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A Level Bio unit 3 > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

Term homestasis

A

Is the maintaince of a constant internal environment

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2
Q

Examples of conditions that must be kept constant include

A

Blood glucose
Core body temp
Blood solute potential

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3
Q

Why is homeostasis important

A

So that even if cells can function efficiently even if
External conditions fluctuate
The body has different levels of activity

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4
Q

Where does control centre send impulses to

A

An effector

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5
Q

What is an effector

A

Muscle or gland

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6
Q

Negative feedback

A

Is a system that restores conditions to a set point when it detects a deviation. This results in narrow fluctuations around the set point

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7
Q

Positive feedback

A

A fluctuation which triggers changes that result in an even greater deviations from the normal level

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8
Q

What is set point

A

A desired value or range of values determined by a coordinator

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9
Q

Describe effectors

A

Muscles or glands which enable a physical response to a stimulus

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10
Q

Describe receptors

A

A specialised cells located in dense organs that detect a specific stimulus

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11
Q

Role or coordinator

A

Coordinates info from the receptors and sends instructions to the effectors

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12
Q

State components of a negative feedback system

A

Set point
Receptors
Coordinator
Effectors

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13
Q

Mammalian kidney

A

One of a pair of organs in the abdomen that has a role in osmoregulation and nitrogenous excretion

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14
Q

What is osmoregulation

A

The regulation of water potential of body fluids (eg blood tissue glue and lymph
By the Kinsey

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15
Q

Define excretion

A

The process of removing metabolic waster from an organism

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16
Q

Describe how excess amino acids are excreted

A

Amino acids deaminated in the liver (removal of amino group) to form ammonia
Ammonia is converted to urea less toxic
Urea is transported into the blood plasma and eliminated by the kidneys

17
Q

Structures of the excretory system

A

Kidney
Renal vein
Renal artery
Ureter
Urethra
Bladder

18
Q

Function of renal artery

A

Supplies oxygen and glucose and has a high concentration of urea
Supplies blood to kidneys

19
Q

Function of renal vein

A

Removes carbon dioxide and has a lower concentration of urea

20
Q

Function of ureter

A

Transfers urine to the bladder

21
Q

Function of urethra

A

Urine is released through the urethra out of body

22
Q

Renal vein

A

Drains blood from kidneys

23
Q

What is nephron

A

The functional unit of the mammalian kidney

24
Q

Where are the nephrons found

A

Part of nephron in medulla other part in cortex

25
Q

Structures of nephron

A

Glomerulus
Bowman’s capsule
Proximal convulated tubule
Collecting duct
Affererent arteriole
Efferent arteriole
Loop of Henle
Distal convoluted tubule

26
Q

Define ultrafiltration

A

The removal of small molecules, water and ions from the blood in the glomerulus of the kidney at high pressure

27
Q

Describe process of ultrafiltration

A

Occurs in bowman’s capsule
High hydrostatic pressure in glomerulus forces small molecules out of capillary against osmotic gradient
Basement membrane acts as a filter. Blood cells and large molecules remain in capillary

28
Q

Why is there a buildup of pressure in the glomerulus

A

Affecting arteriole leading into the glomerulus is wider than the efferent arteriole taking blood from the glomerulus

29
Q

What happens in selective re absorption

A

Useful molecules from glomerular filtrate are reabsorbed into the blood
Glucose, some water, some ions
Involves membrane transport proteins

30
Q

Where does selective re absorption occur

A

Proximal convoluted tubule

31
Q

How are cells in the proximal convoluted tubule adapted for selective reabsorption

A

Microvilli provide large surface area
Many mitochondria produce ATP for active transport of glucose
Folded basal membrane provides large surface area
Tight junctions stop reabsorbed materials leaking back into the filtrate

32
Q

By what mechanism are amino acids and glucose selectively reabsorbed into the blood

A

Secondary active transport
Uses a co transport mechanism involving Na+

33
Q

By what mechanism are mineral ions selectively reabsorbed into the blood

A

Active transport

34
Q

Mechanism water selectively reabsorbed into blood

A

Osmosis

35
Q

How are cultured proteins selectively reabsorbed into blood

A

Via diffusion

36
Q

Describe loop of henle

A

Loop consisting of a descending limb and ascending limb surrounded by blood capillaries

37
Q

Function of loop of Henle

A

It creates a low water potential in the medulla enabling re absorption of water

A Level Bio unit 3 (9 decks)

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