Hormonal communication
The hormonal system is also called the endocrine system , which is
made up of glands and hormones :
Endocrine glands are groups of cells that are specialized to secrete
hormones.
Hormones are chemical messengers. Many hormones are proteins or
peptides eg: insulin. Some hormones are steroids e.g.
progesterone.
Hormones are secreted when an endocrine gland is stimulated :
Glands can be stimulated by a change in concentration of a
specific substance
They can be stimulated by electrical impulses.
, Hormones diffuse directly into the blood, then they are taken around
the body by the circulatory system.
They diffuse out of blood all over the body, but each hormone will
only bind to specific receptors for the hormones, found on the
membrane of some cells called target cells. Tissue that contains target
cells is called target tissues.
The hormones trigger a response in the target cells (the effectors).
Endocrine glands are different to exocrine glands. Endocrine release their
hormones directly into the blood. Exocrine glands secrete their molecules
into ducts which takes the molecules to where they are used. The liver and
the pancreas are both endocrine and exocrine.
Exocrine glands = example sweat glands
Endocrine glands = pancreas ( endocrine- into blood ) = controls blood
glucose , produce digestive enzymes (exocrine – into small intestine).
, Steroid hormones ( cholesterol based) Non-steroid (peptide) hormones (protein based)
· Lipid soluble so can pass through the · Hydrophilic so cannot pass through the plasma membrane e.g.
plasma membrane and into cell. ADH
· Can form transcription factors which can · Formed from amino acids or polypeptides
inhibit or facilitate transcription of specific · Bind to specific receptors (glycoproteins) on the plasma
genes. membrane of the target cell and triggers a sequence of reactions
controlled by secondary messengers .
· A secondary messenger is a molecule that relays signals received
at the plasma membrane to molecules inside the cell e.g. Cyclic
AMP (cAMP)
For respiration for energy.
The hormonal system is also called the endocrine system , which is
made up of glands and hormones :
Endocrine glands are groups of cells that are specialized to secrete
hormones.
Hormones are chemical messengers. Many hormones are proteins or
peptides eg: insulin. Some hormones are steroids e.g.
progesterone.
Hormones are secreted when an endocrine gland is stimulated :
Glands can be stimulated by a change in concentration of a
specific substance
They can be stimulated by electrical impulses.
, Hormones diffuse directly into the blood, then they are taken around
the body by the circulatory system.
They diffuse out of blood all over the body, but each hormone will
only bind to specific receptors for the hormones, found on the
membrane of some cells called target cells. Tissue that contains target
cells is called target tissues.
The hormones trigger a response in the target cells (the effectors).
Endocrine glands are different to exocrine glands. Endocrine release their
hormones directly into the blood. Exocrine glands secrete their molecules
into ducts which takes the molecules to where they are used. The liver and
the pancreas are both endocrine and exocrine.
Exocrine glands = example sweat glands
Endocrine glands = pancreas ( endocrine- into blood ) = controls blood
glucose , produce digestive enzymes (exocrine – into small intestine).
, Steroid hormones ( cholesterol based) Non-steroid (peptide) hormones (protein based)
· Lipid soluble so can pass through the · Hydrophilic so cannot pass through the plasma membrane e.g.
plasma membrane and into cell. ADH
· Can form transcription factors which can · Formed from amino acids or polypeptides
inhibit or facilitate transcription of specific · Bind to specific receptors (glycoproteins) on the plasma
genes. membrane of the target cell and triggers a sequence of reactions
controlled by secondary messengers .
· A secondary messenger is a molecule that relays signals received
at the plasma membrane to molecules inside the cell e.g. Cyclic
AMP (cAMP)
For respiration for energy.
