ANBI 411.3 Lecture Notes - Lecture 4: Umwelt, Peripheral Nervous System, Melatonin
20 Jun 2018
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Lecture 4: Physiology and Behaviour
Tinbergen`s 4 questions:
1. Causation- how does it happen?
2. Function- why does it happen?
a. Function in individual
b. Adaptive function in species
3. Ontogeny- how does it develop?
4. Phylogeny- how/when did it evolve?
Physiology is related to the “how” questions:
- Immediate or proximate causation
- Development (ontogeny)
Behavior involves a coordinated muscular response
Sensory system> nervous system> behavior
- Simple reflexes = peripheral nervous system
- Complex behavior = central nervous system
- Often modulated by hormones: facilitate or inhibit a specific behavior (does not directly
cause effect)
Physiological response in body can result in behavioral effect
Behavior can result in physiological response
Example: high testosterone leads to increased aggression BUT losing a fight decreases
testosterone production (temporarily)
Physiological systems
Neural and sensory systems
- Electrical
- Fast acting
- Central and peripheral
Hormonal and phermonal systems
- Chemical
- Loner acting (example: seasonal)
- Target specific tissues
The two systems are interconnected:
- Neural – > hormonal via hypothalamus
- Pheromonal – > neural via sensory systems
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Neural Connections
- Nervous system affects hormonal system via the hypothalamus
- The primary function of the hypothalamus is to secrete hormones that affect the
pituitary gland and to maintain homeostasis
- The hypothalamus is in the brain, above the pituitary
Neural control of behavior
- Simple reflexes: patellar, blink, swallow
- Complex behavior: courtship, nesting, feeding
- Properties of neural response:
oInitiation
Stimulus
Threshold and action potential
Summation- temporal or spatial
oCoordination
Inhibition
oControl
Latency, refractory period, homeostasis
Initiation
- Neurophysiology
- Electrical activity of neurons
oMoving of ions to reach state where membrane potential is depolarized to
initiate action potential
oResponse to stimulus- neural response must exceed threshold to initiate an
action potential
oIt is an all or nothing response
Summation: multiple inputs combine to initiate a response (inputs to the brain)
-Temporal summation- stimulus is repeated over time
-Spatial summation- repeated at multiple sites
Inhibition
- Is necessary for coordination
-Neural inhibition: opposing muscles are inhibited
-Behavioral inhibition: can only do one thing at a time
oAlternate bouts of different behaviors
oExample: feeding and drinking
oHow do we decide? Brain decides, neuroresponses part of decision
Homeostasis: physiology and behavior balance each other to maintain homeostasis
- Energy balance: input and output (growth and maintenance)
Models of homeostasis
- closed loop systems
find more resources at oneclass.com
find more resources at oneclass.com
