Lecture 9: Integument And Fat Flashcards
Which layer of the skin is made up of stratified squamous epithelium?
Epidermis
What are the four types of cells in the epidermis?
- Keratinocytes
- Melanocytes
- Langerhans cells (protective)
- Merkel cells (tactile)
Which layer of the skin is a deeper layer of dense irregular connective tissue?
Dermis
What are the two layers of the dermis?
Papillary layer
Reticular layer
Which layer of the dermis is made up of receptors for pain, heat, cold, pressure and tactile/touch?
Papillary layer
The papillary layer is made up of ________ papillae and looped ____________ and nerve fiber ___________
Dermal
Capillaries; endings
Which layer of the dermis has blood vessels, fat and lymph cells?
Reticular layer
The reticular layer of the dermis has what type of glands?
Oil and sweat glands
Hair follicles and associated structures are associated with which layer of the dermis?
Reticular layer
Which layer of the skin is also called the subcutaneous layer and is made up of loose connective tissue?
Hypodermis
The connective tissue of the hypodermis is made up of _____________ and _____________
Areolar
Adipose
Which layer of the skin is most of the fat stored and very well developed in humans?
Hypodermis
Which layer of the skin has larger vessels and nerves making it highly vascular?
Hypodermis
What type of tactile mechanoreceptors is for fine touch and pressure?
Merkel disks
What type of tactile mechanoreceptors is for light touch and texture (most sensitive)?
Meissner’s corpuscles
What type of tactile mechanoreceptors is for vibration and pressure found in the deeper epidermis?
Pacinian corpuscles
What mechanoreceptor is for heat and also stretch and pressure?
Ruffini’s end organ
What are the end-bulbs of Krause mechanoreceptors for?
Touch and pressure
What is the root hair plexus mechanoreceptor for?
Touch
What type of mechanoreceptor is for pain and heat and cold that is typically injurious?
Nociceptors/free nerve endings
Where is thick skin found and what layers does it contain?
Palms of hands
Soles of feet
Corresponding surfaces of fingers and toes
All five strata found here
Where is thin skin found and what layers does it contain?
Covers most of body
Lacks stratum lucidum
What glands and follicles are found on thin skin?
Hair follicles
Sebaceous glands
Sweat glands
What type of gland is associated with hair follicles and what does it secrete?
Holocrine, sebaceous gland
Secretes oil that adds to skin’s protective barrier
What type of gland is a holocrine gland?
Sebaceous gland
What type of gland is an apocrine gland?
Type of sweat gland
Where are apocrine glands found in humans?
Axillary and pubic regions
Apocrine glands are made of __________ filtrate that contains ____________ and promotes ___________ growth
Cellular
Nutrients
Bacterial
What might apocrine glands have an important role in?
Olfactory communication
What gland is extensive and very important in other mammals for evaporative cooling?
Apocrine
When might apocrine glands be stimulated?
Cases of fear, pain and emotional arousal
What would a reduction in apocrine glands in humans suggest?
Pheromones may not be as important
What type of gland is an eccrine gland?
Sweat gland
Eccrine glands produce ____________ via filtration of plasma.
Produces very _________ solution made up of mostly _______ containing waste products like ___________
Perspiration
Dilute
Water
Urea
True or false: Eccrine glands are metabolically MORE expensive and LESS wasteful than apocrine sweating
TRUE
True or False: Apocrine glands are better at removing body heat
FALSE
Eccrine are better at removing body heat
What are volar surfaces?
Palms and soles
Describe volar skin of most mammals and primates
Tend to be well-innervated
Thicker
Lined with ridges
In humans and nonhuman primates the volar surfaces are supported by ____________ _________ layers of fibrous tissue and ____________.
This creates __________ _________
They have distinct ridges called _____________
Thickened dermal
Fat
Friction pads
Dermatoglyphs (fingerprints)
Tails of some South American prehensile-tailed monkeys have friction pads with _____________.
Dermatoglyphs
What is a defining characteristic of mammals?
Hair and fur
What is the argument for there being no difference between hair and fur?
- Except overall numbers of individual follicles and placement on bodies of various species
- Chemically indistinguishable
- Both made of keratin
What are some identifiable differences between hair and fur?
