Topics in BiologyBiology Scheme of Work, SS1, First Term Biology Scheme of Work, SS1, 2nd Term Biology Scheme of Work, SS1, 3rd Term Seminal Vesicles and Bulbourethral Glands as Male Accessory Sex Organs Male Reproductive System: Scrotum and its contents Brain: Introduction to the Human Brain Forebrain: Lobes of the Cerebrum and their Functions Cerebellum: Parts and Functions of the Cerebellum Midbrain: Division and Functions of the Midbrain Negative Feedback Mechanism in Homeostasis Arterial Disorders: Characteristics and Causes of Arterial Disorders Types of Desert and their Characteristics Characteristics of Tropical Rainforest Swamp Forest: What are Swamp Forests? Characteristics of Swamp Forests Savanna: Savanna and Grassland explained Savanna - Types of Savanna Tropical Savanna and Temperate Savanna with their Characteristics Introduction to Biomes: What is a Biome? Importance of Swamp Forests
Academic Questions in Biology
Which of the following is a category of long bones?
The end product of photosynthesis is _____.
The above diagram illustrates a _____.
The living cells that makes up cartilages are called _____.
Which of the following statement is incorrect with regards to chitin?
Which of the following is NOT a function of the human skeleton?
Organisms that manufacture their own food through the help of sunlight or chemicals are best referred to as _____.
Organisms that begins a food chain and also manufacture their food through photosynthesis are best referred to as _____.
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The scrotum (or scrotal sac) is visible on every male as it lies underneath the penis, hanging from the midline of the pelvic region just between both thighs. It is a part of the external male genitalia.
Inside the scrotal sac are two oval shaped testicles or testes (singular -> testis) which are responsible for the formation and storage of sperm.
The process of sperm formation is referred to as spermatogenesis.
Note: The scrotum is divided in its midline by the perineal raphe.
The perineal raphe is present in males and females. It is visible as a midline seen on some parts of the human body.
The image below shows the scrotum, perineal raphe and the internal contents of the scrotum:
The scrotum is located outside the body and that's ideal. This is so because the testis requires a temperature slightly lower than that of the normal body temperature (36.5oC) to properly form sperms. In fact, this is the very reason why the testes descends from the abdominal cavity (inside the body) to the scrotum (outside the body). This external position of scrotum therefore presents a temperature reduced by -1oC to -7oC.
Sperm is produced by the testes residing within the scrotum; and the surrounding temperature is extremely important for it's formation. To this end, the cremaster muscles of the scrotum have got a great ability to contract and relax, thus aiding the testes to either move closer to the body or away from it; depending on the surrounding temperature.
Note: Sperm and Semen is not the same thing.
Sperm is the male sex cell (and it happens to be the smallest cell in the human body). It is exactly what meets and fertilizes the female sex cell (ova or egg which is the biggest cell in the human body).
Millions of sperm cells are always introduced into the female’s vagina during ejaculation; and they swim upwards (towards the oviduct or fallopian tube in the female) with the aid of their tail-like structure called flagella.
Semen refers to the thick whitish (or slightly yellowish) and viscous fluid released from the penis. This process of releasing semen in males is termed ejaculation.
Ejaculation is always accompanied with a characteristic feeling of pleasure. In fact, this pleasurable feeling is the climax of sexual excitement and it's referred to as orgasm.
Note: The sperm cells are actually present within the semen. This is shown in the image below:
In summary, we can say that the semen contains the following:
Note: Apart from the sperm cells, many of these components (of the semen) are secretions from the male accessory reproductive glands.
Apart from the testicles, also found in the scrotum are:
The epididymis is a comma-shaped highly convoluted or coiled tubule of about 6 to 7 meters in length. It can be seen on the superior, lateral and posterior sides of each testis.
The epididymis is divided into 3 parts. These are:
The epididymis generally serves the following functions:
The vas deferens is found both within and above the scrotum. It is a long muscular tube that begins at the tail of the epididymis and runs through into the ejaculatory ducts. (Please see the diagram of the spermatic cord below).
Note: The contraction of the smooth muscles of the vas deferens helps in propelling the sperm during ejaculation. Also, as sperm move from the vas deferens into the urethra, secretions are added to it from the male accessory sex glands.
The vas deferens is also called the ductus deferens.
This is a cord-like structure formed by the vas deferens. It plays an important role in the supply of blood to the testes and vas deferens. It also aids the movement of sperm out of the epididymis into the ejaculatory ducts.
Below is an image showing the contents of the spermatic cord:
Note:The spermatic cord contains a large amount of blood vessels and nerves. The blood vessels supply blood to the testes, epididymis and cremaster muscles while its nerves assist in transferring information back and forth from the scrotum, testicles and the cremaster muscles.
They help in the movement of the testicles towards and away from the body in order to achieve an ideal temperature for sperm formation.
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Amazing facts in Biology
Male Seahorses actually give birth to their young ones, NOT the female
All babies are born with blue eyes
Research made at the University of Vienna suggested that yawning may play an essential role in cooling the brains
All voluntary and concious activity of right handed people are controlled from the left part or hemisphere of the brain
A snail can actually sleep for 3 years 😁
An adult human being is composed of about 60% water. In fact, a newly born baby is composed of about 80% of water. This will drop to 65% after a year and finally to about 60% as the child ages
Without saliva, food can never be enjoyed. Food becomes tasteless since saliva is needed to dissolve the chemicals present in food onto the tongue’s taste buds.
Saliva also contains an enzyme called salivary amylase or "ptyalin" which helps to digest cooked starch to maltose. Maltose is a double sugar or disaccharide. Please read on sugars here
NOTABLE POINTS IN Biology
For a thing to be considered Living, it must possess all the Basic Characteristics of Life. These include:
Irritability or Sensitivity
During strenuous exercises like sprinting or 🏃 running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.
This is the concept of anaerobic respiration
A food Chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.
Note: Habitat is a place where an organism live. It is of three types:
The term Biology originated from two Greek words. They are:
Biology can therefore be defined is the study of life
Anything that has life is generally considered as a living organism (or organism) 🌱🐐🐓. All living organisms must be able to carry the following activities:
The above listed points are often regarded as the basic characteristics of life. You can memorize them using the acronym (MR. NIGER DAC).
The gas used in the manufacture of food by plants is Carbon dioxide or Carbon(IV)oxide or CO2.
Plants manufacture food through a process called photosynthesis. Please read on photosynthesis here
Note: Plants are the only orgnisms that take away CO2 from the atmosphere