Integument physiology

Question 1

What are some functions of the integument?

Answer 1

Protection, Immune defence, Sensing environment, Thermoregulation, Storage and excretion, Communication, Camouflage and selective permeability

Question 2

Mechanoreceptors

Answer 2

detect stimuli such as touch, pressure and stretching

Question 3

Ruffini’s end organ

Answer 3

detects skin stretching

Question 4

Krauses end bulb

Answer 4

detects cold

Question 5

Meisner’s corpuscle

Answer 5

detects vibrations

Question 6

Pacinian corpuscle

Answer 6

detects pressure and fast vibrations

Question 7

Nociceptors

Answer 7

Free nerve endings that can detect pain

Question 8

Thermoreceptors

Answer 8

free nerve endings that can detect hot or cold

Question 9

Homeostasis

Answer 9

Maintenance of constant conditions within the body’s internal environment

Question 10

How much of an adults body mass is water

Answer 10

60-65%

Question 11

What part of the brain controls homeostasis?

Answer 11

The Hypothalamus

Question 12

Hypothalamus

Answer 12

Coordinates activities of autonomic nervous system (ANS).
* Sympathetic (fight or flight).
* Parasympathetic (rest and digest).
* Enteric nervous system.
Controls a major part of the endocrine system.
» Detects the osmolarity of the interstitial fluid in the brain via osmoreceptors.
» Monitors brain temperature

Question 13

Why is thermoregulation important?

Answer 13

» Enzymes only work at optimum temperature.
» Below 34°C animals unable to regulate their own temperature.
» At 27 to 29°C cardiac fibrillation and death!
» An increase of temperature to 45°C can cause fatal brain lesions.
» Knowledge of this can improve patient safety

Question 14

Hypothermia

Answer 14

below normal body temperature

Question 15

Hyperthermia

Answer 15

above normal body temperature

Question 16

Fever/Pyrexia

Answer 16

reset of hypothalamic set point to higher temperature, enhances leucocyte

Question 17

Thermoregulation

Answer 17

negative feedback mechanism

Question 18

How do animals produce heat?

Answer 18

» By-product of all metabolic processes.
* Eventually all food energy is converted to heat
either directly or…
» Exercise.
* Work done converted to heat energy.
» Eating.
* Supply of energy, but also digestion is work.
» Muscle contraction (shivering thermogenesis).
* As a means of increasing metabolic heat in
response to a drop in temperature where
antagonistic muscles produce no useful work.
» Brown adipose tissue (non-shivering
thermogenesis).
» (Fever
* Changing the hypothalamic set point to aid in
fighting infection).

Question 19

Non-Shivering Thermogenesis

Answer 19

» Increased heat production via increased
metabolism.
» In response to chronic cold external factors
» Mediated via:
* Increased thyroxine secretion (hormone from
thyroid gland).
* Increased sympathetic (ANS) activity
(norepinephrine).
* Increased metabolism of lipids in response to
circulating catecholamines
(norepinephrine/epinephrine).
» Brown adipose tissue.

Question 20

Where is Brown Adipose Tissue located?

Answer 20

subcutaneous region between scapulae and around kidneys and myocardium

Question 21

Why are lipids near Mitochondria

Answer 21

facilitates rapid store of energy into heat energy

Question 22

What stimulates Brown Adipose Tissue

Answer 22

circulating catecholamines and norepinephrine secreted from sympathetic nerve endings

Question 23

What are the 3 ways animals lose heat?

Answer 23

Radiation, Conduction and Convection and Evaporation

Question 24

Radiation

Answer 24

when the body is warmer than the environment they lose heat by emission on infra-red emission

Question 25

Conduction and Convection

Answer 25

Directly from body surface to cooler objects in contact with the animal. * Transfer of heat by warm air to cooler air.

Question 26

Evaporation

Answer 26

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

Question 27

Brown Adipose Tissue

Answer 27

Specific to mammals (not present in other vertebrates species), predominantly in neonates, present in small hibernating mammals in adulthood, darker colour due to a higher density of mitochondria (smaller numerous lipid droplets)

Question 28

Panting

Answer 28

Patterns to increase heat loss through evaporation

Question 29

Turbinates

Answer 29

tiny structures inside the nose that become engorged along with respiratory and oral mucosa

Question 30

Dead space in lungs

Answer 30

volume of air that is not used for gas exchange

Question 31

Sweating

Answer 31

» Important means of thermoregulation in horses and cattle (from apocrine sweat glands). » Important means of thermoregulation in primates including humans (from eccrine sweat glands).

Question 32

Can cats sweat?

Answer 32

Yes but glands are confined to paws, lips, chin and perineum

Question 33

Cutaneous arteries

Answer 33

volumes of skin and subcutaneous tissue supplied by branches of an artery that perforates the body fascia.

Question 34

Three plexus in the skin

Answer 34

Deep or subcutaneous, Middle and Superficial

Question 35

Heat Transfer within the body

Answer 35

Tissue is a poor conductor of heat. » Heat transported by the blood. » Heat produced primarily in muscles and the liver. » Heat lost through skin and respiratory tract as very good blood supply with many small vessel close to the body surface. » Rise in core body temperature increases blood flow to the skin. » Drop in core body temperature decreases flow and fur or plumage are raised (piloerection/goose bumps) to trap more air as insulation. » Sympathetic nervous system regulates blood flow and piloerection

Question 36

Counter-Current Exchange

Answer 36

Peripheral vessels dilate and transfer heat to the environment

Question 37

Carotid Rete

Answer 37

The carotid rete consists of a compact network of intertwined, freely anastomosing arteries, and is related to the branches of the trigeminal nerve. Seen in cats, pigs, chickens and dogs- not in horses and primates

Question 38

Function of brain cooling

Answer 38

During selective brain cooling, cool venous blood from the nasal mucosa drains into the cavernous sinus via the angularis oculi vein (as well as some deeper veins). » Can be bypassed in periods of high sympathetic activity.

Question 39

Guttural pouch

Answer 39

Air filled sac in the brain that cools down the blood- only found in horses