Communication and homeostasis

Question 1

Endocrine gland?

Answer 1

A gland that secretes its products directly into the bloodstream (travels further distances)

Question 2

Homeostasis?

Answer 2

The maintenance of a condition of equilibrium or of near-constant internal conditions

Question 3

Receptor?

Answer 3

A structure in the body that can detect changes in its environment and react to stimuli

Question 4

Effector?

Answer 4

A structure in the body that responds to a stimulus and brings about a response (e.g muscles/glands)

Question 5

Paracrine signalling?

Answer 5

Occurs between cells that are close together

Question 6

Endocrine signalling?

Answer 6

Involves signalling over long distances, with the cell signalling molecule transported in the circulatory system

Question 7

Oestrogen?

Answer 7

A female sex hormone (although also present in small quantities in males) that inna steroid and plays a role in the female reproductive cycle and the development of female secondary sex characteristics

Question 8

Synapse?

Answer 8

A junction between two nerve cells, consisting of a minute gap across which impulses pass either by an electrical current (electrical synapse) or, more often, by diffusion of a chemical neurotransmitter (chemical synapse)

Question 9

Negative feedback?

Answer 9

Type of control mechanism in which a change from the normal value of a physiological factor is detected and a response is made that restores the value to the norm

Question 10

Thermal regulation?

Answer 10

The control of temperature

Question 11

Endotherm?

Answer 11

An animal that maintains its body temperature using heat generated within its body tissues

Question 12

Ectotherm?

Answer 12

An animal that absorbs heat from its environment to help regulate its body temperature

Question 13

Radiation?

Answer 13

Is the loss of heat (in electromagnetic radiation form) from hot objects into cooler surroundings -main body heat loss

Question 14

Convection?

Answer 14

The movement of currents/warm air upwards, because the density of air decreases when it is warm

Question 15

Conduction?

Answer 15

Transfer of heat energy from a warmer material to a cooler one. The body can lose heat energy to the air by conduction, but because air is a good insulator, if a layer of air can be trapped around the body it will reduce further heat loss by radiation.

Question 16

Evaporation?

Answer 16

Water evaporates from the skin which cools the surface, this is because heat energy from the skin is used to change water to water vapour (this is what happens during sweating)

Question 17

Specific heat capacity?

Answer 17

The energy needed to change the temperature of 1kg of a substance by 1 Degrees Celsius

Question 18

What is vasodilation (of skin capillaries)?

Answer 18

Muscles in arterioles near skin relax, increasing the volume of blood that can flow through them and therefore the capillaries, heat loss is maximised

Question 19

What does flattening of hairs do?

Answer 19

The hair erector muscles in skin relax in warm conditions to thin the insulating layer of air on the skin - more heat is lost

Question 20

What does erection of hairs do?

Answer 20

The erector muscles contract so that the hair stand up on end and a thick layer of air is trapped, insulating the body and reducing heat loss

Question 21

Basal metabolic rate?

Answer 21

The energy used by the body at rest to sustain its vital organs

Question 22

What does boosting metabolic rate do?

Answer 22

In cold conditions a hormone thyroxine is released from the thyroid gland just infant of the larynx, which boosts the basal metabolic rate, increasing heat production (as most chemical reactions in body are exothermic)

Question 23

What does shivering do?

Answer 23

It is a reflex action in response to a small drop in core body temp, a nervous mechanism. The effectors (muscles) rapidly and regularly contract which is the shivering and this generates heat which warms the blood (the heat is generated due to the metabolic reactions going on in the muscle)

Question 24

What does vasoconstriction do?

Answer 24

Arterioles contract/constrict near skin, so that the volume of blood through arterioles is decreased, so little blood reaches capillaries near the skin surface

Question 25

Where does blood go when arterioles go through vasoconstriction?

Answer 25

Blood is diverted to shunt vessels, deeper in the skin and do not lose heat to surroundings - reducing cooling of blood

Question 26

What are peripheral receptors?

Answer 26

Thermoreceptors found in the skin/mucous membrane - receptors for cold and heat. communicate with the hypothalamus

Question 27

How might endotherms also have homeostatic behavioural responses?

Answer 27

For example, if an animal lives in a hot climate they might spend all day in water to keep cool, or a group of cold penguins huddle together for warmth

Question 28

Autonomic nervous system?

Answer 28

The part of the nervous system that controls automatic responses, consisting of the sympathetic and parasympathetic nervous systems

Question 29

Parasympathetic nervous systems?

Answer 29

Rest and digest, slow down heart rate, breakdown food, slow down heart rate

Question 30

Sympathetic nervous system?

Answer 30

Activates fight of flight, increases heart rate

Question 31

What is the hypothalamus?

Answer 31

The centre for temp control, located in the brain - monitors core blood temp as blood passes through. It contains temp receptors and two control centres

Question 32

What are the two control centres in the hypothalamus called?

Answer 32

Heat loss centre and heat gain centre - they send out both nervous and hormonal signals which bring about various actions related to temp control

Question 33

What are the following processes controlled by, sweating/shivering/vasoconstriction/vasodialtion?

Answer 33

Nerve impulses via the autonomic nervous system

Question 34

What two communication systems do animals have?

Answer 34

The nervous system and the endocrine system

Question 35

What does the nervous system do?

Answer 35

Transmit electrical impulses

Question 36

What does the endocrine system do?

Answer 36

Produce hormones

Question 37

Which responses are slower?

Answer 37

Hormone responses are slower but longer lasting

Question 38

What things must be kept at constant levels in the body?

Answer 38

Temperature, water and CO2

Question 39

Core body temperature?

Answer 39

37 degrees Celsius

Question 40

How can body heat be gained?

Answer 40

Through respiration, shivering, exercise

Question 41

How can body heat be conserved?

Answer 41

Decreasing sweating, raising of hairs/feathers, reducing blood flow near the skin surface

Question 42

What are the two cell signalling pathways called?

Answer 42

The paracrine and endocrine signalling pathways

Question 43

How have multicellular organisms evolved?

Answer 43

Specialised cells/tissues have developed which carry out individual functions, but can work together in organs to carry out functions together - relating to the entire body

Question 44

What are cell signalling molecules?

Answer 44

Molecules that communicate with other cells/molecules in other areas of the body