HOMEOSTASIS AND EXCERTION- part 2

Question 1

What is the function of Bowman’s capsule and Glomerulus?
A. Filtration of the blood
B. reabsorption of glucose from the blood
C. reabsorption of urea and water and ions from the blood

Answer 1

A.Filtration of the blood

Question 2

Liquid which collects in the cavity of Bowman’s capsule is
A. Concentrated urine
B. Plasma minus blood proteins and blood cells
C. salt ions and water

Answer 2

B. Plasma minus blood proteins and blood cells

Question 3

Explain how the nephron is adapted to its function

Answer 3

Adaptations for ultrafiltration
It has a permeable Bowman’s capsule that only allows substances such as water, glucose, urea and salt ions to pass through but prevents the passage of proteins and blood cells.

The renal artery is highly branched forming small capillaries in the glomerulus and this provides a larger surface area for blood to flow in the kidney for filtration.
the capillaries get narrower in the glomerulus and this builds up higher pressure necessary for ultra-filtration.

Adaptations for reabsorption
Kidney tubules are long and coiled and this provides a larger surface area for reabsorption and more time is allowed for reabsorption of the useful substances. Also the first coiled tubule (proximal convoluted tubule) can allow reabsorption of glucose by active reabsorption and glucose is needed for the body respiration.
The Loop of Henle is U -shaped and this the efficient reabsorption of water and salts.

Question 4

Explain how the glomerulus is adapted to its function

Answer 4

The renal artery is highly branched in the glomerulus forming a knot of a very small capillaries and this provides a larger surface area for blood to flow in the kidney for filtration.
the capillaries become narrower in the glomerulus this builds up higher pressure necessary for ultra-filtration.

Question 5

The glomerular filtrate is formed during the process of ……………………. it is collected in the ……………………..
It is further processed along the nephron to form………

Answer 5

The glomerular filtrate is formed during the process of ultrafiltration it is collected in the Bowman’s capsule space
It is further processed along the nephron to form Urine

Question 6

Sort the following steps when there is an Increase of body temperature fromnormal level

1. Thermoregulatory centre (hypothamalus in brain)
   receives and processes information
2. Effectors (muscles or glands) bring about changes (decrease)
3. Receptors in thermoregularory centre and skin detect increase

Answer 6

1.Receptors in thermoregularory centre and skin detect increase
2.Thermoregulatory centre (hypothamalus in brain)
receives and processes information
3. Effectors (muscles or glands) bring about changes (decrease)

Question 7

Our body can only stay at a constant temperature if the heat we generate is balanced and equal to the heat we lose

True or False

Answer 7

True

Question 8

How does the body respond to changes in temperature?

Answer 8

Increase in temperature
Sweating
Hairs lie flat
Vasodilation

Decrease in temperature
Shivering
Hairs stand up - goosebumps
Vasoconstriction

Question 9

the blood vessels near the surface of the skin widen to allow heat to be lost from the blood (muscles within the vessels relax).

Answer 9

Vasodilation

Question 10

the blood vessels near the surface of the skin narrow to reduce heat loss (muscles within the vessels contract).

Answer 10

Vasoconstriction

Question 11

branch off from the arteries
thinner, less muscular walls (compared to arteries)
feed blood into the capillaries
narrower than arteries, but wider than capillaries
Function: regulate blood flow through capillaries

Answer 11

Arterioles

Question 12

capillaries join together to form venules
larger than capillaries but smaller (i.e. narrower and thinner walls) than veins
Function: collect blood coming from capillaries

Answer 12

Venules

Question 13

is a blood vessel that directly links an artery and a vein

Answer 13

A shunt vessel

Question 14

label the following diagram

Answer 14

Question 15

Shunt vessels are used when the body is trying to control heat loss through capillaries in the skin:

What happens in a cold environment:

Answer 15

• arterioles get narrower (constrict)
• more blood diverted through shunt vessel
• less blood flows through capillaries
• less heat lost from skin capillaries

Question 16

Shunt vessels are used when the body is trying to control heat loss through capillaries in the skin:

What happens in a hot environment:

Answer 16

• shunt vessel constricts (gets narrower)
• arterioles get wider (dilate)
• more blood flows through capillaries
• more heat lost from skin capillaries
• body cools down

Question 17

describe what happens in Sweating & Shivering

Answer 17

sweating

• Sweat glands in the skin release more sweat
• The sweat evaporates, removing heat energy from the skin.

Shivering

Muscles contract rapidly - we shiver.

These contractions need energy from respiration,
and some of this is
released as heat.

Question 18

describe what happens to hair

Answer 18

Hot environment

Hair muscles relax

Hairs on the skin lie flat

Heat can escape

Cold environment

Hairs muscles contract

Hairs on the skin pulled upwards

Erect hairs trap air

Air insulates against heat loss

Question 19

How does the human body detect and respond to changes in temperature?

