Human Physio Homeostasis and Endocrine System

stimulus -> sensor/receptor -> afferent pathway -> integrating pathway -> efferent pathway -> target/effector -> response

Components of control pathway

Negative feedback

The response counteracts with the stimulus, shutting off the response loop

Negative feedback regulation

Increase or decrease in the variable being regulated brings a response that changes variable in the opposite direction to that of the original change.

Positive feedback

The response reinforces the stimulus, sending the variable further from the set point

Positive feedback regulation

The response of system goes in the same direction as changes that sets in motion

Peptide/protein hormones

_______ composed of linked amino acids
_______ are lipophobic, so only able to enter target cells through receptors

peptide/protein hormones' mechanism of action

membrane receptors, signal transduction system

Steroid hormones

All ________ are derived from cholesterol
_______ controls gene expression
_______ synthesised in smooth ER and on demand and released immediately

Lipophilic

Steroid hormones are _______ as they are derived from cholesterol

diffuse

Lipid-soluble hormones _____ across plasma membrane

receptor-hormone complex

Hormone binds with receptor in cytoplasm, forming ______

nucleus, gene transcription

Receptor-hormone complex enters the ____, triggering _____

proteins

Transcribed mRNA is translated into _______ that alter cell activity

Amino-acid derived hormones

________ are modifications of single amino acids and some are lipophilic
________ are created from either tyrosine or tryptophan

Thyroid hormones

______ affects gene transcription

Catecholamine or Peptide/protein hormones

______ binds to membrane receptors

Hormones

________ enter bloodstream and distribute to target cells.

GRRB (growth, regulation, reproduction & behaviour)

Functions of endocrine system

anterior pituitary

The _________ either stimulate or inhibit the release of hormones.

anterior pituitary

In response to releasing the hormones, the ________ secretes hormones into the secondary capillary plexus.

Hypothalamus

_____ is the master regulatory organ
_____ integrates nervous and endocrine system

control secretion

Hypothalamus secretes regulatory hormones to ____________ from anterior pituitary

endocrine

Hypothalamus acts as ____ gland

neural

Hypothalamus has autonomic centers for _____ control of adrenal medulla

Hypothalamic neurons

________ synthesise hormones.

Humoral

in response to levels of ions or nutrients in the blood

Neural

stimulation by nerve fibres (very fast)

Hormonal

stimulation received from other hormones

Hyposecretion

too little hormone is secreted

Hypersecretion

too much hormone is secreted