Physiology Flashcards
What is anatomy?
the structure of organs and tissues within an animal
What is physiology?
the function of those organs and tissues
What is the common integument?
the skin
What are the seven function of the skin?
protection, immune defense, tactile sensing of the environment, thermoregulation, storage and excretion, communication and camouflage, selective permeability
Mechanoreceptors?
respond to physical stimulation
Bulbous corpuscle?
(Ruffini ending) sense when the skin stretches
Bulboid corpuscle?
(Krause end bulb) - sense coldness
Tactile corpuscle?
(Meissner corpuscle) Change in texture and slow vibrations
Lamella corpuscle?
(Pacinian corpuscle) pressure and fast vibrations
Discoid terminal free nerve ending?
(Merkel disc) sustained during touch and pressure
Three types of receptors?
mechanoreceptors, nociceptors, thermoreceptors
Nociceptors?
free nerve endings can act as nociceptors, pain
Thermoreceptors?
free nerve endings, heat specific ones and cold specific ones
What internal parameters do animals need to control?
temp, pH, electrolytes, water, blood gases (O2 CO2) Blood pressure and cardiovascular functions, hormonal responses etc.
What temperatures do biological processes require?
optimum temps
Endotherms?
derive heat from internal metabolic processes
Homeotherms?
maintain internal temperature within a narrow range
If you are an endotherm, you are also a?
homeotherm
Ectotherms?
derive heat from external environment sources e,g. basking
Poikilotherms?
variable temperature as unable to maintain internally
Animals that are ecotherms are also?
poikilotherms
Mammals and birds are what type of ‘therm’?
Homeotherms
too cold?
HYPOthermia
Hypothermia?
mild –> 32-37
moderate –> 28-32
severe –> <28
(these values are for exposure related hypothermia)
Too hot?
HYPERthermia
hyperthermia?
mild/moderate–> 39.4-41
Severe –> >41
hyperthermia signs?
central nervous system signs - multi organ failure - death
How is any complex maintained?
control centre
supply of info
communication
effectors
responses
effectors?
muscles/glands
Control centre in the body?
Hypothalamic thermoregulatory centre
(dorsal to pituitary gland)
What do afferent nerves do?
come to the brain
Sensory inputs from the body to the hypothalamus
Where do you have thermoreceptors?
In skin, in internal organs, in spinal cord, in hypothalamus itself
Types of thermoreceptors in skin?
hot and cold
Efferent nerves?
outputs from the hypothalamus to the body
Efferent outputs cause?
changes in behaviour, blood flow, other physiological responses, hormones
Thermoregulation is different but…
complementary for heat and cold stress
What is the autonomic nervous system made up of?
sympathetic nervous system
Primary route
Parasympathetic nervous system
sympathetic nervous system?
fight and flight
What increases or decreases the activity to different effectors?
the primary route to effectors in thermoregulation
parasympathetic nervous system?
rest and digest
some involvement in normal thermoregulation
How can an animal lose or gain heat?
smooth muscle within walls of blood vessels:
Dilate - blood vessels to increase blood flow if hot
Constrict - blood vessels to decrease blood flow if cold
How can an animal lose or gain heat? (2)
arrector pili muscles (smooth)
- contract to lift hairs/feathers
-relax to lower hairs/feathers
How can an animal lose or gain heat? (3)
Sweat gland activation
- increase secretions to skin surface for evaporation
How can an animal lose or gain heat? (4)
Panting - change in breathing pattern to increase airflow over moist mucosal surfaces for evaporation - no gas exchange occurs here
How can an animal lose or gain heat? (4) GIVE 2
shivering
behavioural changes (e.g. huddling together)
What information does the hypothalamus receive (and where from) about the temperature?
receives sensory information about temperature from skin surface, internal organs and itself
If temperature increases?
physiology does what it can to reduce it again
If temp decreases?
physiology does what it can to increase it again
How does the hypothalamus maintain its temperature set point?
through sensory and hormonal outputs
What is thermoregulation?
a negative feedback mechanism
Fever or pyrexia?
a reset of the hypothalamic set point to a higher temperature
What does fever/pyrexia enhance?
it enhances leucocyte (white blood cell) function to help fight infection
The hypothalamus has a heat loss centre - what does this do?
