Integument Physiology

Question 1

What is physiology

Answer 1

The function of organs and tissues within an animal

Question 2

What are the functions of skin

Answer 2

Protection
Immune defence
Tactile sensing of the environment
Thermoregulation
Storage and Excretion
Communication and Camouflage
Selective Permeability in some species

Question 3

What are the receptors within in the skin

Answer 3

Mechanoreceptors
Nociceptors
Thermoreceptors

Question 4

What are the type of mechanoreceptors in the integument and what do they sense

Answer 4

Bulbous corpuscle (Ruffini ending) - skin stretch
Bulboid corpuscle (Krause end bulb) - cold
Tactile corpuscle (Meissner corpuscle) - change in texture and slow vibrations
Lamellar corpuscule (Pacinian corpuscle) - pressure and fast vibrations
Discoid terminal free nerve ending (Merkel disk) - sustained touch and pressure

Question 5

What are Nociceptors

Answer 5

Free nerve endings that sense pain

Question 6

What is homeostasis

Answer 6

The maintenance of constant conditions within the bodys internal environment in face of disturbances

Question 7

Why is temperature important to maintain

Answer 7

Biological processes require optimum temperatures
Different species adapted to different temperatures and different regulatory mechanisms

Question 8

What are homeotherms

Answer 8

Animals that maintain internal temperature within a narrow range

Question 9

What are poikilotherms

Answer 9

Animals that have a variable temperature as unable to maintain internally

Question 10

What is the range of temperatures that healthy mammals should be in

Answer 10

36.5-39.5*C

Question 11

What is the range of temperatures that healthy birds should be in

Answer 11

38.0-43.0*C

Question 12

What is mild hypothermia

Answer 12

Between 32C and 37C

Question 13

What is moderate hypothermia

Answer 13

28-32*C

Question 14

What is severe hypothermia

Answer 14

<28*C

Question 15

What is mild hyperthermia

Answer 15

39.4-41*C

Question 16

What is severe hyperthermia

Answer 16

> 41*C

Question 17

What is the control centre for thermoregulation

Answer 17

Hypothalamic thermoregulatory centre

Question 18

What is used to supply information for thermoregulation

Answer 18

Thermoreceptors in skin, internal organs, spinal cord and in hypothalamus
Delivered by afferent nerves

Question 19

What is are the motor ouputs used in thermoregulation

Answer 19

Delivered by efferent nerves and hormones
Causes changes in behaviour, blood flow or other hormone related physiological responses

Question 20

What nervous system is the primary route to effectors of thermoregulation

Answer 20

The sympathetic nervous system
- it increases or decreases activity to different effectors

Question 21

What are some methods of losing heat

Answer 21

Smooth muscle dilates blood vessel to increase blood flow
Arrector pili relax to lower hairs/feathers
Sweat glands activate to increase secretions to skin surface for evaporation
Panting to increase airflow over moist mucosal surfaces for evaporation

Question 22

What are some methods of preventing heat loss

Answer 22

Smooth muscle constricts blood vessels to decrease blood flow
Arrector pili contract to lift hairs/feathers to trap a layer of air for insulation
Shivering

Question 23

How does negative feedback in thermoregulation work

Answer 23

Hypothalamus has a heat loss centre that detects higher than set point so starts the process of heat loss
When temperature corrected, heat loss centre is switched off

Hypothalamus has a heat conservation centre that detects lower than set point so starts process of conserving/generating heat.
When temperature corrected, heat conservation centre is switched off

Question 24

What is a fever/pyrexia

Answer 24

When the hypothalamic set point is reset to a higher temperature
- enhances leucocyte function to help fight infection

Question 25

How do animals produce heat

Answer 25

By product of all metabolic processes so food energy is converted to heat directly or by Exercise (work->heat) Eating (digestion->heat) Muscle contraction Brown adipose tisssue in certain species and ages

Question 26

What is non-shivering thermogenesis

Answer 26

Producing more body heat from metabolic sources of energy

Question 27

How are fat reserves used in non-shivering thermogenesis

Answer 27

Fat reserves are mediated by sympathetic ANS and catecholamines (Adrenaline and noradrenaline) Can adjust basal metabolic rate in response to chronic cold conditions

Question 28

What animals is brown adipose tissue found

Answer 28

Specific to mammals except pigs Predominantly in neonates and small hibernating mammals

Question 29

What is brown adipose tissue

Answer 29

Smaller, numerous lipid droplets in the subcutaneous region between scapulae and around kidneys and myocardium

Question 30

Features of brown adipose tissue

Answer 30

Darker colour due to a high density of mitochondria with cytochrome pigments Close proximity to mitochondria to facilitate rapid transfer of stored energy into heat energy Stimulated by circulating catecholamines and noradrenaline

Question 31

How do animals lose heat

Answer 31

By radiation By conduction and convection Evaporation

Question 32

How do animals lose heat by radiation

Answer 32

Heat produced metabolically by active organs and tissues Heat carried in blood Blood vessels dial ate to allow more blood to flow through and radiate more heat to the environment

Question 33

How do animals lose heat by evaporation

Answer 33

Only form of heat loss that works when ambient temperature equals or is greater than body temperature Evaporation of 1L of water requires 2.43kJ Panting Sweating

Question 34

Features of sweating in animals

Answer 34

Not major cooling mechanism in domestic species - cats and dogs have sweat glands predominantly localised to paws Horses and cattle use apocrine sweat glands Primates use eccrine sweat glands

Question 35

How does panting work

Answer 35

Moisture from mucosal surfaces in upper respiratory tract evaporates - increasing salivation Local vasodilation to increase blood flow and dissipation Heat energy from blood is used to evaporate moisture

Question 36

How is the core body temperature maintained despite cool extremities

Answer 36

Constriction of blood vessels in extremities to reduce heat loss Countercurrent exchange in peripherals to prevent further heat loss

Question 37

How does counter current exchange work in thermoregulation

Answer 37

Peripheral blood vessels constricts and resistance is high This causes blood to flow through deep capillaries to reduce transfer of heat to environment Heat from warm blood in arteries is transferred to cooler blood in deep veins coming from the periphery This means blood returning to the core is warmed up

Question 38

What happens to counter current system when warm

Answer 38

Peripheral blood vessels are dilated Resistance is low Blood flows through superficial capillaries to transfer heat to the environment

Question 39

Features of Brain cooling in artiodactyls

Answer 39

Carotid rete During selective brain cooling, cool venous blood from the nasal mucosa drains into the cavernous sinus via the angularis oculi vein Can be bypassed in periods of high sympathetic activity

Question 40

What is the guttural pouch

Answer 40

In perissodactyla (odd-toed non ruminant ungulates like horses and rhinos) Auditory tube diverticula contains air Arteries pass through and can dissipate heat into the air-filled space