(6 marks – 6 minutes!)

Answer 19

How does the body detect and respond to changes in temperature?

• Temperature receptors in skin detect change in external temperature;
• Temperature receptors in hypothalamus detect change in blood temperature;
• Processing centre is hypothalamus (in brain);
• Nerve impulses sent (from hypothalamus) to effectors;
• Sweat glands produce sweat when too hot; (ora)
• Hair erector muscles contract when too cold; (ora)
• Hairs stand up, trapping a layer of air for insulation; (ora)
• Shivering;
• Is when muscles contract generating heat energy by respiration

Question 20

1. Name the processing centre and an effector which responds to a fall in temperature.
2. State 2 ways in which our bodies respond to a rise in temperature.
3. State what your core temperature is and why it needs to remain constant (hint – think back to our work on enzymes)
4. Explain the difference between vasoconstriction and vasodilation.
5. Explain how our bodies control temperature and why
6. Explain how negative feedback is used to control body temperature.
7. Provide the formula for the reaction that provides heat in our bodies (bonus point for the chemical formula!)

Question 21

Explain the role of ADH in homeostasis

or

Describe the role of ADH in regulating the water content of the blood.

Answer 21

Homeostasis is maintaining a constant internal environment

Keeping the content of water balanced in the body

the way to do this is the ADH

Antidiretic hormone

it is secreted by the pituitary gland in the brain

if water level is decreased in the body

ADH is released more. which increases the premeability of the collecting duct allowing more water to be reabsorbed and less water leaves the body with the urine , meaning more concentrated urine

if the water content is decreased.

less ADH is released, decreasing the mremeability of the colelcting duct allowing less water to be reabsorbed , meaning more water is leaving the body and more dilute urine

Question 22

answer the following question in the attached image

Explain the role of structure A

Explain the role of structure B

Question 23

Explain the cooling mechanisms in humans

(hot environment)

Answer 23

Vasodilation of skin capillaries

Heat exchange (both during warming and cooling) occurs at the body’s surface as this is where the blood comes into closest proximity to the environment

One way to increase heat loss is to supply the capillaries in the skin with a greater volume of blood, which then loses heat to the environment

Arterioles (small vessels that connect arteries to capillaries) have muscles in their walls that can relax or contract to allow more or less blood to flow through them

During vasodilation, these muscles relax, causing the arterioles near the skin to dilate and allowing more blood to flow through capillaries

This is why pale-skinned people go red when they are hot

Sweating

Sweat is secreted by sweat glands

This cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour

Flattening of hairs

The hair erector muscles in the skin relax, causing hairs to lie flat

This stops them from forming an insulating layer by trapping air and allows air to circulate over skin and heat to leave by radiation

Question 24

Explain the warming mechanisms in humans

Answer 24

Vasoconstriction of skin capillaries

One way to decrease heat loss is to supply the capillaries in the skin with a smaller volume of blood, minimising the loss of heat to the environment via radiation

During vasoconstriction, the muscles in the arteriole walls contract, causing the arterioles near the skin to constrict and allowing less blood to flow through capillaries

Vasoconstriction is not, strictly speaking, a ‘warming’ mechanism as it does not raise the temperature of the blood but instead reduces heat loss from the blood as it flows through the skin

Shivering

This is a reflex action in response to a decrease in core body temperature

Muscles contract in a rapid and regular manner

The metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature

Erection of hairs

The hair erector muscles in the skin contract, causing hairs to stand on end

This forms an insulating layer over the skin’s surface by trapping air between the hairs and stops heat from being lost by radiation

Question 25

animals that maintain a constant body temperature by phyiological means (mammals and birds)

Answer 25

homeotherm

Question 26

part of the brain that monitors core body temperature

Answer 26

thermoregulatory centre

Question 27

sking sensory receptors are located in

dermis

epidermis

hypodermis

Answer 27

dermis

Question 28

label the diagram

Vasodilation

Vasoconstriction

Normal

Answer 28

Question 29

explain how controling body temperature is a

negative feedback

Answer 29

negative feedback is

1. normal internal environment
2. change in the internal environemnt
3. change is detected by sensors
4. correcting action
5. internal environment returns to normal

for controlling body temperature

for example in hot environment this is what happens

Core body temperature (37°C)—>normal internal environment

temperature Increase from normal level—>change in the internal environemnt

Receptors in thermoregularory centre and skin detect increase—> change is detected by sensors

Thermoregulatory centre (hypothamalus in brain)receives and processes information .—–>correcting action

Effectors (muscles or glands) bring about changes—–>correcting action

Fall back tonormal level—–>internal environment returns to normal

Question 31

what happens in cold environment ?

A.more blood diverted through shunt vessel

B.shunt vessel constricts (gets narrower)

Answer 31

A.more blood diverted through shunt vessel