Biological Rhythms Skin: Hair & Glands

Mammalogy (Spring 2015 Althoff - reference FDVM Chapters 6 & 8)

LEC 07

Biological Rhythms

• _______ rhythms--a period of 24 hours

• _________ rhythms--a period of about 1 year

• _________ rhythms--anything less than 24 hours

Circadian Rhythms• __________ patterns--active mostly

during the daylight hours

• ___________--active peaks during darkness, rests during daylight

• __________ activity--dawn & dusk hours are peak activity periods

Circadian Rhythms: Activity Patterns

• Influenced by a) __________ pressure b) peak of ________ availability c) ___________ status

1) mating status2) most mammals give birth during “inactive” period

Activity Patterns…con’t

• DAYTIMEAdvantage:

Disadvantage:

Activity Patterns…con’t

• NIGHTTIMEAdvantage: higher ________ enhances olfactory communication reduced ________ stress reduced __________________ Disadvantage:

vision (color) __________

Circannual

• Influences _________________ CYCLE• Influences _________________ PATTERN

• Primary cue is probably _______________ by influencing hormone changes which alter:a) physiology b) morphology c) behavior

Photoperiod influence on...

• ____________--increased levels of reproduction hormones, influences level of “reproductive” readiness

• ____________--change in pelage, enlarged (and scrotal) testes, antler development

• ____________--increased aggression, maternal-type responses (nest building, etc.)

Other influences...

• ______________: beach mouse uses lower temps as cue to breed

• ______________: montane vole reproduction triggered by presence of 6-MBOA (6-methoxybenzoaxazolinone) in fresh plant shoots. Influences number and size of litters (p152, Table 8.1)

6-MBOA affects reproduction effort (Microtus montanus)Table 8.1 (p153)

Ultradian• ____________: some show 6 to 12 evenly spaced

short activity bouts per 24-hour day

• Rheus macaques: observed only during daylight (active) period…with bouts lasting 40-45 minutes.

• In general…still ________ understood, including their significance to survival.

Activity rhythm of female meadow vole (Microtus pennsyvlanicus)Fig. 8.10 (p154)

Mov

emen

ts in

met

ers

Hey...HAIR &

GLANDS!

Skin: Hair & GlandsReference FDVM Chapter 6

________ Mammalian Characteristics Associated

with the Skin

• HAIR

• SWEAT GLANDS

• SEBACEOUS GLANDS

• SCENT GLANDS

• MAMMARY GLANDS

DE

RM

IS

FDVM p98, Fig. 6.2

Hair• Has its origin in the dermal layer (dermis)• Consists of dead epidermal cells

strengthened by keratin (a tough, horny tissue made of protein)

• Functions: a) insulation b) sensory c) camouflage d) defense e) aggression

1

Cells “invaginate”,In the epidermis

= epidermis

= dermal = subcutaneous

HAIR DEVELOPMENT

2

“Hair” projectsdownward aswell as grows up

3

Rooted insubcutaneouslayer

Mescenchmalaggregation Mescenchmal

aggregation

Pigmentcells Hair

cone

Papilla

Hairbulb

Sweat Glands

• Has its origin in the dermal layer (dermis)• Functions: _________________

_________________• Two types:

a) eccrine--separate duct at surface; usually well distributed over body b) apocrine--duct at exit point (pore) of hair; armpits, anogenital

region, naval, nipples, & ears (in primates); in ears: modified to produce wax

DE

RM

IS

FDVM p98, Fig. 6.2

Eccrine sweat pore

ApocrineSweat duct

Sweating part ofapocrine sweat gland Secreting part of

eccrine sweat gland

Sweat Glands…con’t

• Distribution over body surface varies—usually where there is less hair

a) __________--all over bodyb) __________--pads of feetc) __________--feet and/or venterd) ______________________ -- do

not have anye) ________ on head only

f) ______________________________

_______ do not have any

Sebaceous Glands• Associated with ________________

• Produce and secrete oils a) positioned by erector pili muscles b) muscle moves, forces oil around shaft of hair

• Functions: a) ________________b) ________________

• Lanolin produced by sheep unique

• Hartner’s gland: lub for eyes & nictitating membrane

DE

RM

IS

FDVM p60, Fig. 5.2

Sebaceous gland

Scent (musk) Glands

• Either modified ______ glands or modified ____________ glands

• Functions: a) ________b) ______________c) _______________d) _______________

• Distribution varies (chin-to-tail): a) skunk: ____________ b) wolves & coyotes: __________ c) ungulates: _____________

Mammary Glands

• Also known as ____________• Elaborate , elongated duct system with

hollow sacs at end:a) alveolus--individual sac

b) lobules of andular tissue--groupof alveoli

• Function: _________________

first rib

skin cut

suspensory ligamentadipose tissue

pectoralis major muscle

lobeareolanipple

opening of lactiferous ductlactiferous sinus

lactiferous duct

_________________

__________________

ple

ura

l c

avit

y

MONOTREME human UNGULATE

EUTHERIAN (placentals)

Alveoli

• No nipples• No teats• Milk oozes out onto skin

• nipples • teats

MAMMARYTISSUEshowingindividual

_________

LOBULEOF

ALVEOLI

LOBULEOF

ALVEOLI

Mammary Glands…con’t

• Always on ventral sidea) primates: 2 thoracic mammaeb) perissodactyls: 2 inguinal mammaec) most rodents: 5 pairs on belly

(chest to groin)d) NA opossum: 13 (12 in circle, 1 in

center of circle)e) whales: mammary grooves

Milk Production

• __________ is hormone that stimulates milk production

• __________ is hormone that stimulates milk letdown

• Milk content varies in protein & fat content a) b) c)

Bottlenose Dolphin

• Found in warm temperate and tropical oceans and seas worldwide

• 150 – 200 kg (330-440 lbs.)• Gestation period just 12 months, then nurses

young for 12-18 months in wild, longer in captivity

• Diet includes squid, shrimp, eels, and a wide variety of fishes (carnivorous)

Month of Lactation

Milk

Con

stitu

ent

%

_________ inmilk fat and milk water over the course of lactation in bottlenose dolphin

West et al. 2007Journal of Zoology273:148-160 (Fig. 1)

Dolphin K

Dolphin P

Milk fatMilk water

Month of Lactation

Milk

Con

stitu

ent

%

________ inmilk protein and milk sugar over the course of lactation in bottlenose dolphin

West et al. 2007Journal of Zoology273:148-160 (Fig. 2)

Dolphin K

Dolphin P

Milk proteinMilk sugar

Eastern barred bandicoot

• Native to Australia (Victoria) & Tasmania• Medium-sized omnivorous marsupial (~1 kg)• Gestation period just 12 days, then nursed for

~55 days before weaned

_________ inmilk contentover weeks3-9 of lactation in eastern barredbandicoot

Ikonomopoulou et al. 2005Australian J. of Zoology53:59-65 (Fig. 1)

Total solids Lipids = fat

Protein Carbohydrate

MILK CONTENT (%) by Species(selected from FDVM Table 6.1, p103)

Water Protein Fat Sugar Ash

73.5 9.7 8.1 3.1 1.5Kangaroo

71.3 12.3 13.1 1.9 2.3Rabbit

43.8 11.9 42.8 0.0 0.9Harp seal

65.9 10.4 19.7 2.6 1.4W.t. deer

88.0 1.2 3.8 7.0 0.2Human

72.9 9.2 12.6 3.3 1.4Rat

44.9 10.6 34.9 0.9 0.5B-n dolphin

Note: ASH = not water & not organic

77.1 5.8 12.5 3.4 0.9Giraffe