3. integument physiology Flashcards
what are the 7 integument functions?
- protection
- immune defence
- sensing environment
- thermoregulation
- storage and excretion
- communication/camouflage
- selective permeability
what are the 3 skin sensors?
- mechanoreceptors
- nociceptors
- thermoreceptors
what are the 5 mechanoreceptors and what do they detect?
- Ruffini’s end organ or bulbous corpuscle – skin
stretch. - Krause end bulb or bulboid corpuscle–cold.
- Meissner’s corpuscle or tactile corpuscle – change in texture, slow vibrations.
- Pacinian corpuscle or lamellar corpuscle – pressure, fast vibrations.
- Merkel’s disc, a free nerve ending with discoid terminals – sustained touch and pressure.
what are nociceptors?
free nerve endings that sense pain
what are thermoreceptors?
free nerve endings that detect hot or cold
what is homeostasis?
Maintenance of constant conditions within the body’s internal environment in face of disturbances.
what does homeostasis need to balance?
- Concentration of water, salt and electrolytes.
- pH.
- Concentration of blood gases (O2 and CO2).
- Concentration of waste products.
- Responses to infection, injury, pain and emotional stress.
- temperature
what percentage of water is in a total adult body mass?
60-65%
how is water inputted into the body?
- free water intake (drinking)
- water in food
-metabolic water
How us water outputted in the body?
- urine
- faeces
- insensible losses- evaporation from skin and airway
what are electrolytes?
minerals in the blood and other bodily fluids that carry an electrical charge
What do electrolytes impact?
- water balance
- blood acidity (pH)
how are electrolytes maintained?
by adjusting the water concentration detected by osmoreceptors in the hypothalamus
what is acid-base homeostasis?
balance between acids and bases; constant hydrogen ion concentration [H+]
what maintains and controls homeostasis?
Region of the brain called the hypothalamus
what does the hypothalamus coordinate?
Coordinates activities of the autonomic nervous system (ANS) which are sympathetic, parasympathetic and enteric nervous systems
what does the hypothalamus control?
major part of the endocrine system
what does the hypothalamus detect?
osmolarity of the interstitial fluid in the brain via osmoreceptors
what does the hypothalamus monitor?
brain temperature
How does temperature homeostasis work?
- hypothalamus acts as a thermostat
- it receives nerve impulses from cold and warmth thermoreceptors (free nerve endings) within the skin
- also works by thermosensors within the hypothalamus and within the spinal chord, visceral organs and nasal/oral organs
what is the normal body temperature for most species?
38C
what do homeotherms use to thermoregulate?
metabolic heat
what do poikilotherms use to thermoregulate?
external environment
what is hypothermia?
below normal body temperature: when heat loss exceeds heat production
what is hyperthermia?
above normal body temperature: when heat production exceeds heat loss. Can be physiological and pathological
what is fever or pyrexia?
when the hypothalamic set point is reset to a higher temperature, this enhances leucocyte function to help fight infection
is thermoregulation a positive or negative feedback mechanism?
negative
With thermoregulation: what happens if our body temperature gets too high?
hypothalamus heat loss centre detects higher than set point temperature, this makes the blood vessels dilate and actives the sweat glands. Body temperature then decreases to a normal set point.
With thermoregulation: What happens if our body temperature gets too low?
Hypothalamus heat-promoting centre detects lower body temperature, the blood vessels constrict and the skeletal muscles are activated: shivering begins. This increases body temperature to normal
How do animals produce heat?
- By product of the metabolic process: all food energy is converted either directly or indirectly
- exercise
- eating
- muscle contraction ( shivering thermogenesis)
brown adipose tissue (non-shivering thermogenesis) - fever
what is non-shivering thermogeneisis
increased heat production Bia increased metabolism
what is non-shivering thermogenesis as a response to?
cold external factors
what is non- shivering thermogenesis mediated via?
- increased thyroxine secretion (the hormone from the thyroid gland)
- increased sympathetic (ANS) activity (norepinephrine)
- increased metabolism of lipids in response to circulation cetecholamines (norepinephrine/epinephrine)
what is brown adipose tissue
- A tissue predominately found in neonates as they have a large SA:V
- pigs don’t have any as they don’t have a UCP1 Gene
- present in small hibernating mammals in a adulthood
- specific to mammals
What is the structure of brown adipose tissue?
- they have a darker colour due to a higher density of mitochondria with cytochrome pigment
- they have smaller lipid droplets then yellow adipose tissue
- they have many lipid droplets compared to yellow adipose tissue
where is brown adipose tissue located?
in the subcutaneous region between scapular and around kidney and myocardium
what does brown adipose tissue do?
due to lipids being in close proximity to mitochondria it facilitates the rapid transfer of stored energy to heat energy
What stimulates brown adipose tissue?
circulating catecholamines and norepinephrine secreted from sympathetic nerve endings
What are the 3 ways animals lose heat?
- radiation
- conduction and convection
- evaporation
how do animals lose heat by radiation?
when the body is warmer than the environment, it loses heat by emission of infra-red radiation
how do animals lose heat by conduction and convection?
- directly from the body surface to cooler objects in contact with the animal
- transfer of heat by warm air to cooler air
how do animals lose heat by evaporation
ambient air is equal to or greater than body temperature: panting and sweating
what is panting?
A number of pattern acts top increase heat loss through evaporation
what are the 3 panting pattern acts?
- inflation and exhalation through the nose
- inhalation through the nose and exhalation through the nose and mouth
- inhalation through the nose and mouth and exhalation through the nose and mouth
which species is sweating an important means of thermoregulation and from what glands?
- horses and cattle via apocrine sweat glands
- primates via eccrine sweat glands
where are sweat glands confined to in cats?
- paws
- lips
- chin
- perineum
which species have poor developed sweating?
dogs and pigs so have little use in thermoregulation
What supplies blood to the skin?
cutaneous arteries
In blood supply to skin what are the 3 plexus involved?
- deep or subcutaneous plexus ( terminal branches of the cutaneous arteries)
- middle plexus
- superficial plexus
How is heat transferred within the body?
- heat transported by the blood
- heat it is produced primarily in muscles and the liver
- heat is lost through through skin and respiratory tracts as has very good blood supply with many small vessels close to the body surface
- rise is core body temp increases blood flow to the skin
- decrease in core body temp decrease flow
