Lesson 7: Control of Behaviour Flashcards
What is the regulation of homeostasis? Give 2 examples
The maintenance of stable equilibrium in body
E.x. Balancing hunger/satiety, body temperature
What integrates responses from the body?
Hypothalamus
After integrating response from the body, what does the hypothalamus instruct?
Pituitary
What is secreted to help the body respond to internal or external changes?
Hormones
Hormones are released to help the body do what?
Respond to internal or external changes
Where does the hypothalamus receive inputs?
Brainstem
Where does the hypothalamus send outputs?
Projections to limbic areas, brainstem, and autonomic areas
The hypothalamus receiving inputs from brainstem allows for response to ____________ ________ processes and contributes to ___________ role
Behaviourally relevant
Homeostatic
Why does the projections of the hypothalamus goes to limbic areas and such?
To induce behaviour change to resolve physiological needs
The hypothalamus maintains homeostasis by: (2)
Signalling through synaptic projections
Directing hormone release
How does the hypothalamus influence hormone release? (2)
Production of hormones
Axonal projections to the posterior pituitary
Large ______________ cells of the hypothalamus (_____________ cells) extend down the stalk of the pituitary into the _________ lobe
Neurosecretory
Magnocellular
Posterior
Hypothalamic Control of the Posterior Pituitary:
Magnocellular cells secrete ________ and ___________ into posterior pituitary
Oxytocin
Vasopressin (Antidiuretic hormone, ADH)
Where does the magnocellular cells secrete oxytocin and vasopressin into?
Posterior pituitary
What is Vasopressin also known as?
ADH (Anti-Diuretic Hormone)
Where is oxytocin and vasopressin released from the pituitary?
Released directly from pituitary into bloodstream
Low blood pressure or volume causes kidneys to secrete _____ into bloodstream
Renin
What secretes renin?
Kidneys
What does renin do?
Upregulates synthesis of angiotensin II
What does Angiotensin II do?
Excites neurons of subfornical organ
What is the subfornical organ of the brain?
Brain region not protected by BBB so it can detect hormones
What happens when renin/angiotensin II is secreted?
Stimulates hypothalamic response (release of ADH from posterior pituitary, causing feeling of thirst)
Define:
Parvocellular neurosecretory cells
Small neurosecretory cells of the hypothalamus that secrete hormones into blood stream
- Where do the released hormones by the parvocellular neurosecretory cells go?
- What do they do?
- Anterior lobe
- Regulate production of pituitary hormone
How does the hypothalamus control the anterior pituitary?
Small neurosecretory cells of the hypothalamus release hormones to control anterior pituitary
What is stress regulated by?
The HPA axis
Define:
HPA axis
The hypothalamic pituitary adrenal axis
* Regulates physiological responses to stress
Describe:
The HPA Axis
- Hypothalamus secretes corticotropin-releasing hormone (CRH)
- Triggers release of adrenocorticotropic hormone (ACTH) from pituitary
- This stimulates release of cortisol from adrenal cortex
In the HPA Axis:
What does cortisol do to CRH production?
Inhibits hypothalamic CRH production
List:
Hormones of the Anterior Pituitary
- Follicle-Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
- Thyroid-Stimulating Hormone (TSH)
- Adenocorticotropic Hormone (ACTH)
- Growth Hormone
- Prolactin
Describe the target organ and action of:
FSH
- Gonads
- Ovulation, spermatogenesis
Describe the target organ and action of:
LH
- Gonads
- Ovarian and sperm maturation
Describe the target organ and action of:
TSH
- Thyroid
- Thyracin secretion, increases metabolic rate
Describe the target organ and action of:
ACTH
- Adrenal cortex
- Cortisol secretion (mobilizes energy, inhibits immune system etc.)
Describe the target organ and action of:
Growth Hormone
- All Cells
- Stimulation of protein synthesis
Describe the target organ and action of:
Prolactin
- Mammary glands
- Growth and milk secretion
- What regulates homeostasis?
- How?
- Hypothalamus
- By controlling the posterior and anterior pituitary gland
What do magnosecretary cells secrete?
Oxytocin and Vasopressin
What cells secrete oxytocin and vasopressin?
Magnosecretory cells of the hypothalamus
- Where and what do magnosecretory cells secrete?
- Where do these hormones go?
- Secrete into posterior pituitary, oxytocin and vasopressin
- Posterior pituitary releases these into blood stream
Where do parvosecretory cells secrete to?
