Hormones and Behaviour Flashcards
What are hormones?
Chemical substances, formed in a specialised gland or group of cells, released into the blood that affect target cells in another organ.
What parts of the body do hormones reach?
All parts of the body but only target cells that have receptors for that hormone.
What are neurotransmitters?
substances released by neurons and are received by adjacent neurons & alter their membrane potential.
What are pheromones?
Substances released by an individual as scent signals for others.
What does the endocrine system do?
Refers to a set of glands that produce chemical messengers called hormones.
Where do the hormones from the endocrine system go to?
What do they help with?
The brain and other tissues.
Coordinate and integrate complex physiological functions.
Modes of hormone action: what are activational effects?
When does this occur?
Short-term, reversible effects that occur in the fully developed organism e.g., alteration of transmission in neural networks that respond to certain aspects of the environment.
Can occur at any time in lift.
Modes of hormone action: What are organisational effects?
When does this occur?
Long term, irreversible effects on tissue differentiation and development e.g., brain, overt, that can either directly (brain) or indirectly (ovary) influence behaviour.
Occur mostly at a critical stage of development (before birth in humans)
What are the 2 major hormones that the endocrine glands produce?
- Protein hormones
2. Steroid hormones
What is a protein hormone?.
These comprise of amino acids. They exert their effect by binding to the membrane receptor of the target cell.
What is a steroid hormone?
These are derived from cholesterol from the diet and exert their effects in 2 ways.
What 2 ways do steroid hormones exert their effects?
- They bind directly to membrane receptors.
- As they are fat soluble they pass through cell membranes where they attach to receptors in the cytoplasm. Here they determine gene expression.
What are the 3 steps of protein hormones in action?
- Binding with receptors
- Beginning a transduction pathway.
- The transaction pathway ends with transcription factors being activated in the nucleus, and protein synthesis beginning.
What are the different types of protein hormones?
Protein hormones that are only several amino acids long are called peptide hormones.
Larger protein hormones are Called polypeptide hormones.
Insulin: Made in the pancreas
Glucagons: made in the pancreas .
Leptin: produced by the fat cells.
What does insulin do?
increases the entry of glucose into the cells, and regulates fat storage.
What do glucagon do?
responsible for increasing the conversion of stored fats to blood glucose
What does leptin do?
Informs the brain how much fat is contained by the body
what happens when leptin levels are high?
appetite is decreased
What happened when leptin levels are low?
appetite is increased ad bodily activity is decreased.
What happened to mice who inherit 2 copies of the defective gene re leptin?
What reduces their food intake?
unable to produce leptin so they overeat.
Leptin injection.
How do steroid hormones exert their effects?
- they bind directly to the membrane receptors.
2. as they are fat soluble, they pass through cell membranes where attach to receptors in the cytoplasm.
What is the process of steroid hormones attaching to receptors in cytoplasm?
- Entering a cell
- binding to a receptor in the cytoplasm
- the hormone-receptor complex enters the nucleus and triggers gene transcription.
- This starts protein synthesis.
What are the different types of steroid hormones: corticoids:
- Glutocorticoids: (principally cortisol), are released by the adrenal glands in response to stress. They increase the breakdown of fats and proteins into glucose to trigger escape or defence.
- Mineralocorticoids (e.g., aldosterone) are also produced by the adrenal glands and reduce salt secretion in the kidneys.
What are the different types of steroid hormones: sex steroids?
Released mainly by the ovaries and testes but also by the adrenal glands.
- Androgens: testosterone is produced in large quantities.
- Estrogens: estradiol is produced in large amounts in females.
- Progesterone: prepares uterus and breasts for pregnancy and regulates the stages of pregnancy.
Are sex steroids specific?
No, both males and females produce androgens and oestrogen’s.
Do individual differences in behaviour and physiology reflect differences in hormone concentration?
No! even though concentration is important, it is just as important, the receptivity of the hormone.
A high hormone concentration will have little effect if it lacks cell receptivity. e.g., androgen insensitivity syndrome.
What 2 structures in the brain control hormone release?
Hypothalamus and Pituitary gland.
Where is the hypothalamus?
Base of the brain and consists of several interconnected nuclei.
Where is the pituitary gland?
Controls several hormone glands. Just above the bridge of the nose. Size of a pea.
What is the hypothalamus’ main function(s)?
To maintain homeostasis i.e., keep the human body in a stable, constant condition.
Why signals does the hypothalamus respond to?
