homestasis

Question 1

homeostasis

Answer 1

maintaining a relatively stable internal environment with narrow limits even though the environment is changing

Question 2

factors that need to be controlled

Answer 2

body temperature - (37.5) thermoregulation
blood pH 7.4
blood glucose concentration
water potential of blood osmoregulation

Question 3

negative feedback

Answer 3

effector works to reverse change and restore initial conditions

e.g blood glucose and water potential

Question 4

positive feedback

Answer 4

effector stimulated to reinforced b d increase response

e.g giving birth
blood clots platelets

Question 5

Physiological response to temp in ectotherms cooling

Answer 5

cooling
arteriole near surface of skin dilate allowing more of flow through the capillaries close to surface of skin this increases heat loss to surrounding by radiation

increased sweating
sweat is scented by sweat glands as it evaporates from surface of skin heat is lost cooling the blood below it

flattening of hair
hair erector muscles relax causing hair to lie flat. u avoids trapping an insulating layer of air

Question 6

Physiological response to temp in ectotherms warming up

Answer 6

vasoconstriction
arteriole near surface of skin constricts allowing less blood through the capillaries. this reduces heat loss from blood

shivering
rapid involuntary contracting and replacing of large voluntary muscles
metabolic heat is released from the metabolic reactions which drive this process

raising of hair
hair erector muscles in skin contact causing hair to stand
this forms an insulating layer over the skin surface by trapping air between the hairs and stopping heat loss by radiation

Question 7

controlling thermoregulation how it detected and that

Answer 7

heat loss centre and heat gain centre in hypothalamus which contain thermoreceptors

activated when temperature of blood flowing through the hypothalamus increases or decreases. it sends impulses through the autonomic nervous system to effectors

peripheral temperature receptors in skin secrecy change in surface temperature

Question 8

Ectotherms behavioural responses

Answer 8

To warm up/increase body temp so metabolic reactions become fast enough to be active:They bask in the sun, orientate their bodies so max SA exposed to the sun, conduction by pressing their bodies into the ground.
To COOL DOWN they: seek shade/hide in burrows, conduction by pressing their bodies against cool surfaces, minimise movement so less metabolic heat generated through respiration, orientate their bodies away from the sun.”

Question 9

Ectotherm physiological responses

Answer 9

They need less food as a result of as less energy used to regulate temp (Food not used to generate heat eg) so can survive in habitats with difficult environments. Inactive in cold environments, greater proportion of energy used for growth.