The autonomic nervous system Flashcards
What is the ANS designed to do?
To maintain homeostasis by controlling visceral
organs and glandular secretions
Part of the nervous system that is generally ___ under conscious control
Not
What does the ANS innervates?
Smooth muscle, cardiac muscle, glandular muscle and the visceral organs
Innervation of these organs is both……
……central (e.g. hypothalamus) as well as from ‘simpler’ reflex pathways
What is the ANS main function?
Maintain the body’s internal environment (homeostasis)
→ Regulate functions such as blood pressure, heart rate, intestinal motility etc
Name 2 examples of ANS control (5)
- Sweat glands (exocrine gland): sweating as response to hot environment
- Pancreas (endocrine gland): Increase secretion of insulin, a hormone that puts
excess nutrients in storage following a meal - Respiratory muscles: augmented breathing in response to exercise
- Heart (cardiac muscle): increased pumping of blood when BP falls too low
- Stomach (smooth muscle): delayed emptying of stomach till intestine is ready to
process food
Most ANS NS function is what?
Involuntary with exceptions
Reticular formation is what?
The pathway through which hypothalamus exerts its influence
The release of hormones
from the hypophysis is a way for…
the hypothalamus to exercises autonomic control
Reticular efferents reach what?
The sympathetic and parasympathetic nuclei of the brain stem and spinal cord
What influence the cortex has on the ANS?
e.g. sight of food triggers secretion of saliva
or anticipation of a walk increases the heart rate of a dog
The ANS is divided into what two parts?
The parasympathetic and the sympathetic systems
Describe the sympathetic system and its effects
Capable of massive coordinated output,
able to mobilise key resources
* Arousal ↑
* Pupil size ↑
* Heart rate ↑
* Blood pressure ↑
* Glucose ↑
Effects are long lasting by virtue of
secretion of norepinephrine into blood
What is the role of the sympathetic system in non-stressful situations?
Under non stressful conditions
sympathetic system plays a part in
homeostasis, e.g. thermoregulation,
pupil dilation in low light
Describe the parasympathetic system and its effects
Associated with restorative functions
* Gastric secretions ↑
* Intestinal motility ↑
* Pyloric sphincter relaxation
- ‘rest and digest’ system
- Greater degree of independent control of
its targets - No innervation of the body wall or
extremities
