The Endocrine System

Question 1

Homeostasis

Answer 1

The ability to maintain a constant internal environment in response to environmental and physiological changes

Control systems detect and respond to these changes in the internal environment.

The Endocrine system is one of the control systems that helps maintain Homeostasis.

Question 2

Endocrine

Answer 2

Releases hormones
Ductless glands
Directly released into the bloodstream
Endo- (In)

Question 3

Exocrine

Answer 3

Secretes substances
Released through ducts
Secreted outside of the body or into the GI tract
Exo- (Out)

Question 4

Hormones

Answer 4

Chemical signals released into the bloodstream
Transported to target tissues
Coordinate the activity of the cell
Effective in small amounts

Question 5

Hormone Classification

Answer 5

Water Soluble – Peptides/Amines

Lipid Soluble – Steroids

Question 6

These are the main organs of the Endocrine System;

Answer 6

Hypothalamus
Pituitary Gland
Pineal Gland
Thyroid Gland
Parathyroid Glands
Thymus
Adrenal Glands
Pancreas
Gonads – Ovaries/Testes

Question 7

Hypothalamus

Answer 7

Situated in the brain
A collecting centre for information
Regulation of hormone secretion
Forms part of the hypothalamic-pituitary axis

Question 8

Pituitary Gland

Also known as the hypophysis

Answer 8

Pea-sized structure made up of 2 lobes
Situated in a bony hollow beneath the base of the brain – Sella Turcica/Pituitary Fossa

This is an important feature for radiographers – we check there is no rotation of this on lateral skull and lateral cervical spine x-rays. This can be enlarged or eroded which may indicate certain pathologies.

Question 9

Pineal Gland

Answer 9

Tiny structure located at the base of the brain
Produces the hormone melatonin which maintains sleep/wake cycle, i.e. body clock
Often seen calcified on CT Brain scans in the midline

Question 10

Thyroid & Parathyroids

Answer 10

Situated in the neck, near the trachea
Four parathyroid glands embedded in the rear surface of the Thyroid
Thyroid gland controls many body functions, including heart rate, temperature and metabolism.
Both play a role in the metabolism of calcium in the body and growth.

Question 11

Thymus

Answer 11

Situated in superior mediastinum
Secretes hormones responsible for maturation of lymphocytes
Acts independently to hypothalamic-pituitary axis

Question 12

Pancreas

Answer 12

Situated in the epigastric region of the abdomen
Exocrine (Digestive) and Endocrine Gland
Cells in the pancreas regulate the blood sugar that provides the body with energy
Insulin & glucagon

Question 13

Adrenals

Answer 13

Situated just above the kidneys
Consist of two parts – the medulla and the cortex
Produce hormones which help us cope with stress
Also produce hormones to assist kidney filtration
Cortisol, Aldosterone and Ephinephrene

In addition, the kidneys also work with the Endocrine System
Control blood fluid and mineral levels within the body by processing the blood to remove waste products and any excess fluid

Question 14

Ovaries

Answer 14

Situated either side of the uterus
Contain egg cells necessary for reproduction
Produce hormones Oestrogen and Progesterone, necessary for menstruation and producing female sexual characteristics

Question 15

Testes

Answer 15

Situated in a pouch that hangs outside the male body

Produce hormone testosterone necessary for the production of sperm and male sexual characteristics

Question 16

Negative Feedback

Answer 16

The feedback loop will stop

When the level of Thyroid Hormones in the blood reach an upper threshold, the cells in the hypothalamus detect this and stop secreting TRH.
As TRH levels fall, TSH levels also fall, and the level of Thyroid Hormones also falls.
Once this level falls below a lower threshold figure, the negative feedback ends, and the loop starts again.

Question 17

Positive feedback

Answer 17

It keeps going
Childbirth
Pressure receptors in the 
cervix send messages to 
the hypothalamus when 
stimulated.
Causes Oxytocin to be released 
to the uterus where it will cause 
the uterine muscles to contract 
with increasing strength and 
frequency.

Question 18

Conditions are not included look at powerpoint

Answer 18

Conditions are not included look at powerpoint

Question 19

Bone age examination is what

Answer 19

Where you xray the left hand (or non dominate hand) to check the age of the patient or to see if they have growth hormone problems