what are the two parts of the adrenal gland
- medulla
- cortex
what is endocrine system
- collection of glands, that secrete hormones, into circulation, to be carried to distant organs
- long term metabolic processes (via chemical messengers (hormones)
- works in tandem with the nervous system, to regulate/adjust physiological activities
what is the role and function of the endocrine system
- function by synthesising chemical messengers
- specialised epithelial secretory cells manufacture specific hormones
- hormones are then released systemically
- transport of hormones to rest of the body conveys specific regulatory information among cells, and organs.
what are the 4 system that hormones can communicate from
- endocrine
- autocrine
- paracrine
juxtacrine
what are hormones
- hormones, only affect cells, that posses the specific receptors, for that hormone
hormones, ultimately, regulate cell function/metabolism/homeostasis via their effects on enzymes
what factors affect, the magnitude, of a hormone response
- the number of target receptors
- concentration of the hormone
- affinity of receptor for hormone
- influence of other hormones
what are steroid hormones and their properties
what are non - steroid hormones (peptides) and their properties
describe the pituitary gland
- master regulator
- 2 lobes - anterior and posterior lobes
- posterior lobe, store hormones made by hypothalamic neurons and releases into circulation
- Anterior lobe receives hypothalamic hormones via vessels, which stimulates further hormone release by pituitary
what are the two hormones, that are secreted from the posterior lobe
- antidiuretic hormone (ADH) - prevents kidney water excretion
- oxytocin - responsible, for uterus contraction and milk ejection during lactation
describe the role of the pineal gland
- produces melatonin (derivative of serotonin)
- released in rhythmic fashion
- suppressed by light (thus most active at night time)
- modulates sleep patterns in circadian rhythms.
describe the thyroid gland
- butterfly shaped and located in the neck (inferior to the larynx)
Secretes 2 hormones:- Thyoxine (T4 – major hormone produced; 90%)
- Triiodthyronine (T3 : most T4 converted to T3 in target tissues, which has greatest metabolic effect)
- Involved in tissue development and macronutrient metabolism -> (increases heat production and energy consumption
what is the parathyroid gland
- four glands, located, at the posterior of the thyroid gland
- produce, parathyroid hormone (PTH) - calcium absorption)
describe the adrenal glands
- pyramid shaped, and sit on top of the kidneys
- each gland, consists of 2 portions -> outer adrenal cortex and inner adrenal medulla
describe endocrine dysfunction
Abnormal hormone receptor function/levels
- Decreased number of receptors
- Impaired receptor function leading, to hormone insensitivity
- Presence of antibodies against specific receptors, reducing available binding sites.
Altered intracellular response to hormone receptor complex
- Inadequate second messenger synthesis
- Faulty response of target cell to hormone - receptor complex
- Faulty response of target cell to second messenger
Hyper or hyposecretion of hormones by glands
High hormone production
- Failure of negative feedback
- Altered hormone degradation or inactivation by circulating antibodies
- Ectopic hormone production by non endocrine tissues
Low hormone production
- Dysfunctional endocrine gland
- Malfunctioning secretory cells/ insufficient hormone precursors/ inability to convert precursors to active hormone
describe the clinical manifestations of type 1 diabetes
- glucose appearing in urine as renal glucose threshold, is exceeded, causing osmotic diuresis and symptoms of polyuria and thirst
- weight lost - loss CHO as a fuel source, causes excess use of fat energy
- hypoglycaemia
describe ketoacidosis with regards to type 1 diabetes
- lack of CHO - fat used as energy source
- can worsen dehydration via kidneys trying to remove ketones through urine
- pH falls, and acetone exhaled gives breath and sweet odour
describe the fight or flight response
- epinephrine, accounts, for 75-85% of adrenal output, the rest is norepinephrine
- both released into the bloodstream, acting as hormones
which receptor, determines which hormone is released in the flight or fight response