From the internal and external environment including body temp, hunger, feelings of being full up, BO and level of hormones in circulation.
What does the hypothalamus respond to / control?
Repsonds to stress and controls our daily bodily rhythms like the night time secretion of melatonin from the pineal gland and the changes in cortisol (stress hormone) and body temp.
What do the hypothalamic nuclei do?
Synthsise releasing hormones that either stimulate or inhibit the release of hormones form the pituitary gland.
What does the hypothalamus secrete?
Oxytocin and vasopressin
Where does oxytocin and vasopressin from the hypothalamus travel to?
The posterior pituitary gland. This then releases them into the bloodstream in response to certain neural signals.
What are the 2 structures in the pituitary gland that produces hormones?
- Posterior pituitary
2. Anterior pituitary
What does the posterior pituitary do?
Stores and released the hormones created by the hypothalamus,. These hormones are then released directly into the blood stream.
- Anti-diuretic hormone: causes water reabsorption at the kidneys.
- Oxytocin stimulates contraction of the uterus in childbirth and is important for breastfeeding.
What does the anterior pituitary do?
Hormones form the hypothalamus reach the anterior pituitary gland via a network of blood vessels that run down through the pituitary stalk. Hormones produces here are refereed to as ‘tropic; as they stimulate various processes such as; gonads, production and regulation of growth hormone, control of milk production etc.
What feedback system does the hypothalamus have?
Negative feedback system.
What does dimorphic mean?
Humans are dimorphic - exist in 2 forms.
How many pairs of chromosomes are in each cell nucleus?
What are the first 22 pairs called?
What is the 23rd pair called?
23.
Autosomes.
Allosomes.
What do autosomes consist of?
Contain the same genes in same order along their chromosomal arms.
What do allosomes contain?
Sex chromosomes consisting of 2 X chromosomes in women and XY in men.
Which chromo is the sex determining one?
Y chromo
In mammals, what gene does the Y chromo contain?
Gene SRY
Why does the gene SRY trigger?
The development of testis.
When a foetus is developing, what primitive gonads are there intially?
Tesitis and ovary
Cortex - potential to be an ovary
Medulla - potential to be a testis.
If the chromo is XY what does the SRY gene on Y trigger?
What if there is no SRY protein present?
The synthesis of the SRY protein.
Cortex develops into an ovary.
Both sexes begin with 2 sets of reproductive ducts - what are they?
Wolffian system (male) and Mullerian system (female)
What does the Wilffian system contain?
Seminal vesicles, vas deferens.
What does the Mullerian system contain?
Uterus, vagina, Fallopian tubes.
When does the differentiation of ducts happen?
Third prenatal month.
what is the process of the differentiation of ducts?
- Testes produce testosterone and Mullerian-inhibiting substance.
- Wolffian system develops, Mullerian degenerates, testes descend.
- No testes = no testicular hormones.
- Mullerian system develops, Wolffian degenerates.
What happens in the absence of sex hormones at early differential stages?
The mammal becomes a female. Addition of testosterone shifts development towards male.
Estradiol and other oestrogen modify the development of the brain and other internal sexual organs.
What specific areas in the brain do sex hormones bind to in early life?
Receptos in specific areas of the hypothalamus, amygdala and other brain areas.
E.g., the anterior hypothalamus is larger in males than in females and affect the male sexual behaviour.
What do early hormones affect in the brain?
The cerebral cortex, some areas are larger in males while others are larger in females.
According to Halpern, 2004, what do girls do better in than boys?
According to Halari et al., 2005, what do boys do better in than girls?
Reading (on average).
Mental rotation and line orientation tasks (on average).
In adulthood what do sex hormones activate?
How?
Sexual behaviours.
Partly by facilitating activity in the medial prep-tic area (region of the hypothalamus) and anterior hypothalamus.
Hormones prime cells to release dopamine in response to sexual arousal.
Dopamine release evokes effects of addictive drugs.
What does hormones being released around the time of giving brith facilitate?
Maternal behaviour in females.
What hormones do females secrete late in pregnancy?
Estradiol, prolactin and oxytocin.
What is prolactin necessary for?
Milk production.
What is oxytocin associated with?
Maternal behaviour and social attachment.
What does the brain do later in pregnancy?
Increases its sensitivity to estradiol in areas responsible for maternal behaviour, but not for sexual behaviour.
The hormonal changes increase the attention of the mother to the young after birth.
hormones also increase activity in the medial prep-tic area and the anterior hypothalamus.
