorb useful materials
  • Active transport is used to set up a sodium ion concentration gradient
  • as sodium ions diffuse down the concentration gradient, they release energy
  • this drives co-transporters which move other ions and molecules against their own concentration gradient
26
Q

What are the adaptations of the proximal convoluted tubule to reabsorb substances into the blood?

A
  • microvilli to increase surface area
  • infoldings at their base to give a larger surface area
  • a large amount of mitochondria to provide ATP for active transport
27
Q

How does the PCT reabsorb amino acids?

A
  • Na+ ions are pumped out of the epithelial cells
  • Na+ concentration gradient is created between the PCT and the epithelial cytoplasm
  • diffusion of Na+ down its conc. gradient provides the energy to move amino acids into the epithelial cell
  • amino acids move by fascilitated diffusion down its conc. gradient into the capillary
  • water follows sodium and other reabsorbed solutes by osmosis

Biology (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions