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Biology 9.3 > `Homeostasis > Flashcards

`Homeostasis Flashcards

1
Q

How is the intrinsic rhythm of the heart controlled

A

By impulses initiated in the sinoatrial node (SAN) and then spreads through the atrioventricular node (AVN) and the bundle of his to give a regular rhythm

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2
Q

What is the response of the heart to change as a result of

A

A result of the negative feedback system

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3
Q

When your body demands more glucose and oxygen what is one way your heart can respond

A

1)The rate at which the heart beats can increase and the volume of blood pumped at each heartbeat

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4
Q

how can the cardiac volume be increased

A

By a more efficient contraction of the ventricle

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5
Q

How can you calculate the cardiac output

A

Cardiac output = cardiac volume X heart rate

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6
Q

What happens to the heart during exercise

A

The heart rate begins to increase before the exercise begins. The cardiac volume increases more slowly, as it becomes clear from the changes in the body that exercise is going to continue

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7
Q

What is most of the nervous control in the heart

A

By the autonomic nervous system

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8
Q

How are nerve impulses sent to the cardiac centre

How does the cardiac centre respond

A

Chemicals, stretch and pressure receptors in the lining of the blood vessels and the chambers of the heart send nerve impulses to the cardiac centre

By sending impulses to the heart along parasympathetic and sympathetic nerves

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9
Q

How in the SAN stimulated

A

Nerve impulses travel down the sympathetic nerve from the cardiac centre in the brain to the heart to release noradrenaline

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10
Q

What does the stimulation of the SAN cause

A

an increase in the frequency of the signals from pacemaker region so heartbeats faster

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11
Q

What do impulses in the parasympathetic nerve release

what effect does this have

A

acetylcholine which inhibits SAN and slows the heart down

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12
Q

where are baroreceptors found

A

In the sinuses of the carotid arteries in the neck and on the aorta

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13
Q

What are baroreceptors important for

A

In feedback control of the heart rate during exercise

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14
Q

Explain what baroreceptors do during exercise

A

When exercise begins blood vessels dilate (vasodilation) in response to hormone adrenaline and blood pressure falls

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15
Q

What happens when stimulation from baroreceptors are reduced

A

The cardiac control centre immediately sends signals along the sympathetic nerve to stimulate the heart rate and increase blood pressure again by vasoconstriction

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16
Q

Explain what baroreceptors do when Excercise is stopped

A

Blood pressure in arteries increases as the heart continues to pump harder and faster than it needs to so baroreceptor is stretched. They send more sensory nerves via the parasymapthetic system to slow down the heart causing widening blood vessels

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17
Q

Where are chemoreceptors found

A

in the wall of the aorta and carotid arteries

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18
Q

what are chemoreceptors sensitive to

A

Carbon dioxide levels

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19
Q

What do chemoreceptors detect

Explain how this happens

A

As the level of CO2 increases the PH decreases which is detected by the aorta and carotid chemoreceptors
They send impulses along sensory neurons and to the cardiac control centre in the medulla, this increases the impulse traveling down the sympathetic nerve

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20
Q

What does the chemoreceptor do for the heart

A

It reduces the number of impulses to the cardiac centre reducing heart rate and makes it go back to the intrinsic rhythm

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21
Q

What does adrenaline stimulate

A

The cardiac centres in the brain, increasing the impulses in the sympathetic neurons supplying the heart, increasing frequency off excitation and so increasing the heart rate

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22
Q

What is osmoregulation

A

The maintenance of the osmotic potential in the tissues of a living organism within narrow limits by controlling water and salt concentrations

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23
Q

What are the cells of land-living mammals surrounded by

A

Tissue fluids that come from the blood capillaries

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24
Q

How can osmotic damage of cells be prevented

A

By controlling blood potential of blood the body can control the water potential of the tissue fluid

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25
What's the main organ involved in the water balance of the body
The kidney
26
What does lover play an important role in
In the deamination of excess amino acids in protein metabolism
27
What are hepatocytes and what does it do
liver cells and they deaminate excess amino acids
28
What do hepatocytes do to amino acids
They remove amino acid groups and convert it first to ammonia and then less toxic urea, which can be excreted by the kidney
29
What is the ornithine cycle
The process by which the ammonia produced from deamination of proteins
30
How is Osmoregulation brought about What does it help us do
By the kidneys, which is more concentrated than the body fluids. conserve water
31
How does the kidney look in humans
reddish brown organ attached to the back of the abdominal cavity surrounded by a thick layer of fat (protects them from mechanical damage)
32
What do kidneys do
control the water potential of the blood that passes through them
33
Where Is the urine stored
in the bladder
34
What are the two main roles of the kidney
Excretion and osmoregulation
35
What are the three main functions carried out by the kidney in its osmoregulation role
Ultrafiltration, selective reabsorption and tubular secretion
36
What are nephrons
microscopic tubules that make up each kidney
37
What are the two main nephrons | what function do they carry out
Cortical nephrons They have a loop of Henle that only just reaches into the medulla Juxtamedullary nephrons Have loop of Henle that penetrates right through the medulla (particularly efficient for producing concentrated urine)
38
What's the first stage of osmoregulation | What is it responsible for
Ultrafiltration | formation of tissue fluids
39
Why does ultrafiltration occur
Due to the combination of very high blood pressure in the glomerulus.
40
What makes up the malpighian body
The glomerulus and Bowmans capsule
41
Why does high blood pressure develop in the glomerular capillaries
The diameter of the blood vessel coming into the glomerulus is greater than that of the blood vessels leaving
42
What do the cells of Bowman's capsule next to the capillaries act as
an additional filter
43
What are podocytes
Special cells that make up the wall of the capsule
44
What are pedicles
Extensions of the podocytes that wrap around the capillaries, forming slits that ensure any cells, platelets or large plasma proteins that have left the capillary do not get through into the tubule itself
45
What does the filtrate that enters the capsule contain
glucose, salt, urea and man other substances
46
Why is ultrafiltration described as passive and indiscriminative
it removes urea from the blood and but also removes a lot of water, glucose salt, and other substances
47
Why is glucose never ever excreted
It's needed for cellular respiration
48
What is the main function if the kidney tubule after the ultrafiltrate has entered the nephron
To return to the most of what has been removed from the blood back to its rightful place
49
Wat does microvilli do when on the lining on the cell
Increases the surface area through which substances can be absorbed
50
What happens by the time the filtrate reaches the loop of Henle
it is isotonic with the tissue fluids that surround the tubules
51
Where is the loop of Henle found | What does it work closely with
Found in the medulla of the kidney | works with a network of capillaries known as vasa recta
52
What does the Vecta recta and Loop of Henle do
They create water potential gradient between filtrates and the medullary tissue fluid enables water to be reabsorbed from the distal convoluted tubule and collecting duct
53
Why is there a high concentration of sodium and chlorine in the medulla What does this create
Due to the flow of fluid in opposite directions in the adjacent limbs of the loop of Henle countercurrent multiplier
54
What is a countercurrent multiplier
a biological system that uses active transport to set up and maintain concentration gradients
55
What do the changes that take place in the descending limb of the loop of Henle depend on
On the high concentration of sodium and chloride ios in the tissue of the medulla, and these are the result of events in the ascending limb of the loop
56
What is the descending limb permeable of
Water but it isn't permeable of sodium and chloride ions
57
Explain how the descending limb works
The fluid entering is isotonic with the blood As it travels down the lib into the medulla, the external concentration of sodium and chloride ions in the tissue fluid of the medulla and the blood in the vasa recta is higher an higher. Water moves out a concentration gradient It then moves into the blood of the vasa recta down the water potential when the fluid reacher hairpin bend at the bottom of the loop it is very concentrated and hypertonic to the arterial blood
58
What is the ascending limb permeable to
Sodium and chloride ions but no water
59
Explain how the ascending limb works
Sodium and chlorine ions move out of the very concentrated fluid in the loop of Henle into the tissue fluid of the medulla down a concentration gradient The thicker section of the ascending limb I also impermeable to water but sodium and chloride ions are actively pumped out of the tube in the tissue fluids of the medulla and the blood of the vasa recta this gives tissues of medulla very high sodium and chloride ion concentration and causes water to pass out the descending limb Due to the fact that ascending limb is impermeable to water the fluid in ascending limb becomes less concentrated
60
What is distal convoluted tubule permeable to and to what extent
Water | depends on the level of antidiuretic hormone (ADH)
61
What does the collecting duct do
balances water
62
Why is water removed from the medulla | What does this allow
Because of the increase in the concentration of sodium ions | This allows for the creation of hypertonic urine
63
Where is urine first collected
In the pelvis of the organ and then passed to the bladder
64
What is the urethra
The tube in which urine passes out the body
65
Give some reasons why kidneys produce such high concentrated urine
1) A relatively large proportion of juxtamedullary nephrons 2) A long loop of Henle 3) Higher no. of foldings on the cell membrane 3) Higher no. of mitochondria
66
How is the osmotic potential kept at such a narrow range
By balancing water and salt taken in by eating and drinking with the water and salts lost by sweating
67
Where is ADP produced and where is it secreted
Produced in the hypothalamus and secreted into the posterior lobe
68
How does ADP get across the membrane
It binds to a specific receptor and, triggering a reaction forming in cAMP as a second messenger
69
What does the cAMP do
Sets up a series of reactions that cause vesicles within the cell lining the tubules to move out, and fuse with, the cell membrane
70
What does the amount of ADH released control
the number of channels that are inserted
71
What happens when ADH levels drop
cAMP levels drop and water channels are within from the membrane and repackaged in vesicles.
72
What happens when the concentration of inorganic ions in the blood rises
The water potential becomes more negative
73
What do osmoreceptors in the hypothalamus detect
They detect an increasingly negative water potential in the blood
74
How do osmoreceptors detect negative water potential
They send nerve impulses to the posterior pituitary, which in turn releases stored ADH in the blood. the ADH is picked up by receptors in the cell of the kidney tubules.ADH increases the permeability of the distil convoluted tubule and the collecting duct to water. Water leaves the tubules by osmosis into the surrounding capillary network
75
When does water potential become more negative
When it becomes more dilute
76
What is the most common form of diabetes What is it a result of
Diabetes mellitus insufficient insulin being produced
77
What is the name of a rare form of diabetes How is it caused
diabetes insipidus When an individual produces large volumes of ADH
78
What does lack of ADH cause?
The distal convoluted tubules and collecting ducts are permanently impermeable in water
79
What is thermoregulation
The way in which organisms control their internal body temperature
80
What kind of surface area for small animals have
large surface-area-to-volume ratio
81
Give an example of how animals cool down
By the evaporation of water from the body surfaces
82
how can energy be transferred to or from an environment
By radiation
83
Where are convection currents set up
They are set up around relatively hot objects, so adaptations to prevent cooling by these currents are common in animals
84
Why do land habitat animals need to control body temperature
Either to avoid damage to their cells or to enable them to give an active life
85
How are animals often classified
According to the main mechanisms of temperature control as either endotherms or ectotherms
86
What are endotherms
Organisms that rely on their own metabolic processes to provide at least some warming and usually has a body temperature
87
What are endotherms adapted to do
Adapted to conserve body temperature and also take advantage of warmth from the environment when possible
88
What are Ectotherms
Organisms that rely heavily on the external environment to control their body temperature
89
What do ectotherms have
They usually have behavioral and structural modifications that take advantage of the environment
90
How do ectotherms cool down
Move to shade, into water or mud
91
What is one big advantage that ectotherms carry
They need less food | The advantage of environments that don't have
92
What is the main example of endotherms
Mammals
93
What is the difference between human and other mammals in terms of temperature regulation
We can help manipulate the temperature by using things like heaters and air conditioners
94
What is the major homeostatic organ involved in thermoregulation in most endotherms
The skin
95
What does the skin help prevent
overheating in a number of ways
96
How does cooling by radiation, convection, and conduction take place
From the blood flowing through the skin
97
How is the cooling controlled
VIA the arteriovenous shunt
98
What happens when you exercise or external temp rises
The shunt is closed, which allows more blood to flow through the capillaries at the surface of the skin and vasodilation occurs
99
What happens to your skin hairs when you're hot
The erector pili muscles, which are attached to the hair follicles, are relaxed and the body hairs are flat
100
What happens as sweat is released
colling akes place as the water evaporates
101
What is vasoconstriction
The narrowing of the blood vessels by the relaxation of their muscle walls, increasing blood flow
102
What is vasodilation
The widening of the blood vessels by contraction of their muscle walls, reducing blood flow
103
How does the body keep cool
``` .Sweat production is reduced .Cooling by evaporation is reduced .Erector pili is contracted .Metabolic rate of the body speeds up .involuntary contractions, shivering ```
104
What are the two types of receptors in thermoregulation
Receptor in the brain (monitors temp of the blood) | Receptors in the skin (Change in external temperature)
105
Where are the temperature receptors located in the brain
Hypothalamus
106
What happens when the temp of the blood flowing the body increases
The thermoregulatory centre is activated and sends impulses along the autonomic motor nerves to effectors that increase the blood flow through the skin and sweating
107
What are the main things that happen when blood temperature increases
.The erector pili muscles are relaxed so hair lie flat | .The metabolic rate may be reduced to lower the amount of warming in the body
108
What are the main things that happen when blood temperature decreases
The thermoregulatory centre reacts by sending nerve impulses along the autonomic motor nerves to effectors .Reduction in the blood flow through the capillaries in the skin, along with with the reduction n the production of sweat and contractions .The erector pili muscles raise the hairs .shivering etc takes place (involuntary contractions)
109
What have some mammals and birds living in cold environments developed
Countercurrent exchange systems in their limbs that allow body temperature to be conserved Arterial blood is cooled and venous blood is warmed
110
How can the problem of cold environments be overcome
Hibernation
111
What happens during hibernation
Animals go into a deep sleep and metabolic rate is decreased. Then the core temperature is greatly lowered
112
What brings animals out of hibernation
Higher temperature and longer days
113
After hibernation why does the metabolic rate need to increase quickly
So the animal can find something to eat quickly without being preyed on
114
What is a big problem for animals in hot environments
Being able to cool down
115
How do they save a lot of water in hot environments
They do not sweat
116
How is the brain cooled in animals that live in extremely hot environments
A countercurrent exchange system is put into place
117
Give examples of behavioral modifications that help modify both endotherms and ectotherms body temperature
1) Basking (Bask in the sun when body temperature is falling) 2) Sheltering 3) Evaporating 4) moving in and out of the sun
118
What is aestivation
One extreme physiological adaptations for avoiding hot, dry conditions
119
What happens during aestivation
Their metabolic rate slows right down and becomes completely inactive often bury themselves in mud
120
What animals aestivate
molluscs, frogs, crocodiles to lungfish and snakes

Biology 9.3 (1 decks)

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