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Biology A2 Unit 1 - Physiology, Coordination And Control, And Ecosytems > Topic 1 - Homeostasis And The Kidney > Flashcards

Topic 1 - Homeostasis And The Kidney Flashcards

1
Q

What is excretion

A

The removal from the body of toxic waste products of metabolic processes

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2
Q

How and where is Carbon Dioxide excreted from the body in mammals

A

Carbon dioxide is excreted during respiration from the lungs

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3
Q

What is homeostasis

A

The maintenance of steady states within the body

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4
Q

What are the main properties in the kidney

A

An outer cortex
An inner medulla
The pelvis
Nephrons
Connecting Ureter

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5
Q

What are the distinct regions in the nephron

A

A cup-shaped Bowmans capsule
The Proximal Convoluted Tubule
The Loop of Henle
The Distal Convoluted Tubule
The Afferent Arteriole
The Glomerulus
The Efferent Arteriole
The Collecting Duct

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6
Q

What is ultrafiltration

A

The stage in which plasma in the glomerulus is filtered into Bowmans Capsule. Only substances below a certain size are filtered and so the filtrate contains useful molecules as well as toxic ones

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7
Q

Why is the blood entering the glomerulus under high hydrostatic pressure

A

The renal arteries are wide, short and relatively close to the heart
The efferent Arteriole is smaller than the afferent Arteriole which creates a bottleneck

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8
Q

Why is Ultrafiltration so efficient

A

15-20% of the water and solutes are removed from the plasma that flows through the glomeruli

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9
Q

What are the 3 layers separating plasma from filtrate

A

The capillary endothelium, the basement membrane on which the capillary cells lie, and the inner layer of the Bowman’s capsule

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10
Q

What are the porous layers of the plasma and filtrate, and why

A

The endothelium of the capillaries in the glomerulus, which consists of a single layer of squamous cells with pores between them
The inner wall of the Bowmans capsule consists of Podocytes, with foot like processes which surround the capillaries but which have spacious gaps between them

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11
Q

What is the effective filter, and where is it located

A

Basement membrane, this lies on the outer side of the capillary endothelium

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12
Q

What cells can pass through the basement membrane

A

Molecules with a relative molecular mass of less than 68,000

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13
Q

What are the constituents of blood after the filtering of the basement membrane

A

Inorganic ions
Glucose
Amino acids
Urea
Other toxic molecules

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14
Q

How is water, ions, glucose and amino acids, and small proteins reabsorbed in the PCT

A

Water by osmosis
Ions partly by diffusion and partly active transport
Glucose and amino acids by active transport
Small proteins by Pinocytosis

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15
Q

What is the composition of a proximal tubule cell

A

Cuboidal epithelial cells, which line the tubule walls, which have numerous microvilli on the luminal surface and infoldings of the basal cell-surface membrane next to the blood capillaries. The cells have many mitochondria located near the infoldings

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16
Q

What ions pass out of the ascending limb in the Loop of Henle

A

Sodium and Chloride

17
Q

How is an osmotic gradient created in the loop of Henle

A

Sodium and chloride pass out of the ascending limb into the surrounding tissue of the medulla

18
Q

What does an osmotic gradient in the Loop of Henle cause

A

It draws water out of the permeable descending limb, to be carried away by blood in the surrounding capillaries

19
Q

Is water saltier as it goes up or down the Loop of Henle

A

Going down the descending limb

20
Q

How does reabsorption in the DCT occur

A

The ionic composition and the pH of the blood are adjusted. Depending on the permeability of the tubule walls, some water maybe be reabsorbed

21
Q

What is the function of Antidiuretic hormone

A

It increases the permeability to water of the walls of the second convoluted tubule and collecting duct

22
Q

Where is ADH produced, and where is it secreted

A

It is produced by the hypothalamus, but secreted into the posterior lobe of the pituitary body

23
Q

What is the function of Osmoreceptors

A

To detect a rise and decline of blood concentration in the Kidney. They then send impulse to the posterior lobe of the pituitary gland

24
Q

How is a more concentrated (hypertonic) urine produced

A

The lobe of the pituitary gland releases more ADH into the blood which increases the permeability to water of the second convoluted tubule and collecting duct. Water moves through aquaporions which open, under ADH, to let water through

25
Q

How is a less concentrated (hypotonic) urine produced

A

A fall in blood concentration inhibits the release of ADH. As a result, the walls of the second convoluted tubule and collecting duct become impermeable to water, meaning less water is reabsorbed

26
Q

What is feedback in Osmoregulation

A

Since a change in the water potential of the blood will ultimately lead to another change in the water potential of the blood

27
Q

What is negative feedback in Osmoregulation

A

Since an increase in water potential will later result in a decrease in water potential

28
Q

How do the Kidneys excrete nitrogen-containing compounds

A

During the breakdown of excess amino acids and nucleic acids in the liver

29
Q

What is the nephron

A

The functional unit of the Kidney

30
Q

What constituents of blood cannot pass through the basement membrane

A

Plasma proteins

31
Q

Where does Arteriol blood enter and go to in the Urinary system

A

Arteriol blood enters each capsule through an afferent arteriole which branches to form a capillary network called the glomerulus, which leads to the efferent arteriole

32
Q

What are the 3 basic homeostatic response features

A

A control system with sensors
The correct mechanism to bring the changes back to a normal level
A negative feedback system

33
Q

What is Osmoregulation

A

The control of the water potential of body fluids

34
Q

What is reabsorption

A

The selective absorption of useful products back into the bloodstream from the nephron

Biology A2 Unit 1 - Physiology, Coordination And Control, And Ecosytems (9 decks)

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