Domestic Animal Physiology

what is a physiologist?

• A physiologist assimilated knowledge of the body’s systems using the Hypothetico-Deductive Method

homeostasis

maintaining a stable internal environment despite external changes

homeostasis example

body temperature

dynamic changes

processes that respond to environmental or internal stimuli

example of dynamic change

heart rate during exercise

fixed fluctuations

regular, predictable changes in physiology

example of fixed fluctuations

circadian rhythms, seasonal breedingwha

what did Claude Bernard do?

developed concept of milieu interior aka constant interior bodily environment

what did Walter B. Cannon do?

coined the term homeostasis, which describes how biological systems maintain adjusting to changing conditions

examples of homeostasis

body temp regulation, blood pressure, pH balance

examples of homeostatic challenges

environmental stressors, nutritional imbalances, pathogens and diseases

components of homeostatic control

receptors, control centers, effectors

receptors

detect changes in environment and convert signals into nerve impulses or chemical messages

how are receptors sorted/ defined?

by location, stimulus

exteroceptors

detect external environmental changes

interoceptors

detect internal changes in the body

proprioceptors

detect changes in body position and movement

mechanoreceptors

detect mechanical changes, ex: sensing pressure

thermoreceptors

detect temperature changes, ex: hot/cold water on hand

chemoreceptors

detect chemical stimuli, ex: monitor CO2 and O2 levels

photoreceptors

detect light stimuli, ex: light intensity and color

nociceptors

detect painful stimuli, ex: skin and internal pain

exeroceptor

react to changes in external stimuli

thermoreceptor

react to change in temperature

control centers

processes information from receptors and initiates a response chemically, located throughout the body

types of control centers

hypothalamus, pineal gland, pituitary gland, autonomic nervous system

hypothalamus

region of the brain that acts as the body’s master physiological regulator

pineal gland

produce melatonin, attatched to the roof of the brain and produces melatonin based on duration of darkness detected by photoreceptors

pituitary glands

regulates growth, metabolism, and reproduction

autonomic nervous system

involuntary processes (heart rate, breathing ect)

what are hormones?

chemical messenger that is transported by the bloodstream, released by control centers to initiate a response from the body, signal is carried to organs, skin, muscles and other tissues.

effectors

organs, tissues, or systems that carry out the physiological or behavioral responses directly by control centers

signal reception

recieve instructions from control cetners via nerves or hormones

action reception

respond to restore balance

order of simulius, and 3 points of homeostatic control

stimulus—sensor—control—effector—back to stimulus

homeostasis

Maintaining a stable internal environment despite external changes

dynamic changes

Processes that respond to environmental or internal stimuli

fixed fluctuations

Regular, predictable changes in physiology

cyclican rhythm

Occur in repeating patterns, such as daily, monthly, or seasonal rhythms

• Control sleep-wake cycles, feeding behavior, and hormone release

Internal regulation

Governed by biological clocks, such as circadian clock for daily cycles

Environmental cues

Environmental factors like light, temperature, and food availability help reset and synchronize internal rhythms

 

Biological clocks

• Located in the hypothalamus

• Suprachiasmatic nucleus (SCN)

• Coordinates body-wide rhythms by signaling peripheral clocks in organs like the liver and muscles

Hormonal regulation

• Hormones such as melatonin, cortisol, and sex hormones (e.g., testosterone, estrogen) follow fixed patterns, driving rhythmic behaviors

• Environmental triggers

• Photoreceptors in the eyes detect light changes, influencing the SCN and hormonal activity

 

• Reproductive cycles

• Hormonal fluctuations tied to fixed reproductive events

 

• Estrous or menstrual cycles

• Seasonal changes

• Regulate reproduction, metabolism, and hair coat growth in response to photoperiod (day length) or temperature

Growth patterns

• Animals grow rapidly during specific life stages, followed by predictable slowdowns in growth

• What is homeostasis, and why is it critical for maintaining physiological balance in animals? Provide examples of homeostatic processes.

• Homeostatis is the matinence of stable internal envrionment in an organism despite external environment changes.

• Differentiate between dynamic changes and fixed fluctuations in physiological processes, including examples of each.

• Dynamic- respond to environment- rapid short term changes- go for a run

• Fixed fluctuation- happen app the time, long term changes, ex: for seasonal breeding,

• How do the components of homeostatic control (receptors, control centers, and effectors) work together to maintain balance in the body?

• Receptors get info from external stimuli

• Control centers- process info

• Effectors execute what control centers tell them to do

•Endotherms vs. Ectotherms

•Endotherms generate body heat metabolically, using adaptations like fur, feathers, sweating, and shivering, but require higher energy intake.

•Ectotherms rely on environmental temperatures, conserving energy but being less active in extreme temperatures.