Lecture 5 Flashcards
An animal coping with their environment involves maintaining _____
Homeostasis
Homeostasis
The maintenance of an organism’s internal environment which occurs due to a series of functional control systems.
Factors that affect homeostasis
- Environment
- Handling
- Other individuals
- Genetics
- Health
- Food
What is involved in understanding and perceiving the environment?
All 5 senses.
Components of the sensory nervous system
- Sensory neurons
- Neural pathways
- Parts of the brain involved in sensory perception
Function of the touch, taste, smell, hearing, and vision in sensory perception
These senses transduce signals from the physical world to the brain where it can be interpreted, allowing perception of the world
A change in homeostasis activates a range of physiological responses through _______
The central nervous system
Two types of responses from the central nervous system in response to a change in homeostasis
- Autonomic nervous system
- Neuroendocrine response
Two branches of the autonomic nervous system
- Sympathetic nervous system
- Parasympathetic nervous system
Stress
A biological response that occurs when an individual perceives a threat to its homeostasis
A threat to homeostasis
Stressor
Is stress inherently bad?
No, stress is a part of life and is not always bad
Acute stress
A relatively brief exposure to a single stressor which may affect an animal’s biological functions
Chronic stress
Long-term exposure to a stressor, continuous stress.
Distress
An aversive, negative state in which coping and adaptation processes fail to return an organism to physiological and/or psychological homeostasis. Involves a deleterious effect to an animal’s welfare.
Stress vs. distress
Stress: A non-threatening stress response.
Distress: A biological state where the stress response has a deleterious effect on the individual’s welfare.
A challenge is to determine when stress becomes _____
Distress
An animal’s first response to coping with stress
Avoid the stressor by removing itself from the threat
Types of biological responses for coping with stress
- Behaviour
- Autonomic nervous system
- Neuroendocrine system
- Immune system
Are behavioural responses appropriate for all stressors?
No, some situations cause behavioural options to be limited
In what situations are an animal’s behavioural responses to stress limited?
When they are confined
Do animals still have a behavioural response to stress when they are confined?
They can, even if the behaviour will not alleviate the stressor. This can be a sign of distress.
Second line of defence for coping with stress
The autonomic nervous system - specifically, the Sympathetic-Adrenal-Medullary system (SAM) aka. the fight or flight response.
Fight or flight response
Part of the autonomic nervous system. Affects the cardiovascular system, the gastrointestinal system, the exocrine glands and the adrenal medulla. Short duration.
Steps of the fight or flight response
- The sympathetic autonomic nervous system is activated.
- That system activates the adrenal medulla.
- The adrenal medulla secretes catecholamines (epinephrine and norepinephrine).
- Leads to increased heart rate, increased skeletal muscle circulation, decreased glycogen reserves to increase available energy in the form of glucose.
Effects of epinephrine and norepinephrine on the body
- Increase in heart rate and blood pressure
- Glucose is released into the blood
- Bronchioles dilate
- Changes to blood flow patterns (increased muscular activity)
Catecholamines result in a (fast/slow) response
Fast, they are secreted quickly
The fight or flight response can cause death due to
- Over-stimulation by adrenaline causes a myocardial infarction
- Excessive reaction of the parasympathetic system to the sympathetic nervous system response (cardiac arrest)
Third response to cope with stress
Neuroendocrine systems - the hypothalamic-pituitary-adrenal axis (HPA axis)
Effects of the HPA axis
Effects are long-lasting. It affects the immune competence, reproduction, metabolism and behaviour.
Adrenal glands
Above the kidney and have two structures that liberates different substances (cortex and medulla)
What is released by the adrenal medulla
Epinephrine and norepinephrine (catecholamines)
What is released by the adrenal cortex
Glucocorticoids (cortisol), mineralocorticoids (aldosterone), and sex steroids (testosterone)
HPA system mechanism
- Hypothalamus releases corticotropin-releasing hormone (CRH)
- The anterior pituitary receives that signal and releases adrenocorticotropic hormone (ACTH)
- The adrenal cortex releases cortisol as a result
High levels of cortisol help to maintain ____
High levels of energy in the form of glucose
Fourth response to stress
Immune system is suppressed due to stress, leads to disease in stressed animals
Consequences of prolonged stress
- Altered biological function
- Prepathological state
- Development of a pathology
What is the function of a stress response
To return an animal to normal biological function
Stages of general adaptation syndrome (GAS)
- Alarm stage
- Resistance stage
- Exhaustion stage
General adaptation syndrome (GAS)
Describes the pattern of responses that the body goes through after being prompted by a stressor.
Alarm stage of GAS
Initial reaction to a stressor, the fight or flight response.
Resistance stage of GAS
- After the alarm phase, the body releases a lower amount of cortisol, and the heart rate and blood pressure begin to normalize.
- Although the body enters this recovery phase, it remains on high alert for a while.
- If the individual overcomes stress and the situation is no longer an issue, then the body continues to repair itself until the hormone levels, heart rate, and blood pressure reach a pre-stress state.
Exhaustion stage of GAS
- This stage is the result of prolonged or chronic stress.
- Struggling with stress for long periods can drain the physical, emotional, and mental resources to the point where the body no longer has strength to fight stress.
What mechanisms cause the exhaustion stage in response to a stressor?
There is a loss of the negative feedback mechanisms
What are the difficulties of using physiological indicators of stress
- The stress response is nonspecific, multiple situations can result in a stress response (ex. mating).
- Different stressors can cause very different types of biological responses.
- There is individual variation in response. Animals can cope very differently to the same stressor.
- There are many factors that can impact the response.
What factors can alter a physiological response to stress?
- Previous experience
- Genetics
- Age
- Social relationships
- Human-animal interactions
- Physiological status
Heart rate as an indicator of stress
An animal’s heart rate changes in response to activity and the perceived need for activity.
Changes in heart rate due to stress are (prolonged/brief) and can be a good indicator of (short-term/long-term) welfare problems
Changes are brief and can indicate short-term welfare problems
Respiratory frequency as an indicator of stress
- Measures acute stress
- Is related to heart rate
- Easy to observe
Body temperature as an indicator of stress
Can be used to indicate disease (fever) or alterations caused by environmental temperature (heat/cold stress)
The three ways of measuring body temperature from most to least accurate
- Internal temperature
- Rectal temperature
- Superficial temperature
When is internal temperature used
In research studies, a device must be implanted which makes it difficult for clinical use
Blood count as an indicator of stress
- Blood count and the leukocyte counts change in response to stress
- Glucocorticoids increase the percentage of neutrophils and decrease the percentage of lymphocytes
What should be considered when using blood counts as an indicator of stress
The blood sample collection can increase stress and impact the results
How can glucocorticoid concentrations be measured
- Blood
- Saliva
- Feces
- Hair
- Urine
Advantages of measuring glucocorticoid concentrations as an indicator of stress
- Current gold standard
- Easy to collect
- Lots of literature support
Disadvantages of measuring glucocorticoid concentrations as an indicator of stress
- Collection methods elicit stress
- Stability
- Varies with the time of day (diurnally)
- There is individual variation
What can influence glucocorticoid concentration
- Stress during collection
- Circadian rhythm (increased during the day, less at night)
Adrenal volume as a measure of stress
Looks at medullar area and cortical area
Physiological indicators of disease response (blood)
Acute phase proteins and C-reactive proteins
Physiological indicators of physical effort (blood)
Blood lactate and creatinine kinase (CK) levels
Indicator of pleasurable situations
Oxytocin concentration
Physiological indicators of welfare should always be used with
Other types of welfare indicators (ex. behaviour)