- Fur tends to grow in a synchronized fashion and has terminal length
- Hair can grow asynchronously and have areas that keep growing
- While hair and fur are essentially similar in structure, different species can show distinct hair/fur characteristics
Nails, epidermis and hair are all made of what type of cells?
Dead keratinized cells
The root of hair has __________ made of _________ cells that permit _____________ growth
Papilla
Dermal
Continued
What is the main function of mammalian hair?
Insulation
Mammalian hair has ____________ ________ muscles.
Erection of hairs by small ___________ muscles
Allows space between hairs to ____________ and ________ more air that can be __________ by the body and provide this insulation
Arrector pili
Smooth
Increase; trap; warmed
The sensory function of mammalian hair has __________ endings at base of each hair follicle and are extremely sensitive to ________________.
Nerve
Movement
What are the specialized hairs around the face and nose called?
Vibrissae (whiskers)
Who have vibrissae (whiskers)?
All mammals except humans
Humans tend to have more __________ innervated hair follicles all over the body compared to other __________.
______________ function rather than ____________ may account for why humans have retained body hair
Richly
Mammals
Sensory
Insulation
Body size human hair reduction hypothesis:
_____________ size in ape lineage led to hair reduction to allow __________ bodied forms to _________ heat more effectively
Might help explain hair ___________ in apes, but not the extreme _____________ in humans.
Increasing; larger; lose
Reduction; reduction
Aquatic habitat human hair reduction hypothesis:
Hair loss is evident in _____________ _____________.
No hypotheses about ___________ evolution include wholly aquatic phase
Aquatic mammals
Human
Parasite human hair reduction hypothesis:
__________ hair or fur is a great place for some parasites to thrive
_____________ in hair ___________ would make dealing with such parasites much easier
Thick
Reduction; density
Sexual attraction human hair reduction hypothesis:
The ______________ level of sensation around human ________ __________ have been related to sexual attractiveness and _____________.
This does not acknowledge the fact that ________ skin itself is just as, if not more sensitive
Heightened; hair follicles; arousal
Bare
Clothing and culture human hair reduction hypothesis:
Hair reduction may have been __________ _____________ event connected to the use of ___________ and _____________
Would have made __________ hair unnecessary
Relatively recent; clothing; fire
Excess
True or false: Claws evolved from nails
FALSE
Nails evolved from claws
Nails are essentially a _______ that have lost ________ or more tissue layers.
Become ___________ and __________
Claw; one
Broad; flat
Some nonhuman primates have _____________ nails.
Selection for this structure has lead to a ______________ of the nail.
Claw-like
Modification
Early primate ancestor nails
Show evidence of nails
Thought to be uniting characteristic for primates that was shared by a common ancestor
Makes is synapomorphy for primates!
Nails give __________, _______ support to _________ digital pads and help dissipate ____________ forces
Broad, firm; support
Distal; compressive
Initially, features __________ appendages in primates including development of _____________.
Thought to be related to ___________ and particularly small _______ environment
Grasping; nails
Arboreality; branch
Likely the ability to __________ in a _________ environment for insects and fruits necessitated ________ hands and feet and _______ instead of __________ provided an advantage.
Forage; arboreal
Grasping; nails; claws
In small/medium bodied primates what does a presence of a claw-like nail provide an advantage for?
Grasping relatively larger substrates like limbs and tree trunks
What is ungula?
Hoof or nail
What is falcula?
Sharp curved claw
What is tegula?
Claw-like nail found in some primates
What are the functions of the integument?
Protection Excretion Retention of fluid/moisture Temperature regulation Vitamin D3 synthesis Sensory perception Enhancement of interaction with environment
Evolutionary trend of mammal integument
Hair/fur
Sebaceous (oil) glands
Sweat glands
Increased subcutaneous fat layer
Evolutionary trend of primate integument
Nails replace claws
Dermatoglymphs on hands, feet and some prehensile tails
High density of Meissner’s corpuscles in hands and feet
Eccrine sweat glands
Evolutionary trends in human integument
Reduction of body hair
Thermally sensitive eccrine sweat glands
Reduced distribution and importance of apocrine sweat glands
Further increase in subcutaneous fat layer
Fish and amphibian integument
Thinner epidermis has scales
Lacks protective barrier to allow respiration
Terrestrial species integument
Epidermis forms more protective barrier
Epidermis is thicker