From hypothalamus, secrete hormones that travel to anterior pituitary
What do the hormones released by parvosecretory cells do?
They influence release of hormones from anterior pituitary
What does the autonomic nervous system comprise of?
- Sympathetic nervous system
- Parasympathetic nervous system
In general,
What is the function of the autonomic nervous system? (3)
- Regulates alertness state to promote homeostasis
- Regulates heart rate, pupil diameter, breathing rate, and more
- Hypothalamus acts as a control center for regulation
List:
Functions of the sympathetic nervous system
- Stimulates “fight or flight” response
- Prepares the body for action by increasing readiness to make dramatic physical action and suppressing long-term activities (eg. digestion)
List:
Functions of the parasympathetic nervous system
- Stimulates “rest and digest” response
- Activated in safe states, meaning that more energy can be diverted towards digestion and slower homeostatic processes
Structure of the SNS:
What is the plural of ganglion?
Ganglia
Structure of the SNS:
How are the cell bodies of the ANS nervous system organized?
Cell bodies of ANS neurons innervating specific targets organized into ganglia
Structure of the SNS:
Where is the SNS ganglia located?
Near the spinal cord
Structure of the SNS:
Where are key cell populations of SNS located?
Localized in theoracic/lumbar(middle) spinal cord
SNS neurotransmission properties:
- Where do preganglionic neurons project?
- What type are they?
- Project from CNS to ganglia
- Cholinergic (release acetylcholine)
SNS neurotransmission properties:
- Where do postganglionic neurons project?
- What type are they?
- Project from ganglia to their target organ
- Adrenergic (release norepinephrine)
Structure of the PNS:
How are ganglia positioned compared to SNS?
Ganglia much closer to target organ than in SNS
Structure of the PNS:
How are parasympathetic projections regulated?
By nerves projecting directly from the brain (e.g. Vagus nerve)
PNS neurotransmission properties:
Are preganglionic neurons cholinergic or adrenergic?
Cholinergic
Define:
Cholinergic
Release acetylcholine
Define:
Adrenergic
Release norepinephrine
PNS neurotransmission properties:
Are postganglionic neurons adrenergic?
No, they are also cholinergic
SNS vs. PNS:
Function
- SNS: “Fight and Flight”
- PNS: “Rest and Digest”
SNS vs. PNS:
Origin of preganglionic neurons
- SNS: Vesceral efferent column of the spinal cord
- PNS: Arises from cranial nerves/sacral spinal cord
SNS vs. PNS:
Origin of postganglionic neurons
- SNS: Thoracic/lumbar from spinal cord
- PNS: Arises from cranial region of the spinal cord
SNS vs. PNS:
Preganglionic neurotransmitters
- SNS: Cholinergic
- PNS: Cholinergic
SNS vs. PNS:
Postganglionic neurotransmitters
- SNS: Adrenergic
- PNS: Cholinergic
SNS vs. PNS:
Target
- SNS: Smooth muscles, cardiac muscles and endocrine glands
- PNS: Smooth muscles, cardiac muscles and exocrine glands
What are the pathways of the Autonomic Nervous System (ANS)?
- Sympathetic Nervous System (SNS)
- Parasympathetic Nervous System (PNS)
SNS vs. PNS:
Length of neurons and ganglion placement
- SNS: Longer postganglionic neurons, ganglion is further from target
- PNS: Longer preganglionic neurons, ganglion is closer to target
What is body temperature regulated by?
The neurons of the medial preoptic area of the hypothalamus
In terms of temperature sensitivity:
Neurons are…
- Cold sensitive
- Warm sensitive
- Temperature insensitive
State:
Temperature range of warm sensitive neurons
Sensitive to temperatures greater than 37°C
State:
Temperature range of cold sensitive neurons
Sensitive to temperatures less than 37°C
— levels regulate body temperature
TSH (Thyroid-Stimulating Hormone)
What activates hypothalamic neurons?
A decrease in temperature
* Activates hypothalamic neurons, which regulate TSH levels
What is the function of TSH in temperature regulation?
Induces production of metabolic regulators T3 and T4
State:
3 Systemic Effects of T3/T4
- Raise metabolic rate (more energy use leads to higher body temperature)
- Visceromotor response (e.g. constriction of blood vessels)
- Increased glucose uptake by muscle cells to permit shivering
What is hunger/feeding regulated by?
