Day 6 Endocrine systems

Endocrine systems

carry info to and from control centers

2 main endocrine systems in animals

neural signals (action potentials)

hormones (blood-borne messengers)

Nervous messages

faster

more specifically targeted

shorter duration

Hormonal messages

slower

more broadly targeted

longer lasting

How are chemical signals classified

distance of travel and their source

How are neurotransmitters classified

by distance of travel

How are hormones classified

by their source

What most hormones activate

membrane bound receptors

What cells hormones reach

reach almost every cell, but not all cells respond

What type of hormone activates membrane bound receptors

hydrophilic

Which type of hormone activates intra-cellular receptors

lipophilic

Lipophilic hormones

pass through the membrane and activate intracellular receptors

change DNA transcription rates

receptors ___ or ____ biochemical pathways

activate or deactivate

Most vertebrate endocrine glands

1. hypothalamus/posterior pituitary

2. anterior pituitary

3. thyroid gland

4. parathyroid gland

5. adrenal gland

6. pancreas

7. gonads

hormones and other tissue

many other organs secrete hormones in addition to their primary functions

Examples of other organs secreting hormones along with their primary function

1. GI tract secretes hormones that regulate GI function

2. Fat cells release hormones that affect energy homeostasis

3. Heart releases a hormone that affects blood pressure

4. Kidney and Liver release hormones of various functions

endocrine glands

secrete hormones into the blood

What glands aren’t endocrine

exocrine glands

Exocrine glands

secrete/release a liquid/fluid

Examples of exocrine glands

1. salivary glands

2. sweat glands

3. mammary glands

Is both endocrine and exocrine

pancreas

Anterior pituitary gland

produces hormones that control many systems, including the release of other hormones

Produces hormones that control many systems, including the release of other hormones

anterior pituitary gland

controls the anterior pituitary gland

hormones released by the hypothalamus (neurohormones)

What the hypothalamic - anterior pituitary system controls

1. gonadal and reproductive function

2. aspects of metabolism, energy use and growth

Extension of the hypothalamus

posterior pituitary gland

Hormones released by the posterior pituitary

1. ADH

2. Oxytocin

ADH

controls water reabsorption in collecting ducts

Oxytocin

promotes contractions during labor and milk “letdown”

Releases hormones for response to danger

anterior pituitary gland

Danger or stress requires the need for

1. acute responses to support immediate, intense activity (danger)

2. longer term, sustained increases in activity and alertness (stress)

Acute responses to support immediate, intense activity (danger)

“fight-or-flight” response

What the “fight-or-flight” response is driven by

by the hormone epinephrine (adrenaline)

Longer term, sustained increases in activity and alertness (stress)

also, known as stress response

What the stress response is driven by

by the hormone cortisol

Fight-or-flight response pathway

Stress response pathway

What thyroid hormones help control

1. metabolic rate

2. CNS development and activity

3. protein synthesis

4. growth

What thyroid hormones trigger in amphibians

metamorphosis

Experiment one to test if thyroid controls metamorphosis 

Experiment two to test if the thyroid controls metamorphosis

Process/steps of the thyroid in mammals

If thyroid hormones are too high

it inhibits TRH and RSH

If thyroid hormones are too low

increases TRH and TSH secretion

How are hormone levels determined

by classic negative feedback loops

How hormone levels are determined

hormones control effectors that influence a variable; the value of that variable helps determine the amount of hormone released

Long-loop feedback

levels of “downstream” hormones have negative effects on levels of “upstream” controlling hormones

Another name for long-loop feedback

feedback inhibition

How can hormone pathways fail

1. hypersecretion

2. hyposecretion

3. hyporesponsive

Hypersecretion

too much hormone secreted

Example of hypersecretion and symptoms

hyperthyroidism

symptoms are overheating, weight loss, and restleness

Hyposecretion

too little hormone released

Example of hyposecretion

Type 1 diabetes - lack of insulin causes failure to metabolize and store glucose from meals

Hyporesponsive

too few hormone receptors (receptors don’t respond well to hormones)

Example of hyporesponsive

Type 2 diabetes (early stage) - lack of insulin receptors leads to milder type 1 effects

In multi-hormone pathways, impact of problems with upstream hormones

problems with upstream hormones will cause problems with downstream hormones

Leptin helps control

the body’s energy stores

What produces leptin

fat cells - more fat stores leads to higher leptin levels

What leptin influences/impacts

influences appetite and metabolic rate

Leptin in vertebrates helps maintain

maintain normal fat reserves

Pathay of leptin

Leptin levels in overweight people

overweight people show high levels of leptin

Overweight people are ____

are hyporesponsive

Growth and metamorphosis in insects involve what hormones

1. Juvenile hormone (JH)

2. Ecdysone (from “ecdysis” or molting)

High JH + ecdysone surge =

larval growth (via molting)

Low JH + ecdysone surge =

pupation and metamorphosis

Larval stage

an immature stage that looks very different from the adult

for butterflies the larval stage is the caterpillar

for frogs the larval stage is the tadpole

Pupation

process in which a larva transforms into a pupa, the stage between the larva and the adult

example is when a caterpillar is in its cocoon