Integument

Question 1

What are skin associated glands?

Answer 1

1. Sebaceous glands

2. Sweat glands: encrine and apocrins

Question 2

What are sebaceous glands?

Answer 2

1. oil glands
2. nothing to do with thermoregulation
3. Alwasy empty itnto hair follicle
4. secrete sebum: lipds

Question 3

What is the function of sebum

Answer 3

1. escapes when pilorector muscles alongside hairs contract
2. oils hair
3. forms oily film on the skin: lubricates skin, stops water loss, inhibits growth of certain bacteria, spread sweat, territorial marker

Question 4

How are sebaceous glands regulated?

Answer 4

1. regulated by sex steroid hormones
2. more active after puberty
3. larger adn more productive in the breeding season
4. androgens (male) increases activity

Question 5

What are sebaceous glands?

Answer 5

1. oil glands
2. nothing to do with thermoregulation
3. Alwasy empty into hair follicle
4. secrete sebum: lipds

Question 6

Few facts about sebaceous glands comparing with species

Answer 6

1. no sebaceous glands with feathers

Question 7

What are important about sweat glands?

Answer 7

1. involved in thermoregulation

Question 8

Apocrine sweat glands

Answer 8

1. common in domestic species, sparce in primates
2. important in evaporative heat loss in some animals (horses and cattle)
3. autonomically regulated by sympathetic nervous system: noradrenaline
4. oily, opaque secretion, initially odourless but becomes smelly with bacterial breakdown

Question 9

Ecrine sweatglands

Answer 9

1. Common in primates, sparce in domestic animals
2. important evaoprative heat loss
3. Ach releases, sympathetic
4. watery NaCl solution that can be modified by aldosterone

Question 10

What do both apocrine and ecrine sweat glands need and what for?

Answer 10

1. Myoepithelial cells

2. single cells needed to get secretion out

Question 11

Name some glands in our domestic species

Answer 11

1. anal glands in dogs and cats (territorial marking)
2. Interdigital pouch at front of claw in sheep
3. infraorbital pouch in sheep (eye) = territorial marking
4. tail glands in dog adn cat (territorial marking)
5. preputial gland at opening of foreskin in boars - sexual attraction, scent

Question 12

What produced melanin?

Where are they locates and structure

Answer 12

1. Melanocytes
2. These cell bodies interspersed with other cells in basal layer epidermis
3. Cell extensions are squeezed between cells
4. Melanin is shed when keratinocytes reach the surface of the skin

Question 13

What is melanin and what are the types?

Answer 13

1. melanin is a broad term for a group of natural pigments
2. there are 2 pigments
   a) Eumelanins (black and brown colouration)
   b) Pheomelanins (yellow and red colouration)

Question 14

How is melanin synthesised?

Answer 14

1. Controlled by MSH binding to its specific MSH receptor

2. more MSH = more pigment produced

Question 15

What regulated how much of the MSH hormone is produced

Answer 15

1. UV light

2. Disease states e.g. crushings

Question 16

Outline how vitamin D is formed in the skin. what is it inhibited by?

Answer 16

1. DHC in ther dermin + UV –> vit D3

2. inhibited by heavy pigmentation, dense fur coat

Question 17

What is vit D important for and where found?

Answer 17

1. important in calcium homeostasis

2. found in fat, liver, blood, synthesised in skin

Question 18

What is photosensitivty?

Answer 18

1. abnormal reaction to sunlight due to accumulation of photosensitive compounds below the skin. due to the presence of a photodynamic agent.
2. NOT SUNBURN!

Question 19

With endotherms what is included in core temperature?

What is important to remember with core

Answer 19

CORE = brain, thorax and abdomen

2. Core should stay the same, skin temp and extremities etc changes

Question 20

When would you expect to see a normal change in core temperature

Answer 20

DROPS
1. before partuition
2. Sleep, therefore first thing in morning
INC
3. metabollic rate inc - growing, lactating or pregnant

Question 21

How does core body temp fluctuate?

Answer 21

1. between 0.5- 1 degree over 24 hrs

Question 22

Core body temp of species

Answer 22

1. Cattle = 38.5
2. Dogs = 38.5
3. Cats = 38.5
4. Horse = 37.5
5. Pig = 39
6. Sheep = 39.5

Question 23

Thermoregulation overview

Answer 23

1. Temperature receptors detect changes in temp
2. Hypothalamus receives info about both internal and external temp
3. Motor output = Signals for heat or cold stress

Question 24

Where are the cold and warm receptors located?

Answer 24

1. cold = mediated by cold receptors in epidermis

2. warm = mediated by warm receptors in dermis

Question 25

Why can skin temp change greatly? What nervous system? How does it affect blood flow?

Answer 25

1. Blood flow to the skin can vary widely depending on the need to dissipate heat 2. ONLY sympathetic nervous system regulates blood to skin and controls the erector pili muscle 3. Reduced frequency of nerve impulses = vasoconstriction. Increased frequency of nerve impulses = vasoconstriction

Question 26

How are blood vessels arranged in skin?

Answer 26

1. parallel arterioles and veins in dermis and subcutaneous adipose tissue

Question 27

Panting | Why does a dog not develop alkalosis?

Answer 27

1. rapid, shallow breathing 2. Most water coming from nasal turbinantes and not mouth 3. not develop alkalosis as (breathing deep and heavily would) as not changing alveolar gas exchange

Question 28

What is thermogenesis and how do domestic species increase it?

Answer 28

Thermogenesis is the production of heat in the animal body 1. shivering: Primary involuntary measn of increasing heat production. Antagonistic muscles contract simultaneously 2. Non shivering thermogenesis = inc basal metabollic rate

Question 29

At rest where does most heat come from?

Answer 29

1. rest = heart, liver, kidney and brain produce 60-70% body heat

Question 30

Non shivering thermogenesis

Answer 30

1. partly driven by the amount of thyroid hormone produced which will inc general metabollic heat 2. also due to action of sympathetic nervous system which controls blood supply and oxidation of fatty acids in brown adipose tissue

Question 31

What is the thermoneutral zone?

Answer 31

1. range at whihc don't need to expend energy to maintain core temperature

Question 32

What do pyrogens do?

Answer 32

1. change the hypothalamic set point to a higher value than normal 2. This means that animal will feel cold = generates heat 3. because core body temp is 37 but if set point inc to 39 you will feel cold! 4. therefore when have flu you feel cold

Question 33

Recumbent cow with hypocalcawmia. Would you expect core temperature to be higher or lower than normal? Explain

Answer 33

1. Lower 2. Inactive 3. Low calcium = less smooth muscle working

Question 34

Why are sedated animals more at risk of hypothermia?

Answer 34

1. inc SA 2. not moving 3 Losing heat through incision/ prep (surgical spray)

Question 35

How does an adult animals LCT and TNZ compare to that of a neonate?

Answer 35

1. Lower LCT and Wider TNZ as bigger and less likely to lose heat

Question 36

1. If had to draw a somatic reflex arc what would you include?

Answer 36

1. Sensory receptor 2. Sensory neurone into dorsal end 3. interneuron 4. Motor out of ventral and 5. Directly to effector

Question 37

How does a smatic reflex arc differ from autonomic reflex arc?

Answer 37

1. somatic = one neuron to effector | 2. autonomic = motor effector has 2 neurons pre and post ganglionic

Question 38

What are the skin funcitons?

Answer 38

1. Thermoregulation 2. Sensory info 3. Synthesis of vit D 4. Storage of fat and water 5. Protection: mechanical and chemical injury, invasion by microorganisms, underlying tissue from the sun, from dehydration