detects higher than set points - so starts process of heat loss
When temperature is corrected, what happens?
the heat loss centre switches off and in the opposite case, the heat conservation centre switches off
The hypothalamus has a heat conservation centre, what does this do?
it detects lower than set point so starts process of conserving/generating heat
What is a by-product of all metabolic processes?
heat
eventually all food energy is converted into…
heat, either directly or via exercise, eating and muscle contraction
how does exercise produce heat?
work done converted to heat energy
how does eating produce heat?
supply of energy, but also digestion is work
how does muscle contraction produce heat? (shivering)
as a means of increasing metabolic heat in response to a drop in temp where antagonistic muscles produce no useful work
hormones –>
longer term, chronic
Brown adipose tissue?
a form of non-shivering thermogenesis
muscle contraction is:
shivering thermogenesis
non shivering thermogenesis?
produces more body heat from metabolic sources of energy
what is the special type of fat in neonatal mammals?
brown adipose
using fat reserves?
rewatcj lecture
thyroxine?
lecture
what animal does not have brown adipose tissue?
PIGS
what gene did pigs lose meaning that they don’t have brown adipose tissue?
lots the UCP1 gene - 20 million years ago
What is brown adipose tissue predominantly in?
neonates
describe neonates SA:V ratio?
larger surface area to volume ratio
Describe which animals have brown adipose tissue?
in small hibernating mammals in adulthood
Why does brown adipose tissue have a darker colour?
due to higher density of mitochindria with cytochrome (iron-containing) pigments
what does brown adipose tissue contain?
smaller numerous lipid droplets
where is brown adipose tissue located?
located in subcutaneous region between scapulae and around kidneys and myocardium
What does the presence of lipids in close proximity to many mitochondria allow in brown adipose tissue?
facilitates rapid transfer of stored energy into heat energy
What is brown adipose tissue stimulated by?
both circulating catecholaminbes and norepinephrine secreted by sympathetic nerve endings
HOW DO ANIMALS LOSE HEAT?
Where is most body heat produced?
in metabolically active organs and tissues: liver and muscles
What part of the body are good insulators?
tissues - so they hold onto heat and the heat needs to be taken away
Where is heat carried?
in the warm blood
Why do blood vessels dilate?
to allow more blood to flow through and release more heat
Why do blood vessels constrict?
to reduce blood flow and retain more heat
What nervous system regulates heat loss? (via blood vessels)
sympathetic nervous system
Blood supply to skin?
Triple plexuses (superficial, middle, deep)
Immense surface area
piloerection?
hair is standing up - more insulation and is regulated by sympathetic nervous system
slide 36
Describe dogs and cats sweat glands?
poorly developed
apocrine sweat glands?
proteinaceous sweat
eccrine sweat glands?
watery sweat
where are sweat glands predominantly localised in domestic species?
paws
Describe how panting cools the animal down?
evaproationm, moisture from mucosal surfaces in upper resp tract
increased salivation, local vasodilation to increase blood flow and dissipation of heat
differentr breat5hing patterns using nose/mouth and dead space breathing where there is no gas exchange
what is dead space breathing?
no gas exchange
local vasodilation?
heat energy from warm blood evaporates the moisture cooling the blood
when is core body maintained?
in cool and warm environmental temperatures
How do animals prevent cold blood from extremities from cooling the core?
contstriction of blood vessels in extremities to reduce heat loss
Results in cooler extremities with cooler blood
Need to avoid cooling the core so the returning blood needs to be warmed
counter current exchange
more blood goes deeper than superficial so more cool blood goiong into the deep vessels
heat from artery warms blood up in the deep vein
exchange of heat - warm blood going to core and restrict heat loss going to the environment
carotid rete?
expansion of a vein, with coold blood in it which has come from nasal muscosum area, the mesh from the carotid artery, heat radiatyes out of arterial vessels into cool blood in the sinus then the mesh of vessels all comes back together and it is much cooler and this cooler blood can then go to the brain coming from the carotid - cats, pigs and chickens, cattle and sheep horses/primates do not have it
selective carotid rete?
the facial vein dilates and the angularis oculi vein contricts so the blood can avoid the cavernous sinus as much as possible
tmj
tempero mandibure joint
what is rudimentary in dogs?
carotid rete
